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This work aimed to use the biometric measurements of steers in the rearing phase to predict the carcass characteristics of Nellore cattle managed in tropical pastures. Data from 60 young bulls in the rearing phase supplemented and managed on Brachiaria brizantha pastures during the rainy season and dry-rainy transition and slaughtered at 24 months old after 112 days in feedlot. Descriptive statistical analyses and Pearson's correlation coefficients were performed. The goodness of fit of the developed equations was evaluated by the coefficients of determination (R 2 ) and square root mean error (RMSE). The average body weight (BW) in the rearing phase was 295 kg BW corresponding to 72.8 kg BW 0.75 . The average of the loin eye area (LEA), subcutaneous fat thickness (SFT), and rump fat thickness (RFT) measured by ultrasound were 43.5 cm 2 , 3.3 mm, and 3.6 mm, respectively. The correlation between BW and BW 0.75 , and LEA were positively significant. Total weight gain (TWG) and average daily gain (ADG) showed a correlation of 0.4216 and 0.4235 with SFT. To LEA prediction, the best fitting considered BW, TWG, and average daily gain (ADG) variables. Whereas SFT, considered BW, and ADG, and to RFT prediction, the best fitting considered only BW. The internal validation (k = 10) of the equations for predicting observed random error of 98.74% in LEA equation, 71.35% in SFT equation, and 98.59% in RFT equation. Body weight and weight gain during the rearing period can be used as predictor variables for LEA, SFT, and RFT of Nellore cattle kept in tropical pastures., Competing Interests: Declarations. Ethical approval: This study was conducted in strict accordance with the recommendations of the Guide for the National Council for the Control of Animal Experiments (CONCEA). The experimental protocol of research was approved by the Ethics Committee on Animal Use of Federal University of Mato Grosso do Sul (Protocol No. 802/2016). Conflict of interest: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

Bos taurus bulls have been used widely for genetic improvements of Bos indicus cattle in developing countries. However, male fertility has not improved in sync with production performances in resultant crossbred cattle. The molecular basis of influence of genetic background (Bos taurus, Bos indicus, Bos taurus x Bos indicus) on bull fertility has not been understood well. In the present study, candidate genes involved in mitochondrial function (COX5A and COX3) and fertility and embryogenesis (YWHAZ, CHMP5 and GTSF1L) were studied in contrasting genetic backgrounds of bulls. For this purpose, semen from six bulls employed for artificial insemination (AI) purposes per genetic background was used. Since retrieval of RNA from spermatozoa is challenging, a modified protocol was worked out that yielded significant harvest of RNA for downstream applications. The relative expression of genes was studied by real-time PCR in taurine and crossbred in comparison to indicus bulls. The YWHAZ, CHMP5 and GTSF1L genes showed a significant higher expression in the spermatozoa of exotic and crossbred cattle (p < 0.05) vis-à-vis indigenous bulls. Since the bulls are of comparable fertility in terms of seminal attributes and genetic merit of their own order but varying in genetic background, the differences in gene expression may be set due to their biological differences that lead to benchmarking in relative reproductive success of taurine, indicine or crossbred bulls as male genetics., Competing Interests: Declarations. Competing interest: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

The influence of estrus and double ovulations of Holstein heifers on a 5d-Co-synch 72 h protocol during summer was explored. Cycling heifers on the 5d-Co-72 h synchronisation protocol were randomised to carry a progesterone device (116) from day 0 to day 5 of the synchronisation protocol or not (97), from them 100 and 84 underwent fixed-time artificial insemination (FTAI). Another 70 heifers showed estrus before the first GnRH and were inseminated. Heifers were pregnant 34% (33/97) without device, 44.0% (51/116) with device and 44.3% (31/70) inseminated after estrus. Pregnancy per insemination (P/AI) tended to be higher (p = 0.059) inseminating after estrus than after FTAI without device. Three heifers without device and two with it showed double ovulation, four of which became pregnant. Pregnancy loss was similar among groups (0%-10%). P/AI was higher in heifers with estrus before FTAI (OR 13.96, p = 0.027), and with each additional day of age (OR 1.015; p = 0.015). The device was associated with higher progesterone on day 5, with more synchronised heifers, more ovulation frequency after first GnRH (96.6% vs. 84%, p = 0.007), and more heifers showing estrus before FTAI (96.0% vs. 85.7%, p = 0.018). Days to conception after first AI of the study, and after maximum three AIs were similar between synchronised groups, but significantly shorter in heifers inseminated after observed estrus. Fertility was higher in heifers that showed signs of estrus before accompanying the FTAI, while double ovulation seems not to be a major factor for fertility. An intravaginal device slightly improves efficiency under heat stress by increasing ovulation, progesterone, proportion of synchronised heifers and heifers showing estrus at AI., (© 2025 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Objective: To determine the impact of a two-stage rumen cannulation on the health and rumen function of lactating dairy cows., Study Design: Experimental study., Animals: Six lactating Holstein cows., Methods: We performed a two-stage rumen cannulation in six Holstein cows that were 49 ± 11 days in milk. The following clinical health parameters and digestion-associated variables were analyzed on seven measurement days, from before the first surgery until 28 days after the second surgery: body temperature, heart rate, respiratory rate, pain score, rumen fill score, fecal score, wet sieving, auscultation and palpation of the rumen, bodyweight, body condition score, and activity., Results: The pain score of the cows was constantly zero. Similarly, the body temperature and respiratory rate remained within physiological ranges, whereas the heart rate was slightly higher immediately after the second surgery. No differences were observed in rumen fill (2.00-2.67; p = .10) and fecal consistency scores (2.17-2.67; p = .42). The fecal particle size distribution showed negligible differences. The cows lost approximately 43 kg of bodyweight during the experiment (p < .01), which was reflected in a 0.5-point body condition score loss (p < .01)., Conclusion: A temporary minimal negative effect of a two-stage rumenostomy on the health and body condition of early lactating Holstein cows was observed, whereas digestion was unaffected. Considering the limited sample size, further studies are required to substantiate these findings., Clinical Significance: Given that animals are appropriately medically managed, experimental rumenostomy of lactating dairy cows may not compromise their health or rumen function., (© 2024 The Author(s). Veterinary Surgery published by Wiley Periodicals LLC on behalf of American College of Veterinary Surgeons.)

Following a significant increase in herd and farm sizes after the removal of milk quotas in Europe, the past 10 years have seen a slight yet steady decline in the population of cattle. This includes a reduction of approximately 5 % in dairy and beef cattle. This trend is driven by various factors, such as changing market demands, economic shifts, and sustainability challenges in the livestock sector. Despite this, technological advancements in reproductive management have continued to enhance efficiency and sustainability, particularly in dairy production. The main areas of rapid development, which will continue to grow for improving fertility and management, include: i) genetic selection (including improved phenotypes for use in breeding programs), ii) nutritional management (including transition cow management), iii) control of infectious disease, iv) rapid diagnostics of reproductive health, v) development of more efficient ovulation/estrous synchronization protocols, vi) assisted reproductive management (and automated systems to improve reproductive management), vii) increased implementation of sexed semen and embryo transfer, viii) more efficient handling of substantial volumes of data, ix) routine implementation of artificial intelligence technology for rapid decision-making at the farm level, x) climate change and sustainable cattle production awareness, xi) new (reproductive) strategies to improve cattle welfare, and xii) improved management and technology implementation for male fertility. This review addresses the current status and future outlook of key factors that influence cattle herd health and reproductive performance, with a special focus on dairy cattle. These insights are expected to contribute to improved performance, health, and fertility of ruminants in the next 20 years., Competing Interests: Competing interests The authors declare that they have no competing interests., (Copyright © 2024. Published by Elsevier Inc.)

Molecular-based biomarkers are believed to be more accurate in determining bulls' fertility and sperm's various fertility characteristics. The sperm acrosome-associated 1 (SPACA1) molecule, located in the anterior acrosomal and equatorial segments of the sperm head, is thought to be related to the function of binding and fusion between sperm and oocyte. This study aims to analyze the association of SPACA1 mRNA and protein with the fertility rate and semen quality of Bali bulls (Bos sondaicus) and assess its potential as a potential molecular biomarker determining bull fertility and sperm quality. Frozen semen from 20 Bali bulls was used in the research, which was then divided into two groups: high (HF) and low fertility (LF). SPACA1 mRNA abundance was analyzed using qRT-PCR, and SPACA1 protein abundance was analyzed using EIA. The semen quality parameters analyzed were motility (CASA), plasma membrane integrity (HOS test), sperm head morphology abnormalities (William staining), sperm viability (SYBR 14-PI), sperm capacitation (CTC assay), and sperm acrosome integrity (FITC-PNA). The results showed that there was a significant difference (P < 0.05) between high fertility (HF) and low fertility (LF) bulls, both in the abundance of SPACA1 at the mRNA, protein, and semen quality levels. Overall, the correlation test results showed a close relationship (P < 0.01) between the abundance of SPACA1 mRNA and protein with field fertility and various semen quality parameters tested in the study. A low level of SPACA1 molecules indicates low fertility and semen quality in Bali bulls. The SPACA1 molecule has the potential to be developed through further research to become a biomarker for determining fertility and semen quality in bulls., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

In commercial dairy farming, the majority of cows are dehorned or genetically hornless. It is argued that this reduces the risk of injurious and stressful social conflicts. On the other hand, in horned herds, management and housing may be better adapted to the cows, e.g. by avoiding changes in herd structure or by providing more space and resources, which would contribute to reducing stress. This cross-sectional study with 12 horned and 13 hornless organic dairy herds in loose housing aimed to explore the effect of horn status on faecal cortisol metabolites (FCMs) as an indicator for the cows' stress level while taking into account possible differences in the farms' compliance with management and housing recommendations for reducing social conflicts. Repeated faecal samples were collected from 674 cows (n = 2 625 samples), and FCMs were analysed by enzyme immunoassay. A total of 22 housing and management factors relating to guideline recommendations were recorded. Each factor was categorised as compliant, partly compliant, or non-compliant, and percentages of housing, management, and overall compliance were calculated. There was a wide variation in overall compliance between farms, ranging from 20 to 93%. Housing and management compliance correlated positively (r s  = 0.62) and farms with horned cows complied with more recommendations (median: 60 vs 48%). A linear mixed model was calculated with the fixed effects of horn status, overall compliance, and their interaction. Cow was nested within herd as a random effect, and days in milk and time of sampling were included as covariates. FCM levels were not higher in horned compared to hornless herds. However, contrary to expectations, no associations with compliance were found. More knowledge is needed about the extent to which FCM levels reflect social stress and whether individual housing or management factors may be particularly important in reducing stress., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Implantation in cattle is a key developmental checkpoint for pregnancy success. It involves careful spatiotemporal changes to the transcriptional landscape of the endometrium, with the heterogeneous nature of the endometrium increasing the complexity of understanding of the mechanism involved. Implantation is impacted by the developmental competency of the embryo, use of assisted reproductive technologies, and the environment in which this process occurs. We identify the factors that most impact the implantation process in cattle and highlight how it differs with that in other placental mammals. We propose the major areas that lack evidence are the mechanism(s) by which implantation itself occurs and how different stressors alter this process. Our understanding is hindered by a lack of appropriate in vitro models; however, development of novel 3D tools and available data sets will further elucidate the implantation process. Perhaps more importantly, this will develop methods to mitigate against these stressors to improve implantation success and offspring health.

Achieving net-zero greenhouse gas (GHG) emissions in dairy production will require >50% reduction in enteric methane (CH 4 ) emissions together with elimination of emissions from feed production, additional carbon sequestration, reduction in manure emissions, anaerobic digestion of manure, and decreased reliance on fossil fuel energy. Over past decades, improved production efficiency has reduced GHG intensity of milk production (i.e., emissions per unit of milk) in the United States, but this trend can continue only if cows are bred for increased efficiency. Genetic selection of low-CH 4 -producing animals, diet reformulation, use of feed additives, and vaccination show tremendous potential for enteric CH 4 mitigation; however, few mitigation strategies are currently available, and added cost without increased revenue is a major barrier to implementation. Complete elimination of CH 4 emissions from dairying is likely not possible without negatively affecting milk production; thus, offsets and removals of other GHGs will be needed to achieve net-zero milk production.

Precise genetic parameter estimates can allow the breeding value evaluation to be adjusted to meet European requirements and to enable participation in the international evaluation of Simmental bulls conducted by Interbull. Genetic parameters were estimated for a multitrait multilactation random regression test-day model for milk in Simmental cattle in Poland. Data came from the official Polish national recording system. Records of 6 447 Simmental cows born from 2002 through 2021 in 1 046 herds were collected. The cows were daughters of 987 sires and 4 590 dams. A minimum of two daughters per sire was required. Daily yields were collected between 5 and 305 days in milk. The BLUPf90 package and a Bayesian method via Gibbs sampling were used to estimate (co)variance components. The model contained fixed herd-test-date effect, fixed regressions within age-season of calving classes, and random additive genetic and permanent environmental regressions. The Wilmink function was used for fixed regressions, and third-order Legendre polynomials for random regressions. The mean heritability for daily milk yields and milk composition ranged from 0.12 (somatic cell score) to 0.41 (protein content in milk). The majority of the analysed traits were most heritable at the end of 305-d lactation. Genetic correlations between daily milk, fat, protein and lactose yields were positive and high (0.78-0.99). This meant that selection for one of those milk traits indirectly induced a similar response in another milk trait. The lactational heritabilities of all nine traits were much higher than the estimates of average daily heritabilities, and varied from 0.29 for somatic cell score to 0.74 for urea content in milk. For both daily and lactational parameters, traits expressed in percent were more highly heritable than yield traits. The values of the genetic parameters estimated in this paper can be used when a single-trait multilactation random regression test-day animal model for production traits is applied in the official genetic evaluation of the Simmental population, replacing the current lactation model., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Delayed milk ejection (DME) could compromise udder health and milking performance. The objectives of this systematic review and meta-analysis were to (i) explore the current evidence, assess the risk of bias, and identify the knowledge gaps in published studies that investigated the effect of DME on udder health and milking performance in dairy cows, and (ii) quantify the magnitude of the difference in milk yield per milking session (MY), milking duration (MD), and peak milk flow rate (PFR) between cows with and without DME. We performed the current systematic review and meta-analysis according to PRISMA 2020 statement. We tracked the pertinent peer-reviewed publications from PubMed using the following syntax (delayed milk ejection OR disturbed milk ejection OR bimodal milk flow OR bimodality) AND (bovine OR cattle OR cows), and additional relevant studies from the identified articles' reference lists. We calculated the pooled-mean difference in MY (kg), MD (seconds), and PFR (kg/min) between cows with and without DME using the random-effects models. The selection process identified 15 studies as the final number of studies qualified for review, including six interventional and nine observational studies published between 1980 and 2023 conducted in seven countries, including the USA, Germany, Italy, Switzerland, Netherlands, New Zealand, and Portugal. The results indicated that while the DME had a minimal influence on the udder health, it can reduce MY by 1.55 kg per milking session (95 % CI = -2.10, -1.00). The observed evidence here suggests that DME can negatively influence the milking profitability., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest in the research., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Use of desalinated seawater in arid and semiarid regions for domestic, industrial, and agricultural purposes is on the rise. Consequently, in those regions, drinking water offered to lactating cows has lower salinity and mineral concentrations than in the past. Although water with total dissolved solids (TDSs) of up to 1 000 ppm is considered safe for drinking, lower salinity level may affect rumen physiology, feed and water intake, or milk yield. Therefore, we evaluated the effect of drinking water salinity in an electrical conductivity (EC) range of 400 to 1 000 micro Siemens (µS) / cm (TDS of 200 to 500 ppm) on lactating cows' performance by artificially creating water EC > 400 µS/cm by adding NaCl. Following 2 weeks of adaptation to individual feeders and troughs, four Israeli Holstein multiparous lactating cows were offered, in a Latin square design, drinking water with EC levels of 400, 600, 800 or 1 000 µS/cm, through addition of concentrated NaCl solutions (measured EC in troughs averaged 418, 624, 811, and 1 016 µS/cm and 209, 312, 406, and 508 TDS ppm, respectively), for four periods of 18 days each. Water EC in troughs was measured daily. Each period included 5 days for washout, 10 days for collecting data of feed and water intake, milk and milk component yields, and BW and 3 days for samplings of milk, urine, faeces, and rumen fluid. Rumen pH and temperature were recorded continually by inserting loggers into the reticulorumen. We analysed the total tract apparent digestibility, rumen fluid volatile fatty acids and NH 3 , and mineral concentrations (Na, Cl, K, and N) in water, urine, faeces, and milk. Drinking water salinity was positively correlated with DM intake and energy-corrected milk yield, the latter showing the greatest response between EC of 400 and 600 µS/cm. Digestibility of ash-free amylase-treated NDF was negatively correlated with water salinity. There was no significant effect of water EC on rumen volatile fatty acid or NH 3 concentrations, or water intake. The results indicate possible effects of drinking water mineral concentrations on lactating cows' milk yield and rumen physiology, warranting further investigation., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

This study compared the effect of a 7-day estradiol- and a 7-day GnRH-based FTAI protocol versus a presynchronized GnRH-based FTAI protocol (7 & 7 GnRH) on pregnancy per AI (P/AI) in multiparous postpartum Angus cows. Cows were blocked according to presence/absence of a CL, body condition score, and days postpartum and assigned randomly to one of three treatments: I) 7-day EB (n = 368), estradiol benzoate (EB) and intravaginal progesterone-(P4)-releasing device (IVPD) on Day -10, prostaglandin F 2α (PG), equine chorionic gonadotropin (eCG) and estradiol cypionate (ECP) at IVPD removal on Day -3 with FTAI done on Day -1 (54 ± 2 h after IVPD removal); II) 7-day GnRH (n = 367), GnRH at IVPD insertion on Day -10, PG and eCG at IVPD removal on Day -3 with GnRH and FTAI on Day 0 (66 ± 2 h after IVPD removal); and III) 7 & 7 GnRH (n = 361), PG at IVPD insertion on Day -17, GnRH on Day -10, IVPD removal, PG and eCG on Day -3 with GnRH and FTAI on Day 0 (66 ± 2 h after IVPD removal). Preovulatory follicle diameter, corpus luteum (CL) presence, CL area, and P4 concentration were determined at IVPD removal, as well as estrus expression at FTAI and P/AI between 35 and 40 days after FTAI. Plasma P4 concentrations at IVPD removal were greater (P < 0.05) in cows subjected to the 7-day GnRH or 7 & 7 GnRH protocols and a greater number of cows (P < 0.05) had at least one CL at IVPD removal compared to cows subjected to the 7-day EB protocol. However, the 7 & 7 GnRH protocol resulted in more cows with two CLs at IVPD removal compared to the other two protocols. Moreover, cows synchronized with the 7 & 7 GnRH protocol had larger preovulatory follicles (P < 0.05) and larger CL area at IVPD removal (P < 0.05), and a greater rate of estrus expression before FTAI (P < 0.05) than cows synchronized with the 7-day EB, whereas those variables were intermediate in cows synchronized with the 7-day GnRH. Pregnancy per AI was greater (P < 0.05) in cows treated with the 7 & 7 GnRH (63.5 %) treatment compared to the 7-day EB (51.4 %) and the 7-day GnRH (51.3 %) protocols. In summary, the 7 & 7 GnRH protocol enhanced circulating P4 before IVPD removal, increased estrus expression rate before FTAI, and improved P/AI in postpartum Bos taurus grazing beef cows., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Timed artificial insemination (TAI) is a technology widely used in cattle production based on controlling ovarian follicular growth. This study analyzed a large database aiming to determine the influence of several intrinsic and extrinsic female factors, as well as their interactions to determine risk factors and produce prediction ability in beef cattle. A total of 1 832 999 TAIs conducted on 2 002 farms across South American countries were considered for the analysis, including 15 main fixed effects or interactions in the statistical model, in addition to five random effects. The pregnancy/A.I. (P/AI) was affected by Order of service (1st TAI > resynchronizations), body condition class (BCS) (high > medium > low), female genetic group [Bos taurus and crossbreds > Bos indicus], breeding season (reduction of the P/AI every year), female category [Non-lactating multiparous > Suckled multiparous > Suckled primiparous > Nulliparous heifers], period of year (July-September, October-December and January-March > April-June) and climatic region as well as the interactions between Order of service and female category, BCS class and female genetic group (impact of BCS: Bos taurus or crossbreed animals > Bos indicus), BCS and female category (impact of BC:S Suckling > non-Suckling categories), female category and time of female availability, female category and female genetic group, female category and climatic region, and climatic region and period of the year. Farm, technician, and sire were the variables with the highest predictive ability for P/AI. At the same time, breeding season, climatic region, and time of female availability were the variables with the lowest predictive ability. In conclusion, the main female intrinsic factors that affected fertility in commercial beef cattle A.I. programs were the Order of service, BCS class, female category, and female genetic group. The female extrinsic factors that most affected P/AI were the breeding season and the climatic region. Farm, A.I. technician, sire, and the interaction between the female category and BCS class were the variables with the highest predictive abilities on pregnancy per TAI. Conjunctural factors, which are more adjustable, have a higher impact on P/AI prediction ability than structural factors. Thus, farm management and structure, A.I. technician, bull semen, and female BCS should be the main factors of attention to obtain good results in applying this biotechnology in beef cattle. Despite the influence of each factor, this study demonstrated the usefulness of analyzing big databases, allowing to determine effects that cannot be studied with experimental approaches, providing a complementary approach to decide where to focus future studies to enhance TAI pregnancy rates in beef cattle., (Copyright © 2025 The Authors. Published by Elsevier B.V. All rights reserved.)

The reproductive characteristics of Hanwoo play a significant role in farm profitability by decreasing the generation interval. This study analyzed 1015 primiparous and 916 multiparous cows using a genome-wide association study with both single-locus (GEMMA, GCTA) and multi-locus models (FarmCPU, BLINK). A significant marker for age at first service was identified across all methods. For age at first conception, GEMMA identified two markers, while FarmCPU and BLINK identified 14 and two markers, respectively. Regarding age at first calving, GEMMA identified two markers, and FarmCPU and BLINK found 15 and two markers, respectively. In multiparous cows, except for days open, one marker for gestation length and two markers for calving interval were identified in the multi-locus models (FarmCPU and BLINK). Additionally, one marker for the number of services per conception was identified using GEMMA. Key candidate genes included PLCB1 (maintaining pregnancy), MUC1 (fetal development), and ADCY5 (associated with fetal birth), while TXNL1 regulates embryo implantation timing. Gene ontology functions associated with embryo implantation and placental regulation were also confirmed (GO:0046875). Although the multi-locus models identified a greater number of markers and candidate genes, there was no overlap with the results from the single-locus models. The multi-locus models showed enhanced detection power, but slight inflation in test statistics (λ values) necessitates cautious interpretation to avoid false positives. Thus, a combination of both models is recommended to improve reproductive efficiency in cows, providing valuable insights into the genetic aspects of reproductive traits., (© 2024 Stichting International Foundation for Animal Genetics.)

This systematic review compares the health, welfare, and behaviour of dairy cows in year-round loose housing systems against those kept in other housing systems in temperate regions. Year-round loose housing systems comprised housing where dairy cows had no access to the outdoors or only had access to a yard, pen or run. The comparator housing systems also comprised housing with and without outdoor access (including grazing). To contribute to evidence-informed policy, a systematic evidence evaluation was undertaken to assess the scientific evidence base for this question, and determine whether the evidence base is robust enough to determine any association between housing systems and health, welfare and natural behaviour in dairy cows. We assessed 11 181 references and reviewed 53 articles in detail following best practice guidance for systematic review. Seven different types of housing systems were compared and a total of 120 different Health, Welfare and Behaviour (HWB) outcomes were assessed, comprising 839 measurements for HWB. Results indicate both advantages and disadvantages of year-round loose-housing systems. These differences were not just between studies; there were also differences within-studies for individual HWB indicators. There was substantial heterogeneity in methods of collecting and measuring HWB outcomes across the studies; therefore, a robust statistical test (such as meta-analysis) of correlation between potential explanatory variables and HWB outcomes was not possible for any housing comparison or any individual HWB measurement. Assessing the evidence base systematically as a whole, there is only weak evidence that year-round loose-housing is either better or worse than housing systems with grazing for the health and welfare of dairy cows. There is also only weak evidence that year-round loose-housing is either better or worse than housing systems with any outdoor access, including but not limited to grazing, for the health and welfare of dairy cows. Variation in data reporting across studies is too great to allow robust statistical analysis of the direct effects of loose-housing systems and/or grazing on the health and welfare of dairy cows. Data are also often presented in an aggregated form that limits meaningful comparisons. For future research, data collected should be made freely available in a disaggregated form to enable robust meta-analysis to be conducted. In order to change policies and practices, based on evidence, more standardised primary research studies, measuring welfare indicators, including behaviour, are necessary., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Economic efficiency is affected by several traits, and as the unit of selection is the individual, in artificial selection, to promote the maximization of economic genetic gain, the traits to be improved must be weighted by their respective economic values. In Brazil, breeding goals are defined empirically, and not based on an economic evaluation, therefore, the aim of this study was to estimate economic values for traits of economic importance in dairy farming systems based on the use of purebred and crossbred Guzerat animals. The economic values for 305-days milk yield (MY), fat yield (FY), protein yield (PY), and somatic cell count (SCC) were calculated for different production systems based on the feed management: System 1, based on pasture grazing with Brachiaria brizantha or Panicum maximum cv. Mombaça during rainy season, and corn-silage supplementation during the dry season; System 2, based on pasture grazing with Brachiaria brizantha or Panicum maximum cv. Mombaça during rainy season, and the mixture of sugarcane including urea supplementation during the dry season. Bioeconomic models were applied to estimate economic values, and a sensitivity analysis was performed. Four selection indexes were defined, each one with different goals: milk (I 1 ), milk + protein yield (I 2 ), I 2  + fat yield (I 3 ) and I 3  + somatic cell count (I 4 ). The economic values for MY and PY were positive for both production systems. However, for FY, the values were positive for System 2 but negative for System 1. The economic value for SCC was negative (-7.33 per SCS per lactation). The selection responses for I 1 were higher than those for I 2 , I 3 and I 4 , for both production systems. I 4 presented the highest expected genetic gain for each trait, except for fat yield, whose expected genetic gain was greater with the use of I 2 , in both production systems. The results indicates that the inclusion of milk quality traits in the selection index provides better economic return, and due to the small differences in expected genetic superiority, I 1 is still the most suitable for crossbred Guzerat herds whose main activity is milk production in Brazil., Competing Interests: Declarations. Ethics approval: Not applicable. Consent to participate: Consent was obtained from all authors. Consent for publication: All participants have consented to the submission of the review article to the journal. Conflict of interest: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

Animal welfare is integral to sustainable livestock production, and pasture access for cattle is known to enhance welfare. Despite positive welfare impacts, high labour requirements hinder the adoption of sustainable grazing practices such as rotational stocking management. Virtual fencing (VF) is an innovative technology for simplified, less laborious grazing management and remote animal monitoring, potentially facilitating the expansion of sustainable livestock production. VF uses Global Navigation Satellite System technology, wireless communication, and stimuli (auditory and electrical) to manage livestock movements and contain animals without physical barriers. Training animals to associate the auditory cue with the subsequent aversive stimulus enables effective livestock containment without physical barriers. While previous studies have largely dispelled concerns about adverse effects on cattle behaviour associated with the use of VF collars, there is limited knowledge regarding the impacts on animal physiology, particularly in rotational stocking systems. Addressing this knowledge gap, this study investigated differences in diet digestibility, livestock performance, and stress response of beef heifers on pastures using a VF compared to a physical electric fence. The study was conducted over 8 weeks, subdivided into two grazing cycles, with 32 heifers in four groups. Each experimental pasture was subdivided into four paddocks. The study monitored the interaction with the VF by analysing the temporal development of the ratio of auditory and electrical cues (success ratio and confidence ratio) emitted by the collars. Additionally, the grassland herbage quality, BW gain, and concentrations of faecal cortisol metabolites (FCMs) were assessed, as well as the time required for animals to cross into a new paddock. VF success ratios increased in the second grazing cycle, reflecting enhanced adaptation over time. Similarly, the reduction in time taken to cross into new paddocks in the VF groups indicated that animals learned to interact with the VF and rely on the auditory cues for directing movements. The absence of a significant effect of the fencing system on FCMs suggested that stress was unrelated to the VF technology. Further, animal performance was not affected as indicated by similar BW gains under both fencing systems. This study also attempts to establish a benchmark threshold for successful responses to the auditory cues, allowing comparative evaluation of VF systems. Overall, under rotational grazing, VF did not adversely impact animal welfare or performance compared to physical fencing, opening avenues for further exploration of VF technology in diverse grazing conditions., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

This review focuses on bull breeding behaviors and management strategies to improve reproductive efficiency. Breeding soundness evaluations are utilized to classify a bull's physical ability and sperm quality, yet roughly 20 % of bulls fail to meet the minimum criteria. Furthermore, despite achieving the minimum criteria, few bulls in multi-sire breeding groups sire the majority of calves, indicating a need for better understanding of bull behavior that impact siring capacity, and thus, a bull's reproductive efficiency. Several factors influence bull libido such as age, breed, and environmental conditions. Although service capacity tests have been used to measure libido, standardization and repeatability, along with variability in age and breed, can be problematic. Management in collection facilities largely focuses on the pre-stimulation of bulls through behavioral cues for better sperm quality and quantity during collection, thus improving a bull's reproductive efficiency through fewer collections with increased breeding doses harvested. In management of multi-sire breeding groups, understanding social interactions, bull-to-female ratios, synchronization of females, and DNA testing to determine parentage, are techniques that can be utilized to improve reproductive efficiency. New research utilizing remote monitoring technology is being developed to better understand bull behavior without the constraints of direct observation. This technology may be used to predict siring capacity, better manage bulls based on social dynamics, and potentially detect lameness or injury in bulls that may impact siring capacity. A better understanding of developing management strategies of breeding behaviors should be further investigated to improve reproductive success of bulls., Competing Interests: Declaration of Competing Interest None., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Empirical data on livestock contact networks are scarce but digital technologies are increasingly used to characterize animal behavior and describe the dynamics of contact networks. The objective of this study was to use contact network analysis to quantify contacts within three pens of feedlot cattle across three consecutive years at varying temporal resolutions to better inform the construction of network-based disease transmission models for cattle within confined-housing systems. We also aimed to describe the influence of the variation in Real-Time Location System (RTLS) average tag read rates and the effect of increasing minimum contact duration (MCD) on the contact networks of feedlot cattle. Three pens of feedlot steers were tagged with RTLS, one pen in each of three consecutive summers from 2017 to 2019. Contacts were defined with a spatial threshold of 0.71 m and an MCD of either 10, 30, or 60 seconds. Static, undirected, weighted contact networks were created for the full study duration and then split into daily (24-h), 6-h period, and hourly networks to better assess network heterogeneity. For the full study duration time scale, all three networks were found to be densely connected. The networks showed more heterogeneity in network density and clustering coefficient when smaller time scales (6-h period and hourly) were applied. When contacts were defined with a MCD of 30 or 60 seconds, the total number of contacts seen in each network decreased, indicating that most of the contacts observed in our networks may have been transient passing contacts. For example, the total defined contacts for the 2017 native read rate network were 930,843 at 10 s MCD, 95,570 at 30 s MCD, and 19,135 at 60 s MCD. Though the same system was used for all three years, variation in average tag read rate was observed (range: 2.2 readings/min (2018) to 7.4 readings/min (2017)). When the networks were down-scaled from higher average tag read rates to match lower tag read rates, the full study networks maintained similar network density and clustering, though the average edge weight between pairs decreased. Overall, the networks created here from high-resolution spatial and temporal contact observation data provide estimates for a contact network within a commercial US feedlot pen., Competing Interests: Declaration of Competing Interest The authors report no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Exploitation of compensatory growth (CG) is a widely practised management strategy in beef production, especially under pastoral conditions due to its potential to reduce feed costs. The aim of this experiment was to evaluate the effect of nutritional restriction during backgrounding in Angus steers slaughtered at either similar age and/or similar BW on feed efficiency, body composition, carcass characteristics and meat quality attributes under either a forage or feedlot-based finishing diet. Eighty steers (BW: 444 ± 39 kg, age: 18 ± 1 months) were blocked and randomly assigned within block to either an optimal (0.6-0.7 kg/day) or suboptimal (0.3-0.4 kg/day) growth rate, during 97 days of backgrounding. Following, half of the steers in each group were finished on a forage diet while the other half were finished on feedlot-based diet. Half of the steers in each treatment were then slaughtered at similar age (24 months), whilst all remaining steers were slaughtered at similar BW (∼620 kg). Two extra slaughters were done with other representative steers on day 0 and day 97, to provide baseline parameters for carcass and non-carcass measurements. During the backgrounding period, optimal steers gained more than suboptimal (P < 0.01), resulting in higher BW and hot carcass weight (HCW; P < 0.01). During the finishing period, the suboptimal group increased BW gain (P < 0.01) and displayed an improved feed conversion ratio (FCR; P < 0.01). Differences (P < 0.01) in BW and HCW remained between the treatments when slaughtered at a similar age. When the steers were slaughtered at similar BW, after additional days of finishing for the suboptimal groups, no differences (P > 0.05) in backgrounding treatment on HCW, carcass grading, body composition or FCR for the entire period (backgrounding and finishing) were apparent. Indeed, no differences (P > 0.05) by backgrounding growth strategy were observed for any meat quality variables assessed using instrumental or sensory evaluations. During the finishing period, feedlot steers had increased (P < 0.01) BW and HCW gains, improved (P < 0.05) FCR and carcass grading, and had higher (P < 0.05) HCW compared to forage finished steers. However, no differences (P > 0.05) were observed for any meat quality variables assessed by finishing system. Overall, exploiting CG within pasture-based beef cattle production systems improves growth rate and FCR in both forage and feedlot finishing. Suboptimal backgrounded steers required additional days on feed to achieve similar BW to their contemporaries. Nevertheless, at similar BW, there were no residual differences in body composition, FCR during the entire period, meat tenderness or overall meat liking because of the backgrounding conditions., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Available literature on the effect of various physical forms of starter feed (PFSF) on calf performance is conflicting. Thus, this study aimed to investigate the effect of the PFSF on feed intake, growth performance, blood metabolites, and the health of dairy calves. Twenty-four female Holstein calves (5-d-old; 40.4 ± 3.86 kg BW; mean ± SD) were used in a completely randomized block design. Calves were individually housed and randomly assigned to the treatments (n = 12 calves/treatment): (1) textured starter feed (TSF, a mix of pelleted ingredients and whole-kernel corn) and (2) pelleted starter feed (PSF). Both starter feeds had the same ingredients, nutrient compositions and pellet die size. Calves were fed the same milk replacer and weaned in a step-down scheme at 67 d. Health was evaluated daily until weaning. Treatments did not affect starter feed intake, water intake, BW, ADG, withers height, or clinical signs of disease (loss of appetite, ear position, and cough incidence). Nonetheless, scores for abnormal attitude (P = 0.01), ocular discharge (P < 0.01), total respiratory disease (P = 0.02), and fecal consistency (P = 0.04) of PSF-fed calves were higher than those TSF-fed. Based on that, TSF-fed calves exhibited a higher non-disease probability compared to PSF over time. Calves TSF-fed sorted against small particles (0.425-mm sieve; P = 0.01). Coincidently, PSF-fed animals sorted for small particles in the same sieve sizes. No major changes in blood profile were found (P > 0.05). In conclusion, starter feeds containing whole-kernel corn as a texturizer did not improve the intake and performance of dairy calves compared with pelleted starter feed; however, improvements were observed in health scores and non-disease probability of calves fed textured starter feed., (Copyright © 2024. Published by Elsevier B.V.)

A cross-sectional study on 156 smallholder dairy farms in Rwanda was carried out to assess the association between farm management practices and milk yield and quality. A pre-tested questionnaire was used to collect data on cow characteristics and farm management practices. Milk yield was recorded at household level, milk composition was monitored using a Lactoscan device (Milk Analyzer). Somatic cell count (SCC) was determined using a DeLaval cell counter (DCC). A Delvotest SP-NT kit was used to determine antibiotic residues in raw milk. Most dairy cows were kept in zero-grazing system (84.6%) and most farmers had less experience of dairy production (78.2%). Mean daily milk yield was 3.9 L/cow and was associated with type of breed, milking frequency, stage of lactation, and parity. Mean milk content of protein, fat, lactose and solid non-fat, and density were normal and showed no association with different management practices. Based on SCC analyses, 65.8% of the milk samples with less than 300,000 cells/mL were graded as acceptable for delivery to a milk collection centre (MCC) and 12.9% of the samples tested positive for antibiotic residues. These findings suggest low milk yields on smallholder farms in Rwanda that are attributable to type of breed and prevalent high level mastitis, among other factors. The results also indicate possible non-compliance with withdrawal periods, resulting in antibiotic residues in milk, which has public health implications for consumers. Routine testing at MCC for both SCC and antibiotic residues is important for quality control., Competing Interests: Declarations. Ethics approval: This research was reviewed and approved by the College of Medicine and Health Sciences (CMHS) Institutional Review Board (IRB) of the University of Rwanda, with approval notice No. 181/CMHS IRB/2021. Consent to participate: Further approval was obtained from participants before their voluntary participation in the study by signing informed consent forms. Consent for publication: The manuscript is approved by all authors for publication. Declaration of generative AI and AI-assisted technologies in the writing process: The authors did not use any artificial intelligence-assisted technologies in the writing process. Conflict of interest: The authors declare no competing interests., (© 2025. The Author(s).)

Initial periods of life, beginning before birth and lasting until weaning are characterised by the greatest neural plasticity. Early postnatal stress causes lasting changes in a variety of behaviours as well as stress reactivity. Cow-calf contact for an extended period is believed to improve the social skills of calves and has also been linked to improved productivity of mothers. This research was carried out to investigate the impact of weaning stress on the growth, behaviour and performance of Sahiwal cows and their calves. For this, 32 healthy cows and their calves were selected from the Sahiwal herd of the Livestock Research Centre, ICAR-National Dairy Research Institute. They were grouped equally into two groups of 16 cow-calf pairs, which became the treatment groups (i.e., 'Fenceline' contact and 'Separated' groups). Calves in the fenceline contact group were allowed to suckle during the morning and evening milking and were housed together with fenceline separation. In the separated group, calves were separated from their mothers immediately after birth and fed colostrum and milk with a bottle throughout the experiment. Each calf was monitored for its growth and behavioural responses while cows were monitored for their production performance and behaviour. The results showed that growth and behaviour responses were better for fenceline calves compared to separated calves and also production performance and behaviour of Sahiwal cows provided with fenceline contact were better when compared to separated cows. From this study, it was concluded that fenceline cow-calf contact improved growth, behavioural response of calves; and production performance and behaviour of cows compared to separated cows and calves., Competing Interests: Declarations. Ethics approval: The experiment was approved and conducted under the established rules of the Institutional animal ethics committee (IAEC), constituted as per form no. 13 of the committee for the purpose of control and supervision of experiments on animals (CPCSEA) rules laid down by the government authority. Consent to participate: All the authors were aware regarding participation and publications. Consent for publication: All the authors were aware regarding participation and publications. Conflict of interest: There is no conflict of interest among authors., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

Ruminant species are important to human society due to their ability to convert human-inedible sources of energy and protein to human-edible food. Greater efficiency of meat and milk production will require the management of the complex reproductive biology of many cattle with a limited capacity and limited budget within a smaller, hotter, and more climatically erratic land area. The over-riding drivers of new reproductive technologies in North America will be smaller economic margins, larger herd size, fewer agricultural workers per farm, and a greater reliance on automation to offset the reduced agricultural labor force. Climate change and the possibility that consumers may dictate the procedures used for animal reproductive management may present additional challenges. The successes of the past 20 years (timed AI, genomic selection for fertility in both bulls and cows, automated estrus detection, chemical and ultrasonographic pregnancy diagnosis, and gender selected semen) will be improved upon in the next 20 years as most of these technologies can be optimized further. Improving embryo technologies and increasing our understanding of embryonic loss may provide the greatest challenges for the future. Researchers must attempt to devise practical methods to release more follicles from the primordial follicle pool so that a greater number of oocytes and embryos can be harvested from individual animals. Embryonic loss continues to be an unsolved question that cuts the total number of potential offspring by nearly one-third. The identification of fertile embryos in vitro, better methods of cryopreservation, and the optimization of methods of transfer into recipient animals may improve the efficiency of advanced embryo technologies. The derivation of oocytes, sperm, and embryos from pluripotent stem cells may yield a vast supply of gametes and embryos from genetically superior animals and radically change the reproductive management in the future., Competing Interests: Declaration of competing interest The authors claim no conflict for the content of this article., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Antral follicle count (AFC) and anti-Müllerian hormone (AMH) concentrations are reflective for ovarian reserve and have been associated with improved reproductive performance in cattle. Key events for regulation of uterine receptivity are orchestrated by progesterone. As progesterone concentrations are greater in animals with high than low AFC, we tested the hypothesis, if the resulting improved uterine environment will lead to improved conceptus elongation and endometrial response to interferon tau. For four years, 10 heifers with lowest and highest AFC, respectively, were selected from 120 heifers. Reproductive tracts and blood samples for progesterone and AMH analysis were collected after synchronization and insemination. For a recovered conceptus, length was determined, and interferon tau (IFNT) transcript abundance was analyzed. Endometrial transcript abundance of interferon-stimulated gene 15 (ISG15) and oxytocin receptor (OXTR) were analyzed. Progesterone concentrations did not differ between low and high AFC groups (P = 0.1). A difference in conceptus length was not observed. Endometrial abundance of ISG15 did not differ between pregnant low and high AFC heifers. Abundance of OXTR was greater in open low AFC than open high AFC heifers (P < 0.01). Interaction of AMH and pregnancy status was determined, with greater AMH in pregnant than open high AFC heifers (P < 0.05). Improved uterine environment in high vs. low AFC heifers did not result in longer conceptuses or improved endometrial response. As the increase in OXTR transcript abundance was only detected in low AFC heifers, reported differences in reproductive performance might be associated with earlier initiation of luteolysis., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for the Study of Reproduction.)

Sperm motility is the prime functional attribute for semen quality and fertility of the bull. However, the bull's age directly affects the semen quality, and the bull's fertility and productive life decline with age. Even though research on age has been conducted in the past, it is still unclear how old a bull should be maintained at artificial insemination centers. The minimum standard protocol (MSP) states that a bull has an 8-years productive lifespan, yet it has been shown that some bulls older than 8 years have produced freezable ejaculates. It has yet to be established what the bull's ideal productive life is under the tropical climate of India without affecting in-vitro sperm functions. For the validation of the maximum age of a bull up to that it could be utilized in the artificial insemination centers, cut-off values of oxidative stress in freezable semen ejaculates were used. The current study was done at the Artificial Breeding Research Centre, ICAR-NDRI, Karnal, Haryana, India. A total of eighteen Sahiwal breeding bulls were divided into three groups: Young (2-4 years), Adult (> 4-8 years), and Older (> 8-11 years). Three ejaculates were taken from each bull; thus, a total of 18 ejaculates were utilized in each group for semen examination. Semen quality of Young bulls was poor compared with adult and older bulls. Seminal parameters such as dead, moribund, apoptotic, reacted acrosome, and protamine deficient sperms were higher in older bulls than in adult bulls; however, the values were non-significant. Less difference was found in the semen parameters among adult and older bulls. This indicates that the semen quality of older Sahiwal bulls was optimum, freezable, and can be utilized for up to 11 years (Average 9.5 years)., Competing Interests: Declarations. Animal ethics and Consent to participate declarations: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

This article aims to explore milking-ability criteria of Holstein dairy cattle under intensive production system in Egypt and investigate some managerial factors that influence them in dairy farms. The data obtained from five herds belong to a commercial intensive production system farm, Egypt. Data included 3509 records. The values of mean ± SD (CV%) of the milking-ability criteria for Holstein dairy cattle as follow: daily milk yield, kg (dmy), milking duration, min (MD), peak flow rate, kg min -1 (PFR), average flow rate, kg min -1 (AFR), AFR 0:15 s of milking, AFR 15:30 s of milking, AFR 30:60 s of milking, and AFR 60:120 s of milking were 30.34 ± 6.76 kg, (22.27%); 4.16 ± 0.79 min (19.06%); 3.62 ± 0.79 (21.77%); 0.28 ± 0.11 (39.48%); 1.40 ± 0.49 (36.37%); 1.26 ± 0.50 (39.95%); and 1.96 ± 0.71 (36.05%), kg min -1 , respectively. The milking-time (a.m./p.m.) and the herds' men influenced significantly (P ≤ 0.01) on dMY, and milking-ability criteria. In addition, there was a significant effect (P˃0.05) of cows' dry-period on dMY, MD, PFR and AFR. Also, it was clearly appearing that there was a dramatic significant decrease in daily milk yield and AFR by increase mastitis infection times. Milking-ability criteria in Holstien cattle may be go better via good management, hygiene, and well-trained herds' men. The cubic models are higher in determination coefficient (p ≤ 0.05) than linear models for the curve estimates through the time of lactation period for studied traits. The curve of milk yield and milking-abilities were inconstant all over lactation period., Competing Interests: Declarations. Ethics approval: This study was carried out following the guidelines set via The Institutional Animal Care and Use Committee, IACUC; Menoufia University [IACUC Ref. № is MUFAG/F/AP/1/24]. Competing interest: The authors have no relevant financial or non-financial interests to disclose., (© 2025. The Author(s).)

This study investigated the effects of different protein sources on feed intake, nutrient, and energy utilization, growth performance, and enteric methane (CH4) emissions in growing beef cattle, also evaluated against a pasture-based diet. Thirty-two Holstein × Angus growing beef were allocated to four dietary treatments: a total mixed ration (TMR) including solvent-extracted soybean meal as the main protein source (n = 8), TMR with local brewers' spent grains (n = 8), TMR with local field beans (n = 8), and a diet consisting solely of fresh-cut Italian ryegrass (GRA; n = 8). Every 4 wk, animals were moved to digestibility stalls within respiration chambers to measure nutrient intakes, energy and nitrogen (N) utilization, and enteric CH4 emissions. Feed intake (Calan gates), nutrient intakes, and CH4 emissions (GreenFeed) were also measured when animals were group-housed. In respiratory chambers, enteric CH4 yield per kg of dry matter intake (DMI), per kg of organic matter intake (OMI), and per kg body weight were lower (P < 0.05) for GRA. Feces and urine energy outputs were higher (P = 0.007 and P < 0.001, respectively) for GRA steers than concentrate-fed steers. Urinary nitrogen output (UNO, P = 0.026), manure (feces + urine) nitrogen output (MNO, P = 0.034), UNO/nitrogen intake (P = 0.002), and MNO/nitrogen intake (P = 0.006) were higher for GRA. During group-housing periods, CH4 emissions, measured by GreenFeed, were similar to those measured in chambers. Similar CH4 yield between treatments, expressed per kg digestible DMI and digestible OMI, may indicate that the lower diet digestibility was likely the reason for the reduced enteric CH4 emissions in pasture-based diets. The higher energy output and nitrogen losses, and the reduced nitrogen utilization for steers fed the fresh-cut ryegrass diet indicate less efficient energy and nitrogen utilization, which can be considered environmentally undesirable. The lower growth rates in the pasture-based system should also be accounted for when this is adopted for reducing production costs., (© The Author(s) 2025. Published by Oxford University Press on behalf of the American Society of Animal Science.)

We recently reported factors leading to different severity of ruminal pH drop in primiparous cows fed the same diet during transition and early lactation. The present study evaluates the effects of those severities on performance and several blood and balance parameters in the same 24 primiparous cows from 3 wk before calving until week 10 in lactation. The dietary concentrate was increased for all cows from 32 before calving to 60% dry matter (DM) basis over the first week in lactation, resulting in a diet with 40% non-fiber carbohydrates (NFC), and 14.4% physically effective fiber [peNDF > 8]. Ruminal pH was monitored with indwelling systems in all cows during the study; then several indices of duration and magnitude of pH change were used as indicators of the severity of ruminal pH drop. Accordingly, as reported in the companion paper, the cows were classified as either higher pH drop (HIGH; n = 9), moderate (MOD; n = 9), or lower (LOW; n = 6) severity of pH drop. In the present report, body weight, body condition score, and back fat thickness decreased but rumen mucosa thickness increased after calving in all cows (P < 0.05). Post-partum daily energy intake in HIGH was greater (P < 0.05) than in the other categories. In addition, there were 5.6 kg extra of energy-corrected milk in HIGH (P < 0.05). Independent of the severity of pH drop, blood glucose, non-esterified fatty acids, beta-hydroxybutyrate, bilirubin, and cortisol were higher, whereas triglycerides, total protein, globulin, albumin, urea nitrogen, cholesterol, calcium, and phosphorous were lower at calving (P < 0.05). Blood cholesterol was greater in HIGH than the other pH categories (P < 0.05); insulin and reproductive variables were not affected by the severity of the pH drop. Overall, primiparous cows fed the same diet showed different severity of ruminal pH drop, but the individual variation in ruminal pH depression was not related to a negative impact on milk yield, energy balance, or blood metabolites during the study. This indicates that the impact of low ruminal pH on the animals may depend not only on the severity of the pH drop (average of 403 min/d of pH < 5.8 over 13 wk) but also on diet characteristics. Specifically, drops of ruminal pH can be tolerated by primiparous cows during the first 10 wk in milk consuming a diet containing 40% NFC and 14.4% peNDF > 8. It would be worth studying the severity of ruminal pH drop in a larger sample size during the entire lactation and if the severity is sustained on the next lactation., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)

By 2050, the U.S. beef industry must produce an extra 40 million tons of beef to satisfy the global demand. Such an increase in inventory will undoubtedly enhance methane (CH4) production from livestock, which should be reduced by over 20%. The addition of plant secondary metabolites, such as anacardic acid present in cashew nutshell extract (CNSE), has shown promising results in reducing CH4 yield, although its effects seemed to be diet-dependent. This study evaluated the addition of CNSE to a high-grain diet (85:15 grain:forage) on in vivo CH4 emissions, nutrient digestibility, performance, feeding behavior, and ruminal fermentation parameters of beef steers. Sixteen Angus crossbred steers [599 ± 40 kg of bodyweight (BW)] and 6 ruminally cannulated crossbred steers (490 ± 51 kg of BW) were utilized in a crossover design with 2 experimental periods of 56 d each, composed by 14 d of adaptation, 35 d of measurement, and 7 d of washout. Following adaptation, steers were sorted by BW, and assigned to receive no additive (CON) or CNSE at 5 g/steer/d. Data were analyzed using the MIXED procedure of SAS. Inclusion of CNSE increased (P < 0.05) propionate concentration and molar proportion (MP; mol/100 mol), tended to decrease acetate MP (P = 0.10), reduced the acetate:propionate (A:P) ratio (P = 0.05), and MP of branched-chain volatile fatty acids (P < 0.01). Neither in vitro organic matter digestibility nor in vitro CH4 yield were affected by CNSE inclusion (P > 0.05). Steers receiving CNSE exhibited greater (P < 0.05) final BW, dry matter intake (DMI), and average daily gain (ADG) but lesser (P < 0.05) in vivo CH4 emission rate (g/d), yield (g/kg of DMI), and intensity (g/kg of ADG). Meal length, bunk visit duration, and apparent total tract digestibility of DM increased (P < 0.05) after CNSE addition. Considering CNSE-supplemented steers spent more time in the feedbunk and exhibited higher DMI, CH4 mitigation was unlikely associated with intake reduction. The addition of CNSE to a high-grain diet in beef steers demonstrated significant improvements in animal performance and reduced CH4 emissions, as the result of shifts in ruminal fermentation patterns, favoring propionate instead of acetate concentration, leading to a reduction in the A:P ratio. CNSE shows promise as a strategy to enhance beef industry sustainability., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The rumen plays an essential role in the physiology and health of ruminants. The rumen undergoes substantial changes in size and function from birth to adulthood. The cellular and molecular mechanisms underlying these changes are not clear. This study aimed to identify the transcription factors (TFs) and signaling pathways mediating these changes in cattle. We found that the ratios of the emptied rumen, reticulum, omasum, and abomasum to body weight in adult steers were 4.8 (P < 0.01), 3.1 (P < 0.01), 6.0 (P < 0.01), and 0.8 (P = 0.9) times those in neonatal calves, respectively. The length of rumen papillae and the thickness of rumen epithelium, tunica mucosa and submucosa, tunica muscularis, and tunica serosa increased 7.4-, 2.0-, 3.0-, 2.9-, and 4.6-fold (P < 0.01 for all), respectively, from neonatal calves to adult steers. However, the density of rumen papillae was lower in adult steers than in neonatal calves (P < 0.05). The size of rumen epithelial cells was not different between neonatal calves and adult steers (P = 0.57). RNA sequencing identified 2,922 genes differentially expressed in the rumen between neonatal calves and adult steers. Functional enrichment analyses revealed that organ development, blood vessel development, Ras signaling, and Wnt signaling were among the functional terms enriched in genes downregulated in adult steers vs. neonatal calves and that fatty acid metabolism, immune responses, PPAR signaling, and Rap1 signaling were among those enriched in genes upregulated in adult steers vs. neonatal calves. Serum response factor (SRF), interferon regulatory factor 4, and purine-rich single-stranded DNA-binding protein alpha were among the major candidate TFs controlling the expression of genes upregulated, while TCF4, inhibitor of DNA binding 4, and snail family transcriptional repressor 2 were among those controlling the expression of genes downregulated in adult steers vs. neonatal calves. Taken together, these results suggest that the rumen grows by increasing the number, not the size, of cells from birth to adulthood, that the absorptive, metabolic, immune, and motility functions of the rumen are acquired or significantly enhanced during the postnatal life, and that the changes in rumen size and function from birth to adulthood are mediated by many candidate TFs, including SRF and TCF4, and many candidate signaling pathways, including the PPAR and Wnt signaling pathways., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The objective was to evaluate growth performance and carcass traits of finishing beef heifers sourced and finished in different regions in the U.S. Heifers (n = 190; initial body weight [BW] 483 ± 0.4 kg and 425 ± 1.9 kg for South Dakota [SD] and TX sourced, respectively) were used in a 2 × 2 factorial arrangement of origin state (SD vs. TX) and finishing state (SD vs. TX) was used. Heifers were allotted on day -1 to: 1) sourced from SD and finished in SD (SD-SD), 2) sourced from SD and finished in TX (SD-TX), 3) sourced from TX and finished in SD (TX-SD), and 4) sourced from TX and finished in TX (TX-TX). Heifers were weighed on d -1, 3, 15, 28, 56, 78 (TX-TX and SD-TX) and 90 (SD-SD and TX-SD). On day 0, SD-TX and TX-SD heifers were shipped to their respective finishing locations. The following morning (day 1), SD-TX and TX-SD heifers were individually weighed to determine transit shrink. To monitor transit stress effects, vaginal temperature probes were used on all SD-TX and TX-SD heifers and a portion of SD-SD and TX-TX heifers on day -1 and removed on day 3. Clinical attitude scores (CAS) were recorded on days -1, 0, 1, 2, and 3 for bovine respiratory disease symptoms. Transported heifers had decreased temperatures (P ≤ 0.01) during transit and post-transit and increased (P ≤ 0.01) vaginal temperature during loading and unloading compared to non-transported heifers. On days 0, 1, and 3 there was a shift in the distribution of heifers that had a CAS score greater than 0 for TX-TX, SD-TX, and TX-SD. Heifers endured elevated ambient temperatures (temperature-humidity index > 75) for 54% and 18% of the feeding period for TX and SD. Growth performance and carcass trait interactions were significant (P < 0.01) except for day -1 BW, percent shrink during transit, average daily gain, dressing percent, ribeye area, and liver abscess severity, which did not differ (P > 0.30). A shift in the distribution (P < 0.02) towards a greater proportion of Yield Grade (YG) 1 and Select carcasses was observed for TX versus SD. Overall, heifers transported to higher ambient temperatures had improved overall YGs but decreased dry matter intake, quality grades (QG), and limited growth recovery (45 kg lighter) following transit than non-transported heifers. Heifers transported to lower ambient temperatures recovered growth and had improved QG (P < 0.02) at the same thickness of rib fat compared to non-transported heifers but had decreased overall yield and yield grades., (© The Author(s) 2025. Published by Oxford University Press on behalf of the American Society of Animal Science.)

With the growing bourbon industry in the southeastern U.S. leading to increased production of liquid distillery byproducts, there is a pressing need to explore sustainable uses for whole stillage [containing residual grain (corn, rye, malted barley) and liquid after ethanol separation] in livestock nutrition. The objectives of this study were to evaluate the effects of increasing whole stillage inclusion on the in vitro fiber digestibility and ruminal fermentation of tall fescue hay. Ruminal contents were obtained from 2 ruminally cannulated Angus × Holstein steers (390 ± 4.49 kg BW) fed a basal diet consisting of 90% tall fescue hay and 10% cracked corn. Whole stillage was obtained from a local distillery, homogenized, and replaced water in the Goering and Van Soest buffer preparation at 0.00%, 9.06%, 18.1%, or 36.3% on a v/v basis to simulate ruminal fill of whole stillage under practical conditions. Tall fescue hay was used as the substrate and vessels were incubated for 48 h. Results were analyzed with the GLM procedure of SAS using polynomial contrast statements for statistical comparison. Increasing whole stillage inclusion linearly decreased (P = 0.002) apparent dry matter (DM) digestibility, with the lowest (quadratic: P = 0.03) coefficients for true DM and neutral detergent fiber (NDF) digestibility occurring at 36.3% whole stillage inclusion. The rate and extent of gas production, methane production, and total volatile fatty acid (VFA) concentration increased (P < 0.05) with increasing whole stillage inclusion. The final pH of the fermentation media linearly decreased (P < 0.001) with increasing whole stillage inclusion. The molar acetate, valerate, isovalerate, and isobutyrate proportions decreased (P < 0.05) with increasing whole stillage inclusion. The molar propionate proportion responded quadratically (P < 0.01), with the peak proportion occurring at 36.3% whole stillage inclusion. Increasing whole stillage inclusion linearly decreased (P < 0.001) the viable number of cellulolytic and 2-deoxyglucose-resistant cellulolytic bacteria in the fermentation media. Peptide- and amino acid-utilizing bacteria increased linearly (P < 0.001) and hyper-ammonia-producing bacterial concentration peaked (quadratic: P = 0.05) at 36.3% whole stillage inclusion. Increasing whole stillage inclusion in the in vitro ruminal media demonstrated negative effects on the fermentation of tall fescue hay, as indicated by decreased NDF digestibility, cellulolytic bacteria, pH, and branched-chain VFA proportions., (© The Author(s) 2025. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Changes in maternal nutrition during the periconceptional period can influence postnatal growth in cattle. This study aimed to identify the impact of supplementing beef cows with rumen-protected methionine (RP-Met) during the periconceptional period on their female progeny. In experiment 1, plasma methionine (Met) levels were analyzed in samples from 10 Angus crossbred, non-lactating beef cows. Cows were randomly assigned to receive 454 g of cottonseed meal with 15 g/d of RP-Met (RPM; Smartamine M, Adisseo) or not (CON) for 5 d and data were analyzed as a completely randomized design with repeated measures. A treatment-by-day interaction was observed (P < 0.001), where plasma Met concentrations increased in the RPM treatment yet remained basal in CON. In experiment 2, 114 cows were fed a roughage-based diet and randomized to receive 454 g/d of corn gluten supplemented with 15 g/d of RP-Met (RPM n = 56) or not (CON n = 58) from days -7 to 7 relative to timed-artificial insemination using sexed semen to obtain females. Amino acids were measured in plasma samples from days -8, 0, and 7 in cows. In the female progeny, body weight, withers height, body length, and heart girth were measured every 60 d from birth through weaning at an average age of 242 ± 5.8 d. Liver, adipose tissue, and longissimus dorsi muscle biopsies were collected at 187.88 ± 5.5 d of age and a subset of 20 random samples (CON = 10; RPM = 10) were selected for RNA-seq on each tissue. Data were analyzed using a generalized randomized block design with repeated measures. Methionine was increased (P < 0.01) in plasma from cows in the RPM treatment on days 0 and 7. After calving, 34 female calves (CON = 16; RPM = 18) remained in the study and no difference was observed in birth weights between treatments. Calves were taller at the withers for RPM than CON (P = 0.03; CON = 92 ± 1.0 cm; RPM = 95 ± 1 cm) but there were no effects of treatment on other measures of body size. A total of 30, 24, and 2 differentially expressed genes (DEGs; P < 0.01) were observed in liver, longissimus dorsi muscle, and adipose tissue respectively. In summary, feeding RP-Met to cows in the periconceptional period resulted in female calves that were taller than CON before weaning. There were DEGs in the tissue samples but no other changes in measurements associated with body size. In conclusion, supplementation of RP-Met to beef cows during the periconceptional period caused minor changes in the female offspring before weaning., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Our objective was to evaluate the effect of a multispecies fungal extract (MFE) on growth performance, apparent total tract digestibility (ATTD), fermentation characteristics, and rumen microbiome composition of beef cattle fed forage-based diets. For experiment 1, ruminally cannulated Angus × SimAngus cows (n = 4; body weight [BW] = 569 ± 21 kg) were used in a randomized crossover design with two 21-d study periods and a 23-d washout period to evaluate the effect of dietary inclusion of an MFE on in situ digestion, ruminal fermentation, and the composition of the rumen microbiome. Treatments consisted of a forage-based diet with or without the inclusion of a MFE. Rumen samples were collected on days 5, 10, and 20. Experiment 2 evaluated different inclusion rates of the MFE in a randomized complete block design using Angus × SimAngus-crossbred steers (n = 80; BW = 370 ± 44 kg). Steers were blocked by BW and randomly assigned to one of four treatments (2 pens/treatment): diet with no MFE, 0.02%, 0.04%, and 0.08% of the MFE (dry matter [DM] basis). Steers were fed a forage-based diet for 122 d. Subsets of 10 steers/treatment were randomly selected for the determination of ATTD on d 20, 40, and 60. All data were analyzed using the MIXED procedure of SAS. In exp 1, adding the MFE to the diet tended to increase the ruminal disappearance rate of the DM on day 10 (P = 0.06). No interactions or treatment effects were observed for the short-chain fatty acid profile of the rumen fluid (P ≥ 0.13). Metagenomic analysis of the rumen microbiome showed an MFE × d interaction for the Fibrobacter genus (P = 0.01), which on day 20 was less abundant in the rumen of cows fed the MFE. In exp 2, steers supplemented with 0.04% of MFE had a lower average daily gain and were lighter at the end of the experiment (cubic, P ≤ 0.04) compared to steers supplemented with 0.02% MFE. Steers fed the diet with 0.02% of MFE had the greatest gain-to-feed ratio among the MFE-supplemented groups (cubic, P < 0.01). Dietary inclusion of the MFE increased neutral detergent fiber digestibility (linear, P = 0.05). Steers supplemented with 0.04% of MFE had the greatest acid detergent fiber digestibility among treatments (quadratic, P = 0.03). Collectively, results showed that ruminal disappearance rate and digestibility of forage-based diets increased due to MFE supplementation, but did not translate into growth performance improvements or beneficially alter rumen fermentation., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Two experiments were conducted to assess the effects of feeding whole-plant sorghum silage (WPSS) with different kernel processing techniques (KP). Experiment 1 contrasted KP for WPSS on intake and apparent total tract digestibility (ATTD) in beef heifers (n = 24, 13 ± 1 mo, 267 ± 10.9 kg of initial body weight [BW]) housed in individual pens (36 m2). Grain sorghum was harvested at hard dough, switching the kernel processor to obtain the WPSS treatments: A) unprocessed (UNP), B) conventionally processed (CONV), and C) shredlage processed (SHRD). Heifers (8/treatment) received ad libitum WPSS from their respective treatment, plus soybean meal top-dressed at 0.5% BW/d (DM basis). Feed, and feces were collected for 5 d; feed was offered once daily, and orts were collected the following day. Fecal samples were collected twice daily, and ATTD was determined using indigestible neutral detergent fiber (NDF) as a marker. Data were analyzed as a completely randomized design, with heifer as the experimental unit, and the following contrasts were performed 1) Processing: UNP vs. (CONV + SHRD) and 2) Processor: CONV vs. SHRD. Processing WPSS increased the ATTD of starch by 4.5% (P = 0.01), reduced fecal starch by 27.5% (P = 0.01), and reduced the change of NDF from feed to orts by 39% (P < 0.01). Heifers fed SHRD had 6.6% greater ATTD of NDF than CONV-fed heifers (P = 0.04). Experiment 2 evaluated the effects of feeding either SHRD or CONV-processed WPSS on growth performance of beef heifers. Whole-plant grain sorghum was harvested at the hard-dough stage, switching the KP as in experiment 1. Angus heifers (n = 96, 15 ± 1 mo, 249.6 ± 28.6 kg of BW) were blocked by initial BW, and randomly assigned to pens (8 heifers/pen, 6 pens/treatment). Diets consisted, all on a DM basis, of WPSS, either SHRD or CONV, at 90.5%, expeller soybean meal at 7.0%, and a vitamin-mineral-protein concentrate at 2.5%. After 14-d of adaptation, growth was measured for 56 d, and feed was offered once daily. Data were analyzed using a randomized complete block design with the pen as the experimental unit. Heifers fed CONV had a 9.6% greater gain-to-feed ratio (P = 0.05) and a 7.4% greater Kleiber ratio (P = 0.05) than SHRD-fed heifers. Apparent net energy of gain tended to be 7.1% greater in CONV-fed heifers (P = 0.06). In conclusion, kernel processing WPSS increased starch digestibility and reduced fecal starch concentration. Using SHRD increased NDF digestibility and feeding CONV-processed WPSS resulted in enhanced growth performance., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Seventy-two nonlactating, pregnant Angus cows (initial body weight [BW] = 637 ± 13 kg; body condition score [BCS] = 5.5 ± 0.07 yr; and age = 6.1 ± 0.57; exposed to artificial insemination = 54 and bull = 18) were ranked by pregnancy type, BW, and BCS and assigned to receive a supplement containing: 1) Cu, Mn, and Zn sulfate source (INR; n = 24), 2) Cu, Mn, and Zn organic-complexed source (ORG; n = 24), or 3) Cu, Mn, and Zn hydroxychloride source (HDX; n = 24). From day 11 (days of gestation 195 ± 5.1) to calving, cows were allocated to rangeland pasture. From day 0 until calving, cows were gathered and fed the treatments thrice a week. Cow BW and BCS were recorded, and blood was collected on days 11 and 10, upon calving, and at weaning. Liver biopsies were performed in all cows on day 10 and upon calving (cows and calves). Longissimus muscle (LM) biopsies were performed, and blood was collected in all calves upon calving. Calves were weaned on day 260, backgrounded for 99 d, and then sent to a commercial feedyard. Calves blood samples were collected on days 245, 260, 264, 268, 275, 280, and 288. No differences were detected (P ≥ 0.31) for cow BW and BCS changes among treatments during gestation, and mineral sources did not improve (P ≥ 0.16) mineral liver concentrations of Zn, Mn, Se, and Co at parturition. However, there was a tendency (P = 0.07) for HDX to have improved liver Cu concentration vs. ORG and INR cows. Cows fed HDX and ORG had improved (P ≤ 0.03) BCS at weaning, and BCS changed from parturition to weaning vs. INR cows. No treatment differences were detected (P ≥ 0.21) for calf birth measurements, IgG levels, mRNA expression of hepatic enzymes, or LM genes associated with muscle and adipose tissue development. At weaning and during the backgrounding, no treatment differences were detected (P ≥ 0.21) for offspring performance, health outcomes, plasma cortisol, serum nonesterified fatty acids, and serum β-hydroxybutyrate. However, a tendency for a treatment × day interaction was detected (P = 0.07) for haptoglobin concentrations, which was reduced (P < 0.01) in calves from cows supplemented with HDX vs. calves from cows supplemented with ORG and INR 15 d after weaning. No treatment effects were noted (P ≥ 0.35) for final BW, feedyard average daily gain, and carcass traits between treatment groups. Overall, different sources of Cu, Mn, and Zn supplemented to late-gestating beef cows yielded similar cow-calf productive responses from birth to finishing., (© The Author(s) 2025. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

This study aimed to quantify the effects of physiological status (PS) and the potential interaction of this factor with days of pregnancy (DOP) on beef heifers' weight variation, intake, and digestion kinetics. Twelve rumen-cannulated zebu beef heifers (n = 7 pregnant; n = 5 nonpregnant) were used. Heifers were placed in individual pens and fed medium-quality corn silage plus a protein-based supplement. Heifers' body weight was assessed at the beginning and end of each collection period. The feed intake was measured daily. Target outcomes were evaluated at 107, 170, 208, 240, 267, and 286 DOP. The apparent total-tract digestibility was determined considering the fecal spot collection, during 5 d within each collection period. Omasal and ruminal digesta samples were collected at 107, 208, and 267 DOP for determination of partial digestibilities and diet component outflow. For these purposes, Co-EDTA and indigestible neutral detergent fiber (iNDF) were used as indicators. All data were analyzed using a mixed model framework, considering the PS and DOP as fixed effects and the animal as a random effect. Significant differences were declared when P ≤ 0.05. Pregnant heifers showed an increase in body reserves (+35 kg) from 107 to 240 DOP, but experienced a decrease in shrunk body weight (-36 kg) from 240 to 286 DOP. The intake of dry matter (DM), organic matter (OM), crude protein (CP), and ash- and protein-free neutral detergent fiber (apNDF) increased as pregnancy progressed (P < 0.04). The apparent total-tract digestibility of DM tended to be lower (P = 0.09), and the apparent total-tract digestibility of apNDF was reduced (P < 0.01) in pregnant heifers. The digestibility of CP was higher (P < 0.01) on days 267 and 286 in pregnant cows compared to nonpregnant heifers. The ruminal digestibility of OM tended to be lower (P = 0.09) in pregnant beef heifers, while the ruminal digestibility of apNDF was lower (P = 0.02) in pregnant heifers compared to nonpregnant ones. The ruminal pool of wet matter and DM was lower (P ≤ 0.01) in pregnant heifers at 267 DOP. In all periods, the outflow tended to be greater (P = 0.06) in pregnant heifers compared to nonpregnant heifers. Pregnant beef heifers exhibited a faster (P = 0.01) digesta passage rate during late gestation. In conclusion, late-gestating beef heifers are less efficient in extracting energy from feed compared to nonpregnant animals., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The current study was designed to evaluate the effect of particle size (PS) and inclusion level of wheat straw (WS) obtained from genetically improved wheat on the performance and feeding behavior of Sahiwal cows. Twelve multiparous, mid-lactating Sahiwal cows (DIM 135 ± 25, mean ± SD; 12.8 ± 1.6 kg/d milk, 331 ± 21 kg of BW) were split into groups of 4 and subjected to each of four treatments in a 2*2 cross-over design. For experimental diets, TMR differed in the length and inclusion level of the WS component in that diet, (1) straw chopped with a 2 cm screen (Fine chopped- FC, and inclusion, i.e., FCA = 20% and FCB = 30%) or (2) straw chopped with a 4 cm screen (long chopped-LC, and inclusion, i.e., LCA = 20% and LCB = 30%). The increased dry matter (DM) intake (9.10 kg/d) and crude protein (CP) intake (1.25 kg/d) were observed in FCA. The diets with the shorter PS and higher inclusion (i.e., FCB) exhibited higher neutral detergent fibre (NDF) intake (3.77 kg) and acid detergent fibre (ADF) intake (2.72 kg). The findings of digestibility showed higher DM-digestibility in LCA (55.24%). Meanwhile, the higher digestibility of CP (52.9%) and ADF (36%) was found in LCB, and NDF (38.5%) was observed in LCA. Moreover, cows receiving FCA diets showed improved milk (15.5 kg/d), 3.5%FCM (17.76 kg/d), fat (0.683/d Kg), and protein (0.516 kg/d) yields and production efficiency. However, the milk composition was improved in cows fed with LCB diets. Furthermore, the behavioural activities showed higher eating (i.e., 228.3 min/day), rumination (391 min./day), and chewing (617.9 min./day) activities in LCB diets. Whereas, the lying activity (568.5 min/day) was greater in FCA-fed cows. Our study suggests that incorporating fine-chopped WS @ 20% improves the overall production performance and feeding behavior of the cows., Competing Interests: Declarations. Ethical statement: All the experimental procedures were approved by the Institutional Animal Care and Use Committee of the Institute of Animal and Dairy Sciences and the Director of Graduate Studies at the University of Agriculture, Faisalabad (Permit Number: DGS/16421–24, dated 22–05–2023). Conflicts of interest: The author declares no conflicts of interest., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

In livestock breeding, offspring of a particular sex are often favoured. Various biological mechanisms influence the offspring sex ratio (OSR). It has been hypothesised that maternal body condition/nutritional status influence OSR. We analysed the relationship between the nutritional status of the cow and OSR. The analysed dataset contained 40,913 milk recordings of 39,192 cows from 3625 farms. Nutritional status was estimated based on the fat-to-protein (F:P) ratio and urea content in milk in the seven to fourteen days prior to conception. Somatic cell count (SCC) was also considered. Cows with > 150,000 SSC were analysed separately. When SSC was normal (≤150,000), high urea with high F:P resulted in a higher probability of male offspring (61 %), with OSR significantly deviating towards male (1.47). Conversely, a high urea level and low F:P resulted in a higher probability of female offspring (57 %), with OSR significantly in favour of females (0.79). At normal or low milk urea, the sex of the offspring did not change within F:P classes. The sex ratio did not deviate from 1:1 when F:P and urea were in the normal range. When SCC was high, the probability of particular sex did not change significantly in either combination of F:P and urea, but OSR showed a tendency toward males (OSR>1) when F:P and urea were low or normal. Our results confirmed the influence of maternal nutritional status on the offspring sex. Thus, adjusting nutrition in the pre-insemination period seems to be a way to influence the sex ratio of offspring in dairy cows., Competing Interests: Declaration of Competing Interest We wish to draw the attention of the Editor to the following facts which may be considered as potential conflicts of interest and to significant financial contributions to this work. [OR] We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us. We confirm that we have given due consideration to the protection of intellectual property associated with this work and that there are no impediments to publication, including the timing of publication, with respect to intellectual property. In so doing we confirm that we have followed the regulations of our institutions concerning intellectual property. We further confirm that any aspect of the work covered in this manuscript that has involved either experimental animals or human patients has been conducted with the ethical approval of all relevant bodies and that such approvals are acknowledged within the manuscript. We understand that the Corresponding Author is the sole contact for the Editorial process (including Editorial Manager and direct communications with the office). He/she is responsible for communicating with the other authors about progress, submissions of revisions and final approval of proofs., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

India is the largest milk producer contributing 25 % to the global production. From a mere 17 million tons (MTs) in 1951, milk production increased to an inconceivable 230 MTs in 2023. Nondescript cows and buffaloes were the main milk animals. Since 1965, nationwide programs for cross breeding native cattle with exotic milk breeds such as Jersey, Holstein Friesian (HF) and Brown Swiss (BS) and upgradation of buffalo breeds along with disease eradication, feed and fodder development and provision of veterinary and extension services were implemented. Now 75 % of the milk in India is produced by the native, exotic and crossbred cows (43 %) and native breeds of buffaloes (32 %). National Dairy Development Board (NDDB) created dairy cooperatives, an Indian innovation to connect rural milk producers to urban and semi-urban consumers. These cooperatives transformed subsistence dairy farming into a profitable rural enterprise and created millions of jobs. Due to the success of the above activities, since 1998 India continues to produce the highest volumes of milk in the world. It is envisioned to increase (i) milk production to 450 million tons (MTs) (one-third of the global production) (ii) gain a share of 15 % in global milk and milk products exports and (iii) build sustainable green practices to match global standards during the next 25 years. India is increasingly deploying artificial insemination (AI) with sex sorted-frozen semen, embryo transfer and in vitro production of embryos using sex sorted semen, progeny testing and genomic selection to improve reproduction and productivity among dairy animals. Mitigation of disease burden is undertaken through nationwide vaccination against diseases such as Foot and Mouth, TB, Brucellosis etc. Nutritious fodder crops and feed additives that support higher productivity and reduce enteric methane emissions are promoted. Management and interventional practices such as better nutrition, amelioration of summer stress, oestrus synchronisation etc., are increasingly implemented. Use of internet enabled technology services (IETS) for extension activities, mobile veterinary and animal husbandry services are rapidly becoming commonplace. All these practices portend greater achievements in milk production in the fore-seeable future. Achievements, aspirations, accosts, approaches and appraisal are presented., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Temperament (docility) is a key breeding goal in the cattle industry due to its direct relationship with animal welfare, cattle handler's safety and animal productivity. Over the past six decades, numerous studies have reported heritability estimates for temperament-related traits in cattle populations ranging from low to high values. Therefore, the primary objective of this study was to perform a comprehensive systematic review with meta-analysis to obtain weighted estimates of heritability for temperament-related traits in worldwide cattle populations. After data editing and quality control, 106 studies were included in the systematic review, of which 29.2% and 70.8% reported estimates of heritability for temperament-related traits in dairy and beef cattle populations, respectively. Meta-analyses were performed for 95 heritability estimates using a random model approach. The weighted heritability estimates were as follow: (a) flight score at weaning = 0.23 (95% CI: 0.15-0.32); (b) flight speed at weaning = 0.30 (95% CI: 0.26-0.33); (c) joint analysis of flight speed and flight score at weaning = 0.27 (95% CI: 0.22-0.31); (d) flight speed at yearling = 0.26 (95% CI: 0.21-0.30); (e) joint analysis of flight speed at weaning and yearling = 0.27 (95% CI: 0.24-0.30); (f) movement score = 0.12 (95% CI: 0.08-0.15); (g) crush score at weaning = 0.21 (95% CI: 0.17-0.25); (h) pen score at weaning = 0.27 (95% CI: 0.19-0.34); (i) pen score at yearling = 0.20 (95% CI: 0.17-0.23); (j) joint analysis of pen score at weaning and yearling = 0.22 (95% CI: 0.18-0.26); (k) cow's aggressiveness at calving = 0.10 (95% CI: 0.01-0.19); (l) general temperament = 0.13 (95% CI: 0.06-0.19); (m) milking temperament = 0.16 (95% CI: 0.11-0.21); and (n) joint analysis of general and milking temperament = 0.14 (95% CI: 0.11-0.18). The heterogeneity index ranged from 0% to 77%, and the Q-test was significant (p < 0.05) for four single-trait meta-analyses. In conclusion, temperament is moderately heritable in beef cattle populations, and flight speed at weaning had the highest weighted heritability estimate. Moreover, between-study heterogeneity was low or moderate in beef cattle traits, suggesting reasonable standardization across studies. On the other hand, low-weighted heritability and high between-study heterogeneity were estimated for temperament-related traits in dairy cattle, suggesting that more studies are needed to better understand the genetic inheritance of temperament in dairy cattle populations., (© 2024 The Author(s). Journal of Animal Breeding and Genetics published by John Wiley & Sons Ltd.)

This study utilized Bayesian inference in a genome-wide association study (GWAS) to identify genetic markers associated with traits relevant to the adaptation of Hereford and Braford cattle breeds. We focused on eye pigmentation (EP), weaning hair coat (WHC), yearling hair coat (YHC), and breeding standard (BS). Our dataset comprised 126,290 animals in the pedigree. Out of these, 233 sires were genotyped using high-density (HD) chips, and 3750 animals with medium-density (50 K) single-nucleotide polymorphism (SNP) chips. Employing the Bayes B method with a prior probability of π = 0.99, we identified and tagged single nucleotide polymorphisms (Tag SNPs), ranging from 18 to 117 SNPs depending on the trait. These Tag SNPs facilitated the construction of reduced SNP panels. We then evaluated the predictive accuracy of these panels in comparison to traditional medium-density SNP chips. The accuracy of genomic predictions using these reduced panels varied significantly depending on the clustering method, ranging from 0.13 to 0.65. Additionally, we conducted functional enrichment analysis that found genes associated with the most informative SNP markers in the current study, thereby providing biological insights into the genomic basis of these traits., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Enhancing reproductive performance is a key strategy to mitigate involuntary culling rates, thereby extending productive life (PL) and ultimately improving profitability in dairy cattle herds. A piecewise Weibull proportional hazards model was used to investigate the effect of several important reproductive traits on PL in Holstein dairy cows. Data comprised 200,747 lactation records from 82,505 cows sired by 1952 bulls across 36 dairy herds. PL was defined as the number of days from the first calving to the last milk record or censoring. The statistical model accounted for the time-dependent fixed effects of changes in herd size, year-season, milk production, fat and protein contents, and the time-independent fixed effect of age at first calving. Herd-year and sire effects were also included as random effects. Reproductive traits include calving traits such as calving ease (CE), calf size (CZ), and calf survival (CS), as well as female fertility traits such as number of inseminations per conception (NI), days from calving to first service (CFS), days from first service to conception (FSC), and days open (DO). All reproductive traits had a significant effect on PL (p < 0.001). Each reproductive trait was analysed separately. The relative risk (RR) of being culled increased as the severity of calving difficulties increased in both primiparous and multiparous cows. Cows that calved small or large calves showed a higher risk of being culled compared with those that calved medium size calves. The increased RR of culling was observed only for primiparous cows that gave birth to dead calves. In addition, cows that required more NI, a longer CFS, FSC, and DO had shorter longevity. These insights can deepen our comprehension of the factors affecting PL and provide information for refining management and breeding strategies, which could lead to increased profitability and sustainability in Iranian dairy farming., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

The objective was to evaluate the effect of maternal exposure to heat stress conditions at different stages of pregnancy on the reproductive performance and antral follicle count of progeny. The study was conducted at five commercial dairy farms located in southeastern Brazil. Retrospective data (2002 and 2015) on reproductive indices of daughters of Holstein cows that were exposed to heat stress conditions in the first (n = 447), second (n = 729) or third (n = 746) trimester of pregnancy and daughters of cows not exposed to heat stress (n = 359) were analyzed. Antral follicle count (AFC) and ovarian size were determined in a subgroup of animals (n = 242) by transrectal ultrasound. Statistical analysis was performed using the SAS GLIMMIX procedure. The number of services after first calving was lower in daughters of cows not exposed to heat stress conditions than in those exposed during different trimesters of pregnancy (P = 0.03). The calving interval was longer for daughters of cows exposed to heat stress conditions in the second and third trimesters of pregnancy than for those not exposed to heat stress (P = 0.01). In addition, the probability of pregnancy at first AI, (P = 0.01) and the AFC (P = 0.001) were greater in daughters of cows not exposed to heat stress conditions than in those exposed during the different phases of the gestational period. These findings indicate that maternal heat stress in different stages of pregnancy negatively affect the future fertility and AFC of bovine offspring., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In tropical beef cattle production systems, animals are commonly raised on pastures, exposing them to potential stressors. The end of gestation typically overlaps with a dry period characterized by limited food availability. Late gestation is pivotal for fetal development, making it an ideal scenario for inter- and transgenerational effects of the maternal gestational environment. Intergenerational effects occur due to exposure during gestation, impacting the development of the embryo and its future germline. Transgenerational effects, however, extend beyond direct exposure to the subsequent generations. The objective of the present study was to verify these effects on the post-natal performance of zebu beef cattle. We extended the use of a reaction norm model to identify genetic variation in the animals' responses to transgenerational effects. The inter- and transgenerational effects were predominantly positive (-0.09% to 19.74%) for growth and reproductive traits, indicating improved animal performance on the phenotypic scale in more favourable maternal gestational environments. Additionally, these effects were more pronounced in the reproductive performance of females. On average, the ratio of direct additive genetic variances of the slope and intercept of the reaction norm ranged from 1.23% to 3.60% for direct and from 10.17% to 11.42% for maternal effects. Despite its relatively modest magnitude, this variation proved sufficient to prompt modifications in parameter estimates. The average percentage variation of direct heritability estimates ranged from 19.3% for scrotal circumference to 33.2% for yearling weight across the environmental descriptors evaluated. Genetic correlations between distant environments for the studied traits were generally high for direct effects and far from unity for maternal effects. Changes in EBV rankings of sires across different gestational environments were also observed. Due to the multifaceted nature of inter- and transgenerational effects of the maternal gestational environment on various traits of beef cattle raised under tropical pasture conditions, they should not be overlooked by producers and breeders. There were differences in the specific response of beef cattle to variations in the quality of the maternal gestational environment, which can be partially explained by transgenerational epigenetic inheritance. Adopting a reaction norm model to capture a portion of the additive variance induced by inter- or transgenerational effects could be an alternative for future research and animal genetic evaluations., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Greenhouse gas (GHG) emissions from livestock ruminants, particularly methane (CH 4 ), nitrous oxide, and indirectly ammonia (NH 3 ) significantly contribute to climate change and global warming. Conventional monoculture swards for cattle feeding, such as perennial ryegrass or Italian ryegrass, usually require substantial fertiliser inputs. Such management elevates soil mineral nitrogen levels, resulting in GHG emissions and potential water contamination. Mitigating the environmental footprint of these farming practices requires sustainable alternative feeding strategies for cattle production. Multispecies grassland swards (grass + legumes or legumes + herbs) represent a promising alternative to monoculture grassland swards for cattle nutrition due to their reduced nitrogen requirements, excellent herbage yield, and polyphenolic compounds (tannins, formononetin, luteolin, quercetin, and acteoside) which may have positive effects on animals. This study investigated the effects of selected multispecies grassland swards (plant blends) on in vitro ruminal fermentation and DM digestibility. Three experimental blends of plants cultivated without fertilisers were utilised: (1) perennial ryegrass (PRG) + red clover (RC), (2) chicory (C) + red clover (RC), and (3) Tonic plantain (PLA) + red clover (RC). The control blend included perennial ryegrass (PRG), and red clover (RC) cultivated with fertiliser. The in vitro trial showed a reduction in CH 4 production and ruminal NH 3 concentration (by 14.7 and 28.8%, respectively; P < 0.01) in the PLA+RC blend compared to the control. This plant blend also increased propionate concentration (P < 0.05) and reduced acetate and butyrate concentrations and the acetate-propionate ratio (P < 0.01). Additionally, the total protozoal and methanogen counts were mostly reduced by the PLA+RC blend (P < 0.01) among all blends investigated. In conclusion, the Tonic plantain and red clover blend (PLA+RC) cultivated without fertilisers have the potential to be utilised as a sustainable alternative feed source for climate-friendly cattle production, aligning with the aims of the European Climate Care Cattle Farming project., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Efficient and sustainable reproduction and production of cattle and goats are vitally important for ensuring global food security. There is a need for potent biomarkers to accurately evaluate semen quality and predict male fertility. Although there is a reasonable set of biomarkers identified in bull sperm, there is a significant lack of such information in buck sperm along with a lack of transfer of proven technologies in goat reproductive biotechnology. These gaps are important problems because they are preventing advances in fundamental andrology and applied science of goat production. Both cattle and goats are ruminants, and they share significant similarities in their genetics and physiology although subtle differences do exist. This review harnesses the power of utilizing the knowledge developed in bull sperm to generate information on buck sperm fertility markers. These include genomic, functional genomic, epigenomic fertility markers. Revealing molecular underpinnings of such similarity and diversity using systems biology is expected to advance both fundamental and applied andrology of livestock and endangered species., Competing Interests: Declaration of Competing Interest The authors of this manuscript declare that they have no conflicts of interest., (Copyright © 2024. Published by Elsevier B.V.)

Live yeast (Saccharomyces cerevisiae) products have the potential to increase milk yield of dairy cows in early lactation by improving rumen fermentation. Greater milk yields, however, are sometimes associated with poorer reproductive performance. This study aimed to assess the effect of a live yeast supplement on milk yield, methane emissions and reproduction indicators in high-yielding dairy cows. Fifty Holstein cows were paired according to month of calving, parity and predicted milk yield, and allocated at random to either a Control diet or a diet containing live Yeast (Actisaf® Sc 47, 1 × 10 10 cfu/g, Phileo by Lesaffre) supplying 1 × 10 11 cfu/cow per day (10 g). Diets were fed to cows from 7 to 128 days in milk. Live yeast resulted in higher yields of milk (50.1 vs 47.5 kg/day), energy-corrected milk (ECM; 50.5 vs 47.7 kg/day), fat-corrected milk (49.2 vs 46.3 kg/day) and milk fat (1 945 vs 1 823 g/day), compared with Control. There was no effect of treatment on DM intake (DMI), so cows fed on Yeast had greater feed efficiency (2.11 vs 1.98 kg ECM/kg DMI). Enhanced milk yield and feed efficiency were attributed to higher digestibility coefficients for DM (0.80 vs 0.77), NDF (0.66 vs 0.62) and gross energy (0.81 vs 0.78) in cows fed on Yeast compared with Control. Rumen pH, redox potential and volatile fatty acid concentrations, methane emissions, plasma metabolites and immunity indicators, and health events were not affected by treatment. There was no effect of treatment on days from calving to first milk progesterone rise above 3 ng/ml, days to first insemination, days to conception, conception rate, number of inseminations or incidence of atypical ovarian cycles. It was concluded that live yeast enhanced digestibility, milk yield and feed efficiency in high-yielding dairy cows, and that despite increased milk yield, methane emissions, reproduction and health indicators were maintained at the same levels as control cows., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)