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Bovine respiratory disease is a leading health problem in feedlot cattle. Identification of affecting genes is essential for selection for decrease sensitivity. Chromosome X is a special attractive target for gene mapping in light of reports on both sexual dimorphism in immunity and higher susceptibility of males to this disease. However, diagnosis is challenging and clinical signs often go undetected. Kosher scoring of lung adhesions was used as a cost-effective proxy diagnosis. Selective DNA pooling was applied for cost-effective mapping of regions associated with sensitivity to the disease on chromosome X in Israeli Holstein male calves. A total of 9 regions were found, more than twice of any of the autosomes. All regions overlapped or were very close to previously reported regions. Bioinformatics survey found candidate-by-location genes in these regions. Functional analyses identified candidates-by-function among these genes. Network analyses connected the genes and found possible relations of the genes and the networks with morbidity, and specifically with sensitivity to bovine respiratory disease. The relatively large number of affecting regions and the candidate genes on the sex chromosome may explain part of the higher susceptibility of males and provide genomic and management targets for mitigating this disease. [ABSTRACT FROM AUTHOR]

Concerns for farm animal welfare have led to the use of environmental enrichment to stimulate natural behaviours and promote positive emotions. In cattle, the provision of brushes is sometimes recommended but their use in calves and the effects they may have are not well established. The use of precision technologies enables the collection of detailed behavioural data that can be used as welfare indicators. Here we use ultra-wideband location sensors to measure activity and play, along with automatic milk feeders to measure feeding. We assessed the effects of stationary brushes on the behaviour of 226 dairy calves for up to 72 days. Half of the calves had access to the brushes for half of the experimental period. Using a mixed-effects linear model we showed that when brushes were present calves had significantly higher activity, fed slower, had fewer interruptions in their meals and spent less time around the feeder, suggesting reduced competition. Furthermore, calves that had access to brushes during the trial were more active and playful, even on days when the brushes were not available, compared to the control group. This finding indicates for the first time that enrichment may have a lasting effect on calf behaviour and welfare. [ABSTRACT FROM AUTHOR]

Introduction: Antimicrobial resistance (AMR) is one of the leading public health threats globally. AMR genes can be transferred between bacteria through lateral gene transfer, and AMR organisms can spread through environments by contaminated water, agriculture and animals. Thus, widespread environmental dissemination of bacteria and lateral gene transfer facilitate AMR transmission pathways. Farm environments in dairy and calf production are known to harbour AMR bacteria that pose a risk for food contamination and to workers in direct or indirect contact with animals. Escherichia coli is present in farm environments and is known to participate in lateral gene transfer, providing a good marker of resistance genes in each environment. Methods: In this study, E. coli from nine cohorts of calves was isolated at different time points from nine barns, nine trailers and one slaughterhouse environment in a single special‐fed veal calf production facility. The antimicrobial susceptibility to 15 antimicrobials, classified as highly or critically important by the World Health Organization, was characterised for E. coli isolates using Kirby–Bauer disk diffusion. Results: The highest proportion of isolates showing multidrug resistance was present in barn environments (51.7%), where calves were housed from their arrival at < 2 weeks of age until they were transported to slaughter. Additionally, 15 E. coli isolates were resistant to 11 of the 15 antimicrobials tested. Trailer and slaughterhouse environments had greater prevalence of resistance after accommodating calves, including resistance to third‐generation cephalosporins. Conclusion: These data highlight the importance of calf environments in the dissemination of resistant bacteria and gives insight into where interventions could be most effective in combatting antimicrobial‐resistant bacteria that could infect humans and livestock. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Protein-encapsulated fat (PEF) blends are routinely used for manufacturing calf milk replacers (MR). The use of PEF blends improves fat mixability to ensure MR when mixed and fed as a homogeneous solution for neonatal calves. A new alternative PEF based on choice white grease (CWG) has been developed to improve its mixability and solubility to ensure a homogeneous MR solution. The alternative PEF is hypothesized to support similar growth performance (ADG, DMI, and feed efficiency) of neonatal calves and potentially reduce costs. The study objective was to evaluate CWG PEF as an alternative to a standard animal lard–tallow (ALT) PEF blend to mix a MR to be fed to Holstein calves. A total of 40 Holstein bull calves (2–5 d old) were blocked by BW and randomly assigned to 1 of 2 treatments (n = 20/treatment) using a randomized complete block design. The treatments were (1) CWG used to manufacture a PEF blend, and (2) ALT used to manufacture a PEF blend. The PEF blends were then used to manufacture 2 experimental MR. Both MR were formulated to contain a ratio of 22% CP to 20% fat with Met, Lys, Thr, Trp, and Val AA specifications, and fed twice per day along with ad libitum 22% CP mini-pelleted calf starter (CS) and water. The MR were fed at 15% solids at 0630 and 1800 h, fed at 0.567 kg/d for d 1 to 14, increased to 0.85 kg/d for d 15 to 35, and reduced to once per day at 0.425 kg/d for d 36 to 42 to facilitate weaning at 42 d with ad libitum CS fed for the remainder of the 56-d study. Calves fed CWG and ALT PEF blends were similar (P > 0.10) in BW gain (37.4 and 35.9 kg for CWG and ALT, respectively), ADG (679.8 and 652.7 g/d), CS DMI intake (0.69 and 0.67 kg/d), total DMI (1.19 and 1.17 kg/d) and feed conversion (0.559 and 0.543 kg/kg). No significant differences were detected in frame gains and fecal scores among treatments. Choice white grease can be used to manufacture a PEF blend for use in manufacturing MR for feeding neonatal calves by maintaining growth performance and health at potentially lower cost. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Optimizing rumen development is key to preparing calves for weaning; however, it is unclear what effect rumen development has on calf health via ruminal infusion. This study investigated the effects of ruminal short-chain fatty acid (SCFA) concentrations and pH on hematology, gut morphology, and inflammation of liver and rumen tissues in dairy calves. Holstein calves (n = 32) had the rumen cannulated within the first week of life and at wk 2 were blocked by BW and randomly assigned in a 2 × 2 factorial arrangement of treatments. The treatments included 2 different SCFA concentrations (10 vs. 285 m M) and pH levels (5.2 vs. 6.2), yielding 4 treatment groups: low SCFA, low pH (LS-LP); low SCFA, high pH (LS-HP); high SCFA, low pH (HS-LP); and high SCFA, high pH (HS-HP). On wk 3, 5, and 7, calves underwent a 4-h reticulorumen wash procedure with a physiological buffer containing the various treatments. Blood samples were collected weekly after feeding. Rumen biopsies were taken after each infusion, and liver and rumen samples were harvested at necropsy at wk 7. Data were analyzed with repeated measures, using week, SCFA, and pH as fixed effects. Low rumen pH increased respiration rate, but no other changes in clinical parameters were observed. No differences were detected in red blood cells or platelet numbers. Total white blood cell numbers decreased in the LS-LP group from wk 5 to 7 but increased in the HS-LP group along with hemoglobin and the hematocrit during the same period. Cortisol and BHB levels were unchanged by treatment or time, whereas haptoglobin decreased over time regardless of treatment. Calf liver morphology was unaffected by treatment; ruminal tissue changes associated with epithelial cell sloughing tended to increase with low SCFA, and mucosal eosinophil infiltration increased with high SCFA. Gene expression was unchanged by treatment in both rumen (barrier function and inflammation) and liver (inflammation). Overall, the data demonstrate that stress and inflammatory responses can be affected by changing rumen environments. Notably, these changes are transient as values returned to pretreatment baseline levels after a period as short as a week. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Purchase dependent calf rearing systems, such as the white veal industry, systematically rely on antimicrobial mass medication (metaphylaxis) to counter respiratory tract infections. Despite mounting criticism, the industry fears that without metaphylaxis, mortality would drastically increase. This randomized clinical trial aimed to compare the efficacy of a quick thoracic ultrasonography (qTUS) individualized treatment length between oxytetracycline (OTC) and florfenicol (FF). Regression of maximum consolidation depth <1 cm was used as a criterion for cure and to stop antimicrobial treatment. Additionally, the study assessed the associations of consolidation depth at treatment initiation with cure and treatment duration. The trial involved 320 veal calves, randomly assigned into one of 2 groups: one receiving OTC (n = 160) and the other FF (n = 160) on d 1 (2-d metaphylaxis). Clinical scoring and qTUS were done on d 1 and every 48 h for a 10-d period. After d 1, only calves with consolidations ≥1cm were given further treatment. On each time point, maximum consolidation depth was used to categorize calves into 4 qTUS categories: healthy (no consolidation), mild pneumonia (consolidation <1 cm), moderate pneumonia (consolidation 1–3 cm) and severe pneumonia (consolidation ≥3 cm). Cure, treatment duration and the number of antimicrobial dosages (NAD) were compared between treatment groups. In addition, pathogen identification and antimicrobial susceptibility testing was performed on isolates from nonendoscopic broncho-alveolar lavage fluid. On d 1, 30.0% (96/320) of the calves had consolidation ≥1cm, which increased to 50.9% (162/318) by d 9. After single metaphylactic treatment, cure was 20.9% (9/43) and 20.9% (9/43) in the OTC and FF group, respectively. Calves with severe pneumonia had lower odds to be cured after first treatment than calves with moderate pneumonia (odds ratio = 0.17; 95% CI: 0.04–0.63). By d 9, final cure of the initial cases was 27.9% in both the OTC and FF groups. In both groups, cure was similar at all observation points. Overall, final cure of all calves with either moderate or severe pneumonia during the trial was 41.2% (52/102) and 19.0% (12/63), respectively. Median (Med) treatment duration was 4 d (interquartile range [IQR] = 2–6; minimum [Min] = 2; maximum [Max] = 8) and was similar in both treatment groups. Treatment duration for calves with moderate pneumonia (Med = 6; IQR = 4–6; Min = 2; Max = 8) was lower than the median treatment duration of calves with severe pneumonia (Med = 8; IQR = 4–8; Min = 2; Max = 8). When compared with calves with mild pneumonia on d 1, calves with moderate and severe pneumonia had significantly longer treatment durations. In this study, cure was low and not different between both antimicrobials. Categorizing calves based on consolidation depth appears useful as both cure and treatment duration were different for the mild, moderate, and severe groups. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Twin births in dairy cattle is generally unfavorably associated with reproductive performance and calf survival in dairy cows. Genetic selection to reduce twinning rate in dairy cattle may be desirable, provided no undesirable correlated responses in other traits exist. The current study was undertaken to characterize the genomic architecture of twinning rate in the Irish Holstein-Friesian population, and to quantify the genetic relationship of twinning with other reproductive traits and milk yield. Calving records from the years 1996 to 2022 were used together with pedigree information to generate breeding value estimates for twinning rate. Genome-wide association analyses of twinning rate, calving interval, cow survival and age at first calving were conducted using de-regressed breeding values estimates for 2,656 Holstein-Friesian sires. Full genome sequence data imputed from ∼50,000 single nucleotide polymorphisms were available for all sires. The h2 of twinning rate was 0.0118 ± 0.0010. Twinning rate was very weakly genetically correlated with both milk yield (0.13) and the reproductive traits (−0.26 to 0.14). Genomic analyses detected an association with twinning rate at 31.1 Mb on BTA11 in close proximity to genes for FSH receptor and luteinizing hormone-chorionic gonadotropin receptor, supporting previous studies. The most significant SNP in this region was not associated with milk yield, indicating the potential for selection to reduce twinning rate without detrimentally affecting milk yield. Novel SNP associations with age at first calving on BTA27 and from a meta-analysis of calving interval and age at first calving on BTA29 were also identified and are candidates for future validation and study. [ABSTRACT FROM AUTHOR]

The laparoscopic ovum pick-up (LOPU) technique in calves, goats, and sheep is based on the retrieval of cumulus-oocyte-complexes (COC) for reproductive purposes. Transabdominal COC retrieval has been used as a supplement or replacement for transvaginal follicular aspiration in young animals or species where the transvaginal OPU is impossible. This method can be combined with the in vitro production (IVP) of embryos. Laparoscopy minimizes invasiveness, ensuring better recovery rates of viable oocytes while reducing stress and complications for the animals. The success of LOPU depends on factors like the animal's physiological condition, operator expertise, and procedural timing relative to the reproductive cycle. This article provides a description of this method along with elements of the author's own research. [ABSTRACT FROM AUTHOR]

Cryptosporidium sp. is an obligatory intracellular apicomplexan protozoan parasite that causes a disease called cryptosporidiosis with substantial veterinary and medical importance. Therefore, this study aimed to evaluate an early diagnosis of cryptosporidiosis using the anti-Cryptosporidium parvum oocyst immunoglobulin IgG polyclonal antibodies (anti-C. parvum IgG PAbs)-based sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of Cryptosporidium oocyst antigens in fecal samples of farm animals in Egypt. Further molecular identification and sequencing were performed for the detected isolates. Eight hundred and twenty fecal samples of farm animals; 102 buffalo calves, 120 cattle calves, 100 lambs and 98 goat kids, 80 buffaloes, 60 cattle, 160 sheep and 100 goats, collected from different small-scale farms and local holders were examined for cryptosporidiosis by Modified Ziehl-Neelsen (MZN) technique. The percentage of positivity was 45.1%, 50%, 20%, 18.4%, 31.25%, 38.3%, 18.8%, and 11% in buffalo calves, cattle calves, lambs, goat kids, adult buffaloes, adult cattle, sheep, and goats, respectively. Molecular identification of Cryptosporidium samples was performed based on COWP gene, revealing the isolates: GenBank: OQ121955.1, OR029973.1 and PP316107.1 which were identical to the C. parvum and GenBank: PP316108.1 and OR029972.1 which were identical to C. hominis and C. andersoni, respectively. Then, C. parvum oocysts were used for preparation of antigens and rabbit immunization. Anti-C. parvum IgG PAbs were purified and characterized by SDS-PAGE and then labeled with horseradish peroxidase (HRP). Anti-C. parvum IgG PAbs in-house sandwich ELISA was prepared, then tested this ELISA on 820 samples and compared results with MZN microscopical examination and a commercial sandwich ELISA kit. In this study, in-house sandwich ELISA scored higher sensitivity of 98%, 100% specificity, validity 99% and relative agreement 98.6% than (92%, 90%, 91% and 91.4%) of MZN and (96%, 95%, 95.5% and 95.7%) of coproantigen commercial sandwich ELISA kit, respectively. Moreover, we used PCR to evaluate the positivity of in-house sandwich ELISA results, and the total PCR positive samples were 263 out of 268 sandwich ELISA positive samples (98.13%). In conclusion, the prepared Anti-C. parvum IgG PAbs based sandwich ELISA offered a simple and accurate diagnostic method for cryptosporidiosis in the fecal samples of different species of farm animals in Egypt with high sensitivity (98%) and specificity (100%). Further studies on this Anti-C. parvum IgG PAbs may help also in the protection against cryptosporidiosis. [ABSTRACT FROM AUTHOR]

Introduction: Farms are significant hotspots for the dissemination of antibiotic-resistant bacteria and genes (ARGs) into the environment and directly to humans. The prevalence of ARGs on farms underscores the need for effective strategies to reduce their spread. This study aimed to evaluate the impact of a guideline on "best practices for farming" aimed at reducing the dissemination of antibiotic resistance. Methods: A guideline focused on prudent antibiotic use, selective therapy, and hygienic and immune-prophylactic practices was developed and provided to the owners of 10 selected dairy farms and their veterinarians. Fecal samples were collected from lactating cows, dry cows, and calves both before and after the implementation of the guideline. ARGs (bla TEM, ermB , sul2 , and tetA) were initially screened by end-point PCR, followed by quantification using digital droplet PCR. ARG abundance was expressed in relative terms by dividing the copy number of ARGs by the copy number of the 16S rRNA gene. Results: The ARG abundances were higher in lactating cows compared to other categories. Despite similar levels of antibiotic administration (based on veterinary prescription data from the sampled farms) in both sampling campaigns, the total abundance of selected ARGs, particularly bla TEM and tetA , significantly decreased after the adoption of the farming guidelines. Discussion: This study highlights the positive impact of prudent antibiotic use and the implementation of farming best practices in reducing the abundance of ARGs. The lactating cow category emerged as a crucial point of intervention for reducing the spread of antibiotic resistance. These findings contribute to ongoing efforts to address antibiotic resistance in farm environments and strengthen the evidence supporting the adoption of good farming practices. [ABSTRACT FROM AUTHOR]

The improved growth performance of calves at weaning results from an effective pre-weaning feeding strategy. The type and pasteurization process of liquid feed are among the most variable feeding practices affecting calves' growth and health. In previous studies that compared waste milk (WM) vs. milk replacer (MR), little consideration has been given to the variations in chemical composition and feeding behavior between them, and there has been a lack of justification for the crude protein: metabolizable energy (CP:ME) ratio adopted. Hence, this study aimed to evaluate the effects of feeding pasteurized WM or MR differing in energy source (fat vs. lactose, respectively) with similar CP:ME ratio on intake, growth, feeding behavior, and health of newborn Holstein calves. Thirty-two male calves (4-d-old; 40.0 ± 0.58 kg BW) were assigned to the trial and randomly allocated to each liquid feed diet (WM or MR). Calves were housed in individual pens with free access to starter feed and fresh water. Calves were weaned on d 61 and assessed until d 101 as the postweaning period. WM-fed calves had greater total nutrient intake (DM, CP, EE, and ME), weight gain, final BW, skeletal growth parameters, and feed efficiency (d 30). Calves WM-fed sorted less against particles retained on the 2.36-mm sieve but more against particles retained on the sieve of 0.6 mm. In WM-fed calves, the sorting index decreased for feedstuff retaining on the bottom pan compared with MR-fed calves. Irrespective of the type of the liquid feed, all calves sorted for particles retaining on the sieve of 4.75 mm and the bottom pan, and against the particles that were retained on the sieves of 2.36- (MR-fed calves only), 1.18- and 0.6-mm. Starter feed nutrient intake and particle size intake from the sieves of 4.75-, 2.36-, and 1.18-mm increased in WM- vs. MR-fed calves. Eating rate and meal size but not meal frequency and length were greater in WM-fed calves, leading to higher pre- and post-weaning starter feed intake. Calves WM-fed spent less time eating and standing but more time ruminating and lying than MR-fed calves. Calves WM-fed had a lower likelihood of having elevated general appearance (score ≥2; hazard ratio = 2.79), diarrhea (score ≥3; hazard ratio = 1.35), and pneumonia (hazard ratio = 4.77). Calves WM-fed experienced shorter days with elevated general appearance, diarrhea, and pneumonia. Overall, feeding WM led to increased starter feed intake by boosting the eating rate and meal size, promoting greater growth than MR. Additionally, compared with MR, WM feeding increased time spent ruminating and lying and reduced susceptibility to diarrhea and pneumonia. [ABSTRACT FROM AUTHOR]

Long-distance transport and associated fasting of unweaned calves have the potential to compromise the animals' welfare. This observational study aimed to determine how transport and fasting durations impacted the physiology and health of 115 transported calves in three transport groups; IRE (n = 20, mean age 29.8d; short road transport (~ 29 h incl. resting time) and short feed deprivation (~ 11 h)), INT (n = 65, mean age 24.9d; long road/ferry transport (~ 79 h incl. resting times) and long feed deprivation (~ 28 h and 25 h)), and NLD (n = 30, mean age 17.7d; short road transport (~ 28 h incl. resting time) and long feed deprivation (> 18 h)). All calves travelled through an assembly centre. Each calf was blood sampled (arrival at destination farm, 1-week and 3-weeks post-arrival), health scored (arrival, 1, 3, 7, 8, 20d post-arrival) and weighed (farm/mart of origin [IRE and INT only], arrival, and 3-weeks post-arrival). (Generalised) linear mixed models were used to analyse differences in blood variables, weight, and health scores on arrival and during recovery (all other timepoints). Despite differing transport durations, both INT and NLD calves exhibited glucose, beta-hydroxy-butyrate, non-esterified-fatty-acids and sodium levels outside reference limits upon arrival, which were different from values observed in IRE calves (p < 0.05). Lactate and potassium were above reference range for INT calves on arrival, and higher than in IRE and NLD groups (p < 0.05). One- and three-weeks post arrival, most variables returned to within reference ranges, and differences between groups were minimal and not clearly associated with either transport duration or fasting during transport. Health scores did not differ between transport groups at arrival, and differences were minimal during the three-week recovery period. INT calves lost more weight during the journey than IRE calves (p < 0.01), while INT and NLD calves gained similar weight in the 3-weeks post-arrival, but less than IRE calves (both p < 0.01). Overall, changes in the physiological status of calves post transport appeared to relate more to the duration of feed deprivation than to the duration of transport, except for potassium and lactate (muscle fatigue), which were impacted more for INT calves. Most variables showed clear signs of recovery to within reference levels for all groups within three weeks. Minimizing the duration of feed deprivation during transport should be a key consideration for the dairy industry to reduce the impact of transport on calf welfare. [ABSTRACT FROM AUTHOR]

Simple Summary: Dairy cows are essential for milk production, but their productive lifespan—how long they stay healthy and productive—has not increased in recent years. This has led to concerns about animal welfare, environmental sustainability, and farm profitability. Scientists are searching for ways to predict which calves will have longer, healthier lives. One idea is to measure telomeres: tiny structures at the ends of chromosomes that shorten as animals age. In this study, we measured the telomere length of newborn dairy calves and investigated if it could predict their lifespan, milk production, or reproductive performance. We found that telomere length did not predict how long the cows lived or how much milk they produced. However, calves with the longest telomeres were less efficient at producing milk fat and protein. Interestingly, these calves also required fewer inseminations and had slightly longer intervals between calvings, suggesting a possible link to reproductive performance. While telomere length alone may not be a reliable predictor of lifespan or productivity, it could help us better understand the biology of aging and reproduction in dairy cows. Future research could provide more insights into how this information could improve animal welfare and farming efficiency. Telomere length (TL) has gained attention as a biomarker for longevity and productivity in dairy cattle. This study explored the association between neonatal TL in Holstein calves and lifetime parameters (lifespan, milk production, and reproduction). Blood samples were collected from 210 calves (≤10d old) across four dairy farms in Flanders, Belgium. Telomere length was measured using qPCR and analyzed as a continuous variable and across three groups: the 10% shortest, the 10% longest, and the remaining 80%. Survival analyses showed no association between TL and lifespan (p = 0.1) or TL groups (p = 0.8). Similarly, TL showed no significant association with production traits. However, categorical analyses revealed that calves with the longest TL had lower lifetime fat (p = 0.01) and protein yields (p = 0.01) than those with the shortest TL. Reproductive analyses showed cows in the long TL group required fewer inseminations per lactation (p = 0.02) and exhibited longer calving intervals (p = 0.05). These findings suggest that while neonatal TL may not predict productive lifespan, it may provide insight into reproductive efficiency. Future studies should prioritize longitudinal assessments of TL dynamics to better understand their interactions with management practices and application in herd improvement. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Nutritional and metabolic state in dairy cows are important determinants of the immune response. During the periparturient period, a state of negative energy balance in the cow increases plasma concentrations of fatty acids (FA), which are associated with inflammation. Among immune cells, CD4+ T are able to function under high-FA conditions, but the underlying mechanisms regulating these events remain unclear. The objective of this study was to clarify the functional mechanisms of CD4+ T cells under high-FA conditions. The effects of glycolysis and calcium release-activated calcium modulator 1 (ORAI1) on migration of CD4+ T cells exposed to high FA were investigated in vivo and in vitro. The CD4+ T cells were isolated from peripheral blood of healthy (n = 9) and high-FA (n = 9) Holstein cows (average 2.5 ± 0.2 lactations [SE], 12.3 ± 0.8 DIM). In the first experiment, real-time quantitative PCR was used to assess chemokine receptors in isolated CD4+ T cells and migration capacity. The relative mRNA measurements results revealed downregulation of CCR1 and CXCR2 , and upregulation of CCR2 , CCR4 , CCR5 , CCR7 , CCR8 , CCR10 , CXCR1 , CXCR3 , CXCR4 , and CX3CR1. Among them, the expression of CXCR4 was relatively high. Therefore, CXCL12, a ligand chemokine of CXCR4, was an inducer of CD4+ T cell migration. The CD4+ T cells were inoculated in the upper chamber and CXCL12 (100 ng/mL, Peprotech) in RPMI1640 was added to the lower chamber and transmigrated for 3 h at 37°C and 5% CO 2. The cell migration assay revealed that the migration capacity of CD4+ T cells from high-FA cows was greater. Real-time-qPCR indicated greater abundance of the glycolysis-related targets HIF1A , HK2 , PKM2 , Glut1 , GAPDH , and LDHA and Western blotting indicated greater abundance of the glycolysis-related targets HIF1A, HK2, PKM2, Glut1, GAPDH, and LDHA in CD4+ T cells of high-FA cows. To characterize specific mechanisms of CD4+ T cell migration in vitro, cells from the spleens of 3 newborn (1 d old, 40–50 kg) healthy female Holstein calves were isolated after euthanasia. Inhibition of glycolysis attenuated the migration ability of cells, but had no effect on the protein and mRNA abundance of store-operated Ca2+ entry (SOCE)-associated calcium release-activated calcium modulator 1 (ORAI1) and stromal interaction molecule 1 (STIM1). In contrast, ORAI1 was upregulated in CD4+ T cells of cows exposed to high FA. To explore the potential mechanisms whereby an active glycolytic metabolism affects CD4+ T cells under high-FA conditions, we knocked down ORAI1 using small interfering RNA (siORAI1). Isolated CD4+ T cells from high-FA cows with the siORAI1 had an attenuated glycolytic metabolism and migration capacity. Taken together, these data suggested that calcium ions in CD4+ T cells from cows with high FA regulate glycolytic metabolism and influence cell migration at least in part by modulating ORAI1. Thus, these studies identified a novel mechanism of Ca2+ regulation of CD4+ T cell glycolytic metabolism affecting their migration through the SOCE pathway. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The placenta plays a pivotal role in fetal development and the dam's subsequent lactation performance, because it facilitates nutrient transfer, heat dissipation, and gas exchange with the growing fetus, and regulates key hormones essential for mammary gland development. Heat stress experienced during gestation and lactation can significantly reduce the placenta's capacity to perform these critical functions. To investigate the impact of heat stress, trials were conducted over the summer months of 2020, 2022, and 2023 in Florida. Multiparous pregnant Holstein cows were dried off 54 ± 5 d before their expected calving date and randomly assigned to 1 of 2 treatments for the entire dry period: active cooling (CL; access to barn shade, natural ventilation plus forced air circulation via fans, and water soakers; n = 20) or heat stress (HT; access to barn shade and natural ventilation; n = 20). Gestation length and calf birth weights were recorded. Placentas were collected from a subset of cows shortly after calving (4.00 ± 1.54 h; n = 10/treatment) and analyzed for total placental weight, as well as cotyledon weight, number, and surface area within 1 h after expulsion. A representative cotyledon sample was isolated for histological analysis. Tissues were also processed for RNA sequencing and DNA methylation analysis. DNA methylation was analyzed by double restriction enzyme reduced representation bisulfate sequencing. Differentially methylated cytosines between HT and CL were identified via logistic regression with a cut-off value of 15% methylation difference and a q-value <0.2. Morphological and histological data were analyzed using generalized linear mixed models. Results indicate that gestation length was shorter in HT cows compared with CL cows (274.2 vs. 277.2 ± 1.46 d), and heifers born to HT dams were lighter at birth (31.4 vs. 34.8 ± 1.59 kg). Placentas from HT dams tended to have lower total weight (3.54 vs. 4.54 ± 0.38 kg) and fewer cotyledons (66.2 vs. 103.3 ± 8.65). However, placental efficiency was higher in the HT versus CL group (11.5 vs. 8.52 ± 0.91%). Cotyledons from HT cows had greater vascular area (43.1% vs. 31.8% ± 10.4% of total area) and a tendency for less connective tissue (52.7% vs. 65.8% ± 5.39% of total area). A total of 289 differentially expressed genes were identified between HT and CL placentas, with 179 upregulated and 110 downregulated in the HT group. Key genes affected included NPSR1 , SPATC1L , PGF , HSPB8 , IL6 , HBA/HBB , MMP12 , PAPPA2 , PAG14 , and SLC7A10. Dysregulated pathways in HT placentas involved gas and oxygen transport, nutrient transport, inflammatory response, and cortisol biosynthesis. Heat stress induced hypermethylation of regulatory pathways, including collagen biosynthesis and degradation, extracellular matrix structural components, and placental tissue organization. Our findings demonstrate that late-gestation HT causes significant transcript alterations in the placenta, leading to adaptations for thermoregulation and morphological changes. These alterations negatively affect birth weight, health, and dam lactation performance, underscoring the need to address HT during late gestation to ensure optimal fetal development and postnatal outcomes. Addressing these issues can help improve dairy cow resilience to climate change, enhancing animal welfare and productivity. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. Each year ∼150,000 surplus calves are sold at auction markets in Québec, Canada. Surplus calves (male or female not kept in the herd of origin) are sold at a young age, but these animals are at risk of receiving lower quality neonatal care than replacement heifers. Knowledge of factors associated with a higher selling price could help convince farmers to spend more resources in the care surplus calves. Our objective was to explore the associations between farm management practices and the median percentile of surplus calf selling price per farm at auction markets. The price (Canadian dollars/kg of BW) and the individual identification number of surplus calves sold in 2 auction markets in Québec during 4 sale days in the summer 2019 and in the winter 2020 were recorded. The recorded price of each surplus calf was transformed as percentile for each breed and day of sale. Farmers managing the surplus calves were contacted and interviewed on farm management practices. The data from farmer's interviews were analyzed as potential variables associated with the median percentile of calves' selling price per farm (farm-level dependent variable) in a multivariable linear regression model. A total of 509 farmers were contacted, of which 433 farmers agreed to participate, and 409 interviews were retained for statistical analysis. The farms enrolled in the study had sold a median of 2 calves (range 1–19 calves) during the sale days considered. The main breed of surplus calves sold were Holstein (82%) and Angus crossbred calves (9%). The results from the multivariable model showed that median percentile of calves' selling price was positively associated with farms with an average milk production per cow superior to 11,000 L/yr (β 0.13, 95% CI: 0.045, 0.221) and farms with 3 or more workers available to take care of surplus calves (β 0.08, 95% CI: 0.005, 0.167). Those results indicate that farms having an average milk production per cow superior to 11,000 L/yr increase the calves' selling price by 13 percentiles (i.e., from 50th to 63rd) and that farms having at least 3 caretakers increase their median percentile calves' selling price by 8 percentiles (i.e., from 50th to 58th). Median percentile of calves' selling price was negatively associated with farms that vaccinated cows for neonatal calf diarrhea (β −0.06, 95% CI: −0.127, −0.011), that do not disinfect the navel of newborn calves (β −0.07, 95% CI: −0.133, −0.012), that allow transporters to enter the farm's building (β −0.07, 95% CI: −0.130, −0.015) and that used wood shaving as bedding for surplus calves (β −0.08, 95% CI: −0.156, −0.021). Sensitivity analyses performed on farms that have sold 2 or more surplus calves did not show significant changes in the associations found. Despite the fact that the study was based on self-reported questionnaire answers and a small number of calves per farm, it provides insight on farm management practices associated with median percentile of surplus calf selling price at the auction markets. Taking these results in consideration, farmers could potentially improve the market value of their animals. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. This study aimed to evaluate the effects of early group housing on the performance, health, and behavior of dairy calves during the preweaning period using systematic and meta-analysis approaches. Peer-reviewed articles written in English that compared dairy calves individually and group-housed with performance, health, or behavior outcomes were collected from Web of Science, PubMed, and CABDirect databases. The resulting articles (n = 850) underwent a 4-step appraisal process following the Preferred Reporting Items for Systematic Review and Meta-Analyses protocols, resulting in a final sample of 51 articles containing 85 studies. The weighted or standardized mean differences between individually housed and group-housed (pair or group with >2 calves) calves were analyzed for each variable using the DerSimonian and Laird methods. Heterogeneity between calf housing systems was evaluated by the χ2 test and I2 statistics. A meta-regression analysis was conducted to identify categorical covariate effects for variables with high heterogeneity. Most of the studies included in this review evaluated female calves (45.8%) weaned at 8 wk old (52.6%). Housing systems were mainly paired housing (55.3%), followed by groups of 3 to 6 calves (30.65) and groups of 7 to 15 calves (4.7%). We did not find studies with comparable outcomes for more robust health parameters (as occurrence of diseases), only blood parameters, that were not influenced by the housing system. However, weight gain and feed intake parameters were higher in group-housed calves. Through the meta-regression, we found that ADG was positively affected by the group housing in studies with calves housed in small pen areas (<1.5 m2 per calf). Group-housed calves presented more active behaviors (feeding and playing) and less stress-related behaviors (self-grooming and interacting with the pen) than individually housed calves. The behavioral tests most used were novel object, human approach, novel environment, and social tests. Individually housed calves presented fewer vocalizations on these tests and spent more time interacting with humans during the human approach test than group-housed calves. Our findings provide consistent evidence that group housing improves the welfare of dairy calves; however, the effects on health parameters are still scarce and unclear. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. This study investigated the long-term effects of feeding 5-d transition milk (TRANS) compared with milk replacer (MR) on parameters including intake, growth, feeding behavior, and oxidative stress. Fifty Holstein calves (30 females and 20 males) were fed 12 L/d of either TRANS or MR for the first 5 d after an initial colostrum feeding of 3.5 L. Thereafter, all calves were fed with 12 L of MR/d (140 g/L) and were gradually weaned starting in wk 8 until wk 14. Throughout the 14 wk, the calves had unrestricted access to concentrate (up to 9.8 kg/calf per day), hay, and water. After weaning all heifers were fed a TMR for young cows. Oxidative status was assessed in blood samples from birth to first insemination. Parameters assessed included the ferric-reducing ability of plasma (FRAP) for antioxidant capacity and the concentration of reactive oxygen metabolites via detection of reactive oxygen metabolites (dROM) assay. In addition, the activity of glutathione peroxidase (GSHPx) and oxidative damage in the form of lipid peroxidation as thiobarbituric acid-reactive substances (TBARS) and as advanced oxidation protein products (AOPP) were measured. An oxidative stress index was calculated: dROM/FRAP × 100. Total protein concentration was also quantified via Bradford assay. The only significant difference in feeding behavior between the 2 treatment groups was a higher concentrate intake by the TRANS calves during the weaning phase. Body weight and ADG did not differ significantly between the TRANS and MR groups. The TRANS calves showed a trend for fewer cases of health disorders. Markers of oxidative status, including TBARS, AOPP, GSHPx, FRAP, and reactive oxygen metabolites, showed no treatment effects but varied significantly over time. Of note, the oxidative stress index, as ratio between pro- and antioxidants in both groups, peaked during weaning and then returned to baseline, suggesting an effective response to this transition phase. Overall, the results indicate that feeding TRANS during the first 5 d of life had no long-term effect on the parameters studied as compared with MR feeding under the present rearing conditions. These results provide insight into the changes of oxidative status with age and confirm that the relatively high milk feeding level, with slow and late weaning, enables calves to adapt well to solely solid feed. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. This study evaluated the effects of an oral probiotic capsule containing a live culture of Megasphaera elsdenii NCIMB 41125 on performance, feeding behavior, rumen pH and VFA concentration, and development of dairy-beef crossbred calves. Thirty-one male dairy-beef crossbred calves (Holstein × Angus; mean ± SD; 45.3 ± 7.1 kg; 8.2 ± 2.0 d old) were enrolled in a blinded, 76-d randomized trial. Calves were randomly assigned to one of 3 treatments: placebo, probiotic capsule administration on d 15, or probiotic capsule on d 15 plus a second capsule on d 39 of the study. Calves were housed individually with ad libitum access to water and calf starter and were fed 7 L/d of milk replacer (1,050 g of powder/d) in 2 meals until d 41, then 3.5 L/d in 2 meals until weaning on d 56. Behavioral observations were recorded in 1-min intervals using a wall-mounted camera. Rumen fluid samples were collected on d 14, 35, 49, 58, and 70, and analyzed for pH and VFA. Upon euthanasia on d 77, forestomach weights were recorded and rumen papillae dimensions were measured. Mixed linear models were used for statistical analysis. Probiotic treatment resulted in greater daily solid feed DMI and ADG, particularly during weaning and postweaning periods. Additionally, probiotic-treated calves spent more time drinking water and tended to have lower rumen pH compared with control calves. Empty rumen weight and papillae area were greater in calves supplemented with the probiotic capsule on d 15 compared with the other treatments. These findings suggest that preweaning M. elsdenii supplementation enhances performance and rumen development in dairy-beef crossbred calves. However, the effects of timing and number of capsule applications on rumen development and calf performance should be further investigated. Further research should also investigate the probiotic's effect on the rumen microbiome and fermentation dynamics throughout the rearing period using detailed microbiome analysis. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The literature on whether or not to feed forage is marked by inconsistencies, largely due to various factors associated with forage inclusion in calf diets. To elucidate these factors, we conducted a 3-level meta-analysis to comprehensively investigate the overall effects of forage provision in young calves. We searched for studies published between 2000 and 2023 in Google Scholar, ScienceDirect, and X-Mol. Moderator analyses were performed to evaluate the effects of different forage sources, forage provision methods, starter forms, milk levels, and forage levels on the heterogeneity of growth performance, rumen fermentation, and nutrient digestibility outcomes in studies feeding forage to calves. A mixed-effect model was used to predict the relationship between forage level and performance. Funnel plots and Egger's test were used to determine publication bias. A total of 86 treatment comparisons from 36 articles were included in the final dataset. The weighted mean difference was used to evaluate the effect size, and the statistical heterogeneity of the effect size was estimated using Cochrane's Q test. The results showed that forage supplementation improved growth performance, structural growth, and development of rumen fermentation in calves. However, moderator analyses revealed that several factors, including forage source, feeding method, physical form of starter, milk feeding level, and forage feeding level might contribute considerably to variability, resulting in significant heterogeneity in the effects of forage provision in calves. Larger effect sizes were found for oat hay (OH) supplementation rather than alfalfa hay (AH) or straw, and for feeding forage as a free choice (FC) compared with a TMR (defined as a mixture of calf starter and forage), especially when forage was fed as a FC resulting in higher total DMI and body barrel. Forage supplementation was more effective in boosting calf growth in calves provided with ground starter than in calves fed pelleted and textured starter. Greater effects were shown for AH supplementation than OH or straw in improving rumen fermentation parameters. Furthermore, compared with the preweaning period, the effect of providing forage on calves was more noticeable in the postweaning period. The results of the mixed-effects model analysis indicated that calves can be efficiently fed 12% of DM as forage during the preweaning period to support their growth and development. Meanwhile, 9% of DM might be the optimal level for feeding OH and straw to preweaning calves. More studies are essential to explore how different levels of AH dietary supplementation affects calves during the preweaning period and improve the consistency and accuracy of the dose-response curve predictions. Overall, growth performance and rumen fermentation of dairy calves were affected by forage inclusion. Moreover, forage source, feeding method, physical form of starter, milk feeding level, and forage level are essential factors that result in different degrees of effect on the calf's performance and rumen fermentation. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the pharmacokinetics of marbofloxacin after intravenous (IV) administration of a single dose of 10 mg/kg to calves of different ages. The study was carried on 1‐ (n = 6), 2‐ (n = 6), and 4‐month‐old (n = 6) Montofon calves. Plasma concentrations of marbofloxacin were measured using HPLC, and pharmacokinetic data were calculated by non‐compartmental analysis. The elimination half‐life (t1/2ʎz), volume of distribution at steady state (Vdss), total clearance (ClT), and area under the concentration‐versus time curve (AUC0–∞) values of marbofloxacin in 1‐month‐old calves were 10.62 h, 1.03 L/kg, 0.08 L/h/kg, and 127.90 h*μg/mL, respectively. While the t1/2ʎz (from 10.62 to 3.36 h) and AUC0–∞ (from 127.90 to 47.35 h*μg/mL) decreased in parallel with the age of the calves, ClT (from 0.08 to 0.21 L/h/kg) increased. The Vdss of marbofloxacin was higher in 1‐ and 2‐month‐old calves compared to 4‐month‐old calves. After IV administration of marbofloxacin at a dose of 10 mg/kg, an ƒAUC0–24/MIC90 ratio of ≥ 125 was obtained for bacteria with MIC90 values of ≤ 0.60, ≤ 0.39 and ≤ 0.27 μg/mL in 1‐, 2‐, and 4‐month‐old calves, respectively. These results show that the antibacterial effect of marbofloxacin, which has concentration‐dependent activity, decreases due to age‐related pharmacokinetic changes and that the 10 mg/kg dose should be reviewed according to the MIC90 value of the bacteria. [ABSTRACT FROM AUTHOR]

Importance: Enrofloxacin preparations are available for administration daily or every 3 days. This study presents clinical evidence to define which preparation is adequate to treat clinical cases of bovine respiratory disease (BRD) in calves. Objective: To correlate the pharmacokinetics/pharmacodynamics (PK/PD) ratios of three pharmaceutical preparations of enrofloxacin with their clinical efficacy in treating BRD. Methods: The PK/PD ratios of three enrofloxacin preparations were determined in healthy calves. Then, 48 BRD-affected calves initially treated IV with 2.2 mg/kg of flunixinmeglumine, were randomly assigned to treatment with: enrofloxacin dihydrate-hydrochloride (enro-C) 10% water suspension daily (10 mg/kg subcutaneous for three to six days); enro-C with alginate (enro-C/Al), and reference enrofloxacin (enro-R), both intended for treatment every 72-h in two occasions (10 mg/kg). Results: The highest maximum plasma concentration (Cmax)/minimum inhibitory concentration (MIC) ratio was obtained with enro-C and the highest area under the curve (AUC)0-72/MIC ratio with enro-R, and enro-C/Al exhibited an AUC0-72/MIC smaller, but Cmax/MIC higher than enro-R. Based on repeated statistical measurements, clinical progress revealed that the best outcomes were observed with enro-C (p < 0.05), and no statistical differences resulted by comparing enro-C/Al with enro-R. Conclusions and Relevance: If the priority in calves affected by BRD is to speed up their recovery, and despite the more significant amount of enro-C injected, using of lower doses of enrofloxacin as in the long-acting preparations is unsustainable. This study demonstrates that the clinical efficacy of enrofloxacin in cattle is optimally linked to Cmax/MIC rather than to AUC/MIC, which occurs better when injecting enro-C. [ABSTRACT FROM AUTHOR]

Silicon (Si), a newer trace element, is believed to be important for healthy bone formation and to decrease bone resorption, improving the quality of bone by manipulating several hormones and enzymes. Therefore, the current investigation was conducted to determine the impact of Si supplementation on growth, immunity, antioxidant, hormonal profile and biomarkers of bone health in pre-ruminant crossbred calves. Twenty-four crossbred calves (5–7 days) were selected on the basis of their body weight (BW 31.65 ± 0.46 kg) and divided into 4 groups (n = 6) and fed as per ICAR (2013) feeding standards except that these were additionally supplemented with 0 (Si0), 50 (Si50), 100 (Si100) and 150 (Si150) mg of Si/kg dry matter (DM) in four respective groups for 90 days. Every month, peripheral blood samples were drawn (0, 30, 60 and 90 days post supplementing with Si) and analysed for antioxidant status, hormonal profile and bone health biomarkers. It is reported that dietary Si supplementation improved (P < 0.05) net body weight gain (kg), average daily gain (g) and average dry matter intake (kg), whereas feed intake (kg/100 kg BW), was not altered due to Si supplementation. Structural growth measurements were significantly higher (P < 0.05) in Si100 and Si150 groups as compared to Si50 and control groups. However, immune response (humoral as well as cell-mediated immunity), erythrocytic antioxidant enzymes (superoxide dismutase, SOD, glutathione peroxidase, GPx and catalase), plasma ferric reducing total antioxidant power (FRAP) activity and the plasma concentration of total immunoglobulins (TIg) remained unaffected by Si supplementation. Silicon increased (P < 0.05) the concentration of plasma growth hormone (GH), vitamin D3, bone alkaline phosphatase (BALP) and osteocalcin (OCN) in Si100 and Si150 groups, but the levels of calcitonin, parathyroid hormone (PTH) and hydroxyproline (HYP) remained similar among all the groups. As a result of the current investigation, it can be inferred that the inclusion of 100 and 150 mg of Si/kg DM was effective in improving the growth performance, growth hormone, vitamin D3 and bone health status in pre-ruminant calves. However, supplementation of 150 mg of Si/kg DM had no additional benefit; therefore 100 mg of Si/kg DM is the optimum level of Si supplementation in pre-ruminant calves. [ABSTRACT FROM AUTHOR]

Deraniyagala's beaked whale, Mesoplodon hotaula, was previously known from eight published strandings and no confirmed live sightings, making it one of the least‐known cetaceans. We conducted six cetacean survey cruises in the South China Sea between 2019 and 2023, and during 120 sea‐days we recorded 12 sightings of unidentified Mesoplodon. From biopsy samples and acoustic recordings, five sightings were subsequently confirmed as M. hotaula. Using photographs, we provide the first field descriptions and observations of this species. The calf/juvenile has a distinctive facial coloration and dorsal striping pattern that appear to be diagnostic among Indo‐Pacific Mesoplodon; among adult males, the dark rostrum of M. hotaula and the distinctively white‐tipped beak of ginkgo‐toothed beaked whale, M. ginkgodens, distinguish these similar‐looking, partially sympatric species. Mean group size was small (3.0, n = 5), with a preference for deep (2,156 m, n = 5), warm (30.3°C, n = 3) water. We update the known distribution of this species, present evidence of fishery interactions, and document the first reported mixed‐species Mesoplodon group: a juvenile Blainville's beaked whale M. densirostris associated with four M. hotaula. These sightings identify the South China Sea as a potentially important area for this almost completely unknown species. [ABSTRACT FROM AUTHOR]

Neonatal calf diarrhea is a frequent disease of calves and may result in dehydration and metabolic acidosis. The disease causes mortality and reduces growth and future productivity. Early identification of disease improves calf outcomes and thus there is increasing interest in technological methods for detecting disease. Dehydration leads to the blood becoming more concentrated and this can be measured using serum osmolality. Research in humans has shown that saliva conductivity is correlated with serum osmolality. Saliva conductivity may therefore offer a non-invasive opportunity to assess hydration status in calves. Furthermore, as blood pH is a prognostic indicator and there is ion exchange in the salivary ducts, saliva pH may act as an indicator of metabolic acidosis. This observational study aimed to assess the relationship of saliva conductivity and pH with the clinical and biochemical parameters of calves suffering from neonatal calf diarrhea. One hundred and forty-one dairy-bred calves were recruited onto the study at approximately 1 week of age. The health of the calves was assessed daily. Calves had blood and saliva samples taken weekly until 25 days of age or the development of neonatal calf diarrhea. When calves developed diarrhea, they were sampled for three consecutive days. Hematocrit, plasma total protein, saliva pH and saliva conductivity were measured at each sampling. Saliva pH and saliva conductivity were measured using portable meters (LAQUAtwin-pH-33 and LAQUAtwin-EC22). In a subset of 30 matched samples, serum proteins and electrolytes were also measured. Saliva conductivity was not associated with diarrhea or dehydration. Saliva pH was lower in calves with diarrhea, regardless of hydration status. The Lin's concordance correlation coefficients between saliva variables and hematocrit and strong ion difference were negligible. Dehydrated calves with diarrhea had a higher hematocrit and albumin and the lowest sodium and SID. Calves with diarrhea and no dehydration had a lower plasma total protein. While saliva conductivity has been associated with measures of dehydration in humans, this does not appear to be the case in calves. Saliva pH has not previously been considered for disease detection; however as it is associated with diarrhea, further research is warranted. [ABSTRACT FROM AUTHOR]

The objective of this research was to examine the impact of feeding biologically treated rumen digesta (BTRD) to Holstein steer calves at levels of 0, 10, 20, and 30% (DM-based) on feed consumption, nutrient digestion, growth performance, rumen fermentation, and plasma metabolites. Sixteen Holstein steer calves with an initial BW of 113 ± 8 kg were randomly allocated in a randomized complete design. Dietary inclusion of BTRD in calves diet did not altered (P < 0.05) total intakes of DM, OM, and CP, when compared to those on the control diet over the experiment, but improved (P < 0.01) NDF and ADF consumption. Dietary inclusion of BTRD by 20% increased significantly DM and OM digestibility, average daily gain and feed efficiency (FE) (P < 0.05) and decreased feed conversion ratio (FCR) during 60 to 120 days. Plasma glucose, triglyceride, total protein, creatinine, or urea-N concentrations between treatments were not affected, but uric acid was reduced linearly (P = 0.02) in steers given BTRD supplements. Supplemented diets containing BTRD had the highest levels of plasma cholesterol and HDL, which increased with increasing BTRD inclusion levels. BTRD supplements were found to lower MDA levels in steers than control diets. This study found that dietary BTRD supplementation improved performance and health status of Holstein steer calves as well as their oxidative parameters. [ABSTRACT FROM AUTHOR]

The inclusion of forage sources in calf diets is often discussed, and the main point debated is whether the inclusion level, particle size, source, and how forage is offered may impact gut fill and reduce body weight gain, as well as impact gastrointestinal tract development. This study aimed to determine the effects of feeding forage sources with different qualities on rumen fermentation, gut fill, and development of the gastrointestinal tract of dairy calves. Forty-eight Holstein dairy calves were blocked according to sex and body weight (BW) at 28 days of life and randomly assigned to 1 of 4 dietary treatments. Treatments consisted of a no-forage coarsely ground starter (CON) or total mixed rations containing 7.5% on DM basis of Tifton hay of either medium quality (MH) or low quality (LH) or 10% on DM basis of corn silage (CS). The nutritional content, including crude protein, NDF, lignin, and in vitro digestibility, was used as forage quality criteria. During the first 28 days of life, all calves received 3 L of whole milk twice daily, a commercial pelleted starter ad libitum, and no forage. After that, the solid diet was changed to the respective dietary treatments. Rumen samples were taken to determine rumen pH and volatile fatty acid (VFA) proportions. Calves were gradually weaned from 52 to 56 d of age, and 20 calves, 5 per treatment, were harvested two weeks after weaning. The anatomical parts of the gastrointestinal tract were weighed with and without contents, and histological analysis of rumen epithelium was conducted. The CON diet increased total VFA concentration compared to forage diets. The forage diets increased rumen pH, fecal pH, and gut fill. However, regardless of the source, the forage provision did not affect empty body weight. In addition, the forage provision increased the number of papillae in the rumen, but diets did not influence the length and width of papillae. The results suggest that 7.5% of Tifton hay, regardless of the quality, and 10% of corn silage in high-starch mixed diets benefit rumen health and promote greater gut fill without negative effects on final body weight. [ABSTRACT FROM AUTHOR]

Background: Reproductive efficiency is crucial for the long-term economic sustainability of beef cattle production. Pregnancy loss and stillbirth are complex reproductive traits that do not yet have their genomic background fully understood, especially in zebu breeds (Bos taurus indicus). Hence, this study aimed to perform a genome-wide association study (GWAS) and functional annotation for conception success (CS), pregnancy loss (PL), stillbirth (SB), and pre-weaning calf mortality (PWM) in Nellore cattle. In this study, 3,728 cows with 17,094 reproductive records and 11,785 calves were evaluated. A total of 3,351 genotyped animals and 383,739 SNP markers were considered for GWAS analyses. SNP effects were estimated using the weighted single-step GWAS (WssGWAS), which considered two iterations. The top ten genomic windows with the highest contribution to the additive genetic variance of the traits were selected for gene annotation. Candidate genes were then analyzed for Gene Ontology terms (GO) and metabolic pathways. Results: The top ten genomic windows that explained the largest proportion of the direct additive genetic variance () for CS, PL, SB, and PWM accounted for 17.03% (overlapping with 79 genes), 16.76% (57 genes), 11.71% (73 genes), and 12.03% (65 genes) of the total , respectively. For CS, significant GO terms included Somitogenesis (GO:0001756), Somite Development (GO:0061053), and Chromosome Segregation (GO:0007059). Considering PL, the processes annotated were the Regulation of Hormone Secretion (GO:0046883), and Hormone Transport (GO:0009914), along with the Glucagon Signaling Pathway (bta04922). Embryonic Development (GO:0045995), and Cerebellum Development (GO:0021549) were the main biological processes found in the gene enrichment analysis for SB. For PWM, the Regulation of Glucose metabolic processes (GO:0010906), Zinc Ion Homeostasis (GO:0055069), Lactation (GO:0007595), and Regulation of Insulin Secretion (GO:0050796) were the most significant GO terms observed. Conclusions: These findings provide valuable information on genomic regions, candidate genes, biological processes, and metabolic pathways that may significantly influence the expression of complex reproductive traits in Nellore cattle, offering potential contributions to breeding strategies and future genomic selection strategies. [ABSTRACT FROM AUTHOR]

Baleen whale calves vocalize, but the behavioural context and role of their social calls in mother–calf interactions are yet to be documented further. We investigated the context of call production in humpback whale (Megaptera novaeangliae) calves using camera-equipped animal-borne multi-sensor tags. Behavioural states, including suckling sessions, were identified using accelerometer, depth and video data. Call types were categorized through clustering techniques. We found that call types and rates predict the occurrence of a given state. Milling, resting and travelling were associated with a median call rate of 0 calls min−1, while surface play, tagging responses and suckling were associated with higher call rates, averaging up to a median of 0.5 calls min−1 for suckling. Suckling sessions were mainly associated with two sets of low-frequency calls corresponding to previously described burping, barking and snorting sounds. Surface play sessions featured mid-frequency calls with whoop-like sounds and other call types. These results address the significance of vocal signalling in mother–calf communication and the calf's development, including the first identification of potential begging calls. Overall, this study offers new insights into baleen whale behaviour, underscores the importance of social calls in mother–calf interactions and enhances our understanding of communication systems in aquatic mammalian mother–young pairs. [ABSTRACT FROM AUTHOR]

The ability to reliably induce bovine digital dermatitis (DD) in naive calves provides unique opportunities to evaluate immune responses of the calves to infection after disease induction, during healing, and after subsequent re-infection. Dairy calves infected in a previous induction trial were held until lesions resolved and were then re-infected in parallel with naïve calves. Humoral and cell-mediated responses were assessed via serum antibody titer and lymphocyte proliferation analysis with responses of previously infected calves compared with responses of the newly infected calves and naïve calves. In addition, feet of calves in both treatment groups were photographed and scored by a single blinded observer using a previously described induced lesion scoring system. All naïve calves developed lesions after initial infection whereas only 5 of 8 calves developed lesions consistent with DD after a second experimental infection. In the naïve group, lesions commensurate with DD occurred in 15 of 26 experimentally infected feet with 6 feet not included in the analysis due to bandage failure. In comparison, calves in the second infection group developed lesions in 10 of 25 infected feet. Humoral responses or cellular proliferative responses did not differ between the two treatment groups or between calves which developed or did not develop lesions after experimental infection. Our results indicate that resolution of lesions after DD infection, immunity only provides partial protection against reinfection. Further studies are needed to determine immune mechanisms that provide the observed partial protection against reinfection with DD. [ABSTRACT FROM AUTHOR]

The editorial discusses the crucial role of gut microbiota in regulating the host immune system and overall health. It highlights the symbiotic relationship between gut microbes and their hosts, emphasizing the impact on immune responses, metabolic pathways, and physiological functions. Various studies explore how dietary strategies can influence gut microbiome composition, immune responses, and overall health outcomes in animals, including poultry, herbivores, and pigs. The editorial underscores the importance of understanding the complex interplay between gut microbiota, nutrition, and immunity for developing personalized approaches to animal health and nutrition. [Extracted from the article]

Introduction: A harmonized clinical breakpoint for interpreting antimicrobial susceptibility testing of oxytetracycline in cattle is currently lacking in Europe. This study aimed to establish a pharmacokinetic/pharmacodynamic (PK/PD) cutoff to propose clinical breakpoints, facilitating reliable interpretation of antimicrobial susceptibility results in cattle. Methods: A meta-analysis of oxytetracycline pharmacokinetic data from 69 cattle was conducted, including 1,730 plasma concentration samples from animals administered 20 mg/kg intramuscularly and/or 20 or 40 mg/kg intravenously. A three-compartment model with two absorption phases was selected, incorporating age as a covariate for clearances and distribution volumes. The PK/PD cutoff was defined as the maximum MIC for which the f AUC/MIC index achieves the pharmacodynamic target in 90% of cattle given the standard dosing regimen. The pharmacodynamic index (PDI) target selected was established to 24 h, i.e., the average free plasma concentration of oxytetracycline over the 24-h dosing interval, under steady-state conditions, is equal to the selected MIC. Results: Simulations indicated a PK/PD cutoff of 2 mg/L in adult cattle and 1 mg/L in calves for intramuscularly administered long-acting products at 20 mg/kg with a 48-hour efficacy duration. The difference is attributed to higher clearance rates in calves. Discussion: The established PK/PD cutoffs, when used alongside the wild-type bacterial epidemiological cutoff, can aid in setting clinical breakpoints for oxytetracycline, supporting effective antimicrobial therapy in cattle and accounting for age-related pharmacokinetic differences. [ABSTRACT FROM AUTHOR]

Simple Summary: Feeding calves a mixture of oregano essential oil and yeast cultures led to increased rumen microbial richness and diversity, along with regulated relative abundances of particular species. Moreover, pathways associated with metabolism and antimicrobials were enriched. The research indicates that this mixed additive outperforms separate feeding of oregano essential oil and yeast culture in modulating the rumen microbial community of calves. This study hypothesized that combining oregano essential oil (OEO) and yeast cultures (YCs) would modulate rumen microbiota to promote gastrointestinal homeostasis and function. Twenty-four newborn, healthy, disease-free, crossbred Simmental male calves (birth weight ≥ 35 kg) were assigned to one of four treatments based on birth data. Treatments were as follows: (1) Control (CON), calves fed calf starter without additives; (2) OEO, calves fed calf starter containing 60 mg/kg body weight (BW) of OEO per day; (3) YCs, calves fed calf starter containing 45 mg/kg BW of YC per day; and (4) MIX, calves fed calf starter with OEO (60 mg/kg, BW) and YC (45 mg/kg, BW) combination. The experimental period lasted 70 days. Rumen fluid was collected on the final day, and 16S rRNA sequencing was performed to assess alterations in rumen microbiota. Calves fed MIX exhibited significantly greater microbial richness, species diversity, and lineage diversity (p < 0.05) compared with calves in the other groups. MIX-fed calves also showed changes (p < 0.05) in the relative abundance of certain rumen species, identified as through LEfSe analysis (LDA > 4, p < 0.05). These biomarkers included f_Rikenellaceae, g_Rikenellaceae_RC9_gut_group, g_Erysipelotrichaceae_UCG-002, c_Saccharimonadia, o_Saccharimonadales, f_Saccharimonadaceae, and g_Candidatus_Saccharimonas. Pathways enriched (p < 0.05) in MIX-fed calves involved nucleotide metabolism, lipid metabolism, glycan biosynthesis and metabolism, amino acid metabolism, terpenoids and polyketides metabolism, antimicrobial drug resistance, xenobiotic biodegradation and metabolism, antineoplastic drug resistance, and excretory system pathways. In conclusion, this study demonstrates that the OEO and YC combination enhances rumen microbial community modulation in calves more effectively than OEO or YCs fed individually or with the control diet. [ABSTRACT FROM AUTHOR]

Simple Summary: The veal market is picking up speed in Brazil, where it is called 'Vitelão'. This term refers to meat from calves that are under a year old. We investigated the Galician Blond crossed with Nelore cattle to see if they could be a good choice for veal production. Our goal was to help farmers make better decisions when choosing calves for meat. We tested different growth models to find the best way to track how calves grow until they are 12 months old. We discovered that the Logistic model worked best for understanding their growth. These calves grow quickly in their first year, making them ideal for producing high-quality veal. They are also tough and can adapt well to challenging environments. Our findings can help improve the ways in which farmers manage cattle and support breeding programs that aim for faster growth without affecting their adult size. The veal niche market is gaining momentum in Brazil. Locally known as 'Vitelão', veal refers to the meat from calves slaughtered up to 12 months of age. In this study, we assessed the Galician Blond × Nelore cross as a candidate to produce veal. The aim of this study was to establish criteria for selecting 12-month-old calves suitable for slaughter. To find the best fit, we adjusted various growth models for calves up to 12 months of age. Once the best fit was determined, the selected growth model was then used to calculate the relative and instantaneous growth rates to evaluate the slaughtering potential at 12 months. Our study reveals that, under present conditions, the Logistic model is the best fit for characterizing and functionally analyzing growth from birth to 12 months of age in Galician Blond crosses with Nelore. Calves resulting from this cross experience rapid growth in their first 12 months of life, making them an excellent choice for producing high-quality veal while maintaining rusticity and adaptability to extreme environments. The results of this study could contribute to enhancing the growth management systems of Galician Blond and Nelore crosses in Brazilian grazing production systems. Additionally, they can be incorporated into genetic improvement programs as a tool for selecting animals with greater precocious growth without altering adult weight. [ABSTRACT FROM AUTHOR]

Simple Summary: The aim of this study was to evaluate the performance of Galloway (Ga) and Highland (Hi) cattle under low-input, extensive grazing conditions in Transylvania, Romania. The results indicate that both breeds show strong adaptability to these systems, with Ga calves, particularly males, exhibiting a higher average daily gain (ADG) compared to Hi calves. Additionally, this study highlighted that both breeds are resilient to the challenging environmental conditions, as demonstrated by their performance and a comparison with national breed averages. These findings suggest that Ga and Hi cattle, due to their ability to thrive on low-resource grazing lands, are valuable assets for sustainable and climate-resilient livestock systems. This research could be valuable for farmers, policy-makers, and agricultural stakeholders aiming to implement climate-resilient practices in regions with limited resources. Sustainable and climate-resilient livestock systems are increasingly necessary to balance food production demands with environmental conservation. Breeds such as Galloway (Ga) and Highland (Hi) cattle are recognized for their adaptability to extensive grazing systems, low input requirements, and ability to thrive on marginal lands. Despite their potential, research on the performance of Ga and Hi cattle in low-resource, extensive grazing systems, particularly in Romania, remains scarce. This study evaluated the performance of Ga and Hi beef cattle raised under low-input conditions with a focus on the following: (1) the average daily gain (ADG) on low- and medium-quality forage and (2) the cattle's adaptability to extensive grazing systems. The study, conducted at Cojocna Farm, Transylvania, Romania (2023–2024), involved five male and three female calves from each breed. Calves were weighed five times in the entire observation period, and feed quality was analyzed. The results showed that Ga calves, especially males, had a higher ADG than Hi calves (Ga = 676.91 g, Hi = 581.14 g), while females showed more consistent performance during winter feeding. Both breeds demonstrated strong adaptability and satisfactory performance under the extensive conditions of Transylvania, as evidenced by the comparison of the obtained ADG with the values provided by the National Breed Register. Future research should explore the long-term sustainability of these breeds in varying environmental conditions, to investigate genetic factors influencing performance, and assess the broader ecological and economic benefits of integrating Galloway and Highland cattle into diverse farming systems. [ABSTRACT FROM AUTHOR]

Simple Summary: The results indicated that the supply of a blend of essential oils with cinnamon, oregano, and eucalyptus provided the calves with humoral and antioxidant immune system stimulation, minimizing physiological oxidative stress and leading to better efficiency. The health improvement did not enhance the growth of calves that consumed essential oils. The assessments of the abundance and biodiversity of microbiota did not differ between animals that consumed the blend of essential oils and those that did not; however, it allowed the identification of the main genera in the feces of calves in the first weeks of age. The objective of the present study was to determine whether the addition of a blend based on the essential oils of cinnamon, oregano, and eucalyptus to the liquid diets of calves would stimulate the immune system combined with anti-inflammatory action, minimize oxidative responses, and alter the intestinal microbiota, consequently enhancing animal growth. Twenty-four male Holstein calves (approximately five days old) were suckled for 60 days, underwent a weaning process, and were followed up until day 75 of the experiment. The calves were divided into control (n = 12) and phytobiotic (n = 12) groups, receiving commercial milk replacer and pelleted concentrate ad libitum. For the phytobiotic group, we added the blend to the liquid diet twice daily at 5 mL/feeding in the first 15 days and 10 mL/feeding until day 60. We detected no differences in weight gain, but animals in the phytobiotic group tended to consume less feed. Calves treated with phytobiotics showed better conversion and feed efficiency than the animals in the control group. Lower leukocyte and lymphocyte counts were observed, as was a higher cholesterol concentration. Immunoglobulin A, ceruloplasmin, and transferrin also differed between groups, with higher IgA and lower levels of acute-phase proteins (ceruloplasmin and transferrin) in calves that consumed the phytobiotic. Higher glutathione S-transferase activity was found in the serum of calves in the treatment group. The intestinal microbiota did not differ between the groups; however, the genera Acinetobacter, Pseudomonas, and Psychrobacter were the most abundant regardless of treatment. We concluded that the blend of oils based on cinnamon, oregano, and eucalyptus improved the calves' immune and antioxidant systems, improving feed efficiency without affecting the intestinal microbiota. [ABSTRACT FROM AUTHOR]

ABSTRACT There is a growing focus on examining how the order of tasks impacts oral and written output in a second language, particularly concerning syntactic complexity, accuracy, lexical complexity, and fluency (CALF). Despite previous studies, the findings have been inconsistent. This research synthesis and meta‐analysis, centered around Robinson's (2010) SSARC model of pedagogical task sequencing, aims to: firstly, analyze the types of tasks used in investigating task sequencing and its effects on L2 production; secondly, explore the definitions of task complexity and task sequence in research on task sequencing and its impacts on L2 production; thirdly, examine the metrics of CALF in the study of task sequence and its effect on L2 production; and finally, assess the effects of task sequence on CALF in L2 production. The results show consistencies in Second Language Acquisition (SLA) research regarding the manipulation of task sequencing, particularly the progression from simple to complex tasks using features that direct or disperse cognitive resources. Our findings demonstrate positive effects for the sequence of tasks from simple to complex on syntactic complexity and accuracy of L2 production, regardless of the mode of production. In contrast, random task sequencing primarily impacts the accuracy of L2 production, particularly in oral production. [ABSTRACT FROM AUTHOR]

In North American beef production, handling and restraint of young calves is integral to animal welfare and management practices. This study used a mixed-method approach to gather public perceptions of three handling and restraint methods common in western Canada during spring processing (TT—tilt table, RW—roping and wrestling, and NF—roping and NordFork). Canadians (n = 551) participated in an online survey that included videos of each handling method to ascertain preferences and acceptability. Participants were given industry information about handling and restraint or generic information regarding hay as a control information statement within the topic of agriculture. The survey also collected information about knowledge of the beef industry, animal welfare, and empathy toward animals. The reasons for preferences for specific handling methods were described as the presence of a perceived positive attribute and the absence of a perceived negative for most preferred methods, and inversely when explaining the least preferred method. The main themes focused on the calf's experience, perception of handler actions, and pragmatic balancing of needs for a good life for the calf. All methods were rated as more acceptable for participants that ate meat consistently, knew more about the beef industry, and, to a lesser extent, if the individual had a lower animal empathy score. Acceptability was not affected by providing information about the practices; however, information did elicit more pragmatic reasoning. Most participants preferred TT over NF and RW (p < 0.001) and found TT more acceptable as well (p < 0.001). The TT was the most preferred method due to calf experience and human handling—notably the absence of dragging a calf, which was predominant in why participants selected NF or RW as their least preferred method. Consistency of themes highlights that regardless of method or acceptability, the fundamental expectation of the public focuses on the perception of the calf's quality of life, humane handling, and pragmatism, which are values aligned with beef sustainability initiatives. [ABSTRACT FROM AUTHOR]

OBJECTIVE To describe the clinical signs, surgical management, postoperative complications, and outcomes following herniorrhaphy in calves with incarcerated umbilical hernias. METHODS This was a retrospective case series. The electronic medical record databases of 2 veterinary teaching hospitals were searched to identify the records of calves that underwent herniorrhaphy for correction of irreducible umbilical hernias between January 1, 2004, and December 31, 2021. Data collected included signalment, medical history, results of clinical examination and laboratory testing, ultrasonographic and surgical findings (incarceration vs strangulation), postoperative complications, and outcome. RESULTS 19 calves with incarcerated umbilical hernias underwent surgical correction. The incarcerated gastrointestinal tract was identified as the abomasum in 11 calves and jejunum in 8 calves. In 9 calves, the intraoperative identification of strangulation led to 4 intestinal resections and 4 partial abomasectomies, with 1 calf being euthanized intraoperatively. Postoperative complications were reported in 3 calves that underwent intestinal resection. Sixteen calves (84%) survived to discharge and had a median survival time of 1,995 days after surgery. No statistically significant differences were observed between calves with or without gastrointestinal tract strangulation in the short-term survival rate, survival time, or number of lactations after surgery. CONCLUSIONS This study demonstrated that herniorrhaphy for incarcerated umbilical hernias in calves is associated with a favorable prognosis. Postoperative complications are, however, more frequent in calves with strangulated gastrointestinal tract. CLINICAL RELEVANCE Surgical intervention for incarcerated umbilical hernias in calves generally yields a positive prognosis, particularly in the absence of gastrointestinal tract strangulation, highlighting the importance of timely diagnosis and treatment. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the enteric methane (CH4) emission factor (EF) at the national level for Peruvian dairy cattle following the IPCC Tier II (2006, 2019) methodology. Data were collected from seven regions of Peru and classified according to the type of feeding as intensive, semi-intensive or extensive. It included farm information (geolocation) and livestock information for two seasons of the year. At the national level, lactating cows obtained the highest EF with 117 kg CH4/head/year, followed by heifers from 15 to 24 months of age (91 kg), non-lactating cows (74 kg), heifers from 12 to 15 months of age (67 kg), calves (62 kg) and pre-weaned calves (16 kg). Additionally, the highest EF was reported for lactating cows in the intensive system (151.8 kg CH4/head), which is 46.8 kg CH4/head more per year than that reported in the semi-intensive and extensive systems in the same animal category. The combined uncertainty in all animal categories was low to very low (between 9.4 and 18.72%), except for that of lactating cows, which was low to medium (22.24 and 26.72%). These results allowed us to find the EF that exerts the most pressure according to the level of intensity in Peruvian dairy farming. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate radiographic detection by excretory urography of morphological changes in the urinary bladder associated with urachal anomalies in calves. METHODS: Excretory urography was performed to detect morphological changes in the urinary bladder of 13 calves, of which 6 were nondysuric with swelling of umbilical region and 7 were dysuric without clinical umbilical swelling from November 2022 through April 2024. RESULTS: The urinary bladder was delineated in all 13 calves after excretory urography. The aspect ratios (length:height), which objectively evaluate the shape of the urinary bladder, ranged from 1.08 to 2.43 (1.90 in average) and 1.34 to 11.89 (4.75 in average) in nondysuric and dysuric calves, respectively. The ratios of calves with nondysuric were significantly lower than those of dysuric (P < .05). CONCLUSIONS: Excretory urography could play an important role in evaluating abnormal morphological changes due to urachus anomalies in the urinary bladder of calves. CLINICAL RELEVANCE: Among calves with dysuria, urachal anomaly should be included in the differential diagnosis. Excretory urography is proposed as an alternative option for early diagnosis among calves presenting with dysuria to improve livestock productivity. [ABSTRACT FROM AUTHOR]

Background: Cattle colonised by the zoonotic pathogen verotoxin-producing Escherichia coli of serotype O157 (VTEC O157) can shed high levels of the pathogen in their faeces. A suggested key for controlling VTEC O157 is preventing colonisation of individuals. Aim: In this study the role of individual super-shedders and factors related to susceptibility and environmental exposure in the transmission of VTEC O157 among dairy calves are explored. Methods: The association between sex, age, pen hygiene, pen type and stocking density and colonisation of individual calves, established by recto-anal mucosal swabs, on farms where pathogenic VTEC O157 had been confirmed was investigated. In a follow-up sampling, the consistency of previously identified risk factors and the role of shedding pen mates was assessed by studying the risk of new/re-colonisation. Results: The results suggest an important role of stocking density that decreases with age, possibly due to increased resistance to colonisation following exposure. However, previous colonisation did not influence the risk of being colonised in the second sampling. Super-shedders (shedding >103 colony forming units/g faeces) significantly increased the risk of colonisation in peers (OR = 10, CI 4.2–52). In addition, environmental factors associated with survival of the bacteria, affected risk. Conclusion: The results confirm the suggested importance of super-shedders but also emphasises the importance of considering the combined exposure from peers and the environment. [ABSTRACT FROM AUTHOR]

The study was carried out at Holetta agricultural Research center dairy farm to estimate the growth and dry matter intake curves parameters of different genetic groups of crossbred male calves. A total of 48 weaned Friesian Boran (FB) crossbred calves consisting of 24 male calves having 50% Friesian blood level and another 24 growing calves having 75% Friesian blood level were used for this study. The calves were managed under individual feeding management for a fattening period of 626 days. Body weight and dry matter intake data were fitted into Gompertz nonlinear growth model. Mean values for growth parameters in 50% FB and 75% FB crosses were 727.0 and 730.2 kg; 2.85 and 2.78; 0.0019 and 0.0017 kg/day; 547.95 and 595.68 days; 257.46 and 268.63 kg; for mature weight, integration constant, maturity rate, age at inflection point and body weight at inflection point, respectively. This study revealed that 50% FB crossbred bull calves are fast maturing genotype and had significantly lower DMI at mature age than 75% FB crosses. Generally, 50% FB crossbred bull calves can be used for fattening purpose to meet increasing lean meat demand of consumers in Ethiopia with decreased feed cost under improved feeding system. [ABSTRACT FROM AUTHOR]

The effects of various treatment options on the nutritional value of wheat straw as well as the growth performance of crossbred calves fed the treated wheat straw were evaluated. Twenty-four female calves (75% Friesian-Borana), weighing 99.3 ± 19.7 kg (aged 6–9 months), were divided into four groups of six animals using a randomized complete block design. The feeding trial lasted approximately 104 days. The dietary treatments were: untreated wheat straw (control T1), wheat straw treated with urea-molasses (T2), urea-lime (T3), and effective microorganisms (T4). Results showed that the treatment options affected the physical silage quality and chemical composition of wheat straw. Calves in the T3 and T4 groups had a higher daily DM intake (3.7 and 3.5 kg/head, respectively) than those in T2 (3.1 kg/head) and T1 (3.02 kg/head) groups. Calves in the T3 (422.7 g/d) and T4 (391 g/d) groups gained greater weight than those in the T2 (281.7 g/d) and T1 (204.4 g/d) groups (P < 0.001). Thus, improving the feed value of wheat straw with urea-lime or effective microorganisms treatment options suggested in this trial could result in cost-effective and significant growth performances when crossbred calves were supplemented with concentrate at a rate of 1.2% of their live weights. [ABSTRACT FROM AUTHOR]