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The aim of this study was to assess the impact of genotype-environment interaction (GEI) on the manifestation of traits such as age at first calving (AFC), age at first service (AFS), and calving interval (CI) through the application of the reaction norm model in Holstein cattle raised in Paraná state, Brazil. Utilizing data from the milk testing service of the Paraná Association of Holstein Cattle Breeders (APCBRH), this study analyzed records from 179,492 animals undergoing their first, second, and third lactations from the years 2012 to 2022. These animals were part of 513 herds spread across 72 municipalities in Paraná. The environmental gradient was established by normalizing contemporary group solutions, derived from the animal model, with the 305-day-corrected milk yield serving as the dependent variable. Subsequently, reaction norms were determined utilizing a Random Regression Model. Spearman's correlation was then applied to compare the estimates of breeding values across different environmental gradients for the studied traits. The highest EG (+ 4) indicates the least challenging environments, where animals experience better environmental conditions. Conversely, lower EG (-4) values represent the most challenging environments, where animals endure worse conditions. The only trait that exhibited a moderate heritability magnitude was AFC (0.23) in the least challenging environmental condition. The other traits were classified as having low heritability magnitudes regardless of the evaluated environmental gradient. While minimal evidence was found for the influence of GEI on CI, a clear GEI effect was observed for AFC and AFS across all environmental gradients examined. A reversal in genotype ranking occurred under extreme environmental conditions. The findings suggest that the best-performing genotype under one environmental gradient may not necessarily excel under another., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The aim of this study was to estimate the (co)variance components and genetic parameters for milk yield adjusted to 305d (MY305), calving-to-conception interval (CCI), number of services per conception (NSC) and calving interval (CI) of Honduran Holstein cows, by fitting a bivariate animal model using Maximum Restricted Likelihood procedures. Model included the fixed effects of calving number, the contemporary calving group (farm-season-year of calving and the cow age as covariate). The estimated means and standard deviations for MY, CCI, NSC and CI were, 5098.60 ± 1564.32 kg, 168.27 ± 104.71 days, 2.46 ± 1.69 services, and 448.73 ± 109.16 days, respectively; and their estimated heritabilities were 0.21 ± 0.05, 0.03 ± 0.028, 0.02 ± 0.024 and 0.06 ± 0.04, respectively. The genetic correlations between MY305 and CCI, NSC and CI were positive and antagonist, with values of 0.64 ± 0.52, 0.99 ± 0.56, and 0.32 ± 0.24 respectively. Even though moderate to low heritability was estimated for MY305, systematic selection for milk yield, with a reduction in reproductive efficiency, if considered as the only selection criterion is important to be considered. By including reproductive traits and considering permanent environment effects into the breeding program, might yield a slow, but constant and permanent improvement over time., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: Breeding objectives are designed to achieve targeted dairy cow production goals, which can be affected by production type, farmer preferences, environmental factors and genetic factors individually or in combination. Breeding practices, such as both controlled and uncontrolled, and artificial insemination (AI) are the tools used to obtain the desired breeding objectives. The lower reproductive performance of indigenous dairy cows affects the total milk production and calf crops that are produced during their lifetime. Designing appropriate breeding objectives and breeding practices can improve the reproductive performance of dairy cows and their overall production performance., Materials and Methods: The current study was conducted with the objective of evaluating the breeding, practices and performance of indigenous dairy cattle in the south western part of Ethiopia. The districts of Gesha and Chena were purposefully chosen. The study design for the 384 household surveys was a cross-sectional survey with a simple random sample approach. Data analysis was carried out by MS-Excel (2010) and the general linear model procedure of SAS of 2008., Results: The current study revealed that methods of breeding were predominantly natural-controlled mating, followed by natural-uncontrolled mating and AI in descending order. Breeding objectives were input function, output function, sociocultural and economic functions and assets and security functions in decreasing order of rank. Reproduction performance indexes of indigenous dairy cows age at first service (3.72 ± 0.05 years), age at first calving (AFC) (4.71 ± 0.07 years), calving interval (CI) (1.58 ± 0.03 years), days open (DO) (4.26 ± 0.11 months), services per conception in natural mating (1.4 ± 0.08) and AI (2.73 ± 0.14), age of bull at maturity (4.17 ± 0.74 years), interoestrus interval (23.18 ± 0.61 days), calves crop (7.53 ± 0.22) and the life span of indigenous dairy cow (11.94 ± 0.26 years) were significant (p < 0.01) between two districts, whereas the values of age of bull at maturity and number of services per conception in natural mating were significant (p < 0.05) between districts., Conclusions: Using AI and major reproduction performances, such as AFC, CI and DO of indigenous dairy cows in the study area, were very low. Therefore, concerned bodies should intervene to improve reproduction performance through the utilization of AI techniques, with the integration of forage development activities and improvements in livestock health care., (© 2023 The Authors. Veterinary Medicine and Science published by John Wiley & Sons Ltd.)

Nutritional modifications can potentially impact the reproductive performance and ultimately the economic results of dairy herds. The objectives were to investigate the effects of feeding a high starch (HS) diet and body condition score (BCS) at calving on reproductive responses and uterine health in Holstein dairy cows. One hundred seventy-four multiparous cows were randomly assigned to 1 of 2 experimental diets from 16 until 50 days in milk (DIM; n = 87 per group); normal starch (228 g/kg diet DM; NS) or high starch (270 g/kg diet DM; HS) diets. Each dietary treatment group was further subdivided based on BCS at calving as normal BCS (BCS ≤ 3.5; NBCS; n = 45) and high BCS (BCS ≥ 3.75; HBCS; n = 42). Transrectal ultrasonography was carried out at 10 DIM, and thereafter twice weekly until the onset of ovarian cyclicity or d 50 DIM. Feeding HS diet significantly affected the proportion of cows cycling by 30 and 40 DIM. Number of services per conception and calving interval (CI) were significantly improved in cows fed the HS compared to the NS diet (2.08 vs. 2.51 and 427.14 vs. 445.30 days for cows fed HS and NS diets, respectively). In summary, feeding higher starch diets from 16 till 50 DIM could be an effective strategy to improve the economic variables related to reproduction in dairy cows., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Health and reproductive conditions affect milk yields in dairy cows and may lead to differences in technical efficiency across farms. To investigate this, we created a novel panel data set of 197 dairy farms in northern Spain observed over the period 2006-2014 by combining information from 2 different sources and including data on production variables, somatic cell count, and reproduction indicators, as well as a genetic index. We used these data to estimate a stochastic production frontier where the somatic cell count, age at first calving, and calving interval are included as determinants of technical efficiency. Higher somatic cell count, greater age at first calving, and longer calving intervals were found to decrease technical efficiency, translating into significant losses in profits which we quantify through a simulation exercise. We also quantified the effect of genetic selection on profits, taking into account not only its direct effect on productivity but also its indirect effect through reduced technical efficiency due to the effect of genetic selection on the health and reproduction variables., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

A study was carried out to identify prevalence and risk factors for bovine subclinical mastitis (SCM) in crossbred lactating cows within the Kurunagala district of Sri Lanka. In this study, 283 crossbred cows (Jersey x Shahiwal) from randomly selected medium- and relatively large-scale dairy farms were screened for SCM. The Californian mastitis test (CMT) plus microbiological analyses were employed for screening. A pre-tested questionnaire was used to collect information on the cows and their management. When screening was based only on CMT, the prevalence of SCM was 49%, and it was 44% if based on both CMT and pathogen isolation. The isolated pathogens were Staphylococcus spp. (80%, 98/123), Escherichia coli (14%, 17/123), Streptococcus spp. (3%, 4/123) and Pasteurella multocida (3%, 4/123). The age, parity and milk yield showed positive correlations with SCM (p < 0.05). The prevalence of SCM was relatively high after the fifth parity (p = 0.03, odds ratio = 9.49). A positive correlation of increase in calving interval (more than 18 months) with SCM was observed. The prevalence of SCM on the dairy farms can be reduced by implementing more hygienic management practices.

Inheritance of economic traits and their genetic correlation was studied in different breeds and their various grades (crossbred's cattle) under the subtropical condition. Data on principal parameters comprising 10 years, that is 2004-2014, were utilized for the present study. Different grades of dairy cows comprising Holstein Friesian (HF), Sahiwal x Friesian (SxHF), Jersey (J), Jersey x Achai (JxAC) and Achai (AC) were included in the study. Heritability estimates and genetic correlations of some important productive and reproductive traits were worked out. Heritability estimates of certain economic traits were found to be: birthweight, 0.32 ± 0.181; age at maturity, 0.11 ± 0.136; age at first calving, 0.19 ± 0.162; days open, 0.09 ± 0.121; calving interval, 0.14 ± 0.211; dry period, 0.11 ± 0.124; lactation length, 0.04 ± 0.212 and lactation yield, 0.46 ± 0.206. Genetic correlation showed that body weight was significantly and positively correlated with lactation length (0.30) and lactation yield (0.81), while negatively correlated with age at maturity, age at first calving, days open, calving interval and dry period (-0.09, -0.07, -0.16, -0.34 and -0.002, respectively). Calving interval was positively and significantly correlated with the dry period (0.56), lactation length (0.72) and lactation yield (0.37). Moderate to higher heritability estimates with adequate genetic variance was found for body weight and lactation yield. The moderate to higher heritability estimates of birthweight in the present study revealed that this important trait might be considered in selection criteria., (© 2019 Blackwell Verlag GmbH.)

This study estimated the genetic variability and correlations between growth and reproductive traits in Nelore cattle. Annual genetic changes in female reproductive traits were also evaluated using repeated measures. Direct heritability was moderate for the growth traits and scrotal circumference (0.235 ± 0.015 to 0.443 ± 0.006), indicating genetic variability in these traits in the population studied. Maternal heritability was low for weaning height (0.042 ± 0.012) and weaning weight (0.112 ± 0.013). Regarding female reproductive traits, gestation length (GL) exhibited a slightly higher heritability (0.179 ± 0.006) than days to calving (DC) and calving interval (CI) (0.123 ± 0.006 and 0.105 ± 0.008, respectively). Repeatability was lower for GL (0.222 ± 0.006) compared to DC (0.318 ± 0.004) and CI (0.406 ± 0.006). Moderate and positive genetic correlations were obtained between the growth traits and scrotal circumference, ranging from 0.193 ± 0.019 to 0.519 ± 0.007. Weaning height showed low and positive genetic associations with GL (0.138 ± 0.007) and CI (0.189 ± 0.016), but was not correlated with DC (-0.016 ± 0.011). Similarly, weaning weight, yearling height or yearling weight was not associated with any of the female reproductive traits. The genetic correlations between scrotal circumference and female reproductive traits were negative and favorable, but low: -0.116 ± 0.020 (GL), -0.084 ± 0.028 (DC), and -0.054 ± 0.038 (CI). Favorable genetic associations were estimated between all female reproductive traits, ranging from 0.170 ± 0.040 to 0.442 ± 0.050. Genetic changes were favorable for GL and CI (-0.02 days/year and -0.11 days/year, respectively) and unfavorable for DC (0.16 days/year). In conclusion, selection for higher growth using the estimated breeding values for height and weight will not affect the reproductive performance of Nelore females. Nonetheless, simultaneous selection for growth and reproductive traits is possible., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The aim of this study was to assess the reproductive performance of Ankole cattle and its crossbreds with Friesian (F), Jersey (J), and Sahiwal (S). The traits (number of records) studied were calving to first insemination, CFI (797); calving to last insemination, CLI (797); conception rate, CR (4354); number of inseminations, NINS (936); and calving interval, CI (259). The overall means of intervals CFI, CLI and CI, CR, and NINS were 192, 198 and 480 days, 67%, and 1.23 respectively. Breed group was significant (P < 0.05) for all traits except NINS, while season of calving was significant for CFI, CLI, and CI, and season of insemination was significant for CR. The breed group AF had better CR than the purebred Ankole and AS, and AS had lower CR than AJxS and AJ. On the other hand, Ankole (and to some extent AF) had longer CFI and CLI than AJ, AS, and FF. Ankole had 54 days longer CI than all crossbreds taken together. The prolonged intervals CFI, CLI, and CI observed in this study call for proper postpartum anestrus management both in terms of nutrition and calf suckling management.

The size and body condition of cows can affect their reproductive efficiency. However, few studies reported genetic correlations between these traits in beef cattle. Thus, we estimated the genetic parameters and correlations between weight (MW), height (MH) and body condition score (BCS) of cows and reproductive traits (SC: scrotal circumference, AFC: age at first calving, GL: gestation length, DC: days to calving, and CI: calving interval) in Nelore animals. In addition, it has also obtained direct and correlated responses aiming at determining whether changes in cow size and body condition may affect the herd reproductive performance. A series of two-trait Bayesian analyzes were performed including MW, MH or BCS with each of the reproductive traits. The heritability estimated for MW, MH and BCS were 0.46 ± 0.02, 0.35 ± 0.01 and 0.17 ± 0.02, indicating an involvement of additive gene action mainly in cows' size determination. For the reproductive traits of females, heritability ranged from 0.05 ± 0.00 for CI to 0.18 ± 0.01 for GL, and was 0.37 ± 0.01 for SC. Low repeatability were estimates for GL (0.19 ± 0.00), DC (0.19 ± 0.00) and CI (0.05 ± 0.00). The MW was positive correlated with AFC (0.23 ± 0.08), CI (0.25 ± 0.15) and, with lower magnitude, of GL (0.14 ± 0.03). Null genetic correlations were obtained between MW with SC (0.03 ± 0.03) and DC (-0.01 ± 0.04). The MH showed positive and low genetic association with all female reproductive traits, but negative with SC (-0.08 ± 0.03). Negative and favorable genetic correlations were estimated between BCS and females reproductive traits, but unfavorable with SC (-0.13 ± 0.06). In summary, the negative impact of increase the size of Nelore females on their reproductive performance is expected to be small in tropical regions. The use of sires with high genetic breeding values for SC should result in slight reduction of BCS of cows, but no effective genetic response in female size is expected. Selection based on BCS should promote little improvement in reproductive efficiency of cows., (Copyright © 2018 Elsevier Inc. All rights reserved.)

To understand the profitability of reproduction management measures, an economic assessment based on a beef cow life simulation was proposed. It accounted for the discounted feeding costs of the dam and its calves for the different periods of their lives up to their sale and for the overall production from calves adjusted by mortality and culling. The calibration was proposed for various combinations of typical French and European situations. The maximal cash flow was observed for the lowest calving interval, corresponding to the maximal number of calves produced. The marginal cost of the calving interval was not uniform: on average, it was twice as high at a calving interval of 360 days (€1/day) as at 500 days (€0.5/day). It was also higher when age at first calving was lower and when culling was late or the replacement rate was low. The results were sensitive to the costs of the calves' diets and to the market prices for calves. These assessments may assist the evaluation of the profitability of various measures taken in the field when faced with deteriorating calving intervals in beef production., Competing Interests: Competing interests: None declared., (© British Veterinary Association (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Crossbreed dairy breeds, such as Holstein × dairy type of Simmental, have been generally used to improve fertility, udder health, and longevity of dairy herds. The aim was to compare the reproductive performance and survival of Holstein and Holstein × Simmental crossbred cows. Data from two farms were used as follows: one located in Bom Retiro, in the state of Santa Catarina, Brazil. and another in Carambeí, Paraná state. Information concerning birth, inseminations, and parity date were obtained from the management software of the farms, generating information regarding the calving interval, days between calving to first service, conception rate, and age at first calving. At one of the farms, calving was monitoring to quantify dystocia. Live weight as well as body condition score (BCS) of cows and information of culling were obtained to determine the survival rate. Data were analyzed by variance analysis and by logistic regression. Crossbred Holstein × Simmental cows had better reproductive performance than the Holstein cows, characterized by lower calving interval (381 vs. 445 days), higher conception rate (37.3 vs. 33.6 %), and shorter calving to first service interval (65 vs. 89 days). These results were related to a higher BCS in crossbred cows (3.63 vs. 2.94 points). Crossbred Holstein × Simmental cows had higher survival rate than Holstein cows on the second parity (83 vs. 92 %). No differences between genetic groups were observed (P > 0.05) for body weight and dystocia. In conclusion, Holstein × Simmental crossbred cows have better reproductive performance and higher survival rate than Holstein cows.

Data from Bering-Chukchi-Beaufort Seas bowhead whales (Balaena mysticetus), harvested during 1973–2021 by aboriginal subsistence hunters, were used to estimate reproductive parameters: length at sexual maturity (LSM), age at sexual maturity (ASM), pregnancy rate (PR), and calving interval. Sexual maturity (N = 187 females) was determined from the presence/absence of corpora in the ovaries, or a fetus. Using sampling bias-corrected logistic regression, LSM was estimated at 13.5 m, 95% CI [13.0, 13.8]. There was a downward trend in LSM over time, statistically significant with one method but marginal with another. A growth model translated this estimate to an ASM estimate of 23.5 years, 95% CI [20.4, 26.7]. Pregnancy rate was determined from mature females (N = 125), and from a subset limited to certain autumn-caught whales (n = 37) to reduce bias. The PR was estimated at 0.46 globally, 95% CI [0.36, 0.55] and 0.38 for the autumn sample, 95% CI [0.20, 0.51]. Both estimated PRs are consistent with a 3-year calving interval, because the larger estimate includes two cohorts of pregnant whales harvested in spring, and bowhead whale gestation is longer than 12 months. These analyses represent the most conclusive empirical estimates of ASM, LSM, and PR for this bowhead whale stock from the largest available data sets to date.

Understanding reproductive output and success is integral to the conservation and management of threatened species and populations. Little is known about the reproductive parameters of Australian humpback dolphins (Sousa sahulensis), a species subject to cumulative pressures from anthropogenic threats due to their coastal distribution and strong site fidelity. This study assesses several reproductive parameters, including crude birth, recruitment, fecundity, and calf survival rates, in addition to interbirth intervals of Australian humpback dolphins inhabiting the near‐urban embayment of Moreton Bay, Queensland. Between 2014 and 2020, 106 adult females were photographically identified during 222 boat surveys. Of these, 75.5% (n = 80) were observed with calves. Birth seasonality was apparent and coincided with austral autumn and winter months. Interbirth intervals ranged between 1 and >6 years, with an average of 3.1 (SD = 1.1) years if offspring survived. Findings indicate declining fecundity rates (p <.05, M = 0.12, SD = 0.02), relatively low recruitment rates (M = 0.04, SD = 0.01) and calf survival rates to 1 year of age (M = 0.63, SD = 0.15). This study provides a useful baseline that can inform viability assessments and conservation measures, for both this population and others throughout the species range. [ABSTRACT FROM AUTHOR]

Background: The knowledge and estimation of genetic and non-genetic factors on the production and reproduction traits of Ongole cattle are important to enable the breeders to design efficient conservation strategies and adopt better selection methods, management practices and culling operations. Methods: Data available on 220 Ongole cows mated to 22 sires-at the Livestock Research Station, Mahanadi, Kurnool (District), Andhra Pradesh over a period of eight years was used for the present analysis. Result: Results in the present study revealed that performance of animals was improved in lactation milk yield (LMY, 1063.33±31.13), 305 lactation milk yield (LMY, 1019.83±29.22), lactation length (LL, 266.26±5.6), less calving interval (CI, 497.95±8.58), service period (SP, 188.19±5.17) and dry period (DP, 214.79±19.6) compared to earlier reports. Parity and period have shown significant effect on all production traits and calving interval. Effect of season was non-significant on all productive and reproductive traits. Most of the heritability estimates for milk production traits were medium in range but low for reproductive traits. The correlations between productive traits and calving interval were negative. [ABSTRACT FROM AUTHOR]

This research aimed to identify the reproductive characteristics of Gayo buffaloes in the Mesidah Sub-district, Bener Meriah Regency. There were three locations of the current study namely Perumpaken Benjadi, Wer Tingkem, and Simpur, which were determined using the purposive sampling technique. A survey was used as the research method to obtain primary data and secondary data. Primary data were collected through direct interviews with buffalo livestock owners. They were asked a set of questions that had been prepared in a questionnaire. Secondary data were obtained from related agencies in Bener Meriah Regency. The number of respondents was 92 from four villages in the Mesidah Sub-district, Bener Meriah Regency. Breeders as respondents were selected using a purposive sampling method, with minimum requirements that they had raised two buffaloes that had given birth more than once and that the breeders had at least four years of farming experience. The research data were analyzed using descriptive statistic. The results showed that the Gayo buffaloes in the Mesidah Sub-district, Bener Meriah Regency, had reproductive characteristics that met the standards. This can be seen from the obtained data which were almost the same as the average age of the reproductive characteristics of buffaloes in Indonesia. Gayo buffaloes in the Mesidah Sub-district experienced the first estrus (puberty) at 33.83 months old, first mating at 34.61 months old, and first calving at 45.29 months. The average gestation period was 10.51 months, the calving interval was 15.5 months, and the average service period was 3.66 months, while maintenance management was carried out extensively. Based on the results, it can be concluded that the reproductive characteristics of Gayo buffaloes in the Mesidah Sub-district, Bener Meriah Regency, still meet the standards. The average reproductive characteristics of Gayo buffaloes are generally the same as the average characteristics of other buffaloes in Indonesia.

Copyright of Kocatepe Veterinary Journal / Kocatepe Veteriner Dergisi is the property of Afyon Kocatepe University, Faculty of Veterinary Medicine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Indonesian Journal of Veterinary Science / Jurnal Kedokteran Hewan is the property of Universitas Syiah Kuala, Faculty of Veterinary Medicine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aimed to assess the reproduction parameters of modern dairy cattle in the west of Algeria. Our experimentation included 2270 dairy cows selected from three different farms; two of them situated in the Sidi Bel Abbes region (Taleb and Sidi Lahcen) and the third farm situated in the region of Temouchent (Oued Sebbah). These cows were followed from January 2017 to December 2018 to determine their reproduction performance. Our results recorded that the mean cows' age during the first calving was 30± 2.2 months with an extreme of 22 to 43 months. The interval registered between the first calving and mating was 85.0 ± 6.3 days with extremes of 40 to 110 days. In our results, an average of 94.6 ± 7.5 days with extremes of 38 to 152 days was recorded between calving and the fertilizing protrusion. The cow's interval between calving was 423 ± 63.2 days with extremes of 301 to 601 days. Modern infrastructure, food in terms of quality and quantity as well as employing a qualified workforce in farms can significantly improve the performance of our animals. [ABSTRACT FROM AUTHOR]

The article presents studies results on the subject of reproductive capacity indicators of different ages high-yielding Holstein cows in the conditions of an industrial complex for milk production. The study was conducted on the basis of PJSC (Private Joint Stock Company) Agro-Soyuz in the Sinelnikovsky district of the Dnipropetrovsk region (Ukraine). The experimental groups of animals were formed in the following way: group I (n = 35) – first-calving heifers; group II (n = 35) – animals of the second lactation; group III (control), (n = 35) – animals of the third lactation; group IV (n = 35) – cows of the fourth lactation. Certain age dependence of the insemination index has been established. Young first-calving heifers and adult cows of the fourth lactation (groups I and IV) had a relatively better value of this indicator – 4.5 units. At the same time, cows of the second and third lactation (group II; group III – control) were characterized by a sharp decline in reproductive ability, therefore, for one fertilization it was necessary to carry out 5.8 artificial inseminations for them. Based on the level of the insemination index by research groups, it was logical that the calving-to-conception interval for all experimental animals was much lower than the stereotyped value (60–80 days) and averagely amounted to almost 8 months. Infertility in animals of experimental groups was directly determined by the calving-to-conception interval duration and the average value of which was within 165 days. More infertile days were recorded in the dairy complex with group III cows (control) – 195 days. The value of the adaptation index in the experimental groups was unaligned. Cows of the first two lactations (groups I and II) were characterized by this stable value of 7.6 units. After that, during the third lactation (group III – control), it was increased by 2 units – 9.6, and in adult cows of the fourth lactation (group IV), it had a tendency to rapidly decrease to 4.8 units. First-calving heifers (group I) and adult cows (group IV) had the lowest production losses because they had the fewest infertile days. Animals of the third lactation (group III – control) were characterized by the highest production losses – 0.68 calves and 3 166 kg of milk.

Reproductive parameters of 168 franciscana dolphins, Pontoporia blainvillei (73 females and 95 males) incidentally caught (n = 163) or stranded (n = 5) between 2005 and 2016 in southeastern Brazil are presented. Ovarian macroscopic analysis revealed 55 immature (75.3%) and 18 mature (24.7%) females. Annual pregnancy rate was estimated to be 0.36, with a calving interval of 2.8 years. Testicular histology revealed 66 immature (69.5%) and 29 mature (30.5%) males. Males with combined testis weight above 4 g were mature, and 1‐year‐old mature males and a 2‐year‐old pregnant female are reported for the first time for the species. Reproductive seasonality does not seem to occur in the study area. Mean age and length at sexual maturation were estimated to be at 2.7 years and 128.5 cm for females, and 2.7 years and 114.0 cm for males. These estimates are lower than most of the estimates for this species. These results add novel and valuable information on the reproductive patterns of this endangered species, threatened by high levels of mortality in gill net fisheries. The information presented here represents an important effort to obtain more reliable parameter estimates for the studied area, needed for a better assessment of its current conservation status. [ABSTRACT FROM AUTHOR]

Breeding indices and their interrelations were studied with the Dutch and German Holstein cow populations, exploited in the southern part of the Republic of Moldova. It was established that regardless of origins of cow population both duration of service-period as well as during of calving interval significantly prevail admitted optimal value. The best results regarding the time of service -period and interval between calving is registered at the population of Holstein cows of Dutch origin. The calving interval, in the average on population of cows of Dutch origin exceeds the optimal admissible value by 16.93%. Under similar conditions, maintenance and operating on cows of the German origins the calving interval duration exceeds the target value by 21.2%, being higher comparing with the results established at cows of Dutch origins by 3.5%. The coefficient of reproductive capacity utilization on average at cows in cows of Dutch origin is 0.86 and that of German origin is 0.83. In the investigated populations, were established links under medium, weak and very weak, both positive and negative, between breeding indices and the age of cows. [ABSTRACT FROM AUTHOR]

Genetic analysis of reproduction traits for Tharparkar cattle herds was carried out on the data collected from the Livestock Research Station, Beechwal, Bikaner. A total of 284 performance records belonging to 63 Tharparkar cows completing at least three lactations spread over a period of fifteen years (2002 to 2016) were utilized. The overall least-squares means for age at first calving, Service period and calving interval were 1570.88 ± 29.13 days, 136.18 ± 2.19 days, 415.18 ± 3.36 days, respectively. Heritability estimates for age at first calving, service period and calving interval were estimated as 0.44±0.24, 0.17±0.12 and 0.09±0.11, respectively. Sire had significant effect on all traits. The significant effect of period of calving on all traits was found except calving interval. Season of calving and parity did not influence these traits in present study. [ABSTRACT FROM AUTHOR]

Southern right whales (Eubalaena australis) were widespread in New Zealand waters before commercial whaling in the nineteenth century caused drastic declines in their abundance and distribution. Following the cessation of whaling, the population has been recovering and is now slowly recolonising its former range. Estimates of population demographics, including reproductive output, are essential for predicting the trajectory of this population. We gathered photo-identification data on female southern right whales during annual field trips to the Auckland Islands, the principal calving area in New Zealand waters. Forty-five calving intervals were observed between 2006 and 2013 (mean interval = 3.31 years, 95% CI = 3.06-3.57). Incorporating the effects of possible missed calving events produced a plausible range of mean calving intervals from 3.17 to 3.31 years. Our results suggest that the calving interval of New Zealand southern right whales is similar to that found in populations elsewhere. [ABSTRACT FROM AUTHOR]

Reproduction is the main factor in determining the efficiency of animal production. Reproductive efficiency can be described as a measure of the ability of cows to conceive and produce calves. Fertility economic level is usually assessed by the calving interval, the period between 2 successive calving. Management factors conditions the improve reproductive performance to optimize, in herds of cows with high genetic capacity. For the study is analyzing the information collected in three regions of the country (Fier, Durrës, Shkodër) to (n = 1200) cows of Holstein breeds included in the Book of Breed which serves as a basis for evaluating performance production and reproductive of herds milk production. This cattle population is extended (n = 90) dairy farms. The total of (n = 1505) complete lactations and estimates, about (n = 987) met the criteria lactations for further processing for performance evaluation and ranking of cattle production by level of production. The data cover the period from 01.01.2012 - 31.12.2015. The processing of data, resulting an average milk production of 5618 kg / 305 day lactation with a variation of 3176-8128 kg / 305 days lactation and an average age of 4.89 years with a variation from 3.2 to 7.81 years. The survey data show that significant differences are found between herds regarding the production of milk. Also observed differences regard to the average age between herds. 25% of the populations of cows have extended lactations (390-540 days) and therefore long calving intervals across from optimal, which occur primarily in first lactation cows. The interval between calving is the most important indicator of herd reproduction. In the study undertaken this indicator is (431 ± 113) days (n = 621). Reproduction efficiency of cattle with higher production capacity remains one of the challenges facing today's big and medium farms level. In this context, the study aims to optimize reproductive performance through improved breeding conditions influencing the interval calving - calving in cows with high production capacity. [ABSTRACT FROM AUTHOR]

The scientific paper presents the results of research of productive and reproductive parameters of cows of Holstein breed of Dutch and German origin in the herd J-S.C. „Aydyn”, Comrat Administrative and Territorial Unit Gagauzia. For the analysis was used performance control for the year 2015: cows on the first lactation (n=122) and the second lactation (n=43) of Dutch origin and cows on the first (n =129) lactation - of German origin. It was established that from cows of the Dutch origin for the first lactation on average was received 7803 kg of milk, which is with 589 kg more than from the cows of German origin, a highly significant difference (P <0.001). It is established by the analysis that 50,8% of the animals of Dutch origin had the productivity from 7501-8000 kg to 9001 kg, whereas 70,5% of the animals of German origin had the productivity from 6000-6500 to 7001-7500 kg and only 29.5% from 7501-8000 to 9001 kg of milk per lactation. The average length of the dry period at cows of Dutch origin was by 6.5 days less than at the cows of German origin, the difference is authentic at P <0.05. Service period at cows of Dutch origin averaged 219.9 ± 12 days, the German origin - 168.2 ± 15.4 days. This affected the increase of the between calving interval at the animals of Dutch origin (483 days), the German origin (446 days), which exceeds the desired duration by 118 and 81 days, respectively. [ABSTRACT FROM AUTHOR]

The objective of present study was to derive the economic values for number of inseminations to conception, calving interval, milk yield and stillbirth, using economic data of 10 Iranian Holstein herds. The economic values were derived by using the profit function methods and differentiating a profit equation with respect to the traits of interest. The cow fertility costs herd amortization or replacement cost and cow feed cost were included in the profit function. The average of feed cost per cow per day was 8.65 USD. The total feed cost comprised 61 percent of milk production, 23 percent of maintenance, 12 percent of pregnancy and 4 percent of growth. In calculation of cow feed cost, the estimated cost for each Mcal and per g protein of feed were 0.0006 and 0.165 USD, respectively. The replacement cost of each heifer per cow herd was 1719 USD. The average cost of each insemination was 30 USD. The estimated economic values for the number of insemination, calving interval, milk yield and one percent unit of stillbirth, were -82, -2.08, 0.193 and - 1.27 USD per cow/per year, respectively. The results of the current study suggested that improving the number of inseminations, calving interval, milk yield and stillbirth will have a positive effect on the profitability of Iranian Holstein cows. [ABSTRACT FROM AUTHOR]

The association of six linear type traits with calving interval, abortions, incidence of stillbirths and pre-weaning losses in Nguni cows in semi-arid and sub-humid communal areas was investigated. It was hypothesised that the odds of a cow having caving interval greater than 1 year, aborting, experiencing stillbirths or losing a calf from calving to weaning decreased with increase in body depth, rump height, flank circumference, chest circumference, navel height and body length. Navel height was measured as the distance from the ground to the lowest point of the cow's belly bottom (navel). Data were collected from a total of 200 Nguni cows from two sites experiencing sub-humid and semi-arid environments (100 each) between May and June 2013. Cows in sub-humid regions were 2.57 times more likely to have a calving interval of 1 year than cows in semi-arid areas. As body depth increased, the number of calves lost by a cow before weaning decreased linearly ( p < 0.05) in all parities except parity 4. Cows in semi-arid regions were 2.13 times more likely to lose a calf from calving to weaning. For each unit increase in body depth, the odds of a cow aborting decreased by 1.12 and the odds of a cow having stillbirth decreased by 1.15. Rump height, flank circumference, chest circumference, navel height and body length were not associated with calving interval, abortions, incidence of stillbirths and pre-weaning losses. It was, therefore, concluded that body depth influences calving interval, incidence of stillbirths and abortions in Nguni cows. [ABSTRACT FROM AUTHOR]

Os efeitos de fatores genéticos e de ambiente sobre características reprodutivas, a partir de 475 observações de intervalos de partos (IDP) e 401 de fertilidade real (FR) de vacas da raça Nelore, criadas no município de Santa Inês, Estado do Maranhão, em regime de pasto com suplementação na estação seca, no período de 1980 a 1994, foram estudados. Os dados foram analisados por intermédio de modelos lineares, que incluíram efeito de touro (aleatório), mês e ano do parto anterior e atual, ordem de parição e sexo da cria (fixos). O pai da vaca e a ordem de parição influenciaram significativamente ambas as características estudadas, enquanto o sexo da cria influiu apenas na FR. As médias estimada pelo método dos quadrados mínimos, para IDP e FR, foram 433,84 ± 88,20 dias e 184,69 ± 37,09 kg, respectivamente. Os coeficientes de herdabilidade estimados pela correlação intraclasse entre meio-irmãs paternas foram estimados em 0,32 ± 0,15 e 0,49 ± 0,19, respectivamente, para IDP e FR.The effects of genetic and environmental factors on reproductive traits, from 475 records of calving interval (CI) and 401 of real fertility (RF) of Nellore cows reared at Santa Inês county, Maranhão State, in pasture grazing system with supplementation in the dry season, from 1980 to 1994, were studied. The data were analyzed by means of linear models, which included the sire effect (random effects), month and year of the last and the actual calving, calving number and sex of calf (fixed effects). The sire effect and calving number significantly affected both studied traits, while calf sex affected only the RF. The calving interval and R F by least square means were: 433.84 ± 88.20 days and 184.69 ± 37.09 kg, respectively. The heritability coefficients estimated by intraclass correlation of paternal half-sisters were .32 ± .15 and .49 ± .19, for CI. and RF. respectively.

Abstract: A 5-year retrospective (from 2008 to 2012) survey was carried out by analyzing data of high producing dairy cows reared in farms located in an area of southern Apennines. The indicators of fertility obtained were related to either season variations or temperature–humidity index (THI). Conceptions were evaluated per month on an annual basis (NCY), i.e., a parameter obtained by subtracting gestation length to the calving date. A significant reduction of NCY was found during the summer months; furthermore, this parameter decreased along with THI increase. The number of heats detected varied similarly to NCY and represented the main cause of lower fertility consequent to heat stress (HS). The age at first calving was not significantly affected by either the season or the THI. The mean number of AI/pregnancy in relation to the calving date was significantly affected by the season but it was not related to THI. The number of days open was significantly larger in the animals calved from January to July than from August to December (163±33 vs 123±36 days; P<0.001); this causes an annual economic loss of several thousand euro in each farm analyzed. In conclusion, HS causes severe economic loss in dairy farms located in southern Apennines that is mainly due to a lower number of heats detected as well as to a larger number of days open and semen doses used. [Copyright &y& Elsevier]