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Objective We investigated genetic parameters of calving ease (CE) using several animal models in Korean Holstein and searched for suitable models for routine evaluation of CE. Methods Two phenotypic datasets of CE (DS5 and DS10) on first-parity Korean Holstein calves were prepared. DS5 and DS10 included at least 5 and 10 CE records per herd-year level and comprised 117,921 and 80,389 observations, respectively. The CE phenotypes ranged from 1 to 4, from a normal to extreme difficulty calving scale. The CE was defined as a trait of the calf. The BLUPF90+ software was used for (co)variances estimation through four animal models with a maternal effect (M1 to M4), where all models included effects of a fixed calf-sex, a fixed dam calving age (covariate), and one or more fixed contemporary group (CG) terms. The CG effects were different across models—a herd-year-season (M1, HYS), a herd-year and year-season (M2, HY+YS), a herd-year and season (M3, HY+S), and a herd and year-season (M4, H+YS). Results Direct heritability (h2) estimates of CE ranged from 0.005 to 0.234 across models and datasets. Maternal h2 values were low (0.001 to 0.090). Genetic correlations between direct and maternal effects were strongly negative to lowly positive (−0.814 to 0.078), further emphasizing its importance in CE evaluation models. These genetic parameter estimates also indicate slower future selection progress of CE in Korean Holsteins. The M1 fitted many levels with fewer observations per level deriving unreliable parameters, and the M4 did not account for confounded herd and animal structures. The M2 and M3 were deemed more realistic for implementation, and they were better able to account for data structure issues (incompleteness and confounding) than other models. Conclusion As the pioneering study to employ animal models in Korean Holstein CE evaluation, our findings hold significant potential for this breed’s future and routine evaluation development.

Objective: We investigated genetic parameters of calving ease (CE) using several animal models in Korean Holstein and searched for suitable models for routine evaluation of CE. Methods: Two phenotypic datasets of CE (DS5 and DS10) on first-parity Korean Holstein calves were prepared. DS5 and DS10 included at least 5 and 10 CE records per herd-year level and comprised 117,921 and 80,389 observations, respectively. The CE phenotypes ranged from 1 to 4, from a normal to extreme difficulty calving scale. The CE was defined as a trait of the calf. The BLUPF90+ software was used for (co)variances estimation through four animal models with a maternal effect (M1 to M4), where all models included effects of a fixed calf-sex, a fixed dam calving age (covariate), and one or more fixed contemporary group (CG) terms. The CG effects were different across models--a herd-year-season (M1, HYS), a herd-year and year-season (M2, HY+YS), a herd-year and season (M3, HY+S), and a herd and year-season (M4, H+YS). Results: Direct heritability (h2) estimates of CE ranged from 0.005 to 0.234 across models and datasets. Maternal h2 values were low (0.001 to 0.090). Genetic correlations between direct and maternal effects were strongly negative to lowly positive (-0.814 to 0.078), further emphasizing its importance in CE evaluation models. These genetic parameter estimates also indicate slower future selection progress of CE in Korean Holsteins. The M1 fitted many levels with fewer observations per level deriving unreliable parameters, and the M4 did not account for confounded herd and animal structures. The M2 and M3 were deemed more realistic for implementation, and they were better able to account for data structure issues (incompleteness and confounding) than other models. Conclusion: As the pioneering study to employ animal models in Korean Holstein CE evaluation, our findings hold significant potential for this breed's future and routine evaluation development. [ABSTRACT FROM AUTHOR]

Simple Summary: Simple Summary: This study examines how breeding dairy cows with high immune response (HIR) sires affects their reproductive performance. We looked at factors like calving time, how long they stay open for insemination, and the ease of calving. We found that cows related to HIR sires tended to have shorter intervals between calving, which is good for farm productivity. However, there were also more cases of twin pregnancies and difficult births among these cows. This suggests that while there are some benefits to breeding with HIR sires, there are also potential challenges. Understanding these effects can help farmers make better decisions about breeding strategies, ultimately contributing to the efficiency and success of dairy farming. Reproductive traits in dairy cattle are crucial for herd productivity and profitability. This study investigates the influence of relatedness to high immune response (HIR) Immunity+ sires on reproductive performance indicators in Polish Holstein-Friesian cows. A total of 5094 cows were analyzed, categorized based on their relatedness to HIR Immunity+ sires, and assessed for various reproductive parameters, including age at first insemination, gestation length, days open, calving interval, and calving ease. The results showed that the level of relatedness to HIR Immunity+ sires influenced certain reproductive traits, such as service period, gestation length, and age at first and second calving. Additionally, cows related to HIR Immunity+ sires exhibited a higher frequency of twin pregnancies and more complicated births. While some benefits were observed in certain reproductive traits among cows related to HIR Immunity+ sires, such as reduced age at first insemination and shortened gestation length, the overall impact on reproductive efficiency remains inconclusive. Further studies are needed to fully elucidate the effects of using semen from HIR Immunity+ sires on reproductive performance in dairy cattle. [ABSTRACT FROM AUTHOR]

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The aim of the current research was to evaluate the effects of twinning on calving ease and calves' viability in Romanian Spotted dual-purpose breed. Data from 280 births (260 single and 20 twin births) were enrolled in order to assess the twinning and the dystocia incidences. Viability of calves was estimated based on a data set collected from 300 calves (260 singleton and 40 twin calves). The average incidence of twinning in herd was 7.14%, while the incidence of dystocia was 19.23%. The twin pregnancies proved to be the major factor related to dystocia, causing a higher prevalence compared to single pregnancies (15% vs. 4.23%, p≤0.001). Stillborn incidence was the most prevalent in twin compared to single births (5% vs. 2.31%, p<0.001). Dystocia proved to be correlated to both, twinning (R=0.31) and calves' viability (R=-0.44). Also, twinning has a strong correlation with calves' viability (R=0.49). The twinning induced a significant increase of morbidity compared to single births (12.5% vs. 5%, p<0.001). Considering the detrimental effect of twinning on animal health, welfare and subsequent performance, allows the implementation of after-calving dam-calf care protocols in order to mitigate these effects. [ABSTRACT FROM AUTHOR]

Threshold models are often used in genetic analysis of categorical data, such as calving ease. Solutions in the liability scale are easily transformed into probabilities; therefore, estimated breeding values are published as the probability of expressing the category of main interest and are the industry's gold standard because they are easy to interpret and use for selection. However, because threshold models involve nonlinear equations and probability functions, implementing such a method is complex. Challenges include long computing time and convergence issues, intensified by including genomic data. Linear models are an alternative to overcome those challenges. Estimated breeding values computed using linear models are highly correlated (≥0.96) with those from threshold models; however, the lack of a transformation from the observed to the probability scale limits the use of linear models. The objective of this study was to propose transformations from observed to probability scale analogous to the transformation from liability to probability scale. We assessed computing time, peak memory use, correlations between estimated breeding values, and estimated genetic trends from linear and threshold models. With 11M animals in the pedigree and almost 965k genotyped animals, linear models were 5× faster to converge than threshold models (32 vs. 145 h), and peak memory use was the same (189 GB). The transformations proposed provided highly correlated probabilities from linear and threshold models. Correlations between direct (maternal) estimated breeding values from linear and threshold models and transformed to probabilities were ≥0.99 (0.97) for all animals in the pedigree, sires with/without progeny records, or animals with phenotypic records; therefore, estimated genetic trends were analogous, suggesting no loss of genetic progress in breeding programs that would adopt linear instead of threshold models. Furthermore, linear models reduced computing time by 5-fold compared to the threshold models; this enables weekly genetic evaluations and opens the possibility of using multi-trait models for categorical traits to improve selection effectiveness. [ABSTRACT FROM AUTHOR]

The aim of the current research was to evaluate the effects of twinning on calving ease and calves’ viability in Romanian Spotted dual-purpose breed. Data from 280 births (260 single and 20 twin births) were enrolled in order to assess the twinning and the dystocia incidences. Viability of calves was estimated based on a data set collected from 300 calves (260 singleton and 40 twin calves). The average incidence of twinning in herd was 7.14%, while the incidence of dystocia was 19.23%. The twin pregnancies proved to be the major factor related to dystocia, causing a higher prevalence compared to single pregnancies (15% vs. 4.23%, p≤0.001). Stillborn incidence was the most prevalent in twin compared to single births (5% vs. 2.31%, p

Simple Summary: One of the important goals of cattle breeding is increasing the longevity of cows, which is one of the most important economic traits. In our work, we focused on investigating the effects of factors that could be the cause of cow culling before they reach their maximum potential. Calving difficulty and the proportion of stillborn calves reduce the length of the productive life because cows with problematic calving are often culled from the herd. For the farmer, these traits represent additional costs for veterinary procedures and related treatment after calving. We found that factors such as milk production level, parity, age at first calving, herd size, calf sex, herd–year–season, calving ease, and stillbirth had a significant effect on the longevity of cows. The research confirmed that the incidence of difficult births and the proportion of stillborn calves was higher in primiparous cows than in multiparous cows. Our analysis showed that female calves were born more easily than male calves. By selecting animals aimed at reducing the number of difficult calving and the number of stillborn calves, a higher functional, productive life in cows could be achieved. The aim of the study was to determine the frequency of births according to the categories of calving difficulty and stillbirths and to evaluate the effect of these factors on the longevity of cows. Longevity is one of the traits that affect the overall profit in the dairy industry. A Weibull proportional hazard model was used to evaluate the influence of functional traits such as calving ease and stillbirth. Longevity was expressed as the length of a functional, productive life from the first calving to death or censoring, which was corrected for milk yield. The database included 918,568 calvings, where calving without assistance represented 83.34%, calving with the assistance of one person or the use of a slight mechanical pull represented 14.47%, difficult calving with the assistance of several people, the use of mechanical traction or the intervention of a veterinarian represented 2.16%, and cesarean section represented 0.03%. The mortality of calves, stillborn or dead within 48 h of birth, represented 1.07% and 6.59%, respectively. The frequency of alive female calves was higher (46.84%) than male calves (45.50%). Cows with higher lactations had almost half as many stillborn calves as heifers. The most stillborn calves were found in difficult births (59.48%). In easy calving, this proportion was 2.48%. Using survival analysis, we estimated the significant influence of the factors such as parity, milk production, herd size, age at first calving, herd × year × season, sex of calf, calving ease, and stillbirth on the length of the functional, productive life of cows. The risk of early culling of the cows with moderately difficult calving was 1.259 times higher than in the cows with easy calving. Difficult calving and cesarean section shorten the productive life, and the risk of culling reached 1.711 and 1.894, respectively. Cows that gave birth to a dead calf achieved a 2.939 times higher risk of culling compared to cows that gave birth to a live calf. In this study, a higher risk of early culling was found in cows that gave birth to a male calf. Evaluation of the calving ease and stillbirth can be used as indirect indicators at an earlier age of the animal in the selection process for long-lived animals with good productive and reproductive performance. [ABSTRACT FROM AUTHOR]

Objective: To investigate genetic correlation between calving ease (CE) and gestation length (GL) traits of Korean Holstein cattle to understand genetic structures of these two traits and their potential implications., Methods: Records of progenies from first parity (P1, N=117,921) and second parity (P2, N=141,104) Holsteins cows were used for analysis. All phenotypes (CE and GL) were considered as calf traits. The CE was an ordered categorical trait. It was scored from 1 (normal calving) to 4 (difficult calving). GL observations were restricted between 260 and 305 days. Variance components and genetic parameters were estimated through a bivariate animal model with a correlated maternal effect using the BLUPF90+ software package., Results: Heritability (h2) estimates of CE for direct and maternal effects were low (less than 0.01) in all parity calves. For GL, despite lower h2 of maternal effect (~0.03), the direct effect was moderately heritable (0.20 to 0.23) in this study. Direct and maternal effects of CE trait were weakly correlated (P1: 0.09 ± 16.60, P2: -0.04 ± 0.00). GL had similar correlation patterns (P1: 0.03 ± 0.00; P2: -0.15 ± 0.05) across parities. Direct genetic correlations of GL and CE were mostly weak (P1: 0.18 ± 0.31; P2: -0.01 ± 0.06), whereas maternal genetic correlations were moderate and positive (P1: 0.39 ± 0.95; P2: 0.46 ± 0.04). Although the genetic influence of GL on CE was not entirely clear due to large estimation errors for parameters, overall positive associations between direct effects and maternal effects essentially indicate a selection potential for GL as an indicator trait of CE., Conclusion: This is the first genetic correlation investigation of GL and CE in Korean Holstein cattle. It provides important insights into genetic architectures of GL and its future potential as an indicator trait for CE improvements in Korean Holsteins.

Objectives: The objective of this study was to assess the relationship between pelvic measurements viz pelvic width (PW), pelvic height (PH) and pelvic area (PA), and linear body measurement traits viz body weight (BW), shoulder height (SH), chest depth (CD), Hindquarters width (HW), rump length (RL), hip height (HH), body length (BL) and also calve birth weight (CBW) under different calving ease scores viz no assistance, gently pull and hard pull. Material and methods: A total number of fifty-one first calf Sussex heifers at 24 months old, weighing approximately 450 kg were used for this study. A number of two, two-year-old bulls, weighing approximately 800 kg were used for mating the fifty-one heifers with a bull to cow ratio of (1:30 and 1:21). The fertility of bulls was assessed by a private veterinarian before the mating season. Calving ease was scored as follows: 1 = no assistance during parturition (normal), 2 = heifer assistance as gently pull, 3 = heifer assistance as hard pull, 4 = heifer cannot calf, 5 = heifer calved a dead calf, and 6 = heifer calf with abnormal position. Results: Descriptive statistics indicated that PH (p < 0.01) and RL (p < 0.05) were significant different among calving ease scores. Correlation findings for no assistance score revealed that CBW was positively significantly correlated (p < 0.05) PH and low significant (p < 0.01) with HW, HH, RL, PW, CD and SH, respectively. CART results demonstrated that HH and PH play an important role in predicting calving ease on Sussex heifers. Conclusion: The findings suggest that there is a relationship between pelvic areas and linear body measurements. This study might help farmers during breeding to lower incidents of dystocia during parturition. However, further studies need to be done in CART modelling with the main aim of reducing dystocia in Sussex heifer or larger sample size. [J Adv Vet Anim Res 2021; 8(1.000): 164-172]

Genetic selection has been an effective strategy to improve calving traits including stillbirth in dairy cattle. The primary objectives of the present study were to characterize stillbirth data and determine the feasibility of implementing routine genetic evaluations of stillbirth in five non-Holstein dairy breeds, namely Ayrshire, Guernsey, Milking Shorthorn, Brown Swiss, and Jersey. An updated sire-maternal grandsire threshold model was used to estimate genetic parameters and genetic values for stillbirth. Stillbirth data with the birth years of dams from 1995 to 2018 were extracted from the United States national calving ease database maintained by the Council on Dairy Cattle Breeding. The extracted stillbirth records varied drastically among the five dairy breeds. There were approximately 486K stillbirth records for Jersey and more than 80K stillbirth records for Brown Swiss. The direct and maternal heritability estimates of stillbirth were 6.0% (4.5–7.6%) and 4.7% (3.3–6.1%) in Jersey and 6.8% (3.2–10.5%) and 1.1% (0.6–2.9%) in Brown Swiss. The estimated genetic correlations between direct and maternal genetic effects for stillbirth were −0.15 (−0.38 to −0.08) in Jersey and −0.35 (−0.47 to −0.12) in Brown Swiss. The estimated genetic parameters for stillbirth in these two breeds were within close ranges of previous studies. The reliabilities of predicted transmitting abilities in Jersey and Brown Swiss increased substantially, thanks to the substantial increase in available stillbirth data in the past 10 years. The stillbirth records for Ayrshire, Guernsey, and Milking Shorthorn, which ranged approximately between 3K and 12K, are insufficient to implement reliable routine genetic evaluations of stillbirth in these three dairy breeds. Estimated genetic (co)variances and genetic values deviated considerably from the reported ranges of previous studies, and the reliabilities of predicted transmitting abilities were low in these three breeds. In conclusion, routine genetic evaluations of stillbirth are feasible in Brown Swiss and Jersey. However, reliable genetic evaluations of stillbirth in Ayrshire, Guernsey, and Milking Shorthorn require further data collection on stillbirth. [ABSTRACT FROM AUTHOR]

Genetic selection has been an effective strategy to improve calving traits including stillbirth in dairy cattle. The primary objectives of the present study were to characterize stillbirth data and determine the feasibility of implementing routine genetic evaluations of stillbirth in five non-Holstein dairy breeds, namely Ayrshire, Guernsey, Milking Shorthorn, Brown Swiss, and Jersey. An updated sire-maternal grandsire threshold model was used to estimate genetic parameters and genetic values for stillbirth. Stillbirth data with the birth years of dams from 1995 to 2018 were extracted from the United States national calving ease database maintained by the Council on Dairy Cattle Breeding. The extracted stillbirth records varied drastically among the five dairy breeds. There were approximately 486K stillbirth records for Jersey and more than 80K stillbirth records for Brown Swiss. The direct and maternal heritability estimates of stillbirth were 6.0% (4.5–7.6%) and 4.7% (3.3–6.1%) in Jersey and 6.8% (3.2–10.5%) and 1.1% (0.6–2.9%) in Brown Swiss. The estimated genetic correlations between direct and maternal genetic effects for stillbirth were −0.15 (−0.38 to −0.08) in Jersey and −0.35 (−0.47 to −0.12) in Brown Swiss. The estimated genetic parameters for stillbirth in these two breeds were within close ranges of previous studies. The reliabilities of predicted transmitting abilities in Jersey and Brown Swiss increased substantially, thanks to the substantial increase in available stillbirth data in the past 10 years. The stillbirth records for Ayrshire, Guernsey, and Milking Shorthorn, which ranged approximately between 3K and 12K, are insufficient to implement reliable routine genetic evaluations of stillbirth in these three dairy breeds. Estimated genetic (co)variances and genetic values deviated considerably from the reported ranges of previous studies, and the reliabilities of predicted transmitting abilities were low in these three breeds. In conclusion, routine genetic evaluations of stillbirth are feasible in Brown Swiss and Jersey. However, reliable genetic evaluations of stillbirth in Ayrshire, Guernsey, and Milking Shorthorn require further data collection on stillbirth.

In the evolving landscape of beef cattle management, veterinarians are transitioning from their traditional role of treating diseases to becoming proactive advisors. This article explores how veterinarians with knowledge of genetic tools are poised to be vital in addressing the fundamental industry challenges. It highlights the role of genetic selection in reducing calving difficulties, emphasizing its benefits for animal health and welfare. The article also surveys the genomic technologies available and discusses the importance of integrating these insights with veterinary expertise to support informed decisions in selection, mating, and marketing strategies., Competing Interests: Disclosure The authors have nothing to disclose., (Published by Elsevier Inc.)

Genetic parameters of direct and maternal effects for calving ease (CE) in Portuguese dairy cattle were estimated applying a threshold model (TM) and three linear models (LM) using 320,953 CE records. In LM, CE scores were directly used as dependent variables (LM1) or were transformed into values on an underlying continuous liability scale (average and maximum values for LM2 and LM3, respectively). The estimate of heritability for direct effects was lower on linear models (0.04–0.05) than in TM (0.09). Furthermore, direct heritability was higher than maternal heritability, ranging between 0.04–0.09 and 0.01–0.02, respectively. The genetic correlation between direct and maternal effects was negative in all models, ranging between –0.75 and –0.82. We investigated the association between bulls estimated breeding values (EBV) attained by TM and three LM, for 2223 bulls. Results show that all correlations were higher than 0.95 and slightly greater correlations were observed for direct effects than for maternal effects. Particular emphasis was given to individual differences between EBV ranking lists. The average difference between rank positions of TM and the three LM ranged from 64 to 122. Therefore, the selection of breeding animals is influenced by the model’s choice. Even with clear theoretical advantages in analysing categorical data, perhaps due to its more recent implementation, TM has not yet achieved the popularity of LM. The results of this work show that TM ranking list is more in accordance with LM2 than with LM1 or LM3. Therefore, with linear models, CE should be considered as average liability value instead of usual numerical score or maximum liability.

A previous genome scan on 323 Piedmontese individuals identified a cluster of 13 SNPs significantly associated with direct calving ease and centred on the three genes LAP3, LCORL and NCAPG in chromosome 6. We investigated missense mutations affecting calving ease in Piedmontese cattle in the identified region using sequences from the whole exome in eight Piedmontese individuals chosen from the extremes of the direct calving ease estimated breeding values distribution for this trait. The present study has not found missense variants in LAP3 and LCORL, while two were identified on NCAPG by three different variant calling methods. Other gene candidates in the same region harbour missense mutations, such as PPM1K, PKD2, SPP1 and MEPE, but both SIFT analysis and chi-square test on frequency of alleles make us hypothesise that NCAPG is the single gene responsible for the trait variation. The two SNPs on NCAPG are in complete linkage disequilibrium in our samples; therefore, further investigations are needed in order to discriminate their role.

Objectives: The objective of this study was to assess the relationship between pelvic measurements, namely pelvic height (PH), pelvic area (PA), and pelvic width, and linear body measurement traits, such as hindquarters width, rump length (RL), hip height (HH), body weight (BW), shoulder height, chest depth (CD), body length, and also calve birth weight (CBW) under different calving ease scores, namely no assistance, gently pull, and hard pull. Material and Methods: A total of 51 first calf Sussex heifers at 24 months old, weighing approximately 440 ± 40.26 kg, were used for this study. Two-year-old bulls (n = 2), weighing approximately 800 kg, were used for mating the 51 heifers with a bull to cow ratio of 1:30 and 1:21. The fertility of bulls was assessed by a private veterinarian before the mating season. Calving ease was scored as follows: 1 = no assistance during parturition (normal), 2 = heifer assistance as gently pull, 3 = heifer assistance as hard pull, 4 = heifer cannot calf, 5 = heifer calved a dead calf, and 6 = heifer calf with the abnormal position. Results: Descriptive statistics indicated that PH (p < 0.01) and RL (p < 0.05) were positively remarkable and different among calving ease scores. Correlation results of the no assistance Sussex heifers group revealed that CBW was positively correlated (p < 0.05) with PH. Classification and regression tree CART results demonstrated that PH, BW, CD, and HH play an important role in predicting calving ease in Sussex heifers. Conclusion: The findings suggest that there is an association among PAs and biometric traits. The present study might help farmers select animals with higher PH, BW, CD, and HH during breeding to lower dystocia incidents during parturition. However, further studies need to be carried out in CART modeling to reduce dystocia in a larger sample size of Sussex heifers or other cattle breeds. [ABSTRACT FROM AUTHOR]

Calving ease (CE) is a trait of economic importance that affects animal welfare and farm profitability. The objective of present study was to investigate genetic and environmental factors affecting CE among Primiparous (PP) and multiparous (MP) buffaloes. A total of 9,627 records from 1999 MP and 2,110 PP recorded during the period from 1988 to 2018 were considered. Herd, season of calving, year of calving, birth weight, parity order and gestation length significantly affected CE rate, while age at first calving and sex of calf had no significant effects. Direct and maternal heritabilities of CE in PP and MP were 0.06 and 0.01, respectively. The low heritability of CE indicated that direct selection may not be an effective method to improve CE trait in Egyptian buffalo. [ABSTRACT FROM AUTHOR]

The objectives of this study were to investigate the main risk factors associated with calving ease (CE) in Italian Holstein cow herds, and to estimate the association between CE and subsequent survival, fertility and milk production. Data obtained from Holstein cows in 40 Italian herds were retrospectively investigated. Calvings were surveilled and classified into two categories of CE, unassisted calving or assisted calving, based on the need for intervention. The following factors were analyzed as possible risk factor affecting CE: herd, number of calvings/herd/year, age at first calving (AFC), cow parity, gestation length, twinning, calf sex, previous calving-to-conception interval, previous milk yield, dry period and close-up length, and season of calving. The association between CE and culling risk within the first 30 days-in-milk (DIM), cumulative 60-d milk yield and predicted 305-d milk yield, and pregnancy risk within 150 DIM were also investigated. Of the 47,672 calvings, 37,892 (79.5%) were unassisted, while 9780 (20.5%) required some type of assistance. Among the risk factors, only the AFC was not correlated with CE, while for all the other risk factors an association with CE was detected. Assisted calvings were associated with an increased culling risk at 30 DIM, decreased 60-d milk yield, decreased 305-d milk yield and reduced pregnancy risk at 150 DIM. In conclusion, dairy herd management should aim at correcting/reducing the risk factors in order to limit the incidence of assisted calving, and possibly improve the quality of calving assistance; controlling CE within the herd is crucial to reducing culling risk, and achieving higher lactation and reproductive performance.

The aim of this research was to identify the relationship of calvin ease and level of in-line milk urea (MU) and other milk components, namely milk yield (MY), electrical conductivity (EC), milk fat (MF), milk protein (MP), milk fat/protein ratio (MF/MP), and somatic cell count (SCC) in dairy cows. The cows for the research were selected following such criteria: cows were tested within the period of up to the first 30 days after calving and had had a range of lactation numbers from two to four. Each selected farm housed more than 500 dairy cows and a total of 4712 calving cases from the eight dairy farms were studied and evaluated. The 4-point scale was used for the evaluation of the calving according to the point value meanings where 1 = easy, unassisted; 2 = easy, assisted; 3 = difficult, assisted; 4 = difficult, requiring veterinary intervention. A total of 4712 calving cases were researched and scored. The chemical properties of milk in all research cows were analyzed during the early phase of lactation (from the onset of calving to 30 days past calving) every day, during each milking. Cows were classified into groups according to the level of urea in milk: Group 1 had MU ≤ 15 mg/dL (12.6% of cows), Group 2 had MU 16–30 mg/dL (62.4% of cows), and Group 3 had MU > 30 mg/dL (25.0% of cows). We found that cows with milk urea levels between 16 and 30 mg/dL had the lowest incidence of dystocia, and also the highest concentration of milk lactose (ML ≥ 4.6%), the lowest mean value of milk electrical conductivity, and the lowest value of milk SCC. Dystocia increased the risk of somatic cell growth in cow’s milk above the herd average (OR = 1.364; 95% CI = 1.184–1.571, p < 0.001), and normal urea in milk reduced this risk (OR = 0.749; 95% CI = 0.642–0.869, p = 0.05). In all groups of cows, according to the level of urea in milk, the productivity of cows without dystocia at calving was higher (2.50–5.51 kg) as well as the milk protein % (0.13–0.21%) and milk lactose % (0.07–0.19%). We concluded that, in all groups of cows, according to the level of urea in milk, the productivity and milk lactose concentration of cows without dystocia at calving was higher, and lower somatic cells count and electrical conductivity values were found in the milk compared with cows diagnosed with dystocia at calving. We can state that dystocia has a negative effect on milk urea concentration and can increase the risk of mastitis.

Objective Calving ease (CE) is a complex reproductive trait of economic importance in dairy cattle. This study was aimed to investigate the genetic merits of CE for Holsteins in Korea. Methods A total of 297,614 field records of CE, from 2000 to 2015, from first parity Holstein heifers were recorded initially. After necessary data pruning such as age at first calving (18 to 42 mo), gestation length, and presence of sire information, final datasets for CE consisted of 147,526 and 132,080 records for service sire calving ease (SCE) and daughter calving ease (DCE) evaluations, respectively. The CE categories were ordered and scores ranged from CE1 to CE5 (CE1, easy; CE2, slight assistance; CE3, moderate assistance; CE4, difficult calving; CE5, extreme difficulty calving). A linear transformation of CE score was obtained on each category using Snell procedure, and a scaling factor was applied to attain the spread between 0 (CE5) and 100% (CE1). A sire-maternal grandsire model analysis was performed using ASREML 3.0 software package. Results The estimated direct heritability (h2) from SCE and DCE evaluations were 0.11±0.01 and 0.08±0.01, respectively. Maternal h2 estimates were 0.05±0.02 and 0.04±0.01 from SCE and DCE approaches, respectively. Estimates of genetic correlations between direct and maternal genetic components were −0.68±0.09 (SCE) and −0.71±0.09 (DCE). The average direct genetic effect increased over time, whereas average maternal effect was low and consistent. The estimated direct predicted transmitting ability (PTA) was desirable and increasing over time, but the maternal PTA was undesirable and decreasing. Conclusion The evidence on sufficient genetic variances in this study could reflect a possible selection improvement over time regarding ease of calving. It is expected that the estimated genetic parameters could be a valuable resource to formulate sire selection and breeding plans which would be directed towards the reduction of calving difficulty in Korean Holsteins.

Calving is assumed to be an exhausting and painful event. A drug that eases the calving procedure and alleviates pain would help cows, especially those suffering from dystocia. In a randomized, controlled, and blinded trial, we measured the effect of denaverine hydrochloride on physical and physiological calving parameters. Eighty-three Holstein-Friesian heifers were included in the analysis. Pulling force was measured using a digital force gauge interposed between the calf and a mechanical calf puller. The concentration of cortisol was measured in serum before and after parturition. There was no effect of treatment group on calving modality (i.e., spontaneous vs. assisted calving), duration of calving, and cortisol concentration. The area under the curve of pulling force × time (n = 44), however, was significantly smaller in the treatment group compared with the placebo group. Also, duration of calving assistance was numerically shorter in the treatment group compared with the placebo group. The results provide evidence that calving ease can be influenced by denaverine hydrochloride during calving assistance. [ABSTRACT FROM AUTHOR]

The aim of our study was to determine how the ease of calving of cows may influence changes in lactose concentration and other milk components and whether these two factors correlate with each other. To achieve this, we compared data of calving ease scores and average percentage of in-line registered milk lactose and other milk components. A total of 4723 dairy cows from nine dairy farms were studied. The cows were from the second to the fourth lactation. All cows were classified according to the calving ease: group 1 (score 1)—no problems; group 2 (score 2)—slight problems; group 3 (score 3)—needed assistance; group 4 (score 4)—considerable force or extreme difficulty. Based on the data from the milking robots, during complete lactation we recorded milk indicators: milk yield MY (kg/day), milk fat (MF), milk protein (MP), lactose (ML), milk fat/lactose ratio (MF/ML), milk protein/lactose ratio (MP/ML), milk urea (MU), and milk electrical conductivity (EC) of all quarters of the udder. According to the results, we found that cows that had no calving difficulties, also had higher milk lactose concentration. ML > 4.7% was found in 58.8% of cows without calving problems. Cows with more severe calving problems had higher risk of mastitis (SCC and EC). Our data indicates that more productive cows have more calving problems compared to less productive ones.

Genetic parameters of direct and maternal effects for calving ease (CE) in Portuguese dairy cattle were estimated applying a threshold model (TM) and three linear models (LM) using 320,953 CE records. In LM, CE scores were directly used as dependent variables (LM1) or were transformed into values on an underlying continuous liability scale (average and maximum values for LM2 and LM3, respectively). The estimate of heritability for direct effects was lower on linear models (0.04–0.05) than in TM (0.09). Furthermore, direct heritability was higher than maternal heritability, ranging between 0.04–0.09 and 0.01–0.02, respectively. The genetic correlation between direct and maternal effects was negative in all models, ranging between –0.75 and –0.82. We investigated the association between bulls estimated breeding values (EBV) attained by TM and three LM, for 2223 bulls. Results show that all correlations were higher than 0.95 and slightly greater correlations were observed for direct effects than for maternal effects. Particular emphasis was given to individual differences between EBV ranking lists. The average difference between rank positions of TM and the three LM ranged from 64 to 122. Therefore, the selection of breeding animals is influenced by the model's choice. Even with clear theoretical advantages in analysing categorical data, perhaps due to its more recent implementation, TM has not yet achieved the popularity of LM. The results of this work show that TM ranking list is more in accordance with LM2 than with LM1 or LM3. Therefore, with linear models, CE should be considered as average liability value instead of usual numerical score or maximum liability. [ABSTRACT FROM AUTHOR]

A previous genome scan on 323 Piedmontese individuals identified a cluster of 13 SNPs significantly associated with direct calving ease and centred on the three genes LAP3, LCORL and NCAPG in chromosome 6. We investigated missense mutations affecting calving ease in Piedmontese cattle in the identified region using sequences from the whole exome in eight Piedmontese individuals chosen from the extremes of the direct calving ease estimated breeding values distribution for this trait. The present study has not found missense variants in LAP3 and LCORL, while two were identified on NCAPG by three different variant calling methods. Other gene candidates in the same region harbour missense mutations, such as PPM1K, PKD2, SPP1 and MEPE, but both SIFT analysis and chi-square test on frequency of alleles make us hypothesise that NCAPG is the single gene responsible for the trait variation. The two SNPs on NCAPG are in complete linkage disequilibrium in our samples; therefore, further investigations are needed in order to discriminate their role. [ABSTRACT FROM AUTHOR]

Background: The detection of quantitative trait loci has accelerated with recent developments in genomics. The introduction of genomic selection in combination with sequencing efforts has made a large amount of genotypic data available. Functional traits such as fertility and calving traits have been included in routine genomic estimation of breeding values making large quantities of phenotypic data available for these traits. This data was used to investigate the genetics underlying fertility and calving traits and to identify potentially causative genomic regions and variants. We performed genome-wide association studies for 13 functional traits related to female fertility as well as for direct and maternal calving ease based on imputed whole-genome sequences. Deregressed breeding values from ~1000-5000 bulls per trait were used to test for associations with approximately 10 million imputed sequence SNPs. Results: We identified a QTL on BTA17 associated with non-return rate at 56 days and with interval from first to last insemination. We found two significantly associated non-synonymous SNPs within this QTL region. Two more QTL for fertility traits were identified on BTA25 and 29. A single QTL was identified for maternal calving traits on BTA13 whereas three QTL on BTA19, 21 and 25 were identified for direct calving traits. The QTL on BTA19 co-localizes with the reported BH2 haplotype. The QTL on BTA25 is concordant for fertility and calving traits and co-localizes with a QTL previously reported to influence stature and related traits in Brown Swiss dairy cattle. Conclusion: The detection of QTL and their causative variants remains challenging. Combining comprehensive phenotypic data with imputed whole genome sequences seems promising. We present a QTL on BTA17 for female fertility in dairy cattle with two significantly associated non-synonymous SNPs, along with five additional QTL for fertility traits and calving traits. For all of these we fine mapped the regions and suggest candidate genes and candidate variants. [ABSTRACT FROM AUTHOR]

The objective was to validate the iVET ® birth monitoring system and to determine if it reduced fetal death in primiparous dairy heifers over a 1-y interval. There were 359 pregnant heifers enrolled; 167 heifers in the iVET ® group were monitored electronically and the remaining 192 (controls) were monitored visually for onset of Stage 2 labor, according to routine farm management. In addition, as a reference, all heifers were observed throughout the study by two independent investigators. Calves born dead or that died within 24 h after birth were defined as stillborn. The interval from appearance of the chorioallantoic sac to recognition of onset of calving in the control group averaged 21 min longer than the iVET ® signal (p = 0.0001) and rate of fetal death was numerically lower in the iVET ® group (8.9%) than in the control group (10.4%, p = 0.65). Interestingly, dystocia occurred more often in the iVET ® group (58.3%) than in the control group (40.9%, p = 0.001). The iVET ® system detected onset of Stage 2 labor earlier than conventional monitoring by farm staff. However, the device was lacking in several aspects and should be improved before its use in primiparous heifers can be recommended. [ABSTRACT FROM AUTHOR]

Objective: Calving ease (CE) is a complex reproductive trait of economic importance in dairy cattle. This study was aimed to investigate the genetic merits of CE for Holsteins in Korea. Methods: A total of 297,614 field records of CE, from 2000 to 2015, from first parity Holstein heifers were recorded initially. After necessary data pruning such as age at first calving (18 to 42 mo), gestation length, and presence of sire information, final datasets for CE consisted of 147,526 and 132,080 records for service sire calving ease (SCE) and daughter calving ease (DCE) evaluations, respectively. The CE categories were ordered and scores ranged from CE1 to CE5 (CE1, easy; CE2, slight assistance; CE3, moderate assistance; CE4, difficult calving; CE5, extreme difficulty calving). A linear transformation of CE score was obtained on each category using Snell procedure, and a scaling factor was applied to attain the spread between 0 (CE5) and 100% (CE1). A sire-maternal grandsire model analysis was performed using ASREML 3.0 software package. Results: The estimated direct heritability (h2) from SCE and DCE evaluations were 0.11±0.01 and 0.08±0.01, respectively. Maternal h2 estimates were 0.05±0.02 and 0.04±0.01 from SCE and DCE approaches, respectively. Estimates of genetic correlations between direct and maternal genetic components were -0.68±0.09 (SCE) and -0.71±0.09 (DCE). The average direct genetic effect increased over time, whereas average maternal effect was low and consistent. The estimated direct predicted transmitting ability (PTA) was desirable and increasing over time, but the maternal PTA was undesirable and decreasing. Conclusion: The evidence on sufficient genetic variances in this study could reflect a possible selection improvement over time regarding ease of calving. It is expected that the estimated genetic parameters could be a valuable resource to formulate sire selection and breeding plans which would be directed towards the reduction of calving difficulty in Korean Holsteins. [ABSTRACT FROM AUTHOR]

The objective of the study was to compare calving ease, pelvic structure and pelvic angle in 74 Holstein-Friesian and 45 Jersey heifers. The frequency of difficult calving was 15.2% in Holstein-Friesians and only 2.2% in Jersey heifers. Compared with Jersey cows, Holstein-Friesians were characterized by a higher calf weight to cow weight ratio, and higher ratios of pelvic area to cow weight and pelvic area to calf weight. The results of the study show that higher frequency of difficult calving recorded in Holstein-Friesians, in comparison with Jersey heifers, could be a consequence of relatively high calf weight and less preferable pelvic structure. Large variation in the internal dimensions of the pelvis in HF heifers encouraged reducing the occurrence of dystocia through selection of the dimensions of the pelvis.

The experiment involved observations of 2,514 Holstein-Friesian cows to determine the effects of environmental factors (cow’s age, calving season, weight and sex of calves, housing system) and genetic factors on gestation length in dairy cattle and the correlation between gestation length and other reproductive traits (calving ease, stillbirth rates and placental expulsion). Genetic parameters were estimated based on the sires of calved cows (indirect effect) and the sires of live-born calves (direct effect). The following factors were found to contribute to prolonged gestation: increasing cow’s age, male fetuses and growing fetus weight. Optimal gestation length was determined in the range of 275–277 days based on calving ease and stillbirth rates. The heritability of gestation length was estimated at 0.201–0.210 by the direct effect and 0.055–0.073 by the indirect effect. The resulting genetic correlations suggest that the efforts to optimize (prolong) gestation length could exert an adverse influence on the breeding value of bulls by increasing perinatal mortality and calving difficulty. The standard errors of the investigated parameters were relatively high, suggesting that any attempts to modify gestation length for the purpose of improving calving ease and reducing stillbirth rates should be introduced with great caution.

The aim of this study was to compare the effects of two parturition induction protocols with a nontreated control group, on interval to calving, calving ease, postpartum uterine health, and ovarian cyclicity in beef heifers. At Day 285 of gestation, 81 crossbred recipient beef heifers carrying purebred Simmental fetuses, were blocked by live-weight, body condition score, expected calving date and fetal sex, and assigned to one of three groups: (1) control (CON; no induction treatment, n = 29); (2) induction with corticosteroids (CORT; n = 27); or (3) induction with corticosteroids plus prostaglandin (CORT + PG; n = 25). Interval from induction to calving in hours and calving ease on a scale of 1 to 5 were recorded. Vaginal mucus samples were collected on Day 21 and Day 42 after calving (Day 0) by means of a Metricheck and scored on a scale of 0 to 3. Reproductive tract examinations were conducted on Day 21 and Day 42 after calving, and uterine cytology samples were obtained on Day 21. A positive cytologic sample was defined as greater than 18% neutrophils in the sample obtained via a cytobrush technique. Cows were considered to have resumed ovarian cyclicity if the presence of the CL was confirmed. Data were analyzed using the Mixed (normally distributed data) and Genmod (nonparametric data) procedures of SAS (v. 9.3). The interval from treatment to calving was longer (P < 0.0001) for CON (161.9 ± 15.12 hours) animals compared with CORT (39.7 ± 11.64 hours) or CORT + PG (32.6 ± 12.10 hours), which did not differ. Treatment did not affect calving difficulty score. There was also no difference in incidence of retained placenta between the three groups. At Day 21 postpartum, cytology score tended to be higher for both induced groups (48%) compared with the control animals (24%), but this was not the case for vaginal mucus score (CON 52%, CORT 70%, and CORT + PG 52%). A higher proportion of CON had an involuted uterus by Day 21 postpartum (69%) compared with both induced groups (CORT 48%, CORT + PG 32%). Day 21 ovarian cyclicity was higher in both CON (52%) and CORT (59%) compared with CORT + PG (29%). By Day 42, there was no difference in ovarian cyclicity or uterine involution between CON and CORT; however, a positive relationship was observed between uterine involution score on Day 21 and return to cyclicity on Day 42 in these two groups. There was a negative relationship between uterine involution score and return to cyclicity in the CORT + PG group, and these animals were slower (P < 0.05) to resume cyclicity by Day 42 with a larger proportion animals having evidence of having resumed postpartum ovarian cyclicity in both CON (P = 0.03) and CORT compared with CORT + PG on Day 42. In conclusion, the use of corticosteroid-based treatments is an effective strategy to advance parturition in full term dams and does not have a negative effect on calving progress or dam health. However, when prostaglandin is also included in the protocol, these treatments may lead to greater delay in uterine involution with increased chance of uterine infection and slower resumption of ovarian cyclicity. [ABSTRACT FROM AUTHOR]

Abstract In this study, a hierarchical threshold mixed model based on a cumulative t-link specification for the analysis of ordinal data or more, specifically, calving ease scores, was developed. The validation of this model and the Markov chain Monte Carlo (MCMC) algorithm was carried out on simulated data from normally and t4 (i.e. a t-distribution with four degrees of freedom) distributed populations using the deviance information criterion (DIC) and a pseudo Bayes factor (PBF) measure to validate recently proposed model choice criteria. The simulation study indicated that although inference on the degrees of freedom parameter is possible, MCMC mixing was problematic. Nevertheless, the DIC and PBF were validated to be satisfactory measures of model fit to data. A sire and maternal grandsire cumulative t-link model was applied to a calving ease dataset from 8847 Italian Piemontese first parity dams. The cumulative t-link model was shown to lead to posterior means of direct and maternal heritabilities (0.40 ± 0.06, 0.11 ± 0.04) and a direct maternal genetic correlation (-0.58 ± 0.15) that were not different from the corresponding posterior means of the heritabilities (0.42 ± 0.07, 0.14 ± 0.04) and the genetic correlation (-0.55 ± 0.14) inferred under the conventional cumulative probit link threshold model. Furthermore, the correlation (> 0.99) between posterior means of sire progeny merit from the two models suggested no meaningful rerankings. Nevertheless, the cumulative t-link model was decisively chosen as the better fitting model for this calving ease data using DIC and PBF.

to expand knowledge of dependence of these traits as a way to reduce mortality of calves. The research was carried out at the Laboratory of Establishment of Animal Breeding Value and Selection of Lithuanian University of Health Sciences. Records of stillbirth (SB) and calving ease (CE) were obtained from the Centre of State Rural Business Development. In the analysis, stillbirth was defined as a dead born calf or a calf that died within 24 hours after birth. Calving ease was measured on a scale from 0 (no difficulty) to 4 (difficult birth). The calving scores and stillbirths of Black and White cattle recorded since 1981 were used in the evaluation. The dataset had 872,565 records. The SB was estimated to be 5.3% (first-lactation heifer stillbirth rates are higher 0.5-2% than multiparous cows). Analysis of CE showed that 41.6% of cows calving were evaluated without difficulty and 0.3% of cows as difficult births. Difficult calvings are much more common in the first-calf heifers than in older cows. The data of the investigation highlight the dependence of SB on CE of cows, (P<0.0001): the majority (89.6%) of SB were observed in cows with evaluated CE score from 3 to 4. [ABSTRACT FROM AUTHOR]

Abstract: Calving ease (CE) scores on discrete, ordered scale from 1 (malpresentation) to 5 (unassisted), birth weight (BW) (in kg) and gestation length (GL) (in days) data on 233,003 Canadian Simmental animals were analyzed with single and multiple-trait animal linear models, using data from all dams (ALL) or due to heifer calvings only (FIRST). Models included fixed effects of year of calving by season of calving, and age of dam by sex of calf by breed of the dam. Random effects were: herd within year-season of calving, correlated direct and maternal genetic effects, and maternal permanent environment. Bayesian methods with Gibbs sampling were applied to infer genetic parameters and estimated progeny differences (EPD) with respective reliabilities. All models and data gave similar estimates of genetic parameters. Heritability estimates for CE were low; from 3–5% for ALL data to 7–8% for the FIRST scenario. Direct-maternal genetic correlations for the same trait were moderate and non-antagonistic. Mean squared error of prediction statistic for CE favored models using the ALL data, and differences among single and multiple-trait models for CE were small. Correlations among EPD for CE for all animals from ALL and FIRST data were 0.86, and from 0.79 to 0.83, for direct and maternal effects, respectively. An increase of up to 5% in overall reliability of EPD for direct and maternal CE from a single trait model was generated by including records from older dams. Using BW as a correlated trait with the ALL data improved reliability of EPD for direct and maternal CE by 4% and 1%, respectively. Adding GL as another correlated trait to BW and CE increased reliability of EPD for CE only marginally. Results of these large scale genetic analyses indicated that accuracy of genetic evaluation of CE in beef cattle would benefit from including data from all dams irrespective of their age, and by using records on BW as a correlated trait in a multiple-trait model. [Copyright &y& Elsevier]

Abstract: The objective of this paper was to analyze the effects of non-genetic factors affecting calving ease and stillbirths in the population of 1257 Holstein cows, using classification trees. The trees were developed according to the following splitting criterion: the Pearson chi-squared test, entropy function and the Gini index. The quality of decision tree models were compared, taking into consideration the following criteria: the average squared error, misclassification rate, cumulative lift, Kolmogorov–Smirnov statistics and the area under curve of the Receiver Operating Characteristic. A statistical analysis was conducted using the Enterprise Miner 7.1 software included in the SAS package. The calculated quality criteria of the three models that were developed lead to the conclusion that the classification trees established based on the chi-squared statistic and entropy function most accurately define the variability of calving ease. In turn, in the event of stillbirths, classification tree models were identical regardless of the splitting criterion applied. The ranking of variable importance lead to the conclusion that the body weight of the calves, subsequent lactation, husbandry system, gestation length and the sex of the calf are the most significant factors differentiating calving ease. The research showed that stillbirths were diversified only by the body weight of the calves. The present research demonstrates that a graphic model of classification tree can prove a useful tool in distinguishing the factors responsible for calving. It also makes it possible to clearly indicate the factors affecting calving ease and stillbirths that a farmer may observe. [Copyright &y& Elsevier]

As the emphasis in cattle breeding is shifting from traits that increase income toward traits that reduce costs, national breeding indices are expanding to include functional traits such as calving ease (CE). However, one issue is the lack of knowledge of genetic relationships between CE and other dairy traits. The same can be said about gestation length (GL), a potential novel selection trait with considerable heritabilities and possible genetic relationships with the calving process. This study aimed to estimate the genetic relationships between CE, GL, and other dairy traits of interest using a national data set of 31,053 primiparous cow performance records, as well as to separate direct and maternal genetic effects. Chosen dairy traits included fertility (calving interval, days to first service, nonreturn rate after 56 d, number of inseminations per conception), milk production (milk yield at d 110 in milk, accumulated 305-d milk yield, accumulated 305-d fat yield, accumulated 305-d protein yield), type (udder depth, chest width, rump width, rump angle, mammary composition, stature, body depth), and lifespan traits (functional days of productive life). To allow the separation of direct and maternal genetic effects, a random sire of the calf effect was included in the multitrait linear trivariate sire models fitted using ASReml. Significant results showed that easily born individuals were genetically prone to high milk yield and reduced fertility in first lactation. Difficult calving primiparous cows were likely associated with being high-producing, wide and deep animals, with a reduced ability to subsequently conceive. Individuals that were born relatively early were associated with good genetic merit for milk production. Finally, individuals carrying their offspring longer were genetically associated with being wide and large animals that were themselves born relatively early. The study shows that it is feasible and valuable to separate direct and maternal effects when estimating genetic correlations between calving and other dairy traits. Furthermore, gestation length is best used as an indicator trait for lowly heritable calving traits, rather than as a novel selection trait. As estimated direct and maternal genetic correlations differ, we can conclude that genetic relationships between CE, GL, and traits of interest are present, but caution is required if these traits are implemented in national breeding indices. [ABSTRACT FROM AUTHOR]

Up to one-third of dairy calves are born after dystocia and this is a major cause of calf mortality. This study investigated the neonatal physiology, survival, health and subsequent growth of dairy calves following dystocia and is the first longitudinal study to analyse multiple effects and to look beyond the perinatal period. A total of 455 live born Holstein calves (N: No assistance, n = 360; FN: Farmer assistance but normally presented calf, n = 82; FM: Farmer assistance of malpresented calf, n = 13) were followed from birth to first service (heifers) or until leaving the farm (bulls). Compared to N calves, FN and FM animals had higher salivary cortisol concentrations at day 1 (P < 0.001) and FN calves had lower passive immune transfer (P= 0.03). Dystocia had no biologically significant impact on rectal temperature throughout the first 4 days (P > 0.05). During the first 60 days, FM calves had a higher proportion of days with non-routine health treatments (P < 0.05) and, by the time of weaning, mortality in FN and FM heifers was higher than in N calves (2.8x; P < 0.01). However, in surviving calves, growth to first service was not affected by dystocia category (P > 0.05). Calves which survive dystocia experience lower passive immunity transfer, higher mortality and higher indicators of physiological stress. Such calves have poorer welfare in the neonatal period and possibly beyond. Strategies need to be implemented to improve the subsequent health and welfare of such calves and to lower the incidence of dystocia. [ABSTRACT FROM AUTHOR]

The experience of a difficult birth (dystocia) is traumatic and has adverse effects on the newborn in various species. Despite affecting up to 1 in 3 births in dairy cattle, studies on calves have been mostly limited to the first day of life. The objective of this study was to investigate the effects of dystocia on the survival to calving, growth to weaning, and subsequent fertility as nulliparous animals. Historical data from live-born Holstein heifer calves born from cows with various birth difficulty scores (no assistance; moderate; high difficulty) were obtained from 2 herds (Edinburgh herd: n = 1,237; Crichton Royal Farm herd: n = 721). Each herd was analyzed separately for birth weights, weaning weights, growth rate to weaning, number of services to conception, and age at first calving using REML and generalized linear mixed model analyses. Survival analysis (Cox proportional hazards model) was used in the Edinburgh herd to analyze the subsequent survival of live-born heifers, whereas descriptive data are presented for the Crichton Royal Farm herd. A higher mortality risk to weaning and to first service was observed in the live-born heifers that experienced moderate difficulty at birth compared with heifers born naturally. Surviving dystocial heifers had similar growth-to-weaning and fertility performance as heifers born naturally in both herds. It could be that the performance of dystocial heifers that survived to weaning was not affected or that it was compensated for by farm management. This study highlights long-term effects of the early experience of a difficult birth and thereby stresses the importance of preventing dystocia not just from the point of view of the adult cow, but also from the perspective of the calf. This would also improve farm efficiency and calf welfare. [ABSTRACT FROM AUTHOR]

The objective of the study was to compare calving ease, pelvic structure and pelvic angle in 74 Holstein-Friesian and 45 Jersey heifers. The frequency of difficult calving was 15.2% in Holstein-Friesians and only 2.2% in Jersey heifers. Compared with Jersey cows, Holstein-Friesians were characterized by a higher calf weight to cow weight ratio, and higher ratios of pelvic area to cow weight and pelvic area to calf weight. The results of the study show that higher frequency of difficult calving recorded in Holstein-Friesians, in comparison with Jersey heifers, could be a consequence of relatively high calf weight and less preferable pelvic structure. Large variation in the internal dimensions of the pelvis in HF heifers encouraged reducing the occurrence of dystocia through selection of the dimensions of the pelvis. [ABSTRACT FROM AUTHOR]

Abstract: The welfare of dairy cows and their calves is compromised following a difficult calving. A better understanding of what happens during a difficult calving is needed to help prevent and alleviate adverse consequences through early diagnosis and/or pain mitigation. The objectives of this study were to investigate the calving progress and parturition behaviours (with emphasis on potential pain indicators) in cows during normal or difficult calvings, and to describe human intervention in dystocial cows. The following video footage of calvings leading to singleton liveborn calves was used: 12 FN (farmer assisted no calf malpresentation) and 7 FM (farmer assisted with calf malpresentation), each paired to a non-assisted calving (N). Three observation periods relative to full expulsion of the calf (A: −6h to −5:30h; B: −4h to −3h; C: −2h to birth) were observed continuously for 38 calvings. Duration from appearance of calves’ feet until birth did not differ between scores of difficulty (median time in min; N: 54.7; FN: 101.3; FM: 194.0; P >0.05) but there was large individual variability. As early as period B, FN and FM cows displayed more contractions than N cows and this was also the case for FN cows in period C but not for FM cows (P <0.05). FN cows were also more restless (counts of postural transitions) than N cows during periods B and C (P <0.05). Overall, FM cows raised their tail for longer (in % of observation time; N: 33.7±4.2; FN: 42.7±5.1; FM: 54.0±7.0; P <0.05) compared to N cows, and FN cows tended to lie down for longer (P <0.10). There was no effect of calving difficulty on self-grooming, ingestive, lying to standing transitions, exploratory (lick ground and sniffing) or “irritation” behaviours (stamping, tail switching, rubbing, turning head back). The median duration of intervention in dystocial cows varied greatly among animals (median time: 4.7min; range: 30s to 35min) and thresholds were in line with current recommendations. Dystocial cows were in later stages of labour for longer and expressed some of the behaviours differently over the course of parturition. These may relate to different pain levels when dystocia occurs and could also be used in the early detection of calving difficulty. [Copyright &y& Elsevier]