Genetic analysis of calf health in Charolais beef cattle

Estimation of genetic parameters of Holstein calf survival

Calf survival is not only an animal welfare issue but also helps to avoid huge losses in economic and genetic material due to calf mortality. Therefore, improving calf survival is essential in dairy breeding. The objective of this study was to explore the factors affecting the survival of Holstein calves in the Ningxia Region and to estimate the genetic parameters of calves using linear models and threshold models. Descriptive statistics were made for 43,847 Holstein calves born from 2018 to 2022 in Ningxia. The number of calves that died at 2-30 d was the highest, the survival rate was the lowest at 451-750 d, followed by 61-180 d and 2-30 d. Studies on the survival rates of calves born in different months have found that calves born in April have the lowest survival rates and calves born in October and December have higher survival rates. Calves born in autumn, third parity, and singleton calves are more likely to survive. The heritability of calf survival traits ranged from 0.002 ~ 0.136. Thus survival is a low heritability trait. Genetic correlation between different survival stages ranged from 0.3991 (2-30 d to 451-750 d) to 0.9985 (361-450 d to 451-750 d), the phenotypic correlation ranged from 0.1476 (2-30 d to 451-750 d) to 0.9582 (361-450 d to 451-750 d). The low genetic correlation between early and late survival suggests that survival in early and late stages may be influenced by different genetic factors. This study is helpful to understand the survival status of Holstein calves and provide a theoretical basis for improving the survival rate of calves.

Risk factors and genetic parameter estimates for preweaning survival of Fogera calves

This study utilised mortality records of 1 043 Fogera calves maintained at Andassa Livestock Research Center from 1984 to 2021 to investigate the factors that influence survival and estimate genetic parameters for the preweaning survival of Fogera calves. Survival was defined as the probability of surviving in a given length of time. Survival analysis was done using the Weibull proportional hazard model with Survival Kit version 6.1 software. Genetic variance and heritability estimates were estimated using the sire model. The proportion of right-censored calves up to 1, 4, and 8 months of age was 90.8, 87.8, and 83.5%, respectively. Around 55.8% of all deaths (16.5%) occurred up to one month of age. In addition to birth year, sex, season, and weight at birth were the most important risk factors for calf mortality. The heritability estimates for the survival of calves at 1, 4, and 8 months of age were 0.26 ± 0.14, 0.22 ± 0.13, and 0.38 ± 0.18, respectively. Moderate heritability was estimated at the age of eight months, implying that the inclusion of survival traits in the selection criteria and inclusion in the breeding goal will enhance the preweaning survival rate of calves. Similarly, higher differences in estimated breeding values of sires for survival suggest that the selection of sires with higher estimated breeding values could improve the survival potential of calves. The decreased genetic trend of 3.34% year-1 for the survival potential of Fogera calves during the study periods suggested that survival traits should be included in the breeding goal to reduce the mortality rate.

Genetic parameters for dairy calf and replacement heifer wellness traits and their association with cow longevity and health indicators in Holstein cattle

High mortality and involuntary culling rates cause great economic losses to the worldwide dairy cattle industry. However, there is low emphasis on wellness traits in replacement animals (dairy calves and replacement heifers) during their development stages in modern dairy cattle breeding programs. Therefore, the main objectives of this study were to estimate genetic parameters of wellness traits in replacement cattle (replacement wellness traits) and obtain their genetic correlations with 12 cow health and longevity traits in the Chinese Holstein population. Seven replacement wellness traits were analyzed, including birth weight, survival from 3 to 60 d (Sur1), survival from 61 to 365 d (Sur2), survival from 366 d to the first calving (Sur3), calf diarrhea, calf pneumonia, and calf serum total protein (STP). Single and bivariate animal models were employed to estimate (co)variance components using the data from 189,980 Holstein cattle. The genetic correlations between replacement wellness traits and cow longevity, health traits were calculated by employing bivariate models, including 6 longevity traits and 6 health traits (clinical mastitis, metritis, ketosis, displaced abomasum, milk fever, and hoof health or hoof disease). The estimated heritabilities (± SE) were 0.335 (± 0.008), 0.088 (± 0.005), 0.166 (± 0.006), 0.102 (±0 .006), 0.048 (± 0.003), 0.063 (± 0.004), and 0.170 (± 0.019) for birth weight, Sur1, Sur2, Sur3, pneumonia, diarrhea, and STP, respectively. The majority of the genetic correlations among the 7 replacement wellness traits were negligible. The genetic correlations among Sur1, Sur2, and Sur3 ranged from 0.112 (Sur1 and Sur3) to 0.445 (Sur1 and Sur2) when fitting a linear model (estimates in the observed scale), and from 0.560 (Sur1 and Sur3) to 0.773 (Sur1 and Sur2) when fitting a threshold model (estimates in the liability scale). The genetic correlations between replacement wellness and cow longevity were low (absolute value lower than 0.30), but some of them were significantly different from zero. Compared with other replacement wellness traits, Sur3 and STP had relatively high genetic correlations with cow longevity. Replacement wellness traits are heritable and can be improved through direct genetic and genomic selection. The results from the current study will contribute for better balancing dairy cattle breeding goals to genetically improve dairy cattle wellness in the period from birth to first calving.

Direct genetic effects, maternal genetic effects, and maternal genetic sensitivity on prenatal heat stress for calf diseases and corresponding genomic loci in German Holsteins

The aim of this study was to infer the effects of heat stress (HS) of dams during late gestation on direct and maternal genetic parameters for pneumonia (PNEU, 112,563 observations), diarrhea (DIAR, 176,904 observations), and omphalitis (OMPH, 176,872 observations) in Holstein calves kept in large-scale co-operator herds. The genotype dataset included 41,135 SNPs from 19,247 male and female cattle. Temperature-humidity indices (THI) during the last 8 wk of pregnancy were calculated, using the climate data from the nearest public weather station for each herd. Heat load effects were considered for average weekly THI larger than 60. Phenotypically, regression coefficients of calf diseases on prenatal THI during the last 8 wk of gestation were estimated in 8 consecutive runs. The strongest detrimental effects of prenatal HS on PNEU and DIAR were identified for the last week of pregnancy (wk 1). Thus, only wk 1 was considered in ongoing genetic and genomic analyses. In an advanced model considering prenatal HS, random regression coefficients on THI in wk 1 nested within maternal genetic effects (maternal slope effects for heat load) were considered as parameters to infer maternal sensitivity in response to prenatal THI alterations. Direct heritabilities from the advanced model ranged from 0.10 (THI 60) to 0.08 (THI 74) for PNEU and were close to 0.16 for DIAR. Maternal heritabilities for PNEU increased from 0.03 to 0.10 along the THI gradient. For DIAR, the maternal heritability was largest (0.07) at the minimum THI (THI = 60) and decreased to 0.05 at THI 74. Genetic correlations smaller than 0.80 for PNEU and DIAR recorded at THI 60 with corresponding diseases at THI 74 indicated genotype by climate interactions for maternal genetic effects. Genome-wide associations studies were performed using de-regressed proofs of genotyped sires for direct genetic, maternal genetic, and maternal slope effects. Thirty suggestive and 2 significant SNPs were identified from the GWAS. Forty-three genes located close to the suggestive SNPs (±100 kb) were annotated as potential candidate genes. Three biological processes were inferred on the basis of the these genes, addressing the negative regulation of the viral life cycle, innate immune response, and protein ubiquitination. Hence, the genetics of prenatal heat stress mechanisms are associated with immune physiology and disease resistance mechanisms.

Genetic and non-genetic factors associated with health and vitality traits in beef calves

Awareness and interest in calf health and wellbeing is intensifying, prompting change in the management and breeding decisions of producers and associated policy-makers. The objectives of the present study were to 1) quantify the risk factors associated with subjectively measured scores of vigor and birth size as well as diagnoses of scour and pneumonia in a large national dataset of beef calves, and 2) to estimate the contribution of genetic variance to such phenotypic measures. After edits, the data consisted of health and birth size data subjectively scored by producers on 88,207 calves born in 6,126 Irish beef herds. Vigor was recorded on a scale of 1 (very poor) to 5 (very good). Birth size was also scored on a scale of 1 (very small) to 5 (very large). Scour and pneumonia were both scored independently based on the suspected number of occurrence of each (0 = no occurrence, 1 = one occurrence, or 2 = more than one occurrence). On average, 14.7% of calves were recorded as having had at least one occurrence of scour within the first 5 mo of life, whereas 6.4% of calves were recorded as having had at least one occurrence of pneumonia within the first 5 mo of life. Relative to female calves, male calves had a worse vigor score and a suspected greater incidence of both scour and pneumonia. Relative to singletons, twins were, on average, smaller at birth, they had a worse vigor score, and they were more prone to scour. Calves born in the later periods of the calving season (i.e., late and very late) had a greater incidence of scour relative to calves in the herd born earlier in the calving season. Heritability estimates for vigor, birth size, and pneumonia were 0.12 (0.02), 0.33 (0.03), and 0.08 (0.02), respectively; no genetic variance was detected for scour. Breeding for vigorous calves that are less susceptible to pneumonia could provide producers with an additional strategy to ensure consumer concerns regarding food quality, safety, and calf wellbeing are being met.

Genome-wide scan reveals genomic regions and candidate genes underlying direct and maternal effects of preweaning calf mortality in Nellore cattle

We conducted analysis to estimate genetic parameters and to identify genomic regions and candidate genes affecting direct and maternal effects of preweaning calf mortality (PWM) in Nellore cattle. Phenotypic records of 67,196 animals, and 8443 genotypes for 410,936 SNPs were used. Analysis were performed through the weighted single-step GBLUP approach and considering a threshold animal model via Bayesian Inference. Direct and maternal heritability estimates were of 0.2143 ± 0.0348 and 0.0137 ± 0.0066, respectively. The top 10 genomic regions accounted for 13.61 and 14.23% of the direct and maternal additive genetic variances and harbored a total of 63 and 91 positional candidate genes, respectively. Two overlapping regions on BTA2 were identified for both direct and maternal effects. Candidate genes are involved in biological mechanisms i.e. embryogenesis, immune response, feto-maternal communication, circadian rhythm, hormone alterations, myometrium adaptation, and milk secretion, which are critical for the successful calf growth and survival during preweaning period.

Influence of calf vigour and suckling assistance from birth to weaning in Guzerá beef cattle

Context Maternal ability, cow nutrition, and calf sex are factors that affect beef cattle production in extensive systems. The Guzerá cattle is an important breed in Brazil, where satisfactory growth rates are reported; however, studies on post-parturition calf and cow behaviour are scarce. Aims This study aimed to identify the influence of vigour at birth (ability to stand and suckle without assistance) and human assistance in colostrum intake (HA) on the haematological profile, cortisol concentration, and growth until weaning of Guzerá beef calf. Methods The following traits were observed in 73 male and 83 female calves: cow age at calving, sex, birthweight, vigour, HA, haematological profile, cortisol concentration, bodyweight at 120 days (W120), weaning weight, average daily gain and mortality. Variance analysis was performed using the general linear model procedure of the SAS software. Key results Haematocrit (P = 0.04) and red blood cells (P = 0.004) were higher in calves requiring HA. Cortisol was also higher (P = 0.03) in calves that required HA (81.34 ng/mL × 59.40 ng/mL). The weaning weight and average daily gain were higher (P < 0.05) in calves that did not require HA and showed good vigour (200.38 kg and 0.83 kg/day respectively) than in calves that required HA and showed good vigour (163.7 kg and 0.68 kg/day respectively). The mortality rate was higher in calves that showed poor vigour at birth (25%). Conclusions Both vigour and the need for HA are important traits that should be evaluated during the development of newborn calves. These assessments in the herd can contribute to minimise the mortality rate and maximise the health and weight gain until weaning of beef calves. Implications Few studies have reported the role of vigour and colostrum intake in the development of calves. Despite the difficulty of human interference in extensive cattle farming, the calf vigour combined with human assistance at birth can minimise the losses and increase the performance of beef cattle.

A breeding index to rank beef bulls for use on dairy females to maximize profit

The desire to increase profit on dairy farms necessitates consideration of the revenue attainable from the sale of surplus calves for meat production. However, the generation of calves that are expected to excel in efficiency of growth and carcass merit must not be achieved to the detriment of the dairy female and her ability to calve and re-establish pregnancy early postcalving without any compromise in milk production. Given the relatively high heritability of many traits associated with calving performance and carcass merit, and the tendency for many of these traits to be moderately to strongly antagonistic, a breeding index that encompasses both calving performance and meat production could be a useful tool to fill the void in supporting decisions on bull selection. The objective of the present study was to derive a dairy-beef index (DBI) framework to rank beef bulls for use on dairy females with the aim of striking a balance between the efficiency of valuable meat growth in the calf and the subsequent performance of the dam. Traits considered for inclusion in this DBI were (1) direct calving difficulty; (2) direct gestation length; (3) calf mortality; (4) feed intake; (5) carcass merit reflected by carcass weight, conformation, and fat and the ability to achieve minimum standards for each; (6) docility; and (7) whether the calf was polled. Each trait was weighted by its respective economic weight, most of which were derived from the analyses of available phenotypic data, supplemented with some assumptions on costs and prices. The genetic merit for a range of performance metrics of 3,835 artificial insemination beef bulls from 14 breeds ranked on this proposed DBI was compared with an index comprising only direct calving difficulty and gestation length (the 2 generally most important characteristics of dairy farmers when selecting beef bulls). Within the Angus breed (i.e., the beef breed most commonly used on dairy females), the correlation between the DBI and the index of genetic merit for direct calving difficulty plus gestation length was 0.74; the mean of the within-breed correlations across all other breeds was 0.87. The ranking of breeds changed considerably when ranked based on the top 20 artificial insemination bulls excelling in the DBI versus excelling in the index of calving difficulty and gestation length. Dairy breeds ranked highest on the index of calving difficulty and gestation length, whereas the Holstein and Friesian breeds were intermediate on the DBI; the Jersey breed was one of the poorest breeds on DBI, superior only to the Charolais breed. The results clearly demonstrate that superior carcass and growth performance can be achieved with the appropriate selection of beef bulls for use on dairy females with only a very modest increase in collateral effect on cow performance (i.e., 2-3% greater dystocia expected and a 6-d-longer gestation length).