Predictive equations for early-life indicators of future body weight in Holstein dairy heifers

Birth Traits Associated with Pre-Adulthood Disease Manifestations in Calves

The objective of this study was to explore the relationship between calf birth traits and their susceptibility to diseases before reaching adulthood. A total of 5253 birth traits of Chinese Holstein calves were examined, including gestation length (GL), calf weight at birth (CW), and calving ease score (CES), which ranges from 1 (easy) to 5 (very difficult). Furthermore, monthly medical records were scrutinized for pneumonia and diarrhea in these calves. The study assessed five aspects of disease manifestation in calves: age at first onset, frequency of illness, longest duration of treatment, and total duration of treatment. The link between age at onset and disease manifestation prior to adulthood was analyzed using general linear models and regression models. The GL of calves significantly correlated with the risk of pneumonia, with the risk decreasing as the GL increases. A higher CES was associated with a later onset of diarrhea in calves. Furthermore, the CES was significantly negatively correlated with the duration of diarrhea treatment in calves. These results suggest that implementing different preventive measures for calves with different birth traits and modifying treatment protocols for affected calves could enhance the productivity of dairy cows and reduce losses on farms.

Small for Gestational Age Calves: Part II-Reduced Fertility, Productive Performance, and Survival in Holstein Friesian Heifers Born Small for Their Gestational Age

Recently: more attention has been given to low-birth-weight calves, often without considering gestation length. Calves can be classified as small for gestational age (SGA) when their birth weight is below the 10th percentile, similar to the definition in human medicine. While SGA babies face various health risks, it remains unclear if SGA calves face similar long-term health consequences. This study aimed to investigate the long-term effects on fertility, productive performance, and overall survival in Holstein Friesian (HF) heifers born SGA. Chi-squared analysis assessed culling and survival rates, and linear mixed-effect models evaluated the impact of gestational age group (small, average, or large for gestational age, respectively, SGA, AGA, and LGA) on growth, fertility, milk yield, and lifespan. SGA calves showed catch-up growth at six months but weighed significantly less at twelve months (p = 0.003). Age at first insemination and calving did not differ significantly, although SGA heifers required more inseminations (2.3 ± 1.50) compared to AGA and LGA heifers (1.7 ± 0.98 and 1.5 ± 0.89, respectively, p = 0.006). SGA calves tended to be culled more during the first lactation than AGA calves (25.0% vs. 11.9%, p = 0.078) and showed lower survival to second calving (p = 0.019) compared to AGA and LGA heifers. The Kaplan-Meier analysis indicated a tendency for gestational age to affect overall survival (p = 0.1), with SGA heifers having a higher risk of leaving the herd prematurely (p = 0.035, hazard ratio = 1.53). Milk yield per productive day was significantly lower in SGA heifers (21.2 ± 8.73 kg) compared to AGA and LGA heifers (26.9 ± 5.01 kg and 26.3 ± 3.38 kg, respectively, p = 0.006). This study reveals that HF calves born SGA suffer long-term consequences, although further research is needed to understand the economic impact of rearing SGA heifers.

Small for Gestational Age Calves: Part I-Concept and Definition, Contributing Prenatal Factors and Neonatal Body Morphometrics in Holstein Friesian Calves

Low birth weight (BW) calves exhibit higher mortality rates, reduced body weights at parturition, lower first-lactation milk yields, and longer parturition to first insemination intervals. In human medicine, small for gestational age (SGA) births are associated with increased perinatal morbidity and long-term metabolic risks. This study aimed to define SGA in Holstein Friesian (HF) calves, evaluate their body measurements and proportions, and identify its prenatal risk factors. Four linear regression models were built with weight as a function for gestation length for bull and heifer calves born from nulli- or multiparous dams. Calves with a BW below the 10th percentile were classified as SGA. Differences in body measurements were analyzed using ANOVA, and logistic regression models identified prenatal risk factors to be born SGA. Gestation length, calf sex, and dam parity were crucial variables in defining SGA. SGA calves had significantly smaller body measurements (p < 0.001) and larger body proportions (p < 0.001) compared to average and large calves. For nulliparous dams, a higher 2nd trimester temperature-humidity index (p = 0.032) and older age at parturition (>26 months, p = 0.026) significantly increased the birth of SGA calves. For multiparous dams, both low (<5800 kg, p = 0.049) and high (6700-8600 kg, p = 0.027) milk yields during gestation lead to more SGA births, although very high-yielding dams (>8600 kg) did not birth more SGA calves. This study establishes SGA in HF calves, suggests SGA calves are asymmetrical with evidence of "brain sparing", and highlights the impact of prenatal factors on calf size at birth. Further research is needed to determine the long-term effects of being born SGA on growth, reproductive performance, and productivity.

Genetic parameters for calf feeding traits derived from automated milk feeding machines and number of bovine respiratory disease treatments in North American Holstein calves

Precision livestock farming technologies, such as automatic milk feeding machines, have increased the availability of on-farm data collected from dairy operations. We analyzed feeding records from automatic milk feeding machines to evaluate the genetic background of milk feeding traits and bovine respiratory disease (BRD) in North American Holstein calves. Data from 10,076 preweaning female Holstein calves were collected daily over a period of 6 yr (3 yr included per-visit data), and daily milk consumption (DMC), per-visit milk consumption (PVMC), daily sum of drinking duration (DSDD), drinking duration per-visit, daily number of rewarded visits (DNRV), and total number of visits per day were recorded over a 60-d preweaning period. Additional traits were derived from these variables, including total consumption and duration variance (TCV and TDV), feeding interval, drinking speed (DS), and preweaning stayability. A single BRD-related trait was evaluated, which was the number of times a calf was treated for BRD (NTT). The NTT was determined by counting the number of BRD incidences before 60 d of age. All traits were analyzed using single-step genomic BLUP mixed-model equations and fitting either repeatability or random regression models in the BLUPF90+ suite of programs. A total of 10,076 calves with phenotypic records and genotypic information for 57,019 SNP after the quality control were included in the analyses. Feeding traits had low heritability estimates based on repeatability models (0.006 ± 0.0009 to 0.08 ± 0.004). However, total variance traits using an animal model had greater heritabilities of 0.21 ± 0.023 and 0.23 ± 0.024, for TCV and TDV, respectively. The heritability estimates increased with the repeatability model when using only the first 32 d preweaning (e.g., PVMC = 0.040 ± 0.003, DMC = 0.090 ± 0.009, DSDD = 0.100 ± 0.005, DS = 0.150 ± 0.007, DNRV = 0.020 ± 0.002). When fitting random regression models (RRM) using the full dataset (60-d period), greater heritability estimates were obtained (e.g., PVMC = 0.070 [range: 0.020, 0.110], DMC = 0.460 [range: 0.050, 0.680], DSDD = 0.180 [range: 0.010, 0.340], DS = 0.19 [range: 0.070, 0.430], DNRV = 0.120 [range: 0.030, 0.450]) for the majority of the traits, suggesting that RRM capture more genetic variability than the repeatability model with better fit being found for RRM. Moderate negative genetic correlations of -0.59 between DMC and NTT were observed, suggesting that automatic milk feeding machines records have the potential to be used for genetically improving disease resilience in Holstein calves. The results from this study provide key insights of the genetic background of early in-life traits in dairy cattle, which can be used for selecting animals with improved health outcomes and performance.

The importance of developmental programming in the dairy industry

The concept of developmental programming suggests that environmental influences during pre- and early postnatal life that can have long-term effects on future health and performance. In dairy cattle, maternal body growth, age, parity and milk yield, as well as environmental factors during gestation, have the potential to create a suboptimal environment for the developing fetus. As a result, the calf's phenotype may undergo adaptations. Moreover, developmental programming can have long-term effects on subsequent birth weight, immunity and metabolism, as well as on postnatal growth, body composition, fertility, milk yield and even longevity of dairy cows. This review provides an overview of the impact of developmental programming on later health and performance in dairy cows.

The association between insemination eligibility and reproductive performance of nulliparous heifers on subsequent body weight and milk production of primiparous Holstein cows

The objective of this retrospective cohort study was to determine the association between insemination eligibility and reproductive performance of nulliparous heifers with subsequent body weight (BW) at 30 d in milk (DIM) and milk production at wk 4, 8, and 12 of lactation of primiparous cows. The final data set included 1,849 primiparous Holstein cows from a commercial dairy herd. Data extracted from a commercial dairy herd management software program included parent average predicted transmitting abilities (PTA), bovine respiratory disease (BRD) incidence, pregnancies per artificial insemination (P/AI) at first insemination as nulliparous heifers, BW at 30 DIM, percent mature body weight (%MBW), and mean weekly milk production at wk 4, 8, and 12 of lactation. Heifers were eligible for first insemination at 380 d of age and were detected in estrus and artificially inseminated with sexed semen. Quartiles based on BW at 30 DIM and %MBW were created in ascending order as follows: Q1 (lightest; n = 462), Q2 (light-moderate; n = 456), Q3 (moderate; n = 472), and Q4 (heaviest; n = 459). Only Q3 and Q4 cows achieved ≥85% MBW postcalving based on the herd MBW of 686.2 kg. The incidence of BRD during heifer development was greatest for Q1 cows, and Q1 cows had fewer days on feed as heifers than Q4 cows, resulting in a shorter growth period to achieve ≥85% MBW postcalving. Overall, Q1 cows had a greater PTA for daughter pregnancy rate and heifer conception rate than Q4 cows, which was associated with approximately 26 percentage points more P/AI at first insemination as heifers for Q1 than for Q4 cows. Finally, Q1 cows yielded approximately 5 kg per cow/d less milk than Q4 cows. Thus, insemination eligibility and reproductive performance of heifers, calfhood BRD incidence, and genetic potential for reproductive performance were associated with BW at 30 DIM and milk production at wk 4, 8, and 12 of lactation of primiparous cows.

Early life indicators of first lactation milk yield and the effect of treatment for bovine respiratory disease on survivability and risk of pregnancy in Holstein dairy cattle

The primary objective of this study was to evaluate the long-term effects of variables that could be measured early in life events on first lactation milk production. The secondary objective was to evaluate the long-term effects of treatment for bovine respiratory disease (BRD) within the first 120 days of life on survivability to 850 days and reproductive success. Data from Holstein heifer calves was collected from 1 October, 2015 to 31 January, 2020 and included milk consumption (MC; n=10,431), bodyweight (BW; n=9,825), average daily gain (ADG; n=6,194), heifer conception age (n=10,112), and 305 day first lactation milk production (305M; n=5,823), and treatment records for BRD (n=12,485). Calves were fed pasteurized whole milk through an automated calf feeding system for 60 days (range, 48 - 126 days), with a 30% crude protein (CP) and 5% crude fat enhancer added at 20g/L milk. Calves were weighed at birth, weaning, and several other times prior to 2 years of age. Daily BW were predicted for individual animals using a third order orthogonal polynomial to model individual BW regressions. Daily BW predictions were used to calculate ADG and BW predictions on specific days of interest. Season born, ADG (0-400 days), milk production potential, and heifer conception age had a significant impact on 305-day first lactation milk production (all P≤0.05; r² = 0.31). A retrospective cohort study was conducted utilizing data collected from a commercial farm with cohorts defined by BRD status. Calves treated for BRD from 61 to 120 days old had a significantly lower chance of survival to 850 days of age than animals not treated for BRD. Additionally, calves for BRD from 61 to 120 days old had reduced risk of pregnancy. The results show the impact of early life on future milk production, survivability, and pregnancy risk on a commercial dairy herd.

Overview of common practices in calf raising facilities

In this literature review, we overview some of the common management practices associated with calf rearing in specialized operations of the United States. Given the growing importance of dairy-beef calves entering the beef production of the United States, we overview aspects related to housing, nutrition, and health events during the pre- and post-weaning period. Based on data on dairy animals, we hypothesize how early life experiences could impact the feedlot performances of dairy-beef animals. Most of the large calf raising operations, where the majority of dairy-beef animals are raised, are located in the Central Great Plains and West regions of the United States. Approximately 80% of calves are individually housed, but the type of housing (e.g., outside hutch, inside a barn) varies based on location of calf-raising facilities. Milk-replacer is fed in more than 80% of operations, while milk (saleable or nonsaleable) is fed in approximately 30% of calf raising facilities (some operations fed more than one type of liquid diet). In addition to liquid feed, water and calf starter are offered ad libitum to calves. Adequate starter intake at weaning is crucial for feed transition from pre- to post-weaning period, which occurs at approximately 2 months of age. Then, calves are mainly housed in group pens and transition from calf-starter to total mixed ration (TMR). Health challenges such as scours and bovine respiratory disease (BRD) can hinder the performance of calves and are major causes of morbidity and mortality in calf ranches. Transportation at a very young age and comingling with animals from other dairies can increase the risk of diseases. Current research efforts are focusing on determining individual factors such as body weight (BW) at arrival or biomarkers of inflammation and stress that can be predictive of disease morbidity, mortality, and performance of calves. Future research should focus on how to utilize this information to optimize management and to develop targeted preventative strategies to reduce incidence of diseases and mortality and improve performance during the pre-weaned period. Also, more research is needed to understand how colostrum management, housing, and nutrition can impact the adult performance of dairy-beef animals.