Pulmonary arterial pressure measured in beef cattle at a year of age is used to indicate pulmonary hypertension and an individual’s susceptibility to high-altitude disease. When measured at 14 months of age, PAP is related to heart score, an indicator of Bovine Congestive Heart Failure (BCHF). A genetic correlation between 14-month PAP and heart score of 0.94 ± 0.17 has been reported. The relationship between PAP collected around a year of age, at low elevation in a feedyard, and degree of BCHF as indicated by heart score remains unknown. Therefore, the objective of this study was to determine if pulmonary arterial pressure (PAP) measures taken in beef cattle during the mid-finishing period are predictive of heart score. The degree to which an individual is experiencing BCHF at harvest is measured by a heart scoring system developed by Dr. Tim Holt that assesses the degree of physiological remodeling of the right side of the heart. Scores range from 1 to 5, where 1 represents a physiologically normal heart and a 5 represents a heart with severe remodeling. Yearling PAP and heart scores were collected on 107 Angus-influenced steers (n=67) and heifers (n=40). All 107 cattle were finished at the same elevation. Yearling PAP was collected around the average age of 405 days for all cattle. The average PAP was 45.38 mmHg, with minimum and maximum values of 33 and 77 mmHg, respectively. The distribution of heart scores was 33, 60, 12, and 2, corresponding to heart scores 1, 2, 3, and 4, respectively. There were no scores of 5. A simple linear regression model was used to evaluate the relationships between heart score and PAP. Effects in the model for PAP included heart score, sex, and PAP age in days as a linear covariate. Heart score (P< 0.006) and age (P< 0.05) were significant sources of variability in PAP. Yearling PAP least squares means were 46.7 mmHg, 43.4 mmHg, 48.1 mmHg, and 58.7 mmHg, corresponding to heart scores 1, 2, 3, and 4, respectively. In summary, PAP measurements taken around a year of age during an animal’s mid-finishing point may be used as an indicator of BCHF, potentially leading to earlier detection of feedlot heart diseases.

Porcine respiratory and reproductive syndrome is a viral disease that impacts the health and profitability of swine farms, largely due to significant variation in the vaccination response. The objective was to identify and validate molecular markers associated with the antibody response in gilts following vaccination against the PRRSV. The study included one hundred (n = 100) 6-month-old Yorkshire gilts that were negative for the PRRSV. Gilts were randomly assigned to one of two treatments, PRRS-vaccinated (n = 75) and control (n = 25) groups. Blood samples collected on day 21 were analyzed to evaluate the antibody response, as indicated by the sample-to-positive (S/P) ratio, to the PRRSV following vaccination. DNA was extracted and genotyped using a low-density chip containing 10,000 single nucleotide polymorphisms (SNPs). A genome-wide association study (GWAS) was conducted to identify candidate SNPs associated with the S/P ratio, which were validated in two independent gilt populations (n = 226). The SNPs rs707264998, rs708860811, and rs81358818 in the genes RNF144B, XKR9, and BMAL1, respectively, were significantly associated (p < 0.01) with the S/P ratio and demonstrated an additive effect. In conclusion, three SNPs are proposed as candidate markers for an enhanced immune response to vaccination against the PRRSV and may be beneficial in genetic selection programs.

In livestock production, the primary greenhouse gases (GHG) contributing to climate change are methane (CH₄), nitrous oxide (N₂O), and carbon dioxide (CO₂). Reducing methane and nitrogen emissions is essential for enhancing the sustainability of beef cattle production systems. The objective of this study was to estimate heritabilities for CH₄, dry matter intake (DMI), and blood urea nitrogen (BUN), as well as estimate the genetic correlations between DMI and both CH4 and BUN in Angus [SS1] [MOU2] cattle to assess their potential as selection criteria for mitigating environmental impact. The dataset included measures for at least one of the traits on 1,036 Angus cattle, comprising both steers and heifers. Two bivariate animal models were utilized to estimate genetic parameters for DMI and CH₄, as well as for DMI and BUN.[ME3] For DMI, age and weaning weight were included as linear covariates in the statistical model, along with a contemporary group (CG) defined as a combination of start date, pen, and sex. For CH₄, the statistical model included age and CG as fixed effects, while for BUN, the effects of date, age, and weaning weight were incorporated. The heritability estimates for DMI, CH4, and BUN were found to be 0.22 ± 0.08, 0.32 ± 0.18, and 0.45 ± 0.24, respectively. Genetic correlations between DMI and CH4 and between DMI and BUN were calculated to be 0.78 ± 0.26 and 0.06 ± 0.31, respectively. The residual correlation between DMI and CH4 was estimated to be 0.37 ± 0.11, while the residual correlation between DMI and BUN was calculated to be -0.02 ± 0.17. The near-zero genetic correlation between DMI and BUN suggests that selection for reduced feed intake is unlikely to significantly impact circulating nitrogen metabolism. In contrast, the strong genetic correlation between DMI and CH₄ indicates that improving feed utilization could provide indirect environmental benefits by lowering CH4 emissions. However, the moderate heritability estimates for CH₄ and BUN suggest that direct selection for reduced CH4 production or nitrogen excretion may be more effective than relying solely on selection for lower DMI. These findings underscore the importance of incorporating multiple traits into genetic selection strategies to enhance both efficiency and environmental sustainability in beef cattle production.

This study aimed to develop a preliminary understanding of the relationship between heart scores (HS) and carcass value in Angus steers. One significant economic consequence of right heart failure in cattle is mortality before slaughter; however, the economic impact of heart remodeling on carcass performance in animals that survive to slaughter is less understood. Carcass value, HS, back fat depth (BF; mm), marbling score (MARB), hot carcass weight (HCW; kg), ribeye area (REA; cm²), and calculated yield grade (CYG) were collected from 299 Angus steers at slaughter. The steers originated in southeastern Wyoming and were harvested between January 2023 and October 2024. Heart scores indicate the severity of right heart remodeling on a scale from 1 to 5, where 1 represents a normal heart with no remodeling, and 5 indicates a heart with severe remodeling. Carcass values were determined using a quality-based Angus grid. Of the 299 scored steers, the HS distribution was 128, 116, 44, 8, and 3 for scores 1, 2, 3, 4, and 5, respectively. Carcass values ranged from $2567.04 to $3146.01, with a mean of $2572.25 and a standard deviation of $245.49. All linear regression models included categorical fixed effects of HS and kill date. When the kill date was held constant, the average differences in carcass value for animals with HS of 4 compared to HS of 1, and those with HS of 5 compared to HS of 1, showed decreases of $161.51 and $345.31, respectively (P = 0.04; P = 0.007). When adjusting for HS, four of seven kill dates had significant effects on carcass value compared to the reference date, with a range of effects from $186.61 to $353.75 (P < 0.05). Linear regression models with outcome variables of BF, MARB, HCW, REA, or CYG were fitted to investigate potential HS relationships with carcass characteristics that can contribute to carcass value. Heart score did not have a statistically significant effect on CYG or MARB (P = 0.21; P = 0.65). When adjusted for kill date, there was a statistical tendency for HS effects on REA (P = 0.08) and BF (P = 0.06). After accounting for kill date, HCW for animals with HS of 4 compared to HS of 1 and HS of 5 compared to HS of 1 had average decreases of 31.82 kg and 60.56 kg, respectively (P = 0.01; P = 0.002). The relationship between HS and carcass value, as well as HCW, indicates a potential economic loss in carcass value due to the negative effects of severe heart remodeling on HCW. Further research is required to gain a comprehensive understanding of how HS affects carcass value in beef cattle.

From a genetic improvement perspective, the overarching challenge in the beef industry is its segmented nature, where there is limited flow of animal performance information from later to earlier stages of the production system. For instance, often there is limited animal performance information passed from the feedlot stage back to the commercial cow-calf producer (and to the backgrounder in between) and ultimately back to the seedstock supplier. In a perfect system, information would be transferred along with value signals from the end user up through the production chain to incentivize the genetic improvement of economically relevant traits. Except for a limited number of vertically integrated production and progeny test programs, most of the industry is subject to this data disconnect. This issue remains a concern for the Beef Improvement Federation, where producers, industry-affiliated professionals, and academics gather annually to facilitate the overall genetic improvement of the beef industry, providing a unique opportunity to develop cooperative research programs. Even with these efforts, the lack of data transfer makes the evaluation of emerging traits of economic relevance in late-stage segments of the production chain even more difficult to improve at the seedstock level—the driver of industry genetic improvement. Traits such as susceptibility to bovine respiratory disease, the more recent bovine congestive heart failure, and environmental sustainability-related traits remain challenging. Still, partnerships amongst these groups are helping to leverage information collected at later stages of production. While funding for these partnerships is challenging, relationships amongst academics, producer-centric industry organizations, and industry-service providers have increasingly provided a mechanism for the development of tools for the seedstock and commercial breeders to improve these late-stage traits, overall animal performance, and industry success. The transfer of data is being facilitated by the use of genomic technologies that are able to, at least partially, bridge the lack of data flow from one segment of the beef industry back to the previous segment. With that transfer of genomic information, individual animal performance information (e.g. bovine congestive heart failure incidence, methane emission rate, etc.) can contribute to selection tools used at the seedstock and commercial breeding levels, increasing ability to accurately select breeding animals and create genetic improvement for these new traits.

The aim of this study was to estimate the influence of heterosis and breed percentage on birth weight (BW) and weaning weight (WW) in a multibreed beef herd in a tropical environment. Data consisted of 2,006 BW and 900 WW records, and 2,843 individuals in the pedigree from the multibreed herd of the Panama Agricultural Innovation Institute (IDIAP) in Gualaca, Panama. A bivariate animal model was utilised to estimate variance components. The estimated regression coefficient for BW on heterosis was not significant (-0.04 +/- 0.06 kg, P > 0.05), however, for WW the estimated regression coefficient was 0.07 +/- 0.03 kg (P <= 0.05). Heritability for BW was found to be low (0.14 +/- 0.06) and moderate for WW (0.26 +/- 0.09). The proportion of variation of WW accounted by the maternal permanent environment for WW was (0.20 +/- 0.09). The estimated genetic correlation between additive genetic BW and WW was 0.63 +/- 0.30, while a negative, additive genetic correlation was observed for WW direct and WW maternal (-0.43 +/- 0.37). These results suggest that heterosis has a beneficial influence on WW but a limited effect on BW. Additionally, increasing the percentage of Wagyu and Brahman negatively influenced WW measurements in these data.

Dairy farms located in semi-arid regions face significant challenges in maintaining milk production under a heat-stressed environment. Despite these adverse conditions, some cows are able to sustain adequate milk production, most likely due to genetic factors. Then, objective of this study was to validate three single nucleotide polymorphisms (SNPs) as predictors of milk production and thermo-tolerance in heat-stressed Holstein cows. The study was conducted during summer (June-August) at a dairy farm located in the Yaqui Valley, Mexico. A total of 148 lactating Holstein cows were included, housed in open pens, and provided a ration to meet their nutritional requirements. Milk production was measured twice daily (05:00 an 15:00 hours) through an electronic system, and used to determine the average daily milk yield (DMY). Ambient temperature and relative humidity were recorded with a Kestrel weather meter (DROP D2AG), and used to calculate the temperature-humidity index (THI). Physiological traits, including rectal temperature (RT) and respiratory rate, were measured biweekly (06:00 and 16:00 hours). A blood sample was collected from each cow for genotyping of the SNPs rs8193046, rs43410971, and rs382039214, located within the genes TLR4, GRM8, and SMAD3, respectively. The TaqMan method and real-time PCR were used for genotyping, whereas mRNA expression of these genes was measured through quantitative PCR. Additionally, a blood sample was drawn to analyze serum levels of cortisol and heat shock protein-70 (HSP-70). The THI increased from 76 to 83 units, indicating that heat stress intensified from moderate to severe during the study period. The SNPs in the genes TLR4 and GRM8 were found to be predictors of DMY and RT. Their favorable genotypes (AA and GG, respectively) showed the higher DMY (22.67 ± 1.02 and 23.21 ± 0.89 liters; P< 0.05)) and the lower RT (37.82 °C and 37.65 °C; P< 0.05). The mRNA expression of the genes TLR4 and GRM8 were higher (P< 0.01) in cows with favorable genotype (6.44 and 4.98, respectively) compared to cows without favorable genotype (3.25 and 2.21, respectively). Serum levels of cortisol and HSP-70 were lower (P< 0.05) in cows with favorable genotype (19.75 ± 4.06 ng/mL and 38.65 ± 7.95 pg/mL) compared to cows with non-favorable genotypes (28.64 ± 4.73 ng/mL and 46.38 ± 8.12 pg/mL). Gene expression was strongly correlated (r2=-0.63 to -0.78; P< 0.01) with serum levels of cortisol and HSP-70, which are physiological markers of heat stress. In conclusion, our findings suggest that the genes TLR4 and GRM8 play a critical role in regulating physiological mechanisms associated with thermo-tolerance that contribute to sustain milk production in cows affected by environmental heat stress. Thus, SNPs in these genes may serve as reliable predictors of milk production and thermo-tolerance in Holstein cows managed in warm semi-arid regions.

Anti-Müllerian hormone (AMH) is proposed as a biomarker for fertility in cattle, yet this associative relationship appears to be influenced by heat stress (HS). The objective was to test serum AMH and AMH-related single nucleotide polymorphisms (SNPs) as markers potentially predictive of reproductive traits in dairy cows experiencing HS. The study included 300 Holstein cows that were genotyped using BovineSNP50 (54,000 SNP). A genome-wide association study was then executed. Nine intragenic SNPs within the pathways that influence the AMH gene were found important with multiple comparisons adjustment tests (p < 1.09 × 10−6). A further validation study was performed in an independent Holstein cattle population, which was divided into moderate (MH; n = 152) and severe heat-stressed (SH; n = 128) groups and then subjected to a summer reproductive management program. Serum AMH was confirmed as a predictor of fertility measures (p < 0.05) in MH but not in the SH group. Cows were genotyped, which revealed four SNPs as predictive markers for serum AMH (p < 0.01), reproductive traits (p < 0.01), and additional physiological variables (p < 0.05). These SNPs were in the genes AMH, IGFBP1, LGR5, and TLR4. In conclusion, serum AMH concentrations and AMH polymorphisms are proposed as predictive markers that can be used in conjunction with genomic breeding value approaches to improve reproductive performance in Holstein cows exposed to summer HS conditions.

Abstract Congestive Heart Failure (CHF) is a cardiopulmonary condition observed in cattle raised in feedlots situated at elevations above 800 m. This condition leads to right-sided heart failure caused by increased pulmonary vessel pressures and cardiopulmonary remodeling, known as pulmonary hypertension (PH). In cattle experiencing PH, pulmonary arterial pressure (PAP) becomes abnormally high, increasing heart muscle load. This load stretches muscle fibers and enlarges the right side of the heart which can lead to heart failure and death. To assess the severity of PH, animals are assigned a heart score (HS) on a scale ranging from 1 to 5 at harvest. A score of 1 represents a normal heart, while a score of 5 indicates extreme heart remodeling. Understanding the relationship between hot carcass weight (HCW), fat depth (FD), and HS in Angus cattle will provide useful information on the impacts of this condition on feedlot performance and profitability. The objective of this study was to determine if a phenotypic relationship between HCW and FD with HS in Angus-influenced cattle. For this experiment, a total of 798 black, Angus-influenced cattle were used (245 steers, 553 heifers) that were fed near Greeley, CO. The HCW, FD, and HS data from each animal were recorded at harvest. Three general linear models were used to estimate the effects of HS on HCW and FD. Mean HCW and FD were 393.1 kg, (SD = 90.9) and 0.66 mm, (SD = 0.18), respectively, with an average HS of 2.08 (SD = 0.77). For all models, HCW and FD were fit as dependent variables, while lot and HS were included as fixed effects. Model 1 included all HS categories independently. Model 2 divided HS into 2 groups of normal (HS = 1 or 2) or remodeled (HS = 3+). For model 3 HS 3 was removed leaving only HS of 4 or 5 in the remodeled group. For both HCW and FD in Model 1, the overall effect of HS was not significant (P = 0.82 and P = 0.40, respectively). However, when comparing individual scores, animals with a HS = 4 were 15.0 kg lighter for HCW than individuals with a HS = 1 (P < 0.05). Conversely for FD, a non-significant difference (P = 0.74) of -0.33 mm was observed between animals with a HS = 4 versus a HS = 1. Grouping HS into 2 categories in Model 2 did change the outcome, yielding non-significant HCW and FD differences. However, when eliminating the HS = 3 data, a significant reduction in HCW of 16.9 kg (P = 0.05) was observed between the 2 HS groups, whereas non-significant effects on FD remained. These data suggest that at extreme levels of heart remodeling HCW may be extremely impacted negatively.

Abstract This preliminary study aimed to estimate the heritability of liver abscess incidence in fed, beef on dairy crossbred progeny. Liver abscesses affect approximately 20% to 30% of livers at slaughter. They are commonly identified during viscera inspection at slaughter due to difficulty with antemortem diagnosis. All livers with abscesses are condemned, causing a profit loss for producers. This loss is increased when the abscesses are ruptured or adhered to the gut due to additional condemnation of the gut. The most common prevention techniques include antimicrobial feed additives and nutritional management; however, mitigation has not been highly effective. Few studies have attempted to ascertain if a genetic component for liver abscess incidence exists. Determining if there is a genetic component to liver abscess occurrence could enable the ability to utilize genetic selection as a preventative measure. Liver abscess scores were collected on 1,492 crossbred beef on dairy heifers at slaughter. Cattle were harvested in Kansas. Individual livers were scored using the Elanco scoring system of 0, A-, A, A+. Scores of A+, A+AD, and A+O were combined into the A+ category. A score of 0 indicates a normal liver, as scores of A-, A, and A+ indicate increasing severity of abscesses. Scores of A+AD and A+O represent animals with adhesion to the gut or ruptured abscesses, respectively. In the dataset, the distribution was 903, 168, 69, and 352 for scores of 0, A-, A, and A+, respectively. Overall, the prevalence of liver abscesses was 39.5% in this sample. All 1,492 heifers had recorded sire information, but no dam information existed other than knowing they were of dairy origin. In total, 19 unique sires were represented in the data, with six of the sires producing 89.4% of the heifers. A 3-generation sire pedigree was built from the data, and heritability was estimated using a sire model and the statistical software package ASReml 3.0. Fixed effects included the number of bovine respiratory disease treatments, age in days, and a contemporary group consisting of kill lot and treatment type. These cattle were part of an additional study evaluating the effectiveness of various treatment regimens for mitigating the incidence of liver abscesses. There were three treatment groups, one control and two treatments. Genetic and phenotypic variation for this model was estimated to be 2.70 × 10-7 ± 9.99 × 10-9 and 1.58 ± 5.86 × 10-2, respectively. With such a small genetic variance estimate, the heritability of liver abscesses was effectively 0 (1.70 × 10-7), which suggests the lack of a genetic component for liver abscesses in these data. This was a preliminary study that had limited sire variation. Currently, dam information is being accumulated in an attempt to account for dam genetic variation.

Feedlot heart disease (FHD) is a condition in fattening beef cattle that arises from right-side heart remodeling resulting from alveolar hypoxia. This hypoxic environment is hypothesized to result from the large body mass of fattened cattle. Sensitive cattle have increased incidence of pulmonary hypertension resulting from compensation mechanisms of the individual. The severity of this remodeling is quantified at harvest by gross examination of the heart utilizing a visual grading system of 1-5, where a score of 1 is a normal heart and a score of 5 is a severely remodeled heart. Previously, heart score was found to contain sire differences and to be moderately heritable. This led to more questions regarding other potential factors influencing heart scores, one of which was breed differences. Therefore, the objective of this study was to examine the prevalence of heart remodeling in beef and dairy cattle breeds and to investigate whether some breeds had a greater prevalence of heart remodeling. Heart scores were collected on Angus-influenced animals raised in the panhandle of Texas (1,103 m) and a Beef x Dairy group raised in western Kansas (846 m). The total number of animal observations was 2,069. Twenty-four percent of the individuals exhibited moderate to severe remodeling (score 3 and greater). Of this cohort, 1,307 animals had breed composition data (i.e., Angus, Simmental, Jersey, and Holstein) suitable for use in the analysis. Breed proportions ranged from 0% to 100% for Angus, 0 to 93.25% for Simmental, 0% to 69.22% for Jersey, and 0% to 78.06% for Holstein. Utilizing a linear regression model with heart score as the response and breed percentages and heart scorers as fixed effects, the importance of breed composition (covariate) was determined. The percentages of Angus influence tended to be associated with heart score (P = 0.0506), with a regression coefficient of -0.005. The percentage of Simmental had an association with the variation in heart score (P < 0.05) and had a regression coefficient of -0.008. Additionally, the percentages of Jersey and Holstein were found to reduce the incidence of heart score by a factor of -0.014 and -0.018 (P < 0.05), respectively. In summary, an increased percentage of either Jersey or Holstein breed resulted in reduced heart scores, while the incidence of beef breeds was found to be associated with some to little difference in the improvement of heart scores, alluding to potential breed advantages in mitigating right sided heart remodeling.

Objective: The objective was to determine the effects of liver abscesses on complete blood counts (CBC) and liver function and to identify blood -based biomarkers for detection of liver abscesses in feedlot cattle. Materials and Methods: Blood samples were collected on a subset of beef x dairy crossbred heifers with and without liver abscesses (n = 94; n = 113, respectively). From these blood samples, CBC and serum chemistry analytes related to liver health (alkaline phosphatase, gamma glutamyl transferase, bile acids, total bilirubin, and cholesterol) were analyzed to characterize animal health and model for liver abscesses. Abscess presence was predicted using logistic regression models and machine learning algorithms, with individual heifer serving as the experimental unit. Results and Discussion: In a binary system (abscessed or not), heifers with liver abscesses had lower concentrations of lymphocyte (LYM) and total white blood cell (WBC) concentrations but elevated platelet-to-LYM ratio. Serum chemistry measures were not affected by abscess presence or liver score (severity). In univariate, predictive modeling of CBC measures, only total WBC concentration was accurate (65.85%) at predicting liver abscess presence; however, this was not deemed an acceptable biomarker due to its poor specificity (54.79%). Using total WBC, basophils, red blood cells, and procalcitonin as variables to predict liver abscess condition, the LogitBoost model produced the greatest accuracy (80.65%) and specificity (85.71%). An accurate blood test that allows for the detection of liver abscesses during the finishing phase may allow for therapeutic management or alternative marketing of cattle; however, the marginal accuracy demonstrated in this study combined with the impracticality and cost of analyzing a blood sample may not be feasible. Regardless, the most explanatory CBC variables in cattle with abscessed livers were suggestive of an immune response. Implications and Applications: Liver condition influenced the CBC of beef x dairy heifers but not serum chemistry. Multivariate predictive models showed potential for predicting liver abscess condition based on CBC. The results of this study warrant further investigation for biomarkers of the liver abscess condition. An antemortem indicator for liver abscesses could prove useful for making management decisions and in research applications, particularly in evaluating interventions.

Abstract The objective of this study was to determine if a phenotypic relationship between pulmonary arterial pressure (PAP) and oxygen consumption exists in beef cattle. Pulmonary arterial pressure is used as an indicator of pulmonary hypertension in cattle which is indicative of the susceptibility to both high-altitude disease and feedlot heart failure of an individual. Cattle with greater PAP are typically hypoxic and have initiated expression of compensatory mechanisms their cardio-pulmonary systems employ to combat this alveolar hypoxia. In turn, this causes an increase in PAP and, ultimately, right-sided heart failure. If hypoxic individuals consume more oxygen as a compensation mechanism, oxygen consumption as a trait could be used as an indicator of the prediction of PAP and feedlot heart failure and would be especially useful for cattle in deep phenotyping systems. Data used in the study included cattle with PAP measures on a total of 132 individuals. The data consisted of both steers (n = 99) and heifers (n = 33) from a ranch located in southern Wyoming at an elevation of approximately 2,195 m. After weaning on the ranch, cattle were transported to Colorado State University’s Agriculture Research, Development and Education Center located in Fort Collins, CO (elevation: 1,558 m). Oxygen consumption was measured using a Greenfeed system (C-Lock, Rapid City, South Dakota). To determine if a relationship exists between oxygen consumption and PAP, a simple linear regression model was used to regress PAP on average daily oxygen consumption. Effects included in the model were sex and phenotypic PAP. Average daily oxygen consumption was measured in kilograms per day and averaged 6.6 ± 1.66 kg with a range of 2.3 to 10.45 kg. Pulmonary arterial pressure averaged 42.6 ± 7.96 mm Hg and ranged from 33 to 81 mm Hg. In this data, sex did not account for a significant amount of variability in phenotypic PAP (P > 0.05). Oxygen consumption did account for a significant amount of variability in PAP (P < 0.05), and it was found that with every 1 kg increase of oxygen consumption, PAP is estimated to increase 1.02 mm Hg. These results indicate that a statistical relationship between oxygen consumption and PAP exists. Although these findings suggest that greater oxygen consumption leads to greater PAP, further research is required to fully comprehend the relationship between beef cattle PAP and oxygen consumption.

Abstract Heifer pregnancy (HP) in beef cattle is a heritable and economically relevant trait but is challenging to predict using best linear unbiased prediction (BLUP) methodology due to the binary nature of the phenotypes. The observed categorical responses (e.g., 1 = pregnant; 0 = non-pregnant) are due to an animal either exceeding a particular threshold for pregnancy or not on an underlying genetic distribution which is why this binary trait is commonly evaluated using a threshold model (TM). However, TM are susceptible to scenarios where only 1 category of observation is predominant. In this study we compare genetic evaluations including “partial” and “whole” data to cross-validate methodologies for the prediction of HP. The objectives of this study were then to evaluate estimators of prediction accuracy, bias, and dispersion. Heifer fertility data were obtained from the Red Angus Association of America. Evaluations for HP were performed using ASREML3.0 and a univariate, BLUP, traditional TM; and a linear continuous BLUP animal model (LM) on both reference (whole) and validation (partial) datasets. Reference data included all animals with HP phenotypes, and validation data had censored the most recent 5 yr of HP phenotypes (~16% of HP phenotypes). Reference and validation estimated breeding values (EBV) were then compared using linear regression (LR) methods. Heritability estimates were 0.05 (± 0.007) and 0.15 (± 0.009) for LM and TM respectively. The average BIF accuracy of censored validation animals (n = 10,175) using a LM on whole and partial datasets were 0.07 and 0.03 respectively, and using a TM on whole and partial datasets were 0.09 and 0.04 respectively. Comparing the mean EBV from the partial and whole datasets can be a good estimator of bias in the model as the difference is expected to be 0. The difference between the mean EBV from partial and mean EBV from whole datasets were –0.003 and –0.016 for LM and TM respectively, suggesting that the TM is a slightly more biased evaluation. The regression of EBV obtained with whole data on EBV estimated with partial data has an expected value of 1 if there is no over/under dispersion which can be a useful tool in determining model correctness and gauge bias in an evaluation. The closer a regression coefficient is to 1, the less biased the evaluation is. The slope of the regression of EBV estimated from whole data on partial data for validation animals were 0.98 (P < 0.0001) and 0.91 (P < 0.0001) for LM and TM respectively. Although both regression coefficients were above 0.90 suggesting both evaluations are performing well, these results suggest that TM models may be a more biased predictor of HP than LM despite a small benefit in prediction accuracy for the trait.

Excess Nitrogen excretion is a growing concern worldwide within animal agriculture, and blood urea nitrogen (BUN; mg/dL) is known as a predictor of nitrogen excretion in cattle. The objective of this study was to determine sire differences in BUN within a population of Hereford steers. Steers (n = 74) were born between March and June of 2021 from a reference sire herd for The American Hereford Association in Western Nebraska. Sixteen different Hereford sires from The American Hereford Association reference sire program produced offspring used in this study. The steers entered an on-site feed intake unit and were fed a finishing diet consisting predominantly of corn, corn distiller grain, and corn silage. Animals were subjected to a 21-d warm-up period with a 55-d individual feed intake test period. Blood samples were collected on day 43 of the test period. Blood samples were then centrifuged to extract serum. The Urea Nitrogen (BUN) Colorimetric Detection Kit by Invitrogen was used for the assay. The average BUN concentration for all animals in this study was (0.492 ± 0.061 mg/dL). A generalized linear regression model was used to determine sire differences in BUN concentrations. Factors considered were sire and pen group. The sire with lowest least squared mean progeny BUN concentration estimate was (0.0362 ± 0.08 mg/dL; n = 4), and the highest was (0.605 ± 0.03 mg/dL; n = 7). Sire differences (P < 0.05; r2 = 0.36) were found to be important sources of variation as evidenced by its r2; however, pen group (P = 0.65; r2 < 0.05) appeared to have little impact on variation. The differences in sires indicate genetic differences could be leveraged to reduce excess nitrogen excretion in cattle populations.

High pulmonary arterial pressure (PAP) is a predisposing factor in the development of high mountain disease in cattle. Since PAP testing is often used to prevent disease, a better understanding of the genotype X environmental interactions that drive PAP may lead to the development of additional management and selection strategies. Hypoxia during gestation promotes adaptive fetal programming, a hallmark of which is altered cardiovascular development and disease. However, to our knowledge, no studies have investigated the link between maternal gestational environment and offspring cardiovascular performance as indicated by PAP score. Thus, the objective of this preliminary study was to evaluate the impact of temperature during gestation on yearling PAP in offspring from cattle residing at high altitudes. Yearling PAP data from Colorado State University’s Beef Improvement Center located near Saratoga, Wyoming (7,200 m elevation) was used in the analysis. Data were collected on individual Angus animals born from 1993 to 2021. There were 8,080 individuals with PAP phenotypes averaging 42.23 ± 9.59 mmHg. PAP testing was performed in individuals at an average age of 338.1 ± 46.4 d. Local historical temperature data from September to March, representing the time frame of middle to late gestation, were collected from the [National Oceanic and Atmospheric Administration (NOAA) database] and averaged. This historical average was compared with the yearly mid- to late gestational average temperatures to classify whether an individual animal went through gestation in an above or below-average temperature year. To determine the influence of temperature during gestation on PAP, a single trait linear regression model was used to regress PAP on age at PAP, sex, and temperature classification. The effects of age (P < 0.005), sex (P < 0.0005), and temperature classification (P < 0.05) all accounted for a significant amount of variation in PAP. The least-square means for temperature classification were 42.8 ± 0.51 and 42.3 ± 0.17 for above and below-average temperatures, respectively, which suggests that cows experiencing colder temperatures during gestation produce calves with lower yearling PAPs versus those from cows experiencing warmer temperatures. The internalization of maternal blood during cold temperatures may protect fetal oxygen and nutrient delivery, promoting normal heart development in a high-altitude environment.

The aim of this study was to estimate the influence of heterosis and breed percentage on calving interval (CI) and gestation length (GL), and the correlation between age at first calving (AFC) and CI, in beef cows. Data included 1,291 repeated observations of CI and GL from 502 cows with 2,840 individuals in the pedigree, including 3 generations from the multi-breed herd of the livestock experimental station of the Panama Agricultural Innovation Institute (IDIAP) in Gualaca, Panama. The herd was composed of the following genetic groups based on their breed percentage: tropically adapted Brahman (BR), Nellore (Ne), Undefined Bos indicus (BI), Guaymi Creole (CR), Senepol (SP) and Romosinuano (RS); Bos taurus (BT), Simmental (SM), Angus (A), Red Angus (AR), Limousin (LM), Charolais (CH), Wagyu (Wa), and Others (Oth); crossbreeds (cx), Beefmaster (BF), Three CX (F1 x different BT), R1(Backcross BR), R2 (Backcross BT), Composite (combination of at least 4 different breeds with less than 25% of Zebu), Upgrade (87.5% BR 12.5% BT), B1 (62.5% Zebu + 37.5% BT), and B2 (62.5% BT + 37.5% Zebu). The Zebu influenced breed group represents 50.03% of this population, followed by the F1, the three CX, composites, and R1, representing 22%, 13.89%, 6.11%, and 5.34%, respectively. The other breed groups represented less than 2.5% of the population. A repeated records animal model was used to estimate variance components for both CI and GL. A bivariate animal model was used to estimate the genetic correlation between CI and age at first calving (AFC). Fixed effects for all models consisted of contemporary group, age of dam, calf sex, degree of outcross, and breed percentage. Contemporary group was defined by calving year and season of birth. The average CI was 572.6 ± 140 d, with a range of 315 d to 910 d; and the average GL was 284.2 ± 6.3 d. The estimated regression coefficient for CI on heterosis was -0.114 ± 0.10 d/heterosis % (P = 0.266), and for GL was -0.01 ± 0.052 d/heterosis %. A shorter CI was observed for the F1, and three CX, with 558.7 days and 567.2 days, representing a 2.3% and 1.3% reduction in CI, respectively, when compared with the Zebu group. A larger CI was observed for the Nellore and Romosinuano breeds % with 0.17 ± 1.23 d, (P = 0.373) and 0.64± 0.13 d (P = 0.406), respectively. A low heritability (0.037 ± 0.026) for CI was estimated, with a positive genetic trend over the duration of the study. The analysis between CI and AFC revealed a moderate genetic correlation (0.49 ± 0.36) that allows the establishment of a selection program to improve AFC and CI, which would improve the fertility of this multi-breed herd in Panama.

The dairy and beef industries have been identified as an important producer of methane emissions, yet little is known of its relationship to other economically relevant traits. Stayability (STAY) is a fertility and longevity-related trait with EPD (Expected Progeny Differences) representing predicted genetic differences in the probability of daughters remaining in the breeding herd until six years of age. Understanding the relationship between methane emissions and STAY might inform breeders of the consequences of selection on either trait. The objective of this study was to determine the relationship of methane emissions with STAY in Angus cattle (Bos Taurus) from Colorado State University’s John E. Rouse Beef Improvement Center located in southern Wyoming. A total of 123 animals (86 steers, 37 heifers) were sorted into four different pens where individual methane emissions were measured using a GreenFeed system (C-Lock, Rapid City, South Dakota). Stayability was evaluated using EPD values. A general linear model was used to calculate the regression of the average methane emission of each animal measured in grams/day (mean = 163.08, SD = 38.75, min = 87.72, max = 247.03) on STAY (mean = 0.59, SD = 0.69, min = -2.41, max = 2.36), including age in days (mean = 258.2, SD = 20.01, min = 200, max = 298) and pen as effects in the model. The regression of methane emission on STAY EPD was 0.52, however, it was not significant (P = 0.87). The effect of pen was significant (P < 0.001?). Age was significant, having an effect of 0.6794 (P = 3.93e-08). This suggests that younger individuals had decreased methane emissions. These preliminary results indicate that there is no significant relationship between methane emissions and STAY EPD.

Bovine Congestive Heart Failure (BCHF) exists in feedlot cattle at low to moderate elevations, but previous studies focused solely on beef cattle. The economic advantage of breeding beef sires to dairy dams results in an increase in the number of beef on dairy (DXB) crossed cattle in the feedlot system, though not much is known on the comparative prevalence of BCHF in DXB compared with beef cattle breeds. The inclusion of a new breeding program for dairy producers leads to another potential source of variability (i.e., dairy influenced genetics) for heart disease research in the feedlot sector. Heart failure in the feedlot is typically known as Feedlot Heart Disease (FHD) and has been reported to result in unfavorable carcass and growth performance damaging quality and efficiency throughout the lifetime of cattle. The unknown prevalence of heart failure in DXB cattle may be a problem for producers since little is known about which breeds are at greater risk. The severity of FHD for both beef and DXB cattle was determined by individually grading hearts at harvest using a 1 to 5 grading system corresponding to the stage of heart remodeling with a score of 1 (normal heart) and greater scores indicating increased remodeling. The objective of this study was to examine the prevalence of heart remodeling in both an Angus influenced group of beef cattle and a sample of DXB cattle. Heart scores were collected on an Angus influenced group raised in the panhandle of Texas (1,103m) and totaled 1,634 animals (Grade 1: 347; Grade 2: 848; Grade 3: 371; Grade 4: 68; Grade 5: 0). Heart scores were collected on a DXB group raised in western Kansas (846 m) and totaled 2,328 animals (Grade 1: 913; Grade 2: 1,162; Grade 3: 225; Grade 4: 27; Grade 5: 1). Proportions of moderate to severe heart remodeling were 0.27 and 0.11 for Angus influenced and DXB, respectively. In conclusion, preliminary research on heart remodeling in both samples indicates a greater proportion of cattle experiencing heart remodeling in beef breeds versus the DXB cattle, although further investigation is needed to make conclusions about the consistency of heart remodeling and breed effects.

Porcine Reproductive and Respiratory Syndrome (PRRS) is a viral disease that seriously affects the swine industry. The main method of control is vaccination, which has shown variable effectiveness partly attributed to genetic variability in sows. The objective was to validate single-nucleotide polymorphisms (SNPs) associated with performance traits following PRRS vaccination in replacement sows. A population of 100 Landrace(¾) / Yorkshire(¼) commercial line sows of 6 months of age, an average weight of 108 kg, and negative for PRRS virus were used. After an acclimatization stage, sows were vaccinated against PRRS (day 0). Daily weight gain (DWG) and rectal temperature (RT) were recorded on days 0, 7, 14, 21, and 28. A blood sample was individually collected on day 40 and used for DNA extraction and genotyping of 59 SNPs. These SNPs were previously identified through genomic analysis as associated with a vaccination response indicator. The 59 SNPs were validated in this study using a statistical mixed-effects model that included DWG or RT as response variables. From 59 SNPs, 5 of them were associated with DWG (P < 0.05), and 3 with RT (P < 0.05). Interestingly, the SNPs in the genes DENND5A (rs81409931 and rs81216494) and COL22A1 (rs329119519 and rs81381462) were associated with both DWG and RT, and they showed a higher allele contribution effect on phenotypes. These 2 genes appeared to be functionally related to DWG; therefore, their corresponding 4 SNPs are proposed as genetic markers associated with the response to PRRS vaccination in replacement sows from southern Sonora.