Scott E. Speidel

This study aimed to identify and validate functional genetic markers associated with fertility and thermotolerance traits in dairy cows exposed to HS. Spring-calving Holstein cows (n=400) from three dairy farms located in the Yaqui Valley, Mexico, were genotyped using the BovineSNP50 panel. Reproductive traits such as days open (DO) and services per conception (SPC) were recorded following a fixed-time artificial insemination protocol. After quality controls 45,832 SNPs were included in a genome-wide association study, which identified 21 and 20 SNPs associated with DO and SPC (P < 0.05), respectively. Five SNPs common to both traits were selected for a marker-assisted association study using a mixed effects statistical model. This validation analysis was performed in an independent Holstein cow population (n=184) confirming associations of the SNPs rs136074864, rs109479159, rs43520457, and rs133770320 in the genes EXOC4, GLI3, GPR151, and TRHDE1, with reproductive and thermotolerance traits. Cows carrying favorable genotypes showed increased gene expression, higher serum AMH, progesterone and HSP70, and lower cortisol levels. Correlation analyses confirmed the physiological relevance of these genes. In conclusion, these results highlighted the key role of four candidate genes as molecular markers for improving reproductive efficiency and thermotolerance in Holstein cows managed under HS.

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.

Porcine respiratory and reproductive syndrome (PRRS) is a viral disease that affects health and profitability in swine farms, largely due to a high variation in vaccination response. The objective was to discover and validate molecular markers associated with the antibody response in gilts after vaccination against PRRS virus. The study included one hundred (n=100) 6-month-old gilts from the breed Yorkshire that were PRRS virus-negative. After 7 days of acclimation period, all gilts were vaccinated with a modified live PRRS virus (day 0). Blood samples collected on day 21 were used to evaluate the antibody response, as the sample-to-positive (S/P) ratio, to PRRS virus after vaccination. DNA was extracted and genotyped using a low-density chip including 10,000 single nucleotide polymorphisms (SNPs). A genome-wide association study (GWAS) was performed to discover candidate SNPs associated with the S/P ratio, which were validated in two independent gilt populations (n=226). The SNPs rs80904326, rs80896559 and rs81358818 in the genes RNF144B, XKR9 and BMAL1, respectively, were associated (p < 0.01) with the S/P ratio and exhibited an additive effect. In conclusion, three SNPs are proposed as candidate markers for an improved immune response to vaccination against PRRS virus and may be useful in genetic selection programs.

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.

Anti-Müllerian hormone (AMH) has been proposed as biomarker for fertility in cattle, yet this associative relationship appears to be influenced by heat stress. Objective was to test serum AMH and AMH-related single nucleotide polymorphisms (SNPs) as markers potentially predictive of reproductive traits in heat-stressed dairy cows. The study included 300 Holstein cows that were genotyped using BovineSNP50 (54,000 SNP) after blood samples were collected and DNA extracted. 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 test (p<1.09x10-6). 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 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 SH group. Cows were genotyped using the TaqMan allelic discrimination method and qPCR, which revealed four SNPs as predictive markers for serum AMH (p<0.01), reproductive traits (p<0.01) and physiological variables (p<0.05). These SNPs were in the genes AMH, IGFBP1, LGR5 and TLR4. In conclusion, both serum AMH concentrations and AMH-related SNPs appear to be associated with fertility traits in dairy cows managed during summer.

The objective of this study was to determine the relationship between pulmonary arterial pressure (PAP) expected progeny differences (EPD) and methane emissions. Pulmonary arterial pressure is an indicator of pulmonary arterial hypertension in cattle and is especially relevant at high altitudes, with increasing importance in moderate elevation feedlot and finishing systems. Enteric methane emissions from cattle are increasingly emphasized due to their contribution of greenhouse gases in the agricultural sector. As pulmonary arterial hypertension continues to be an issue in high altitudes and feedlots, understanding relationships with methane emission rates will be useful for both concomitant selection with the goal of improving environmental sustainability. The PAP EPD data were collected on 123 total heifers (n = 37) and steers (n = 86) located on a ranch in southern Wyoming at an elevation of 2,194.56 meters. Gas emissions were collected using a GreenFeed system (C-Lock, Rapid City, South Dakota), which measures the gas fluxes of individual animals at the CSU ARDEC facility at an elevation of 1,557.53 meters. Individual animal methane emissions were measured as grams/day. A generalized linear regression model was used to regress average daily methane emissions (mean = 163.08, SD = 38.74, min = 87.72, max = 247.03) on PAP EPD (mean = -0.464, SD = 1.565, min = -6.382, max = 4.286), pen, and age in days (mean = 258.2, SD = 20.009, min = 200, max = 298). The PAP EPD (P = 0.484) did not account for a significant amount of variation in methane emissions. Additionally, the effect of pen (P < 0.05) and age (P < 0.05) were significant sources of variation for methane production. The effects of pen had a range of 60.916 units of methane emission/day (P < 0.05). Age of the individual was evaluated as a linear covariate and had a solution of 0.678 units of methane emission/day (P < 0.05), suggesting that older individuals had increased methane emissions. These results show no statistical relationship between PAP EPD and methane in these data. While preliminary results suggest that selection for low PAP EPD individuals will have no adverse effects on sustainability metrics, future research is needed to fully understand the relationship between beef cattle production traits and sustainability metrics.

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.

As students progress through their undergraduate education, information from previous classes culminate to lay a foundation for academic success in upper-level courses. However, there is a lack of evidence and implementation for formative assessment methods in undergraduate education. Traditional summative assessments are often cited as being high stress by students and are studied for by cramming material. Both high stress and cramming can reduce long-term knowledge retention in the average student, which is problematic when students need to retrieve this knowledge for future classes. Thus, our objective was to evaluate student knowledge retention coming from a prerequisite course divergent in assessment strategy and/or environment. The prerequisite course, ANEQ 328: Foundations of Animal Genetics, used either 4-unit exams or 16 weekly quizzes with identical questions to assess learning of course material. The course was either delivered in person or online, covered the same material, and all students received the same post-test at the end of the semester. Furthermore, in the quiz-based courses students were surveyed at the end of the semester to gather perceptions of learning with varying course formats. In the subsequent course, ANEQ 330: Principles of Animal Breeding, the same post-test from ANEQ 328 was given as a pre-test. On the pre-test, students were asked to indicate in which year and semester they completed ANEQ 328 so an assessment type and environment could be identified. Scores on the pre-test were analyzed as a measurement of retention across courses, and effects of time elapsed between courses, the type of assessment strategy used, and the physical environment in which the class was delivered were considered. Time between courses impacted retention, as students who took ANEQ 330 within two semesters of ANEQ 328 had higher scores (P < 0.05) than all other timepoints. Student retention was not different between students who took the prerequisite course online or in-person (7.65 ± 0.19 and 7.61 ± 0.23, respectively). Additionally, student retention was not impacted by whether the prerequisite course used quiz or exam-based assessment strategies (7.58 ± 0.16 and 7.89 ± 0.33, respectively). These data indicate that both assessment strategies are interchangeable when considering impacts on long-term retention; however, survey data showed that formative assessments, such as quizzes, are better received than summative assessments, as they help to ease testing anxiety, better pace student learning, and provide consistent feedback. Therefore, instructors may choose to use formative assessments to improve student perceptions of learning without impacting knowledge retention.

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.

Pulmonary hypertension is a historical issue in high elevation beef production and is increasingly occurring in moderate elevation beef finishing systems (i.e., feedlots). Pulmonary arterial pressure (PAP) is the mean pressure (mmHg) measure in the pulmonary artery and is an indicator of pulmonary hypertension. To measure PAP, a certified veterinarian threads a catheter through the jugular vein to the heart and into the pulmonary artery. A total of 3 measures are recorded, including mean pulmonary arterial pressure (mPAP), systolic pulmonary arterial pressure (sPAP), and diastolic pulmonary arterial pressure. Systolic pressure is the pressure in the pulmonary artery during the contraction of the heart, whereas diastolic pressure is the pressure in the pulmonary artery during relaxation of the heart. For cattle living in high elevations, the Beef Improvement Federation Guidelines outline the risk of an individual by accounting for the elevation of the test and range of elevations at which that animal is expected to survive based on mPAP. The objective of this study was to estimate the genetic correlations between systolic and diastolic PAP. The data consisted of 1,352 animals with a mPAP, sPAP, and dPAP measured from 2011 to 2015. The systolic pulmonary arterial pressure has a mean of 65.4 ± 15.95 mmHg. The diastolic pulmonary arterial pressure has a mean of 18.2 ± 11.22 mmHg. Data were analyzed using a multiple trait, mixed effect animal model using the statistical software package ASReml 3.0. Fixed effects in the model included sex, birth year, wean date, and yearling date. Individual animal was included as the random effect. The respective heritabilities from the model were mPAP at 0.13 ± 0.05, sPAP at 0.9 ± 0.05 and dPAP at 0.09 ± 0.05. The phenotypic correlation between systolic and diastolic PAP was 0.18 ± 0.03, and the genetic correlation was 0.46 ± 0.32. The phenotypic correlation between sPAP and mPAP was 0.49 ± 0.02, and the genetic correlation was 0.69 ± 0.21. The phenotypic correlation between dPAP and mPAP was 0.83 ± 0.01, and the genetic correlation was 0.93 ± 0.07. Previous research with sPAP and dPAP has been conducted in humans, investigating methods to predict the likelihood of a person of developing pulmonary hypertension. These results provide a foundation to focus on how sPAP and dPAP impact the mPAP and current selection tools for a PAP measure and if the additional information could be useful for selection.