West Texas A&M University

Bovine respiratory disease (BRD) remains the leading cause of morbidity and economic loss in North American cattle production. Cattle at high risk of BRD are often managed through antimicrobial metaphylaxis, although there are growing concerns regarding the use of antimicrobial drugs in food animals. To better understand host immunological responses to BRD and the effects of metaphylaxis, this study evaluated whole-blood gene expression patterns in high-risk stocker heifers using RNA sequencing (RNA-Seq). Eighty-four commercial heifers were randomly assigned to receive metaphylaxis with tulathromycin (META) or no metaphylaxis (NO META) upon arrival. Cattle were monitored over a 70-day period for clinical BRD, with whole blood collected from a subset of 60 heifers across multiple timepoints in both cattle that developed (TREAT) or failed to develop BRD (HEALTHY) for RNA-Seq. Principal component and differential gene expression analyses (FDR ≤ 0.05) were conducted to explore transcriptomic differences associated with BRD diagnosis over time, metaphylactic treatment, and disease severity. Minimal differences in the transcriptome were observed between META and NO META cattle at the time of BRD diagnosis, while comparisons between HEALTHY and TREAT cattle at onset of clinical disease revealed greater than 2000 differentially expressed genes (DEGs), with significant functional enrichment of immune-related pathways, including cytokine signaling, lymphocyte activation, and inflammatory responses. Notably, five genes (IL1R2, HP, S100A9, TLR4, and ALOX15) were consistently up- or downregulated in BRD cases, regardless of study group allocation. These observations align with previous studies, which support their candidacy as useful biomarkers for BRD detection. Despite the significant changes observed at the onset of clinical BRD, no differences were identified among these animals at the start of the study. This inability to predict future disease development or severity may have been affected by the low morbidity rate observed in this cohort. Expression of genes coding for heat shock proteins at subsequent treatments suggested that these may be useful markers of disease persistence or severity. These findings suggest that while metaphylaxis reduces BRD incidence, host transcriptomic profiles at disease onset offer improved insight into BRD pathophysiology.

Introduction The present study evaluated oxidative stress indicators in plasma of beef calves supplemented with a rumen-protected methionine (L0 = receiving ration top-dressed with a ground corn carrier, L1 = receiving ration top-dressed with 10.0 g of rumen-protected methionine supplement in a ground corn carrier, L2 = receiving ration top-dressed with 20.0 g of rumen-protected methionine supplement in a ground corn carrier) and administered lipopolysaccharide (LPS). An additional objective evaluated the effect of LPS on plasma metabolites. Methods Following an initial feeding period (40 d), steers (n = 32; 379 kg ± 30.7) were intravenously administered LPS (0.25 μg/kg BW). Blood was collected via jugular catheter at -2, 0, 2, 4, 6, 8, 10, 12, 18, 24, 36, and 48 h relative to LPS administration (0 h). Plasma was analyzed for amino acid (AA) concentrations, ferric-reducing antioxidant power (FRAP), thiobarbituric reactive substances (TBARS), and reactive oxygen species (ROS). Metabolomic analysis occurred for control cattle at -2, 2, and 8 h. Results and discussion Plasma AA asparginine and methionine were increased with supplementation ( P < 0.01). The greatest FRAP values were observed at -2, 0, 2, 36, and 48 h ( P < 0.001). At 6 and 8 h, FRAP decreased to their lowest values ( P < 0.001). Amount of TBARS increased at 2 h but declined at 4h ( P < 0.001). A treatment × time interaction occurred for ROS ( P < 0.001). At 2 h, ROS was greatest in L0 cattle, least in L2, and intermediate in L1 but declined at 4 h in all treatments ( P < 0.001). Values peaked at 6 h for L1 and L2 cattle, followed by a decline at 8 h ( P < 0.001). Values for L0 cattle were similar from 4 to 6 h ( P = 0.371) but increased at 8 h ( P < 0.001). Finally, L0 plasma metabolites present at -2 h segregated from those present at 2 and 8 h ( P < 0.05). Differences were primarily driven by taurocholic acid, LysoPE, butyric acid, acitretin, and tauromuricholic acid. These data demonstrate that LPS may alter oxidative stress indicators and plasma metabolites. However, methionine supplementation may mitigate oxidative stress.

An optical fiber chemical sensor using a molecularly imprinted chitosan membrane coated on the surface of a bent optical fiber probe was developed for selectively analyzing 4-nitrophenol (4-NP) in water samples. When the sensor probe is exposed to a water sample, the chitosan MIP membrane extracts/concentrates 4-NP from the water sample into the membrane. The 4-NP extracted into the membrane was detected by passing a light beam through the optical fiber and the interaction of the 4-NP in the membrane with an evanescent wave of light guided through the optical fiber was detected as a sensing signal. This sensor detects the intrinsic optical absorption signal of 4-NP itself as a sensing signal. No chemical reagent was needed in analyzing this compound in a sample. The sensor is reversible, can be used for continuous monitoring of 4-NP in a sample, and has a quick response with a response time of 5 min. The sensor has high sensitivity and selectivity because the MIP membrane selectively concentrates 4-NP by 1.4 × 104 times into the membrane from a sample solution, but blocks out interference species, including its isomers and derivatives, from entering the membrane. The sensor achieved a detection limit of 2.5 ng/mL (0.018 µM), which is lower than most reported analytical techniques for analyzing this compound in water samples. This sensor can discriminate 4-NP from its isomers and derivatives, such as 2-NP, 3-NP, 2-Cl-4-NP, and 2,4-di-NP, with a selectivity factor ranging from 104 to 1922. This is the first reported case of an MIP-based optical fiber chemical sensor with the capability of discriminating an organic compound from its closely related positional isomers, which demonstrates the high selectivity nature of the MIP-based optical fiber chemical sensor technique. The sensor has been used for analyzing 4-NP in a standard addition sample. The obtained recovery rate ranged from 93% to 101%, demonstrating the application potential of this sensor in water quality analysis.

This study examined the effect of cultural immersion experiences during study abroad programs on students’ professional career development skills. A survey was conducted among 78 participants from a Texan university, exploring the relationship between various aspects of cultural immersion and career skill development. Results show that confidence in career pre-immersion and incorporating cultural experiences into professional networking positively affect skill acquisition. However, the number of immersion experiences and belief in their career impact from their experience did not significantly predict outcomes. These findings highlight the value of cultural immersion in enhancing students’ global competency and career readiness in college students.

Abstract The objectives of this study were to: (1) determine the magnitude of circulating cortisol increase following administration of adrenocorticotropic hormone (ACTH; 100 IU) every 12 hours for 7 days; (2) assess how soon after the beginning of ACTH treatment an increase in hair cortisol can be detected; and (3) evaluate the immune response to ACTH treatment. Nonpregnant, nonlactating Holstein cows were assigned to one of two treatment groups: Control (n=12), receiving 2 mL of saline intramuscularly every 12 hours from day 0 to 6, or ACTH (n=12), receiving 100 IU ACTH (2 mL) intramuscularly every 12 hours from day 0 to 6. Blood samples were collected twice daily from days 0 to 7, once daily from days 8 to 14, and on days 21, 28, 35, 42, and 49. Additionally, intensive blood sampling every 2 hours was conducted on days 0, 3, and 6 to characterize cortisol concentration profiles. Weekly assessments included leukocyte cell counts, serum haptoglobin concentrations, neutrophil phagocytosis capacity, oxidative burst, and L-selectin (CD62L) expression. Tail-switch hair samples were collected weekly to measure hair cortisol concentrations. Cortisol levels were analyzed by ELISA, leukocyte counts by a hematology analyzer, neutrophil function and CD62L expression by flow cytometry, and haptoglobin levels by a colorimetric method. Data were analyzed using ANOVA with a repeated measures model. ACTH treatment significantly increased (P < 0.01) circulating cortisol concentrations on days 0 (13.8 ±2.1 vs. 1.8 ±0.3 ng/mL), 3 (22.0 ±2.0 vs. 1.6 ±0.1 ng/mL), and 6 (15.5 ±1.5 vs. 1.4 ±0.1 ng/mL) compared to the control. Hair cortisol concentrations increased (P < 0.01) by day 14 (24.0 ±1.1 vs. 6.7 ±0.9 pg/mg) and day 21 (11.5 ±5.3 vs. 5.3 ±0.8 pg/mg) following ACTH treatment but showed no differences (P > 0.20) on days 28, 35, 42, or 49. Total circulating leukocyte counts increased on day 7 (P < 0.01), primarily driven by neutrophilia (5.4 ±0.2 vs. 1.7 ±0.2 million cells/mL; P < 0.01). Lymphocyte counts tended to decrease (P = 0.10) from days 7 to 28 post-treatment. Neutrophil CD62L expression decreased on day 7 (10.0 ±0.08 vs. 10.6 ±0.09; P < 0.01), while lymphocyte CD62L expression increased (P < 0.01) on days 7 (8.4 ±0.1 vs. 8.1 ±0.1) and 14 (8.6 ±0.1 vs. 8.1 ±0.1). No significant differences were observed in neutrophil phagocytic capacity (P = 0.83) or oxidative burst (P = 0.32). Serum haptoglobin concentrations were increased (P = 0.05) only on day 7 (0.60 ±0.06 vs. 0.44 ±0.05). In conclusion, ACTH treatment effectively elevates cortisol concentrations, induces immune alterations, and leads to a detectable increase in tail-hair cortisol 14 days after the initial rise in circulating cortisol.

Abstract The goal was to evaluate the effect of daily low doses of hCG starting on D13 of the estrous cycle in the luteal and follicular dynamic of bos indicus Nelore beef heifers (n=31). Heifers were induced to ovulate using estradiol base synchronization protocol (estradiol benzoate [2mg] and a 0.5g intravaginal P4 insert [D-10]; insert was removed, followed by eCG [200IU], estradiol cypionate [0.5 mg], and cloprostenol sodium [0.5 mg] treatments [D-2]. On day zero (D0), all heifers received buserelin (0.08mg) but were not inseminated. Ovarian ultrasound was performed on D5 to confirm ovulation by checking the presence of at least one corpus luteum (CL) with a dominant follicle (≥ 8mm in diameter). On D13, heifers were randomized to either receive daily low doses of hCG (100 IU) until D23 (hCG; n=15) or 1mL of saline (Control; n=16). From D13 to D25, blood samples were collected, and ovarian ultrasounds were performed to track follicular dynamics and CL blood perfusion using the color Doppler. Functional luteolysis was defined as the first day with P4 < 1ng/mL, and structural luteolysis was considered the first day CL had less than 25% of the total area with blood perfusion. The largest follicle on D13 was assumed to be the dominant follicle of the second follicular wave and was similar (P=0.53) between hCG (8.4 ±0.4) and Control (8.8 ±0.5). There was an effect of circulating progesterone for TRT (P=0.03) and Day (< 0.01) but no interaction of Trt*Day (P = 0.18). On D15, specifically, there was a greater CL volume (cm3; P=0.03) for hCG (9.3 ±0.8) compared with Control (6.9 ±0.7), while there was a tendency for greater circulating P4 for hCG (3.0 ±0.3) compared with Control (2.3 ±0.2), and similar (P=0.61) CL blood perfusion (hCG 69% ±5% vs. Control 65% ±6%). The dominant follicle on D13 underwent atresia followed by a new follicular wave emergence in all heifers in the Control group, while in 53.3% (8/15) of hCG-treated heifers, the dominant follicle of the second follicular wave kept growing until ovulation (two wave patterns [hCG_2wave]). Day of functional and structural luteolysis was similar (P=0.98 and P=0.41) among groups (Control [17.6 ±0.24 and 18.5 ±0.5], hCG_3waves [17.6 ±0.36 and 18 ±0.5], and hCG _2waves [17.6 ±0.3 and 19.3 ±0.6]. The size of the largest follicle at structural luteolysis and at ovulation was greater (P < 0.01) for hCG_2waves [17.4 ±1.2 and 19.1 ±1.4], intermediary for hCG_3waves (13.4 ±1.1 and 13.8 ±1.4), and smaller(Control [9.1 ±0.5 and 11.5 ±0.4]. Day of ovulation was similar among groups (Control 20.2 ±0.6; hCG_2waves 18.7 ±1.0; and hCG_3waves 20.7 ±0.7). Daily low doses of hCG change the follicular dynamic of bos indicus beef cattle but do not affect time to luteolysis.

Abstract The feedlot industry is an evolving system that continues to innovate and adapt based on market supply and demand. In recent years, the shift in favor of carcass-based marketing has led to increased days on feed in an effort to increase hot carcass weight, improve quality grade distribution, and realize greater economic returns. In addition, consolidation of cow herds, rising environmental pressures, and an increase in the proportion of beef × dairy crossbreds on feed has stimulated cattle feeders to explore placement of lighter weight cattle, further increasing days on feed and subsequently the risk for morbidity and mortality from respiratory and metabolic health challenges. In these scenarios, the diet and management strategies used during both the receiving period and immediately before harvest may be critically important to maximize health, performance, and profitability. During the marketing process cattle are exposed to a series of stressors and novel pathogens which can induce immunosuppression and increase susceptibility to bovine respiratory disease. After arrival, cattle are exposed to additional stressors such as processing and provision of novel feedstuffs, and typically exhibit low DMI for the first 7 to 14 d of the receiving period. Most feedlots supply newly received cattle with a diet containing a high proportion of roughage, which is paradoxical, as these animals are likely in a negative energy balance from lack of feed and water during transport and marketing, low DMI following arrival, and increased nutrient requirements to support immune and inflammatory processes. To offset these challenges, researchers have explored feeding high concentrate diets at arrival to increase dietary energy intake. Both protein concentration and degradability in receiving diets also warrant further investigation. Modifying the timing and duration of the transition from the receiving to the finishing diet and use of program or limit-feeding regimens are also alternative management strategies that can be used to influence performance and growth composition of lighter weight cattle. In addition to the receiving period, the end of the finishing period immediately before harvest represents a crucial time where mortalities are most economically impactful, feed efficiency declines, and management strategies such as terminal sorting and use of beta-adrenergic agonists may influence consumption patterns and composition of gain. Modifying the fiber concentration during the later portion of the finishing period and protein concentration during beta-agonist administration have been explored to improve digestive health, performance, and carcass outcomes. Therefore, the objective of the current symposia is to summarize the performance, health, and economic implications of dietary nutrient density and targeted management strategies that can be used at both arrival and the end of the finishing period in feedlot cattle.

Abstract Finished slaughter cattle increase in size by approximately 2.5 kilograms of additional carcass weight annually. Additionally, as cattle weights have increased, the frequency of late term mortality has increased concomitantly. Proportional size of the lungs and heart may affect risk of cardiovascular stress, and thus the ability of an animal to live and thrive. Our objective was to quantify the association of body mass and organ mass in cattle. Cattle (n = 2,030) were harvested in Canyon, TX, Amarillo, TX, Lubbock, TX, and Kuna, ID. Breeds of cattle varied; cattle included finished steers and heifers (n = 654), cull cows and bulls (n = 1,015), steer calves (n = 157), and fetuses (n = 204). Body mass (kg) was recorded immediately before or after immobilization. Fetal weights were recorded after evisceration of the dam and removal of amniotic sac. After evisceration, heart, lungs, and liver were separated and weighed. Data were subjected to regression analyses and used to identify the association between calculated empty body mass and mass of each organ (heart - HP; lung - LuP; liver - LiP) expressed as percentage of body mass. Body mass range varied (0.11 kg to 1,080 kg) due to the wide variation in life stages. Variability in percentage of organ mass for heart was moderately associated with body mass (Adj R² = 0.49; P < 0.01), conversely, lung (Adj R² = 0.88; P <0.01) and liver (Adj R² = 0.64; P < 0.01) mass were strongly associated. As body mass increased, percentage of organ mass decreased at an exponential (heart) or logarithmic (lung and liver) decreasing rate. The rate of change for HP was best estimated by the equation: HP = 0.70491e-0.00089x. The rate of change for LuP was estimated as LuP = -0.54180ln(calculated EBW, kg) + 4.08306. Moreover, the rate of change for LiP was estimated by the equation LiP = -0.43960ln (calculated EBW, kg) + 4.40514. Further analysis distinguished the cull and finished cattle populations. Finished cattle had lower proportions of heart (cull µ = 0.48%, fed µ = 0.40%, P < 0.01), lung (cull µ = 0.78%, fed µ = 0.52%; P < 0. 01), and liver (cull µ = 1.85%, fed µ = 1.31%; P < 0. 01) compared to cull cattle. These results suggest organ mass as a percentage of live bovine body mass decreases notably as cattle reach maturity, particularly for finished cattle. Specific to the cardiovascular system, proportional lung mass declined at a rate 3-fold faster than the heart. This data may provide insight into the stress placed on organs as cattle approach maturity.