Browsing by Author "Rathmann, Ryan J. (TTU)"
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Item Effect of exogenous melatonin on the cellular response of Holstein heifer calves during vaccination(2024) Martin, Allie E. (TTU); Machado, Vinicius S. (TTU); Rathmann, Ryan J. (TTU); Crossland, Whitney L. (TTU)Despite rigorous vaccination protocols, calf morbidity is the primary contributor to economic loss in the calf sector of the dairy industry. Melatonin has modulated immune response in other mature animal species. We hypothesized that exogenous melatonin may improve the cellular response to vaccination in dairy calves. Our objective was to evaluate the effect of exogenous melatonin on polymorphonuclear leukocyte (PMN) function in Holstein heifer calves during immunization. Sixty neonatal Holstein heifers were enrolled by birth cohort (block) and randomized to one of four treatments: control (CON), vaccination of 0.5 mg ovalbumin on days 0 and 21 (VAC), implantation of 24 mg melatonin on day 0 (MEL), or both melatonin and vaccine treatments (MVAC). Jugular blood was collected on days 0, 21, 42, and 63 to measure circulating melatonin, anti-ovalbumin immunoglobulin-G, and PMN function. Calves implanted with melatonin had greater circulating melatonin than non-implanted on day 21 (P < 0.01). Anti-ovalbumin IgG was greater for vaccinated than non-vaccinated calves (P < 0.01). Anti-ovalbumin IgG was greater for MVAC than VAC calves on day 63. Percent of cells and mean florescence intensity of cells performing oxidative burst decreased from day 0 to day 63 (P < 0.01) but were not affected by treatment (P ≥ 0.26). There was a tendency (P = 0.10) for an interaction of melatonin, vaccination, and day for the mean florescence intensity of cells performing phagocytosis where MVAC was greater than all other treatments on d 42. Exogenous melatonin may alter PMN function of calves during vaccination. Further research is needed to define the effect of melatonin on development of antigen-specific IgG during programmed vaccination protocols.Item Identification of blood-based biomarkers for detection of liver abscesses in beef × dairy heifers(2024) Wilson, Reese A. (TTU); Johnson, Bradley J. (TTU); Sarturi, Jhones O. (TTU); Crossland, Whitney L. (TTU); Hales, Kristin E. (TTU); Rathmann, Ryan J. (TTU); Bratcher, Christy L. (TTU); Theurer, Miles E.; Amachawadi, Raghavendra G.; Nagaraja, T. G.; Speidel, Scott E.; Enns, R. Mark; Thomas, Milton G.; Foraker, Blake A.; Cleveland, Matthew A.; Woerner, Dale R. (TTU)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 × 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 Logit- Boost 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 × 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.Item Influence of dietary roughage level and Megasphaera elsdenii on feedlot performance and carcass composition of thin cull beef cows fed for a lean market(2020) DeClerck, Jonathan C. (TTU); Reeves, Nathan R. (TTU); Miller, Mark F. (TTU); Johnson, Bradley J. (TTU); Ducharme, Gary A.; Rathmann, Ryan J. (TTU)One hundred forty-four cull cows (body condition score = 2.10 ± 0.61; BW = 456 ± 47 kg) were organized into a 2 × 2 factorial design (48 pens, 12 pens/treatment, and 3 cows/pen) to evaluate the effect of dietary roughage level and oral drenching of Megasphaera elsdenii NCIMB 41125 (M. elsdenii culture; Lactipro Advance; MS Biotec Inc., Wamego, KS) on performance and carcass characteristics. Cattle were finished over a 42-day realimentation period, and aggressively stepped up over a 10-day period to either a high roughage finisher (HRF; 25% roughage) or a low roughage finisher (LRF; 10% roughage). Within diet, cattle were administered no probiotic or 100 mL of M. elsdenii culture (M. elsdenii NCIMB 41125, 2 108 cfu/mL) on day 0. No diet × probiotic interactions were detected (P ≥ 0.15), suggesting that the magnitude of the response was not influenced by the concentrate level of the diet. The main effect of diet triggered several significant responses. Decreasing roughage level tended to improve average daily gain (ADG) by 9.7% (0.26 kg, P = 0.08), while decreasing dry matter intake (DMI) by 0.9 kg (P = 0.09), provoking a 19.7% enhancement of feed efficiency (0.036 units, P < 0.01). However, interim data revealed declines of performance parameters among both diets with a significant difference between treatments only documented during the final phase of the realimentation period. During the final 14 days, LRF posted a 0.68 kg increase in ADG (P = 0.05) and a 2.0 kg decrease in DMI (P = 0.01), translating to improved feed efficiency (0.054 units, P = 0.03). This suggests that increasing the caloric density of finishing diets may help offset the regression of performance typically observed following a compensatory gain. No carcass traits were impacted by either diet or M. elsdenii culture (P ≥ 0.08). Overall, oral drenching of M. elsdenii culture tended to augment ADG (0.26 kg, P = 0.08) and carcass ADG (0.20 kg, P = 0.10). Implying that M. elsdenii culture was effective at alleviating the acidosis risk prompted by the rapid step-up period employed in the trial and may help capitalize on the narrow timeline of compensatory gain in cull cow realimentation.Item Influence of megasphaera elsdenii and feeding strategies on feedlot performance, compositional growth, and carcass parameters of early weaned, beef calves(2020) DeClerck, Jonathan C. (TTU); Wade, Zain E. (TTU); Reeves, Nathan R. (TTU); Miller, Mark F. (TTU); Johnson, Brad J. (TTU); Ducharme, Gary A.; Rathmann, Ryan J. (TTU)Simmental-Angus calves [n = 135; 72 steers and 63 heifers; body weight (BW) = 212.4 kg ± 36.1] were early weaned (~5 mo) to evaluate multiple feeding regimens (conventional vs. aggressive energy diets ± Megasphaera elsdenii NCIMB 41125 (M. elsdenii culture (MEC); Lactipro Advance; MS Biotec Inc., Wamego, KS) in order to elucidate the optimal development strategy. Objectives were measured by tracking the effects of caloric density and oral drenching of growing phase performance and subsequent carcass traits. The 72-d experiment featured three groups: 1) control (CON), fed exclusively a 35% roughage diet; 2) aggressive (AGR), fed a blend of a 10% and 35% roughage diets; 3) MEC, fed the same diet as AGR and drenched with 50 mL of M. elsdenii NCIMB 41125 on day 1. A subset of calves (n = 45) was equipped with wireless rumination tags (Allflex Flex Tag; SCR Engineers, Ltd; Netanya, Israel), which logged daily rumination and general activity. Skeletal growth variables were assessed by measuring wither and hip height pretrial and post-trial. Ultrasonography provided additional resolution concerning growing phase compositional gain, which was later verified by carcass data collection. Data were analyzed as a nested analysis of variance with BW and gender serving as blocking factors. The increased caloric density of the diets administered to MEC and AGR calves resulted in greater average daily gain and gain:feed values compared with CON even during the first 21 d of diet acclimation (P ≤ 0.05). Additional fiber concentration of CON diets led to increased rumination times in 9 of the 10 wk of trial (P ≤ 0.10). No differences amongst treatments were detected for skeletal variables or ultrasound 12th rib fat. Cattle fed CON diets posted 3.4% inferior BW at the end of the growing period trial and a 3.8% reduction in hot carcass weight (HCW), reinforcing the theory that intensifying caloric intake during the growing phase does not compromise future feedlot performance. Ultrasound marbling scores for MEC-treated cattle were 19° greater than AGR treated cattle (P ≤ 0.05) at the end of the growing phase trial. Nearly the exact same advantage (22°) was observed in the cooler 5 mo later (P = 0.42). Implying MEC metabolically imprinted cattle to favor marbling development. It appears that maximizing dietary caloric density in light-weight calves does not adversely affect the growth curve, while oral dosing of MEC during the growing period may be a precursor for enhanced quality grade.Item Influence of ractopamine hydrochloride and days on feed on feedlot performance and red meat yield in thin cull beef cows targeted for a lean market(2020) DeClerck, Jonathan C. (TTU); Lucherk, Loni W. (TTU); Reeves, Nathan R. (TTU); Miller, Mark F. (TTU); Bernhard, Bryan C. (TTU); Rathmann, Ryan J. (TTU)Thin, beef, cull cows [n = 144; initial body weight (BW) = 465.8 ± 56.9 kg, initial body condition score (BCS) = 2.13 ± 0.68] were serially slaughtered to evaluate the relationship between ractopamine hydrochloride (RH) administration and days on feed (DOF) on feedlot performance and carcass cutout value in a lean cow market. Cows were organized into a 3 × 2 factorial arrangement of treatments (48 pens, 8 pens per treatment, 3 cows per pen) and blocked by BW nested within pregnancy status. Treatment pens were top-dressed 400 mg per cow per day of RH (Actogain 45; Zoetis, Parsippany, NJ) for the final 28 d prior to slaughter to cows spending 28, 42, or 56 DOF. Pen served as the experimental unit, for all calculations. No RH × DOF interactions were detected (P ≥ 0.11), indicating that despite a majority of compensatory gain occurring during the first 28 d of the trial, the magnitude of the RH response was not affected by DOF. Compared to controls, RH incited improvements in feedlot performance, but had a greater extent on carcass weight gain and efficiency. Specifically, RH improved average daily gain (ADG) by 13.7% (P = 0.04) and carcass ADG by 16.9% (P = 0.02) Cattle fed RH displayed a 15.5% improved gain to feed ratio (P = 0.02) and a 20% improved carcass gain to feed ratio (P = 0.05). Inclusion of RH in the finishing diet increased hot carcass weight by 4.5% (P = 0.05; 12.9 kg). However, supplementation of RH did not alter red meat yield (P ≥ 0.16), but provoked a 11.1% improvement in lean maturity (P < 0.01). Evaluation of the main effect of DOF provided insight into the compensatory state of beef cull cows on a high-concentrate diet. Serial slaughter offal weights presented confounding results. With additional DOF, a numerical increase in liver weights (P = 0.20) suggested that organ tissue replenishment occurred throughout the trial, and cattle experienced compensatory gain during the entire feeding phase. In contrast, lung and heart weights were not altered, while kidney tended to decrease linearly (P = 0.08) despite additional DOF. Furthermore, extending DOF generated a linear increase in dry matter intake (P < 0.01) yet a tendency for a decline in ADG (P = 0.10), reinforcing the premise that most of compensatory gain occurred during the first 28 d of the trial. If thin (BCS ≤ 4), healthy candidates can be finished, feeders can reap the benefits of an additive relationship between compensatory gain and RH.Item The influence of Megasphaera elsdenii on rumen morphometrics of cull cows immediately stepped up to a high-energy finishing diet(2020) DeClerck, Jonathan C. (TTU); Reeves, Nathan R. (TTU); Miller, Mark F. (TTU); Johnson, Bradley J. (TTU); Ducharme, Gary A.; Rathmann, Ryan J. (TTU)Forty-five beef cull cows [body weight (BW) = 503 ± 58 kg; body condition score (BCS) = 2.1 ± 0.6] were randomized into two treatments to compare the effects of oral drenching of no probiotic vs. 100 mL of Megasphaera elsdenii NCIMB 41125 (M. elsdenii culture; Lactipro Advance; 2 × 108 cfu/mL; MS Biotec, Inc., Wamego, KS) on the realimentation of cull cows. The study featured a rapid 0-d step-up of concentrate-naïve cull cows to a 90% concentrate diet (1.43 Mcal/kg of NEg). The cows were finished for 35 d and were fitted with a wireless rumination tag (Allflex Flex Tag; SCR Engineers, Ltd, Netanya, Israel), which tracked head movement to record eating and chewing activity. Rumen morphometrics was recorded on the harvest floor, with each carcass assigned a rumenitis score, and a fragment of the cranial sac removed for further papillae analysis. An additional 23, thin, non-fed cull cows were harvested at the same abattoir to compare the effects of concentrate realimentation on ruminal morphometrics. Megasphaera elsdenii culture-drenched cattle registered a 13.3% increase in rumination time (39.27 min/d, P = 0.03) during the first week of the trial compared to controls. A numerical rumination advantage for M. elsdenii culture-administered cattle was observed during week 2 of trial (P = 0.17), with no differences between treatments from weeks 3 to 5 (P ≥ 0.40). Subjective rumenitis evaluations approached a tendency (P = 0.12), with non-M. elsdenii culture-drenched concentrate-fed cattle logging twice the score of their day 0 cohorts (2.52 vs. 1.17) suggesting considerable lactic insults occurred to the ruminal epithelium in the short 35-d trial. Despite the short feeding duration, concentrate realimentation prompted a significant improvement in mean papillae area (P < 0.01). Among concentrate-fed treatments, M. elsdenii culture-drenched cattle posted superior absorptive surface area (P = 0.01) and a greater ratio of papillae area of absorptive surface area (P = 0.05), suggesting that M. elsdenii culture is favorably altering the ecology of the rumen and promoting papillae growth perhaps by mitigating lactate-driven pH drops. In conclusion, M. elsdenii culture application in a 0-d step-up protocol to finishing diets can help mitigate the effects of ruminal acidosis.