Management of Feedlot Cattle Under Stressful Conditions
Abstract
Four experiments were conducted to evaluate the (1) effects of an immunomodulatory feed ingredient (Omnigen-AF®) on body temperature, physiological and productive responses in heat-stressed finishing cattle, (2) effects of magnesium oxide supplement on ruminal, physiological, and productive parameters of finishing cattle consuming a corn-based diet, (3) effects of a synbiotic product, (i.e., a combination of yeast-derived product (prebiotic) and Bacillus subtilis (probiotic)), to replace or fed in conjunction with traditional feed-grade antimicrobials on performance, physiological and health parameters of receiving cattle during a 45-day feedlot receiving period, and (4) evaluate the impacts of administering a bovine appeasing substance at feedlot entry on respiratory disease incidence, physiological responses, feed intake, feed efficiency and body weight gain of feedlot cattle. In experiment 1, a treatment x day interaction (P < 0.01) was noted for vaginal temperature where animals consuming Omnigen-AF comparing with control had reduced vaginal temperature, which resulted in reduced (P < 0.04) mRNA expression of HSP70 and HSP72 towards the end of the study. In experiment 2, magnesium oxide supplementation linearly increased (P = 0.03) ruminal pH and linearly reduced (P < 0.01) hair concentration of cortisol at the end of the study (treatment x day; P = 0.02). In experiment 3, a reduced (P < 0.03) proportion of steers consuming the synbiotic supplement required a second antimicrobial treatment upon bovine respiratory disease diagnosis. Morbidity and mortality rates were also reduced (P = 0.02) for animals consuming the synbiotic supplement. In experiment 4, body weight gain and feed efficiency were improved (P < 0.05) for animals that received the appeasing substance comparing with control cohorts. Administering appeasing substance upon feedlot arrival also reduced (P = 0.05) plasma cortisol concentration and reduced the amount of antimicrobial treatments to heal upon respiratory disease incidence comparing with steers from control group. Collectively, these studies investigated and confirmed novel nutritional and management strategies to enhance the performance of feedlot cattle experiencing stressful conditions, mainly by improving their physiological and health conditions.
Citation
Colombo, Eduardo Antonio (2023). Management of Feedlot Cattle Under Stressful Conditions. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /199782.