Submitted to: Joint Abstracts of the American Dairy Science and Society of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 6/21/2002
Publication Date: 7/21/2002
Citation: CHIRASE, N.K., PURDY, C.W., LOAN, R.W., BRIGGS, R., DUFF, G., AVAMPATO, J.M. EFFECT OF ENVIRONMENTAL STRESSORS AND PROPHYLACTIC ANTIBIOTIC ON SERUM ANTIOXIDANT CONCENTRATIONS AND INCIDENCE OF BOVINE RESPIRATORY DISEASE OF FEEDER STEERS. JOINT ABSTRACTS OF THE AMERICAN DAIRY SCIENCE AND SOCIETY OF ANIMAL SCIENCE. 2002.
Technical Abstract: Feeder cattle often encounter many environmental stressors and pathogens associated with the marketing process and translocation to the feedyard. Exposure to stressors could compromise the antioxidant and immune defense systems, resulting in morbidity and mortality of these calves. An experiment was conducted to determine the effects of prophylactic antibiotic treatment and posttransit commingling of feeder calves obtained from two sources (New Mexico and Tennessee), to measure serum antioxidants (retinol, - and -tocopherol) concentrations and assess the rate of bovine respiratory disease (BRD). One hundred twenty one (121) crossbred feeder steers (average BW 190 kg) were purchased in TN and eighty four (84) crossbred steers of similar size and age were purchased in NM and calves were vaccinated, weighed, and blood obtained via jugular venipuncture. The calves were randomly allotted into 3 commingling treatment groups (3 replicates per group): 1) New Mexico (NM), 2) Tennessee (TN) and 3) Commingled (Mixed). One-half of the steers in each treatment group received pretransit prophylactic Nuflor (1 mL/15 kg of BW, s.c.). Upon arrival at the research feedyard in NM, all steers were managed similar to commercial feedyard management protocols. Steers were also scored daily for BRD and blood was obtained via jugular venipuncture upon arrival (d 0), 7, and 28 d posttransit. The data were subjected to the analysis of variance using the General Linear Models procedure of SAS. There was no antibiotic treatment by commingling interaction (P >0.05) for serum free retinol, - and -tocopherol concentrations and incidence of BRD. Regardless of commingled group, transit stress decreased (P<0.01) serum free retinol and -tocopherol concentrations of feeder steers on d 7 and 28 posttransit. By d-28, serum -tocopherol concentrations decreased from 6.3 ug/mL to 1.65 ug/mL, far below the critical levels for cattle. Prophylactic antibiotic treatment did sustain (P>0.05) serum antioxidant concentrations of steers. Although, -tocopherol also decreased regardless of commingled or antibiotic treatment, they increased three-fold by d-28. These results suggest that transit stress reduced serum antioxidant concentrations to critical levels at the feedyard and supplementation may be required to restore them.