Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2001
Publication Date: 7/28/2001
Technical Abstract: Feeder cattle often encounter many environmental stressors such as dust. An experiment was conducted to determine the effects of short term (28 d) feeding of vitamins A (Vit A) and E (Vit E) on the performance of beef steers exposed to feedyard dust. Thirty six (36) crossbred feeder steers (average BW 260 kg) were allowed 28 d to recovered from transit stress and sickness and assigned randomly into four groups of 9 steers. Steers were housed in pens equipped with calan gate feeders for individual feed intake measurement. The diets consisted of 1) Control (Vit A=20,240 IU/kg DM; Vit E=300 IU/kg DM) and 2) Antioxidants (Vit A=60,700 IU/kg DM; Vit E=760 IU/kg DM). Diets and dust treatments were arranged in a 2 X 2 factorial design. Steers were trained to feed from calan gates, adapted to diets for 14 d and assigned the following dust treatments: 1) Control (not exposed to tent or dust) and 2) Dust (exposed to dust suspension inside tent). Simulated dust storm was produced in an enclosed canvas tent. There were six consecutive daily dust events each lasting 4 h. Steers were weighed every 8 d. The data were subjected to the analysis of variance using the General Linear Models procedure of SAS. An interaction occurred between the dust and antioxidants for feed intake and ADG on d 8 and 17. Steers fed the control diet and not exposed to dust consumed less (P<0.08) feed and gained less (P<0.05) weight than all other groups. Although not significant (P>0.05), the feed to gain ratio for steers not exposed to dust was 36% greater than those exposed to dust (8.0 vs 5.9). The feed to gain ratios of steers fed the control and antioxidant diets were not different (P>0.05). There results suggest that short term feeding of dietary antioxidants during the receiving period to reduce oxidative stress required additional investigation.