Effects of supplemental vitamin E on performance, health, and humoral immune response of beef cattle.

Three experiments were conducted to examine the effect of dietary vitamin E on receiving performance and health and on finishing performance of beef cattle. One hundred twenty beef steers (Exp. 1; initial BW = 173 kg) and 200 beef heifers (Exp. 2; initial BW = 204 kg) were assigned randomly to one of three treatment diets formulated to supply 285, 570, or 1,140 IU/animal daily of supplemental vitamin E during the receiving period. Average daily gain, gain:feed, and DMI were calculated every 14 d, with pen as the experimental unit. Morbidity and retreatment data were analyzed using a nonparametric procedure. After the receiving period, cattle were assigned to a grazing period followed by a finishing program and fed until slaughter. In Exp. 3, 17 beef steers were used to evaluate effects of the same three vitamin E levels on humoral immune response to an ovalbumin vaccine given on d 0 and 14. Jugular blood samples were collected on d 0, 7, 14, and 21. In Exp. 1, vitamin E did not affect (P > 0.10) ADG, DMI, or gain:feed for d 0 to 14, 14 to 28, or 0 to 28. No effects were noted for percentage of morbidity; however, cattle receiving 1,140 IU/d had a numerically (P = 0.15) lower incidence of retreatment. During the 91-d finishing phase, a quadratic effect (P < 0.08) was noted for DMI, ADG, backfat thickness, longissimus muscle area, and yield grade. In Exp. 2, a tendency for a linear (P = 0.10) increase in ADG was observed for the first 14 d of receiving; however, ADG decreased linearly (P = 0.06) with vitamin E concentration thereafter. For the 28-d period, ADG and DMI did not differ among treatments, but gain:feed decreased linearly (P < 0.05) for d 14 to 28 and for d 0 to 28. No effects on percentage morbidity were noted in Exp. 2, and no differences were detected for ADG, gain:feed, or DMI for the 98-d finishing period. There was a linear increase in yield grade (P < 0.05) and a linear (P < 0.08) decrease in longissimus muscle area with increasing vitamin E. Heifers receiving 570 IU of vitamin E during the receiving period tended to have a higher (P < 0.09) dressing percentage at slaughter. In Exp. 3, no significant differences were detected in serum IgG titers to ovalbumin on d 0, 7 or 14; however, on d 21, a linear increase (P = 0.07) in serum IgG titers was noted with supplemental vitamin E. Supplemental vitamin E had limited effects on performance; however, effects on humoral immune response and recovery from respiratory disease warrant further research.