Three trials using 156 Yorkshire x Hampshire x Duroc crossbred pigs (avg initial wt, 7.9 kg) were conducted to evaluate the effects of two supplemental dietary vitamin E (11 vs 220 IU/kg of diet) and weaning age (21, 28 or 35 d) on performance and immunocompetence of pigs. Supplemental vitamin E (220 IU/kg of diet) increased (P less than .01) serum concentrations of vitamin E for all weaning ages compared with pigs fed 11 IU of vitamin E/kg of diet. However, supplemental vitamin E did not affect performance, serum cortisol concentration or the primary and secondary antibody response to sheep red blood cells. As weaning age increased, weekly ADG and avg daily feed intake increased linearly (P less than .01). Cortisol levels decreased during the 1st wk following weaning and then increased linearly (P less than .01) over time; pigs weaned at 35 d of age had higher (P less than .01) cortisol values initially and over time than pigs weaned at 21 and 28 d. Pigs weaned at 35 d had a higher (P less than .01) primary response to sheep red blood cells than pigs weaned at 21 and 28 d of age, but this effect was not observed for the secondary response. There were no interactive effects (P greater than .10) of dietary vitamin E level and weaning age. In summary, the highest level of supplemental vitamin E increased serum vitamin E concentration but did not affect performance, cortisol levels or one test of the immune response, antibody titers to red blood cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Three trials using 80 Yorkshire x Hampshire x Duroc crossbred pigs (avg initial wt, 6.9 kg) were conducted to determine the effects of four dietary vitamin E levels (11, 110, 220 and 550 IU/kg of feed) on the humoral and cell-mediated immune response and performance of 4-wk-old weanling pigs housed at two nursery temperatures (19 or 30 degrees C). Interactive effects of temperature and vitamin E were not observed for any measurements. Serum and liver vitamin E levels increased linearly with increasing level of dietary vitamin E, but performance, cortisol, antibody levels and mitogen-induced stimulation indices were not affected by supplemental levels of vitamin E. Average daily gain and feed intake were higher (P less than .01) for pigs housed at 19 degrees C than for pigs housed at 30 degrees C, but feed:gain ratios, mitogen stimulation index of white blood cells, plasma cortisol levels and antibody titers were not altered. Although supplemental vitamin E above the NRC estimated requirement increased serum and liver vitamin E concentrations, no differences were observed in humoral and cell-mediated immune response, cortisol levels or performance for weanling pigs housed at either 19 or 30 degrees C temperatures.

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