Feeding concentrate pellets enriched by natural vitamin E keeps the plasma vitamin E above the critical level in calves post-weaning

Calves are often lower in plasma vitamin E concentration than the recommended level (3 mg/L) after weaning, which seems to be a challenge for a good immune response. Two studies were performed investigating if a natural vitamin E supplement in the starter concentrate could increase the plasma vitamin E concentration of calves around weaning. Each study was conducted at three Danish farms producing rosé veal calves. Studies 1 and 2 included a total of 318 and 421 calves, respectively, from at least 3 weeks pre-weaning until at least 2 weeks after weaning. In study 1, the standard concentrate used at the farm was fed either unsupplemented (CON) or supplemented with 490 ± 24 (Means ± SD) mg of RRR-α-tocopherol (RRR-α-T)/kg of diet by mixing a vitamin E-enriched pellet with the standard concentrate pellet in the ratio of 1:10. In study 2, calves were fed either a common concentrate pellet with 48 ± 8 mg/kg all-rac-α-tocopheryl acetate (CON) or a common concentrate pellet with 245 ± 30 (Means ± SD) mg/kg RRR-α-T with a similar dietary composition. Performance data were analyzed for each farm per study; however, plasma parameters were analyzed across the three farms in each study. In both studies, the plasma vitamin E concentration was analyzed at start (approximately 3 weeks pre-weaning), at weaning, and 2 to 3 weeks after weaning; however, the concentrate intake and thus vitamin E intake was not recorded. In both studies, the overall average daily gain (ADG) from start to weaning was not affected by vitamin E supplementation. In study 1, the plasma vitamin E concentration at weaning in RRR-α-T calves (5.09 ± 0.58, LSmeans ± SEM) was higher (P = 0.01) than in CON calves (3.35 ± 0.55, mg/L). Similarly, the plasma vitamin E concentration post-weaning in RRR-α-T calves (3.71 ± 0.27) was markedly higher (P < 0.001) than in CON calves (1.27 ± 0.29 mg/L). In study 2, the plasma vitamin E concentration at weaning in RRR-α-T calves (4.9 ± 0.4) was higher (P = 0.003) than in CON calves (3.6 ± 0.4 mg/L). Similarly, post-weaning, the plasma vitamin E concentration in RRR-α-T calves (4.1 ± 0.5) was higher (P = 0.004) than in CON calves (1.6 ± 0.5 mg/L). At post-weaning, serum amyloid A (SAA; P = 0.02) and cortisol concentration (P = 0.04) were lower in RRR-α-T calves than in CON calves. In conclusion, regardless of the approach used for preparing the concentrate pellets, supplementation with a high amount of natural vitamin E (RRR-α-T) significantly increased the plasma vitamin E concentration above 3 mg/L at weaning and post-weaning and decreased the plasma cortisol and SAA concentration in calves post-weaning.