Influence of vitamin A supplementation in milk on growth, health, concentrations of vitamins in plasma, and immune parameters of calves.

Seventy-seven Holstein calves were used to determine effects of vitamin A supplementation (0, 15,000, or 30,000 IU/d) of milk fed to calves through 6 wk of age. Effects of gender of calves and parity of dams also were considered. Supplementation with vitamin A did not affect retinol concentrations in plasma; however, calves fed milk containing supplemental vitamin A had decreased alpha-tocopherol concentrations in plasma at 6 wk compared with the concentrations in plasma of calves that were fed milk without supplemental vitamin A. Growth, serum protein, serum immunoglobulin (Ig) M and IgG, leukocyte proportions, and weekly fecal scores were not affected by vitamin A supplementation. Calves that scoured were fed milk supplemented with an additional 0 or 30,000 IU/d of vitamin A. Supplementation with an additional 30,000 IU/d when calves were scouring increased treatment days. Female calves had lower body measurements (weight, length, and height) at birth and greater fecal scores for wk 2 and 3 than did male calves. Gender did not affect serum protein, IgM, or IgG; however, female calves had higher percentages of monocytes and lower percentages of T cells than did male calves. At 6 wk, female calves also had higher percentages of B cells than did male calves. These data indicate that ratios of vitamins A and E should be considered in dietary formulations for calves. Also, additional vitamin A provided by some scour treatments could be detrimental to calves that are already receive vitamin A supplementation.