Dietary supplementation with phosphorylated mannans improves growth response and modulates immune function of weanling pigs.

Phosphorylated mannans derived from the yeast cell wall of Saccharomyces cerevisiae may beneficially modulate immune function in the weanling pig, possibly providing an alternative to the use of dietary growth-promoting antibiotics. Therefore, in this study, 32 pigs averaging 19 d of age and 5.7 +/- 0.2 kg initial BW were randomly assigned to 16 pens in an environmentally controlled nursery to determine the effects of dietary supplementation with phosphorylated mannans on growth and immune function. Average daily gain and G:F ratio increased (P < 0.05) when pigs were fed diets supplemented with mannans from d 0 to 14 after weaning and in the overall experiment. Percentage of neutrophils was lower (P < 0.08) and percentage of lymphocytes was higher (P < 0.05) in blood from pigs fed mannans than when pigs were fed the basal diet. Lamina propria macrophages isolated from pigs fed diets containing mannans phagocytosed a greater (P < 0.05) number of sheep red blood cells (2.63 +/- 0.11) than did lamina propria macrophages isolated from pigs fed the basal diet (2.31 +/- 0.11). On d 19 after weaning, pigs fed diets supplemented with mannans tended to have a greater (P < 0.10) percentage of CD14+ lamina propria leukocytes than did pigs fed the basal diet. On d 21 following weaning, the percentage of CD14+MHCII+ leukocytes isolated from lamina propria tissue tended (P < 0.10) to be lower when pigs were fed mannans than when pigs were fed the basal diet. Pigs fed diets containing mannans had a lower (P < 0.05) ratio of CD3+CD4+:CD3+CD8+ T lymphocytes isolated from jejunal lamina propria tissue only on d 21 after weaning compared with pigs fed the basal diet. Supplementation of mannans in the diets of weanling pigs improved gain and efficiency, and intermittently affected selected components of the young pigs' immune function both systemically and enterically.