Immunomodulatory feed additives might offer alternatives to anti-microbial growth
promoters in swine production. The present study was conducted to assess the effects of
b-1,3 ⁄ 1,6 glucans, i.e. of specific yeast cell wall components, on immune function and
growth performance in pigs. After weaning at 4 weeks of age, 75 piglets were allocated to 3
different groups for 4 weeks, the diet was supplemented with 0, 0.015 or 0.03% of
b-glucan, respectively. All animals were vaccinated against porcine reproductive and
respiratory syndrome (PRRS). After 4 weeks, average daily gains (ADG) of b-glucan
treated pigs were not different from the controls. Feed intake was tendentiously (p < 0.1) increased at 0.03% b-glucan, without alteration of feed efficiency. Serum haptoglobin concentrations at the end of the 4 week treatment were increased in all groups when compared to the initial levels (p < 0.001), without differences between the groups (p > 0.05). Haptoglobin levels were inversely related to ADG. Lymphocyte proliferation
indices were not different in control and treatment groups. Specific vaccination responses,
as quantified by the PRRS antibody titres occurred in all animals, but no relation with
b-glucan feeding was observed. Our results indicate marginal benefits of b-glucan
supplements for growth performance and no effect on the immune parameters tested. The
observed trend towards increased feed intake needs further elucidation.