Influence of dietary ß-glucan on growth performance, lymphocyte proliferation, specific immune response and haptoglobin plasma concentrations in pigs

Immunomodulatory feed additives might offer alternatives to anti-microbial growth promoters in swine production. The present study was conducted to assess the effects of beta-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 beta-glucan, respectively. All animals were vaccinated against porcine reproductive and respiratory syndrome (PRRS). After 4 weeks, average daily gains (ADG) of beta-glucan treated pigs were not different from the controls. Feed intake was tendentiously (p<0.1) increased at 0.03% beta-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 beta-glucan feeding was observed. Our results indicate marginal benefits of beta-glucan supplements for growth performance and no effect on the immune parameters tested. The observed trend towards increased feed intake needs further elucidation.