Influence of β-glucan on nonspecific immunity and growth performance in weanling pigs

Three experiments, using 344 pigs, were conducted to evaluate the influence of β-glucan (MacroGard™-S) on neutrophil and macrophage function, resistance to Streptococcus suis challenge, and growth performance in weanling pigs. β-glucan, when fed at inclusion rates of .05 and .1 %, did not influence neutrophil or macrophage function or increase overall growth performance. Similarly, .025% β-glucan did not alter neutrophil or macrophage bactericidal activity or production of superoxide anion. However, diets containing.025% β-glucan increased average daily gain, average daily feed intake, and pigs weights and decreased plasma haptoglobin levels on d 21. Unfortunately, pigs fed a diet containing .025% that exhibited increased growth performance were more likely to die after challenge with S. suis. These data suggest the existence of a complex interaction involving growth performance and resistance to S. suis in pigs fed .025% β-glucan. The interaction should be investigated further.