Microbial protease addition to a soybean meal diet for weaned piglets: effects on performance, digestion, gut flora and gut function

摘要

Transient hypersensitivity to soy (Glycine max) proteins, resulting in postweaning lag, is well known in pig nutrition. This hypersensitivity precedes the induction of oral tolerance, fully established by the age of 12 weeks. As antigenic soy proteinsare not much reduced by heat and show resistance to mammalian proteases, the alleviation of antigenic effects by using a microbial exogenous protease in a soybean meal (SBM) based weaner diet, was studied in a combined growth trial and slaughter experiment (1 h, 2 h, 3 h post-prandial). There was a non-significant trend for piglets to perform better (growth, F:G ratio) on the protease containing diets. Also on the protease diets, ileal digestibility, and to a lesser extent faecal digestibility, of drymatter (DM), organic matter (OM), crude protein (CP), HCl fat and energy were increased, although again not significantly. Electrophoretic profiles of SDS-PAGE and ELISA and immunoblotting tests showed less residual antigenicity against the soy protein in the stomach and foregut content of piglets on the protease diets. Also the IgG titers to soy proteins in the sera of protease fed piglets were lower. Furthermore, protease addition significantly reduced total anaerobic flora in the stomach and the foregut in a dose/time dependent manner. The number of intra-epithelial lymphocytes (IELs) and the crypt depth was reduced giving a higher villus heightxrypt depth (V:C) ratio. Both phenomena (V:C ratio; IELs) indicate a healthier and better functioning mucosa when protease was used. For nearly all parameters studied, the effects were more pronounced at 2 h post-prandial at the lower enzyme dose. There is little published data on the potential use of proteases in animal diets. Our data shows that the addition of protease may be a potential way of increasing the amounts of SBM in piglet starter diets.