Of piglets, dietary proteins, and pancreatic proteases

Newly weaned piglets often show digestive disorders, frequently resulting in diarrhoea. These disorders may be related to the dietary protein source, since young piglets are less capable of digesting proteins of vegetable origin than older pigs. This study was undertaken to investigate the development of protein digestive capacity in weaned piglets. In the first part of the thesis it was established that the difference in nitrogen digestibility between milk, soya and fish proteins was mainly due to differences in endogenous nitrogen losses and not to differences in true digestibility. In the second part, the pancreatic protease activities of newly weaned piglets fed various dietary protein sources was investigated. It was found that dietary protein source affected trypsin and chymotrypsin activities in pancreatic tissue and jejunal digesta, however, these differences could not explain the differences in endogenous nitrogen losses. It is more likely that other sources of endogenous nitrogen, e.g. the small intestinal wall, are responsible for the differences in protein digestibility observed in young piglets.

Furthermore, it was concluded from the experiments described in this thesis, that postweaning feed intake has a greater effect on the development of pancreatic enzyme activities than dietary protein source per se. Young piglets are capable of increasing their pancreatic secretion in response to appropriate stimuli. Stimulating post-weaning feed intake may help to smooth the development of protein digestive capacity in young piglets. In this respect, feed intake patterns may be at least as important as quantitative feed intake.