Endogenous ileal nitrogen losses in pigs. Dietary factors.

The determination of endogenous protein from the gastro-intestinal tract of the pig is of fundamental importance in nutritional science. It is generally known that various dietary and animal factors may cause additional endogenous protein losses at the terminal ileum in the pig. In this thesis, endogenous ileal nitrogen (N) losses, as affected by a) neutral detergent fibre (NDF) purified from wheat bran, b) trypsin inhibitors (TI) and c) lectins (Le) isolated from soybean, were studied in young growing pigs using the <sup><font size="-2">15</font></SUP>N- isotope dilution technique. From methodological studies, it was concluded that the <sup><font size="-2">15</font></SUP>N-isotope dilution method is a valid method for determining endogenous ileal N losses in the pig. It was found that the inclusion of purified NDF, isolated TI and Le in the pigs' diet, led to an increased amount of total N passing the terminal ileum of the pig. This increase was caused by additional ileal losses of both endogenous and exogenous N. Even a very small amount of ingested lectins, similar to amounts found in well toasted soybeans, caused an increase in endogenous ileal N loss. The increase in additionally excreted endogenous ileal protein was found to be linear with the amounts of purified NDF and TI. Purified NDF from wheat bran and NDF in sun flower hulls, induced similar endogenous ileal N losses in the pig. The dietary inclusion of whole wheat bran showed that apart from the NDF, there are some other factors, which induced an extra endogenous N loss