Non-protein nitrogen is used efficiently for improving protein deposition and feed efficiency in growing pigs

Nitrogen (N) absorbed by the lower gut (caecum and large intestine), primarily in the form of ammonia, is generally considered to be of little nutritional value for growing pigs. The main objective of research presented in this thesis was to explore the effects of providing non-protein N (NPN) on N retention, urea kinetics, activity of key liver enzymes, and growth performance of pigs fed diets deficient in non-essential amino acid N (NEAA-N). Urea-N infused into the lower gut increased N retention, with an estimated efficiency of 96%. Whole body urea flux and urea recycling into the gastro-intestinal tract were not affected by urea infusion into the lower gut. When feeding growing pigs NEAA-N deficient diets, feed efficiency increased linearly with level of dietary supplementation with ammonium salts. These data support that NPN can be efficiently used for improving N retention and feed efficiency in pigs fed diets deficient in NEAA-N.