Nitrogen retention of growing pigs obtained by nitrogen balance technique or comparative slaughter technique

Abstract

A study was realized to compare nitrogen retention assessed either by nitrogen balance technique (NB) or by comparative slaughter technique (CST) in growing pigs feeding diets with different crude protein levels. Thirty five castrated pigs (34 ± 0.9 kg) were used, being 9 in the NB and 26 in the CST. Pigs were fed with isoenergetic and isolysinic diets formulated with the ideal ratio of amino acids. A randomized complete design was used with a 2x3 factorial arrangement of treatments: method (NB X CST) and protein level (12, 14 and 16%). The nitrogen retained was lower in CST and there was not influence of crude protein levels. The protein retained was influenced by crude protein levels of diet in the BN method. The protein retained was about 30% overestimated when calculated by BN method in comparison with CST method. These results confirm that the nitrogen retention and protein retention are overestimated by nitrogen balance method and the protein levels of diet increase the differences.