Effect of varying supply of amino acids on nitrogen retention and growth performance of boars of different sire lines

Three diets with varying amino acid levels were fed in two nitrogen balance studies and two fattening experiments in order to determine the nitrogen retention and growth performance of boars of different sire lines. A total of 12 boars, 6 crossbreed boars sired by Piétrain boars (Study 1) and 6 crossbreed boars sired by Duroc boars (Study 2) were used in the nitrogen balance studies. The feeding trials with 214 boars (109 crossbreeds of Piétrain sire line 1×hybrid sow [Pi 1] and 105 crossbreeds Piétrain sire line 2×hybrid sow [Pi 2]) in Experiment 1 and 212 boars (106 Piétrain sire line 3×hybrid sow [Pi 3] and 106 Duroc×hybrid sow [Du]) in Experiment 2 were carried out in three performance test centres in parallel to the nitrogen balance studies. Three diets with increasing content of amino acids were used; it was intended to use the same diets in nitrogen balance studies and the fattening experiments in order to compare the N retention and performance of boars during the growth period. The diets used in all experiments contained 13.4 MJ ME and 11.5 g lysine/kg (Diet 1), 13.2 g lysine/kg (Diet 2) and 14.9 g lysine/kg (Diet 3). The increase of the amino acid content of the diets seemed to have only a very minor impact on the nitrogen retention and on the growth performance of growing boars, whereas the location effect was found to be significant.