Feed intake, growth and protein deposition of pigs fed three protein levels

Abstract

Abstract A group of 96 pigs were fed ad libitum on three dietary treatments with 1.1, 1.2 and 1.3% lysine, 18.5, 21.3 and 24.3% crude protein (CP) and 14.5 MJ/kg DE from 8 weeks of age to slaughter, for whole body chemical analysis, at ± 50, ± 70, ± 90 or ± 110 kg live weight. Regression analyses were used to measure the effect of protein level on the patterns of DE intake (DEI), daily gain (DG) and the deposition rates of protein (PDR) and fat (FDR). CP had no significant ( P > 0.05) effect on mean DEI, DE conversion, DG, PDR or FDR. Significant sex effects were found for all parameters studied. DEI, DG, PDR and FDR followed curvilinear patterns. PDR curves peaked at 69 kg live weight for boars and 54 kg for gilts. PDR increased from 126 g/ d to 154 g/d (167 g/d for boars) at peak deposition. FDR continued to increase throughout the experiment in boars (230 g/d at 90 kg), but reached a peak at 81 kg (258 g/d) for gilts. It is concluded that an 18.5% CP, 14.5 MJDE diet, when optimally balanced for amino acids, is sufficient to sustain a mean DG of ± 850 g and a maximum PDR of up to 167 g/d.