Effect of Ad libitum Feeding of Gilt Developer Diets Differing in Standard Ileal Digestive Lysine Concentrations on Growth Traits

An experiment was conducted to determine the optimum dietary lysine concentration for optimum growth rate of replacement gilts during the growing-finishing period. A total of 2,960 gilts (Large White x Landrace), 42.3±7.0 kg average BW were allotted to randomized completely block design (RCBD). Three grower and finisher diets were formulated to contain low lysine (0.68 and 0.52% standard ileal digestible (SID) lysine), medium lysine (0.79 and 0.60% SID lysine), and high lysine (0.90 and 0.68 % SID lysine) at data recording day (142, 160 and 200 d of age). Covariate of body weight at 100 days was included in the models and it had significant influence on growth traits (P < 0.05). Gilts fed the high lysine treatment had increased body weight (BW), flank-to-flank, backfat thickness, loin depth, fat-free-lean, and average daily gain (ADG) (P < 0.05) when compared to gilts fed the medium and low lysine treatments. The results indicated that gilts require higher dietary lysine concentrations to maximize growth rate and high lysine diet may useful to impact growth traits when fed to developing gilt from 142 to 200 kg BW.