LAUSR

Unacceptable sow longevity in modern production systems has placed nutritional programs for developing gilts into question. Nutritional programs are well defined for terminal pigs, but not for developing gilts. To achieve breeding targets and allow gilts to meet their maternal genetic potential for lifetime productivity, the optimum lysine requirement for developing gilts should be well understood. The National Pork Board Animal Science Committee commissioned trials to determine the optimum lysine levels for developing gilts in U.S. pig production systems. An experiment was conducted to challenge proposed dietary lysine concentration for optimum growth rate during gilt development. A total of 2,960 growing crossbred gilts were fed three grower-finisher diets, formulated to provide low lysine (0.68 and 0.52% SID lysine), medium lysine (0.79 and 0.60% SID lysine), and high lysine (0.90 and 0.68% SID lysine) levels and fed to developing gilts starting from 142 to 200 d of age. Gilts fed the high lysine dietary treatment had significantly increased body weight (BW), flank-to-flank length, backfat thickness (BF), loin depth (LD), average daily gain, and fat-to-lean ratio (P < 0.05). Moreover, gilts fed the high lysine treatment during development phase had greater BW (202.4 ± 1.2 kg), BF (14.8 ± 0.2 mm), and LD (5.4 ± 0.5 cm) at first farrowing and BF (15.1 ± 0.2 mm) at weaning when compared with gilts fed the medium and low lysine treatments (P < 0.05). Litter birth weight (17.4 ± 0.3 kg), number weaned (9.0 ± 0.2), and litter weaning weight (46.6 ± 0.9 kg) from the gilts fed the high lysine sow treatment were greater when compared with performance from gilts fed the medium and low treatments (P < 0.05). Gilt development diets containing 2.79 g and 2.08 g SID lysine per MCal ME (high lysine grower and finisher diets, respectively) allowed gilts to achieve good growth and first parity reproductive performance.