LAUSR

Three trials occured to estimate the optimal dietary level of lysine (Lys) and its ratio with metabolizable energy (ME) using pigs from 50 to 70 kg BW. The first with 72 barrows (49.75±0.41 kg initial BW) and second with 72 gilts (46.05±0.38 kg intial BW). Dietary levels of Lys were: 7.00, 8.00, 9.00, 10.00 11.00 and 12.00 g/kg, and 14.25 MJ/kg ME. The thirth with 12 barrows and 12 gilts were fed with four diets (7.00, 9.00, 10.00 and 12.00 Lys g/kg) from the performance trial to evaluate apparent nutrient digestibility. In the first trial, there was a linear improve on feed conversion ratio, crude protein intake (g/day) (CPI) and crude protein efficiency (CPE) of the gilts from 0 to 16 days. From 0 to 32 days dietary lysine levels continued to show linear increase in CPI and CPE and a quadratic effect on relative weight gain (RWG) and FCR of the gilts. There was linear increase on CPE for barrows from 0 to 16 days and quadratic effect on CPI from 0 to 32 days. Data from digestibility and metabolism assay did not show interaction between sex as effect of Lys, although N retention (g) was higher in gilts than barrows. Therefore, it was concluded that for gilts and barrows from 50 to 70 kg, the recommended levels were 10.14 and 7.00 g/kg Lys or 0.71 and 0.49 g Lys/MJ ME, respectively.