Digestible lysine in diets for primiparous lactating sows

Sixty commercial hybrid first litter sows, during lactation (20, 2 ± 0, 13 days), with average body weight of 183, 6 ± 1,46 kg, were used to evaluate digestible lysine intake (DLI) (45; 50; 55 e 60 gr/day). The feed intake was kept at 5.0 kg /day. A completely randomized blocks design, with four treatments (45, 50, 55 and 60 gr DLI/day), fifteen replicates, and the sow considered as the experimental unit, were used. The levels of lysine tested had significant influence on subsequent reproductive performance of sows in the second parity, affecting the number of total born, live born, and litter weight at birth. However, there was no effect of DLI on average piglet birth weight and piglet`s birth weight coefficients of variations on the second delivery. There was no effect of DLI on body reserves mobilization, back fat thickness and muscle depth in sows during lactation. There was no effect on daily body weight gain of piglets and on milk production and composition according to the DLI. It was concluded that the DLI of 42.00 g/day, with a LD/EM ratio corresponding to 2.49 g/Mcal ME, meets the requirements for females during lactation, and the increased lysine intake up to 53.9 g/day, corresponding to a LD/EM ratio of 3.15 g/Mcal ME, results in a higher number of piglets born alive in the second delivery.