Sixty-five crossbred sows (Landrace x Large White) averaging 217.36 ± 21.35 kg were used to evaluate increasing dietary total lysine levels (0.950, 1.025, 1.100, 1.175, and 1.250%) during 21 days of lactation. The experiment was analyzed as a randomized block design, with five treatments, 13 replicates of one sow per experimental unit. The daily total feed intake was fixed for all treatments. The dietary lysine levels did not affect sow weight at weaning, body weight loss, backfat thickness (BT), BT change, body fat loss, number of weaned piglets per litter and weaning-to-estrus interval. However, there was a linear decrease on body protein loss expressed as kg and percentage and on daily milk production of sows, as the dietary lysine levels increased. The treatments affected litter weight gain, that decreased linearly. The results of this work showed that sows fed decreasing lysine levels retained significant amounts of body protein reserve to maintain their productive performance. However, the protein mobilization of these animals (2.2 kg corresponding to 6.45% of body protein loss) was not enough to affect the productive and reproductive performance. It was concluded that a daily total lysine intake of 45 g, correspondent of 40 g of digestible lysine meets the requirements for productive and reproductive performance of lactating sows and that they require 58.9 g of estimate total lysine/day, that corresponds to 53.5 g/day of digestible lysine to minimize body protein loss during the lactation.
lactation; litter; lysine; requirement; reproduction; sows
