Effects of lysine and protein intake over two consecutive lactations on lactation and subsequent reproductive performance in multiparous sows

The aim of the study was to evaluate that the effect of lysine and protein intake over two consecutive lactations on lactation and subsequent reproductive performance in multiparous sows. The experiment was designed in a 2×2 factorial arrangement with 2 levels of total lysine (0.95% and 1.10%) and 2 levels of crude protein (17.5% and 19.0%). The treatment diets were the same for all sows within each treatment combination during two consecutive lactations. The average ambient temperature of the semi-enclosed farrowing room during the first and second lactation were 28.3±1.7 °C and 23.4±2.2 °C, respectively. The results showed that the 19.0% CP diets increased the first and second lactating sow CP intake compared with the 17.5% CP diets (P<0.05). Likewise, the 1.10% lysine diets increased (P<0.05) the first and second lactating sow lysine intake than the 0.95% lysine diets. Remarkably, as a result of ambient temperature difference between the first and second lactation, the sow practical lysine intake (43.4 g/d, 55.1 g/d, 49.3 g/d, and 55.9 g/d, respectively) in the first lactation not reached estimated lysine requirement (52.4 g/d, 57.1 g/d, 55.7 g/d, and 60.0 g/d, respectively), while the sow practical lysine intake (55.4 g/d, 60.8 g/d, 58.3 g/d, and 61.0 g/d, respectively) in the second lactation both exceeded estimated lysine requirement (54.4 g/d, 57.2 g/d, 56.1 g/d, and 58.7 g/d, respectively). Compared with the 0.95% lysine diets, the 1.10% lysine diets decreased the first lactating sow body weight loss, and the culling rate of sows failing to display estrus within 21 d after weaning (P<0.05). In contrast, the 1.10% lysine diets increased the second lactation sow body weight loss (P<0.01), and the culling rate of sow failing to display estrus within 21 d after weaning than 0.95% lysine diets (P<0.05). Average weight at weaning, litter weight at weaning, little weight gain, and litter growth rate were not affected by treatments (P>0.05). These results indicated that, at low levels of lysine intake, increasing lysine intake was beneficial for reducing sow lactation weight loss and culling rate of sow failing to display estrus within 21 d after weaning, while increasing lysine intake at high levels of lysine intake increased sow lactation weight loss and culling rate of sow failing to display estrus within 21 d after weaning.