Effect of feeding supplemental fat or lysine during the postweaning period on the reproductive performance of sows with low or high lactation body weight and fat losses

Abstract

The effects of feeding supplemental fat or lysine during the postweaning period on breeding and subsequent reproductive performance were determined in two experiments of a 2 × 3 factorial design, using 168 Landrace × Yorkshire first-parity (exp. 1) and 180 Yorkshire second-parity (exp. 2) sows. At the end of lactation, they were divided into two groups: LWL (< 14 kg) and HWL (> 14 kg) based on 3 wk lactation weight loss. The three experimental diets fed during the postweaning period were: (1) control; a 12% gestation diet fed 2 kg d −1 (24.7 MJ DE, 9.4 g lysine d −1 ); (2) Fat; control diet plus animal fat to provide approximately 50% more daily energy intake (37.0 MJ DE d −1 ); and (3) Lysine; control diet plus lysine to provide approximately 50% more daily lysine intake (14.4 g d −1 ). After breeding, all sows were fed the control diet at 2 kg d −1 , and they were killed at 30 d of gestation to evaluate their reproductive performance. High weight loss during the lactation period increased the incidence of anestrus and reduced the pregnancy rate in first-parity sows. Feeding supplemental fat was beneficial in increasing the proportion of sows in estrus within 7 d postweaning and the pregnancy rates of first-parity sows with high lactation weight loss. Supplemental fat also had a beneficial effect on ovulation rate, the number of normal embryos, fetal survival and the fetal weights, whereas supplemental lysine improved only fetal weights. Feeding supplemental fat or lysine improved only ovulation rate in second-parity sows with high lactation weight loss. The results indicated that feeding supplemental fat or lysine can improve the postweaning reproductive performance of sows that had high weight and fat losses during lactation. Key words: Sows, estrus, ovulation, embryo survival, fat, lysine