Four experiments were conducted, using a total of 356 Landrace × Yorkshire crossbred gilts, to determine the influence of flushing, supplemental fat and supplemental lysine fed from puberty to breeding (exps. 1 and 2) and from puberty through early gestation (exps. 3 and 4) on the reproductive performance of gilts. All gilts were housed in total confinement and fed ad libitum a 16% protein swine grower diet until 150 d of age. The diet was then restricted to 2 kg d−1 until puberty. The treatment diets fed from puberty to breeding in exps. 1 and 2 were: (1) control, a 12% protein barley-soybean meal gestation diet fed at 2 kg d−1 (24.4 MJ DE d−1); (2) flushing, control diet fed at 3 kg d−1 (36.6 MJ DE d−1; (3) animal fat, control diet fed at 2 kg d−1 plus 622 g of fat premix (36.6 MJ DE d−1; and (4) lysine, control diet with supplemental lysine (14 g d−1) fed at 2 kg d−1 (24.4 MJ DE d−1). After breeding, all gilts were fed control diet at 2 kg d−1 until approximately 30 d at gestation. In exps. 3 and 4, the same treatment diets were used except flushing was omitted and they were fed from puberty to approximately 30 d of gestation. No significant differences (P > 0.05) among the treatment groups were found in any of the experiments for the number of corpora lutea and normal embryos, and ovarian, uterine, and fetal weights. In exp. 2, the embryo survival rate (%) was significantly lower (P < 0.05) in the flushing (81.7 ± 3.3) and animal fat (78.3 ± 3.3) groups than in the control (92.9 ± 3.0); however, the lysine (88.8 ± 3.5) group did not differ significantly from the other groups. The embryo survival rate was also reduced (P < 0.05) by supplemental fat (81.5 ± 2.7) when compared to the control (86.8 ± 3.0) and lysine (88.8 ± 2.7) diets in exp. 3 but not in exp. 4. The serum progesterone level (ng/mL−1) was lower (P < 0.05) in the animal fat group (4.1 ± 0.6) than in the control (6.3 ± 0.6) and lysine (6.1 ± 0.6) groups in exp. 4. However, progesterone level of allantoic fluid in exp. 4 and estrone sulfate levels of both serum and allantoic fluid in exps. 3 and 4 were similar for the three treatment groups. The overall results indicated that flushing, supplemental fat or supplemental lysine fed from puberty to breeding, and supplemental fat or supplemental lysine fed from puberty through early gestation did not improve the ovulation rate, embryo survival or fetal development in gilts. Key words: Ovulation rate, embryo survival, flushing, fat, lysine, hormones, gilts
Effect of parity on reproductive performance sows of different breeds