Duration of lactation, endocrine and metabolic state, and fertility of primiparous sows.

摘要: The objectives of this study were to determine factors affecting the reproductive performance primiparous sows early weaned (EW; n = 35) at d 14 or conventionally (CW; 24 lactation. Sow BW and backfat recorded farrowing, weekly until weaning, standing heat. Feed intake was controlled throughout lactation standardize nutritional effects on subsequent performance. Litter size standardized across treatments within 48 h after litter weight weaning. In subsets sows, blood samples collected from 10 before then every 6 ovulation. Sows heat checked twice daily bred 24-h intervals during using pooled semen. Ultrasonography determined time either slaughtered ovulation assess rate, fertilization embryonic development in vitro, 28 gestation rate survival. Compared with CW EW had more weaning (15.9 +/- 0.5 vs. 14.7 mm; P < 0.001). Also, tended lose have lower IGF-I concentrations, indicating poorer body condition. Duration did not affect (EW 17.6 0.7; 18.7 0.6), 96.0 2.2; 88.2 4.7%), embryo survival 62.5 4.5; 63.1 5.0%). There a marginal effect duration weaning-to-estrus interval 120 3; 112 3 h; 0.06) estrus 52.4 2.3; 46.3 2.2 0.08). Overall, survival, seems be limiting factor for potential second parity. Although fertility both studied compromised, endocrine metabolic data indicate that mechanisms may differ between two systems. LH, FSH, estradiol are characteristic animals limited follicular incomplete recovery hypothalamic-pituitary-ovarian axis; consequently, integrity uterine environment adversely affected limit variability state seemed key fertility, again