AbstractThe effects of two feed levels offered during two estrous cycles before insemination were evaluated on the reproductive performance of gilts. A total of 93 gilts (PIC Hendersonville, TN) were individually housed and manually fed twice a day with 2.1 or 3.6 kg/d of a corn and soybean meal-based diet (3.15 Mcal ME/kg and 0.64% standardized ileal digestible lysine), during two estrous cycles before breeding (cycle 1, between first and second estrus; cycle 2, between second and third estrus). Gilts were weighed at the beginning of the experiment, at second and third estrus, and at slaughter (30.2 ± 1.2 d of gestation). Follicles were counted at second estrus, and the embryo-placental units and the corpora lutea were individually counted, measured, and weighed at slaughter. Gilts fed 3.6 kg/d had greater BW gain during cycle 1 and cycle 2 (P < 0.001; + 9.8 kg and + 10.0 kg, respectively) becoming heavier at second and third estrus (P < 0.001). At second estrus, gilts fed 3.6 kg/d had 1.6 more medium-large follicles (P = 0.074) but no difference in follicle size (P = 0.530) was observed. Gilts fed 3.6 kg/d in cycle 1 or cycle 2 had a greater ovulation rate at third estrus (P < 0.016) than those receiving 2.1 kg/d. Also, 3.6 kg/d in cycle 2 increased early embryo mortality (P = 0.006; 2.3 vs. 1.1 dead embryos) and consequently reduced total embryo survival (P = 0.002; 84.6 vs. 90.1%). Gilts fed 3.6 kg/d during cycle 1 had two more total embryos (P < 0.001; 17.2 vs. 15.1) and two more vital embryos on day 30 (P < 0.001; 16.7 vs. 14.5) in comparison with gilts fed 2.1 kg/d. The coefficient of variation for placental length was greater for gilts fed 3.6 kg/d during cycle 1 (P = 0.003). No further significant effects of feeding levels were observed on embryo and placental traits (P ≥ 0.063). These results suggest that the feeding level during the first cycle after pubertal estrus is crucial to set ovulation rate and potential litter size for breeding at next estrus. However, flush feeding gilts before insemination can negatively impact litter size by reducing embryo survival when breeding at third estrus.

中文翻译：

---

育种前同种饲喂策略对现代代用小母猪繁殖性能的影响：对排卵率和垫料性状的影响。

摘要评价了在授精前两个发情周期中提供的两种饲料水平对后备母猪繁殖性能的影响。单独安置了总共93头母猪（田纳西州Hendersonville市），每天手动饲喂2.1或3.6千克/天的玉米和豆粕基日粮（3.15麦卡尔ME /千克和0.64％的标准化回肠可消化赖氨酸）。 ，在繁殖前的两个发情周期内（第一发情和第二发情之间的周期1；第二发情和第三发情之间的周期2）。在实验开始时，第二和第三发情期以及宰杀时（妊娠期30.2±1.2 d）称量母猪的体重。在发情期对卵泡计数，对胚胎-胎盘单位和黄体分别进行计数，测量和称重。在第1周期和第2周期，饲喂3.6 kg / d的后备母猪的体重增加更大（P <0.001；在第二次和第三次发情时，体重分别增加了9.8公斤和+ 10.0公斤（P <0.001）。在第二次发情期，以3.6千克/天的速度饲喂的小母猪多了1.6个中等大小的卵泡（P = 0.074），但卵泡大小没有差异（P = 0.530）。在第1周期或第2周期饲喂3.6 kg / d的母猪在第三发情期的排卵率高于接受2.1 kg / d的母猪（P <0.016）。同样，第2周期3.6 kg / d增加早期胚胎死亡率（P = 0.006； 2.3对1.1个死亡胚胎），因此降低了总胚胎存活率（P = 0.002； 84.6对90.1％）。第一周期饲喂3.6 kg / d的小母猪的胚胎总数增加了两个（P<0.001; 与饲喂2.1千克/天的小母猪相比，第30天的存活率分别为17.2和15.1）和另外两个重要的胚胎（P <0.001； 16.7和14.5）。在第1个周期中，饲喂3.6 kg / d的后备母猪的胎盘长度变异系数更大（P = 0.003）。未观察到对胚胎和胎盘性状（进给水平没有进一步显著效果P ≥0.063）。这些结果表明，青春期发情后的第一个周期的饲喂水平对于设定排卵率和下一个发情期的潜在产仔数至关重要。但是，在授精前先进行小母猪冲厕，会降低胚胎在第三发情期的存活率，从而对产仔数产生负面影响。