NUTEGA, Madrid, Spain.
Theriogenology. 2011 Jan 1;75(1):34-41. doi: 10.1016/j.theriogenology.2010.07.009. Epub 2010 Sep 15.
The Mediterranean Iberian pigs are obese genotypes, due to a leptin resistance syndrome related to leptin receptor gene polymorphisms. The Iberian pig is affected by a lower prolificacy when compared to lean breeds, and thus may constitute a good animal model for adverse effects of obesity in reproductive performance. The present study determined possible differences in rates of ovulation and embryo implantation and later incidence of embryo mortality and intrauterine growth retardation (IUGR) in sows of Iberian breed (n = 23) and highly-prolific lean commercial crosses (Large White × Landrace, n = 17) at two critical periods of swine pregnancy: Day 21 (just after achievement of trophoblast attachment) and Day 35 (just after completion of the transition from late embryo to early foetal stage). Two different reproductive performances were identified in the Iberian breed; 58.3% of the females had lower ovulation rates than LWxL (13.2 ± 2.3 vs 22.5 ± 1.6, P < 0.05), but 41.7% had a similar number of ovulations (18.2 ± 3.9). However, those Iberian sows having high ovulatory rates showed a high incidence of regression of corpora lutea and embryo losses between Days 21 and 35, which was not found in Iberian females with low ovulation rates; therefore, the number of viable embryos was similar in both Iberian groups (8.2 ± 1.0 and 8.4 ± 1.0) and lower that in highly-prolific LWxL (14.8 ± 1.8, P < 0.05). At Day 35, a total of 167 conceptuses (73 LWxL and 94 IB) were evaluated for IUGR. The LWxL conceptuses were longer and wider than Iberian (69.5 ± 0.1 and 64.4 ± 0.1 vs 49.9 ± 0.1 and 41.9 ± 0.1 mm, P < 0.0001). However, Iberian conceptuses were heavier than LWxL (107.4 ± 6.6 vs 68.6 ± 2.4 g) due to a lower quantity of fluids and a higher development of the placental tissues in comparison to the embryo itself. In conclusion, current study indicates a bimodal effect of obese genotypes on reproductive performances, either by lowering ovulation rate or by increased embryo losses in the first third of pregnancy.
地中海伊比利亚猪是肥胖基因型，由于与瘦素受体基因多态性相关的瘦素抵抗综合征。与瘦肉型品种相比，伊比利亚猪的繁殖力较低，因此可能成为肥胖对生殖性能不良影响的良好动物模型。本研究在猪妊娠的两个关键时期（第 21 天（刚刚完成滋养层附着后）和第 35 天（刚刚完成晚期胚胎向早期胎儿期的过渡后））确定了伊比利亚品种（n = 23）和高繁殖力瘦肉型商业杂交品种（长白猪×大白猪，n = 17）母猪排卵率和胚胎着床率的可能差异，以及随后胚胎死亡率和宫内生长迟缓（IUGR）的发生率。在伊比利亚品种中发现了两种不同的繁殖性能；58.3%的雌性排卵率低于 LWxL（13.2 ± 2.3 对 22.5 ± 1.6，P < 0.05），但 41.7%的排卵率相似（18.2 ± 3.9）。然而，那些排卵率高的伊比利亚母猪在第 21 天至第 35 天期间黄体和胚胎损失的回归发生率较高，而排卵率低的伊比利亚母猪则没有发现这种情况；因此，两个伊比利亚组的活胚胎数量相似（8.2 ± 1.0 和 8.4 ± 1.0），低于高繁殖力的 LWxL（14.8 ± 1.8，P < 0.05）。在第 35 天，总共评估了 167 个胚胎（73 个 LWxL 和 94 个 IB）是否存在宫内生长迟缓。LWxL 胚胎比伊比利亚胚胎更长更宽（69.5 ± 0.1 和 64.4 ± 0.1 对 49.9 ± 0.1 和 41.9 ± 0.1 mm，P < 0.0001）。然而，由于胚胎本身与胎盘组织相比，伊比利亚胚胎的液体含量较低，胎盘组织发育较好，因此比 LWxL 胚胎更重（107.4 ± 6.6 对 68.6 ± 2.4 g）。总之，目前的研究表明，肥胖基因型对繁殖性能有两种双峰效应，要么通过降低排卵率，要么通过增加妊娠早期的胚胎损失。
