Department of Animal Sciences, Endocrinology and Animal Biosciences Program, Rutgers University, 84 Lipman Drive, New Brunswick, NJ, 08901-8525, USA.
Department of Anatomy, Physiology and Pharmacology, Cellular and Molecular Biosciences Program, College of Veterinary Medicine, Auburn University, Auburn, AL, 36849-5517, USA.
Animal. 2019 Dec;13(12):2978-2985. doi: 10.1017/S1751731119001654. Epub 2019 Jul 30.
Maternal effects on development are profound. Together, genetic and epigenetic maternal effects define the developmental trajectory of progeny and, ultimately, offspring phenotype. Maternally provisioned environmental conditions and signals affect conceptus, fetoplacental and postnatal development from the time of conception until weaning. In the pig, reproductive tract development is completed postnatally. Porcine uterine growth and uterine endometrial development occur in an ovary-independent manner between birth (postnatal day = PND 0) and PND 60. Milk-borne bioactive factors (MbFs), exemplified by relaxin, communicated from lactating dam to nursing offspring via a lactocrine mechanism, represent an important source of extraovarian uterotrophic support in the neonatal pig. Lactocrine deficiency from birth affects both the neonatal porcine uterine developmental program and trajectory of uterine development, with lasting consequences for endometrial function and uterine capacity in adult female pigs. The potential lactocrine signaling window extends from birth until the time of weaning. However, it is likely that the maternal lactocrine programming window - that period when MbFs communicated to nursing offspring have the greatest potential to affect critical organizational events in the neonate - encompasses a comparatively short period of time within 48 h of birth. Lactocrine deficiency from birth was associated with altered patterns of endometrial gene expression in neonatally lactocrine-deficient adult gilts during a critical period for conceptus-endometrial interaction on pregnancy day 13, and with reduced litter size, estimated at 1.4 pigs per litter, with no effect of parity. Data were interpreted to indicate that reproductive performance of female pigs that do not receive sufficient colostrum from birth is permanently impaired. Observations to date suggest that lactocrine-dependent maternal effects program postnatal development of the porcine uterus, endometrial functionality and uterine capacity. In this context, reproductive management strategies and husbandry guidelines should be refined to ensure that such practices promote environmental conditions that will optimize uterine capacity and fecundity. This will entail careful consideration of factors affecting lactation, the quality and abundance of colostrum/milk, and practices that will afford neonatal pigs with the opportunity to nurse and consume adequate amounts of colostrum.
母体对子代发育的影响是深远的。遗传和表观遗传的母体效应共同决定了后代的发育轨迹，并最终决定了后代的表型。母体提供的环境条件和信号会影响胚胎、胎仔-胎盘和出生后的发育，从受孕开始一直持续到断奶。在猪中，生殖道发育在产后完成。猪的子宫生长和子宫内膜发育在出生后（产后第 0 天=PND0）至 PND60 期间与卵巢无关。乳源性生物活性因子（MbFs），以松弛素为例，通过泌乳激素机制从哺乳期母体传递给哺乳后代，是新生仔猪卵巢外支持子宫生长的重要来源。出生后泌乳激素缺乏会影响新生仔猪的子宫发育程序和子宫发育轨迹，对成年母猪的子宫内膜功能和子宫容量产生持久影响。潜在的泌乳激素信号传递窗口从出生一直延伸到断奶。然而，母源泌乳激素编程窗口——即 MbFs 传递给哺乳后代的时期，最有可能影响新生儿的关键组织事件——很可能在出生后 48 小时内相对较短的时间内。出生后泌乳激素缺乏与在妊娠第 13 天的关键胚胎-子宫内膜相互作用时期，新生仔猪泌乳激素缺乏的成年后备母猪的子宫内膜基因表达模式改变有关，并导致产仔数减少，估计每窝减少 1.4 头仔猪，且不受胎次的影响。研究数据表明，出生后未能获得足够初乳的母猪的繁殖性能会受到永久性损害。迄今为止的观察结果表明，泌乳激素依赖性母体效应对猪子宫的产后发育、子宫内膜功能和子宫容量具有编程作用。在这种情况下，繁殖管理策略和饲养指南应加以完善，以确保这些实践促进优化子宫容量和繁殖力的环境条件。这需要仔细考虑影响泌乳的因素、初乳/牛奶的质量和丰度，以及为新生仔猪提供哺乳和摄入足够初乳的机会的实践。
