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Abstract: Accompanying the beneficial improvement in litter size from genetic selection for high-prolificacy sows, within-litter variation in birth weight has increased with detrimental effects on post-natal growth and survival due to an increase in the proportion of piglets with low birth-weight. Causes of within-litter variation in birth weight include breed characteristics that affect uterine space, ovulation rate, degree of maturation of oocytes, duration of time required for ovulation, interval between ovulation and fertilization, uterine capacity for implantation and placentation, size and efficiency of placental transport of nutrients, communication between conceptus/fetus and maternal systems, as well as nutritional status and environmental influences during gestation. Because these factors contribute to within-litter variation in birth weight, nutritional status of the sow to improve fetal-placental development must focus on the following three important stages in the reproductive cycle: pre-mating or weaning to estrus, early gestation and late gestation. The goal is to increase the homogeneity of development of oocytes and conceptuses, decrease variations in conceptus development during implantation and placentation, and improve birth weights of newborn piglets. Though some progress has been made in nutritional regulation of within-litter variation in the birth weight of piglets, additional studies, with a focus on and insights into molecular mechanisms of reproductive physiology from the aspects of maternal growth and offspring development, as well as their regulation by nutrients provided to the sow, are urgently needed.

母猪营养状态对仔猪初生重窝内变异的影响

概要：本综述旨在总结仔猪初生重窝内变异对仔猪健康、生长及生产管理造成的不利影响、形成因素、以及改善窝内变异的措施。在现代化高产母猪养殖中，仔猪初生重窝内变异程度及低初生重猪的比例大幅增加，导致新生期存活率、生长性能大大降低。初生重窝内变异的影响因素包括母猪排卵率、卵子质量、排卵持续时间、胚胎附植能力、子宫容积、胎盘体积和效率等；品种差异对仔猪初生重的均匀度也有很大影响。在妊娠的三个关键阶段（断奶-配种间隔期、妊娠早期和妊娠后期）进行针对性的营养调控有望一定程度上提高窝内初生重均匀度。目前已被报道的包括：在配种前母猪日粮中添加葡萄糖或者维生素Ａ，妊娠后期添加谷氨酰胺均可改善仔猪初生重均匀度，精氨酸以及支链氨基酸也有提高仔猪初生重一致性的潜能。但总体而言，目前相关研究相对较少、潜在的分子机制仍不明确，需要大量深入的研究来加深对妊娠期母体与胎儿发育过程相关生物学事件、营养素作用机制的理解，为制定出更加科学有效的母猪饲喂措施提供理论基础。

关键词：窝内变异；猪；死亡率；发病率；生长性能；母猪营养

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