Intrauterine Growth Retardation in Livestock: Implications, Mechanisms and Solutions

摘要

Intrauterine growth retardation (IUGR) is a significant problem in livestock production. There is growing recognition that IUGR adversely affects neonatal survival, hormone secretion and action, postnatal growth, efficiency of feed/forage utilization,whole-body and tissue composition, the distribution of muscle fiber type, meat quality, long-term health, and reproductive performance of the offspring. Compelling evidence shows that genetic, epigenetic and environmental factors (including nutrition), as well as maternal maturity impact on crucial events during gestation, including the size and functional capacity of the placenta, placental vascular growth, uteroplacental blood flows, transfer of nutrients from mother to fetus, conceptus nutrient availability, the endocrine milieu, covalent modifications of proteins and DNA, metabolic pathways, and embryonic development of myocytes and adipocytes. Emerging findings suggest that arginine-derived signaling and regulatory molecules (NO and polyamines)play an important role in regulating these key physiological and biochemical processes. Thus, hormonal and nutritional treatments for pregnant dams with IUGR, which directly or indirectly promote placental growth and uteroplacental blood flow through modulating the arginine-NO pathway, can enhance fetal growth. Particularly, supplementing arginine to diets for pregnant gilts markedly increased the number and litter birth weight of live-born piglets, as well as their postnatal growth. Additionally, either administration of Viagra or intravenous infusion of arginine to underfed ewes was effective in ameliorating IUGR. Also, the arginine treatment increased lamb birth weight in ewes with multiple fetuses that exhibited litter size-dependent IUGR. Therefore, arginine supplementation may offer a novel and effective means to prevent IUGR and enhance the efficiency of animal production. Promoting an optimal intrauterine environment will not only ensure optimal fetal development, but also will improve postnatal growth performance and meat quality of livestock.