Maternal nutrient restriction during pregnancy alters fetal programming, which modifies the growth and health of the offspring in postnatal life. In cattle, nutrient restriction during pregnancy can be a result of environmental or economic factors, but little is known about how it alters the physiology of the fetus and affects future reproductive or growth efficiency. This study used female monozygotic twins, produced through in vitro fertilization and embryo splitting, to determine the effect of moderate maternal nutrient restriction on fetal development. Recipient Angus cross heifers pregnant with one twin were fed a diet meeting 100% National Research Council (NRC) total energy requirements (n = 4; control), whereas recipient heifers pregnant with the second twin were fed at 70% of NRC total energy requirements (n = 4; restricted) from gestational day (GD) 158 to GD 265 in Calan gate feeders. Recipient heifers were killed at GD 265. Change in maternal metabolic body weight was greater from zero in restricted heifers than controls (P < 0.05); restricted heifers lost weight during the nutrient restriction period. There was no difference in last rib back fat or rib eye area between groups (P > 0.10). There was no difference in fetal weight, uterine weight, or total placentome weight between groups (P > 0.10). The pancreas weight was reduced in restricted fetuses compared with control fetuses (P < 0.01), but there were no other differences in fetal organ weights (P > 0.10). Plasma insulin concentrations were reduced in restricted fetuses compared with controls (P < 0.01), but there was no effect of maternal diet on plasma glucose or glucagon concentrations in the fetus (P > 0.10). Histological analyses of the fetal pancreas revealed no differences in endocrine cell number or localization. Results indicate that a modest late gestation nutritional restriction impairs development of the fetal pancreas in the cow. Additional research will be needed to determine if these developmental changes lead to altered glucose and insulin homeostasis in the adult.

孕期母体营养限制会改变胎儿程序，从而改变后代在出生后的生长和健康。在牛中，怀孕期间的营养限制可能是环境或经济因素的结果，但人们对它如何改变胎儿的生理机能并影响未来的生殖或生长效率知之甚少。本研究使用通过体外受精和胚胎分裂产生的雌性同卵双胞胎来确定适度限制母体营养对胎儿发育的影响。怀有一对双胞胎的接受者安格斯杂交小母牛被喂养满足 100% 国家研究委员会 (NRC) 总能量需求的饮食（n = 4；对照），而怀有第二对双胞胎的接受者小母牛被喂养满足 NRC 总能量需求的 70% (n = 4; 限制）从妊娠日 (GD) 158 到 GD 265 在卡兰门喂食器中。受体小母牛在 GD 265 时被杀死。 与对照相比，受限小母牛的母体代谢体重变化从零开始更大（P < 0.05)；受限制的小母牛在营养限制期间体重减轻。组间最后肋背脂肪或肋眼面积无差异（P > 0.10）。组间胎儿体重、子宫重量或胎盘总重量无差异（P > 0.10）。与对照胎儿相比，限制胎儿的胰腺重量减少（P < 0.01），但胎儿器官重量没有其他差异（P > 0.10）。与对照组相比，受限胎儿的血浆胰岛素浓度降低（P < 0.01），但母体饮食对胎儿的血浆葡萄糖或胰高血糖素浓度没有影响（P> 0.10）。胎儿胰腺的组织学分析显示内分泌细胞数量或定位没有差异。结果表明，适度的晚期妊娠营养限制会损害母牛胎儿胰腺的发育。需要进一步的研究来确定这些发育变化是否会导致成人葡萄糖和胰岛素稳态的改变。