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Interpretive Summary: Smith Nutrient Restriction followed by Realimentation sheep

By Caitlin Vonderohe

Nutrient restriction in pregnant females has been repeatedly shown to have adverse effects on the growth and development of their offspring. Realimentation following nutrient restriction may be a strategy to mitigate the negative growth effects that maternal nutrient restriction has on offspring. Smith et al., recently published “Mid- to late-gestational maternal nutrient restriction followed by realimentation alters development and lipid composition of liver and skeletal muscles in ovine fetuses” in the Journal of Animal Science with the objective of critically examining the effects of maternal nutrient restriction followed by realimentation on markers of growth and development in sheep fetuses. 

The authors hypothesized that maternal nutrient restriction would impair fetal liver and muscle development and affect tissue composition, gene expression, and lipid composition, but realimentation would prevent these negative effects. Forty-eight pregnant ewes were assigned to a treatment: 7 BASE ewes were euthanized at gestation day 50, remaining ewes were either fed the control diet to meet 100% nutrient requirements or RES diet which met 60% of requirements for the duration of mid-gestation (day 50-90). Seven RES and 7 control ewes were euthanized at day 90. Here, the rest of the ewes (control and restriction fed) were feed either the control or RES diets until gestation day 130 (creating Control – Control, Control-RES, RES-Control, and RES-RES treatments). Tissue was collected from fetuses for histologic analysis, gene expression and lipidomic analysis. 

Results of this study demonstrate that maternal nutrient restriction has detrimental effects on fetal liver and muscle morphology and lipid metabolism, as shown by the fatty acid profiles. Mid-gestation realimentation attenuated some of the negative effects of nutrient restriction, which was demonstrated by the gene expression of growth factors in liver and muscle. This means that realimentation may be a viable strategy in maternal nutritional management in the future.