Effects of nutrient restriction of bovine dams during early gestation on postnatal growth, carcass and organ characteristics, and gene expression in adipose tissue and muscle.

Angus x Hereford heifers (15 mo and artificially inseminated to a single sire) were used to evaluate the effect of prenatal nutritional restriction on postnatal growth and development. At d 32 of gestation, dams were stratified by BW and BCS and allotted to a low-nutrition [55% of NRC (1996) requirements, n = 10] or moderate-nutrition [100% of NRC (1996) requirements, n = 10] diet. After 83 d of feeding, dams were commingled and received a diet in excess of requirements. Dams were allowed to calve naturally, and birth weights and growth of calves were recorded. Bulls were castrated at birth. Steers (16 mo of age, 5 per treatment) received a high-concentrate diet ad libitum to a constant age (88 ± 1 wk). Steers were slaughtered and weights of the empty body and organs were recorded. Samples of organs, muscle (complexus), and perirenal and subcutaneous adipose tissue were stored at -80 degrees C, and then DNA and protein concentrations were quantified and expression of genes associated with fatty acid metabolism and glucose uptake were measured in adipose and muscle tissue. Dams had similar (P > 0.33) BW and BCS at the beginning of the experiment. At the end of restriction, dams on the low-nutrition diet weighed less (P ≤ 0.01) and had less BCS (P < 0.001) than those on the moderate-nutrition diet. Length of gestation was 274 ± 2 d for dams in the low-nutrition treatment and 278 ± 2 d (P = 0.05) for dams in the moderate-nutrition treatment. Nutrient restriction during gestation did not influence birth weight or postnatal growth of calves. Lungs and trachea of steers whose dams were fed the low-nutrition diet weighed less (P = 0.05) at slaughter than those of steers whose dams were fed the moderate-nutrition diet; weights of other organs were not influenced by treatment. Complexus muscle from steers whose dams were fed the low-nutrition diet had a greater (P = 0.04) concentration of DNA and larger muscle fiber area compared with steers whose dams were fed the moderate-nutrition diet. Abundance of mRNA for fatty acid binding protein 4, fatty acid translocase, and glucose transporter 4 was less in perirenal adipose tissue of steers whose dams were fed the low-nutrition diet compared with those whose dams were fed the moderate-nutrition diet. Nutritional restriction of dams during early gestation did not alter postnatal calf growth. However, concentrations of DNA in muscle tissue and muscle fiber area were greater in steers from dams exposed to restricted nutrient intake during early gestation.

Effects of nutrient restriction of bovine dams during early gestation on postnatal growth and regulation of plasma glucose.

Angus x Hereford heifers (15 mo and AI to a single sire) were used to evaluate the effect of prenatal nutritional restriction on postnatal growth and regulation of glucose in plasma. Dams (d 32 of gestation) were stratified by BW and BCS and allotted to low [LN, 55% of NRC (1996) requirements, n = 7] or moderate nutrition [MN, 100% of NRC (1996) requirements, n = 7]. After 83 d of feeding, dams were commingled and received a diet in excess of requirements. Dams were allowed to calve naturally, and bull calves were castrated at birth. Dams and calves were maintained as a group until weaning, and calves were maintained as a group after weaning. Calves (15 mo of age) were adapted to a similar diet during 2 wk; catheters were placed in both jugular veins; and calves were confined in stalls. Two days later, calves were subjected to an intravenous glucose challenge and the next day to an insulin challenge. Dams had similar (P = 0.31) BW at the beginning of the experiment. At the end of restriction, LN dams weighed less (P ≤ 0.01) and had less BCS (P < 0.001) compared with MN dams. Length of gestation was not affected by prenatal nutritional treatment. Nutrient restriction during gestation did not influence birth weight or postnatal growth. Concentrations of glucose (P = 0.49) and insulin (P = 0.29) were not different in plasma of LN and MN calves before glucose infusion. Plasma concentrations of glucose, after intravenous administration of glucose, decreased more rapidly (P = 0.05) in LN compared with MN calves. Concentrations of glucose (P = 0.68) and insulin (P = 0.55) in plasma of LN and MN calves were similar after infusion of insulin. Nutritional restriction of dams during early gestation did not influence postnatal growth, but altered clearance of glucose after a bolus infusion of glucose.