Age at First Gestation in Beef Heifers Affects Fetal and Postnatal Growth, Glucose Metabolism and IGF1 Concentration

Abstract

This study aimed to determine the effects of age at first gestation on offspring growth performance, glucose metabolism, and IGF1 concentration. Heifers impregnated by AI from a single bull at 15 months of age (15 M, n = 20), or 27 months of age (27 M, n = 20), and multiparous cows (adult, n = 20) were used. Dams from all groups were managed in a single group during gestation and lactation. Gestational length was longer in the 15 M and 27 M than in adult dams (p = 0.009). Bodyweight at birth, at weaning and ADG during lactation were higher in calves from adult dams than in those from 27 M dams, and higher in calves from the latter than in 15 M calves (p < 0.001). Calves from 15 M dams had an increased head circumference/BW ratio compared to calves from 27 M dams, while calves from this latter group had an increased ratio compared to calves from adults (p = 0.005). Body mass index was greater in calves from adults than in those from 15 M and 27 M dams (p = 0.002). Milk production from 15 M and 27 M dams was similar but lower than that from adults (p = 0.03). Calves born from adult dams had greater blood glucose concentrations than those from 15 M and 27 M dams (p < 0.05). Serum IGF1 concentrations were higher in calves from adults than in calves from 15 M and 27 M dams (p = 0.01). This study showed that age at first gestation affects offspring postnatal growth performance, glucose metabolism and IGF1 concentration.

Keywords: bovine; dam age; fetal programming; growth; offspring.

Figure 1

Milk production from pregnant heifers at 15 months (••••), 27 months (– – –) and multiparous cows (–––) until weaning. Different letters indicate difference between means is significant (p < 0.05) between treatments. Values are means ± SEM. Treatment, p = 0.03; time, p < 0.0001; treatment × time, p = 0.94.

Figure 2

Glucose (A), serum insulin (B), and serum IGF1 (C) concentrations in calves from heifers impregnated at 15 months (••••), 27 months (– – –) and multiparous cows (–––), from birth until weaning. Different letters indicate that the difference between means at a specific time point is significant (p < 0.05) between treatment offspring. Values are means ± SEM. For glucose: treatment, p = 0.03; time, p < 0.0001; treatment × time, p = 0.05. For serum insulin: treatment, p = 0.99; time, p < 0.0001; treatment × time, p = 0.98. For serum IGF1: treatment, p = 0.01; time, p < 0.0001; treatment × time, p = 0.34.