Differential Average Daily Gain of Pregnant Holstein × Gyr Heifers: Effects on Growth, Performance, and Metabolic Responses of Their Calves

This study aimed to evaluate the effects of different average daily gains (ADGs) in dairy heifers during gestation on the subsequent performance of their female calves. Sixteen 3/4 Holstein × 1/4 Gyr female calves, originating from two maternal nutritional treatments, were used: moderate feeding to achieve an ADG of 0.37 kg/day (MOD) and high feeding to achieve an ADG of 0.72 kg/day (HIG). Calves received colostrum within the first 4 h after birth, equivalent to 15% of their body weight. They were then fed 6 L of transition milk daily until 2 days of age, followed by 6 L of whole milk daily until weaning at 90 days of age. Feed intake and refusals were monitored throughout the study. Morphometric measurements, body weight, and blood samples for hormone and serum metabolite analyses were collected on days 1, 31, 61, and 91. Calves from the HIG group tended to have greater birth body weight (p = 0.09) and body length (p = 0.09) than calves from the MOD group. However, MOD calves had greater ADG (p < 0.01) and feed efficiency during the preweaning period, resulting in similar body weight at weaning between treatments. HIG calves also had greater rump height (p = 0.04) and tended to have greater withers height (p = 0.08), whereas differences in body length were observed primarily at birth and did not persist throughout the preweaning period. Blood metabolite concentrations were influenced primarily by calf age. Treatment effects were observed for triglycerides (p = 0.02) and globulin (p = 0.04), and a treatment × days interaction was detected for total cholesterol (p = 0.03), whereas BHB, IGF-1, and glucose concentrations changed with calf age (p < 0.001, p < 0.01, and p = 0.01, respectively). These findings indicate that, although maternal nutrition influenced prenatal growth, differences observed at birth did not persist throughout the preweaning period.