Maternal parity modulates the impact of lactation management on fetal programming of postnatal performance in Nelore...

Fetal programming occurs when conditions that affect a pregnant cow's health and physiological status have long-term impacts on the offspring. The present study evaluated the effects of early weaning (150 days) and conventional weaning (240 days) of the previous offspring on the body weight, testosterone levels and puberty attainment in male Nelore offspring from the subsequent pregnancy of primiparous or multiparous cows. A total of 56 animals that were in fetal development at the time of weaning were assessed at mean ages of 12.5, 14.3, 15.5 and 17.3 months. Statistical analyses were performed using the Statistical Analysis System (SAS) in a 2 × 2 factorial design (maternal parity category and weaning type, with significant differences were considered at p ≤ 0.05. There was interaction between the maternal parity category and weaning type for body weight of the subsequent offspring (p < 0.01). The subsequent offspring of primiparous cows belonging to the early weaning group reached 319.9^a ± 6.9 kg, compared to a body weight of 304.6^b ± 5.9 kg for subsequent offspring in the conventional weaning group. Furthermore, maternal parity category affected testosterone levels (p = 0.02), whereby the offspring of multiparous cows showed concentrations of 4.8^a ± 0.3 ng/mL and those of primiparous cows showed 3.6^b ± 0.3 ng/mL. Early weaning of the previous offspring from primiparous cows improved the body weight of the subsequent offspring. Multiparous cows' offspring are heavier and show higher testosterone concentrations. These results highlight the need to consider fetal programming as a critical factor for offspring development and underscore the importance of identifying strategies to optimize gestation in beef cattle.