Work

Early weaning in pregnant Nelore cows as a foetal programming strategy: 1. Effects on cow-calf and backgrounding offspring growth, and skeletal muscle gene expression in beef cattle

Year: 2025

Type: article

Abstract: In tropical beef systems, the dry season coincides with mid-to-late gestation, creating a nutritional conflict between lactation and foetal development. Early weaning (EW) mitigates this stress, but its impact on Bos indicus offspring muscle development via foetal programming remains unclear. This study evaluated the effects of weaning strategy and dam parity on maternal performance and offspring postnatal growth and skeletal muscle gene expression. A randomised 2 × 2 factorial design was utilised with 58 Nelore cow-calf pairs. The treatments were composed of early (EW; 150 d lactation) versus conventional weaning (CW; 240 d lactation) and dam parity (multiparous (MP) or secundiparous (SP)). The data were analysed considering the animal as an experimental unit by using the Mixed procedure, considering the WS, DP as a fixed effect, and the two-way interaction in the model. Maternal BW and body condition score (BCS) were monitored during gestation. Offspring growth was assessed from birth to 18 months, and Longissimus thoracis mRNA abundance was analysed at 5, 13, and 18 months. During gestation, MP dams had greater BCS (P = 0.01) and BW (P < 0.001) compared to SP dams. During the dam's gestation, EW and MP dams had greater BCS (P < 0.001), BW (P < 0.001), non-pregnant empty BW (P = 0.002) and pregnant compound (P = 0.034) compared to CW and SP dams (P < 0.001). The EW calves increased birth BW (P = 0.054), weaning BW (P = 0.034), and average daily gain (ADG; P = 0.015) compared to CW calves. Calves born to MP dams increased weaning BW (P = 0.005) and ADG (P = 0.008) compared to SP calves. There was a WS × DP interaction for the mRNA abundance of MTOR (P = 0.011) and EIF4E (0.017), where EW-SP calves showed smaller mRNA abundance compared to CW-SP calves at 18 months. The CW calves showed greater mRNA abundance of PAX7 (P = 0.05) at weaning, TRIM63 (P = 0.006) at 13 months of age (P = 0.006), PAX7 (P = 0.04), NFB1 (P = 0.01) and IGRF1R (P = 0.05) at 18 months of age compared to EW calves. In conclusion, early weaning effectively improves maternal nutritional status during gestation, which positively programmes offspring's prenatal and pre-weaning growth. Furthermore, this strategy induces long-term alterations in the expression of genes related to muscle hypertrophy and atrophy, indicating that alleviating maternal nutritional stress via early weaning can modulate the physiological potential of the progeny.

Source: animal