Our objectives were to determine the effects of two herbage allowance levels during mid to late gestation on growth performance, physiological responses of cow-calf pairs, and offspring skeletal muscle development through weaning. Fifty-six pregnant Nellore cows 444 ± 42 kg initial shrunk body weight (SBW) and 3.66 ± 0.28 body condition score (BCS), each carrying a male fetus, grazed Urochloa brizantha cv. Marandu pastures under either low HA (LHA; 2.80 kg dry matter (DM)/kg BW) or high HA (HHA; 7.60 kg DM/kg BW) during the final 151 days of gestation (d 140 ± 15 of gestation). As intended, differences in HA (P < 0.01) were established by manipulating stocking rate (P < 0.01; 1.70 vs. 3.40 AU/ha for HHA and LHA, respectively). LHA cows had lower body weight (BW; P < 0.001), average daily gain (ADG; P < 0.001), BCS (P < 0.001), Longissimus muscle area (LMA; P = 0.002), and subcutaneous fat thickness (SFT; P = 0.02) than HHA cows during gestation. During lactation, LHA and HHA cows showed similar BW, LMA, and SFT (P ≥ 0.12); however, LHA cows had greater ADG (P < 0.001) and lower BCS (P < 0.001) than HHA cows. In late gestation, LHA cows exhibited higher plasma urea (P < 0.01) than HHA cows, but no differences were detected in milk yield or composition during lactation (P ≥ 0.20). HHA calves had greater BW at birth (P < 0.01), at 120 days of age (P < 0.01), and at weaning (P < 0.01) than LHA calves. HHA calves also had more muscle fibers at 30 (P < 0.01) and 240 (P < 0.01) days of age than LHA calves, whereas muscle-fiber cross-sectional area did not differ at either 30 or 240 days days of age (P ≥ 0.21). In conclusion, adequate herbage allowance during mid- to late gestation improves maternal performance and metabolic status, supporting fetal skeletal muscle development and enhancing offspring growth through weaning.
Souza et al. (2026) studied this question.