Can early weaning in previous lactation of beef cows affect the puberty and reproductive performance of female offspring?

We aimed to compare the effects of early (EW; 150 days) or conventional (CW; 240 days) weaning of the previous offspring on the reproductive performance of heifers born from secondiparous (SEC) and multiparous (MULT) Nelore cows. For this experiment, 55 Nelore female calves were used: 30 from CW (15 from SEC and 15 from MULT) and 25 from EW (10 from SEC and 15 from MULT). Calves had access to creep-feed provided 5 g/kg of body weight (BW) from 90 days of age until weaning. After weaning, calves were maintained on pastures and received a supplement provided at 10 g/kg of BW until 16 months (mo). From 12 to 16 mo, blood samples were collected for serum antimullerian hormone (AMH) concentration, and reproductive tract score (RTS; scale 1 to 5), endometrium thickness, and pregnancy rates were evaluated. At 14 mo, a subgroup of 23 heifers (n = 6 EW MULT, n = 6 CW MULT, n = 4 EW SEC, and n = 7 CW SEC) were submitted to ovum pick-up for in vitro embryo production (IVP) and were submitted to a P4/E2-based protocol for two timed-artificial insemination (TAI). No interactions between dam parity, weaning strategy, or time were observed for serum concentration for AMH, RTS, or endometrium thickness (p > 0.1). Weaning strategy or dam parity did not affect the antral follicle count and IVP (p > 0.1). The RTS (overall mean: 2.9 ± 0.1) and pregnancy rates (overall for two TAIs: 76%) were not affected by weaning strategy or dam parity (p > 0.1), but, unexpectedly, the endometrium thickness (mm) was greater in heifers from CW (10.5 ± 0.28 vs. 9.8 ± 0.32). In conclusion, weaning at 150 days did not effectively affect the reproductive tract development, antral follicle count, IVP, and reproductive performance in the Nelore heifers that were in utero during the EW of their dams.