Effects of altrenogest treatment in sows on the variation of piglet birth weight and pre-weaning piglet performance

The effect of altrenogest (ALT) feeding combined with induced ovulation by human chorionic gonadotropin (hCG) in sows was evaluated on piglet birth weight (BW) variation and pre-weaning performance. Sows were divided into four groups: the control (no ALT; without hCG induction; artificial inseminated (AI) at 12 and 36 h after estrus; n = 40), ALT + hCG72 (ALT 20 mg/d, D-4–D2 (D0: weaning day); hCG 750 IU at 72 h post ALT; AI at 24 and 40 h after hCG; n = 41), ALT + hCG96 (ALT 20 mg/d, D-4–D2; hCG 750 IU at 96 h post ALT; AI at 24 and 40 h after hCG; n = 41) and ALT + no hCG (20 mg/d, D-4–D2; without hCG induction; AI at 12 and 36 h after estrus; n = 41). The results revealed that piglet BW was not different among the groups (p > 0.05). However, the standard deviation of piglet BW (SDBW) was lower in ALT + hCG72 (0.32 ± 0.02 kg; p = 0.032), compared to ALT + hCG96 (0.40 ± 0.02 kg) and ALT + no hCG (0.40 ± 0.02 kg), except for the control (0.39 ± 0.02 kg). In addition, the pre-weaning mortality rate (%PWM) due to underweight elimination at weaning (below 3.50 kg) was decreased in ALT + hCG72 (8.33%) compared to the control (32.50%; p = 0.007) but similar to ALT + hCG96 (10.71%) and ALT + no hCG (24.05%). Therefore, ALT + hCG72 treatment in sows could reduce piglet BW variation and the number of piglets eliminated at weaning