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

Abstract 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.