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Altrenogest treatment before weaning improves litter size in sows

Lopes, TP, Bolarín, A, Martínez, EA, Roca, J
Reproduction in domestic animals 2017 v.52 Suppl S4 pp. 75-77
estrus, follicular development, lactation, liquids, litter size, ovarian follicles, piglets, semen, sows, spermatozoa, weaning
The study aimed to assess whether altrenogest treatment, fed before weaning (from −8 to −2 days), could improve fertility of sows showing reproductive seasonality. Ninety sows (50 in winter–spring [WS] and 40 in summer–autumn [SA]) were randomly selected and assigned to control (C; 27 in WS and 20 in SA) or altrenogest treatment (A; 23 in WS and 20 in SA) groups. The diameter and number of ovarian follicles were transrectally scanned at the onset of oestrus. Oestrus was evaluated twice daily from weaning to day 8 post‐weaning. Sows in oestrus were post‐cervically inseminated at 0 and 24 hr after the onset of oestrus with liquid stored semen (1.5 × 10⁹ sperm/doses), and farrowing rates (FR) and total piglets born (LS) were recorded. More (p < .01) sows showed no signs of oestrus within 8 days after weaning in SA (30%) than in WS (2%), without differences between A and C groups. The diameter (cm) of the follicles at the onset of oestrus was larger in A than in C sows (0.76 ± 0.01 vs 0.73 ± 0.01; p < .01), irrespective of the season. No differences in the number of follicles were found. FR did not differ between seasons and groups, being always above 85%. LS was larger (p < .01) in A (14.00 ± 0.46) than C (12.27 ± 0.44) sows, irrespective of the season. In conclusion, a short‐term altrenogest treatment at the end of lactation improves the total number of piglets born from weaned sows, probably by promoting a better and more homogeneous follicular development at the start of oestrus.