Association of colostrum traits with the farrowing process and reproductive performance of sows in a free farrowing system.

Colostrum is vital for neonatal piglets, supplying energy, immunoglobulins, hormones, and other bioactive compounds critical for early survival. Beyond its nutritional role, colostrum also reflects the sow's physiological and hormonal state during the periparturient period. This study investigated associations between colostrum composition, farrowing traits, and reproductive performance in a free farrowing system. Sixty sows were monitored, and colostrum samples (5-10 mL) were collected after the birth of the first piglet. Concentrations of progesterone, albumin, and alpha-lactalbumin were measured in colostrum serum. Farrowing characteristics and litter outcomes were recorded. Across all sows, 897 piglets were born and the mean farrowing duration was 242 min. Colostrum progesterone averaged 21.6 ± 10.8 ng/mL, albumin 7.33 ± 1.47 mg/mL, and alpha-lactalbumin 1602.7 ± 506.9 ng/mL. Progesterone concentrations were positively correlated with albumin (r = 0.29; p = 0.02) and alpha-lactalbumin (r = 0.38; p = 0.002). Progesterone also correlated positively with log-transformed farrowing duration (r = 0.27; p = 0.03), piglet to placenta expulsion duration (r = 0.26; p = 0.04), and incidence of severe meconium staining (r = 0.27; p = 0.04). Sows requiring more than one obstetrical intervention had significantly higher progesterone concentrations (25.9 ng/mL) compared to those with none or one intervention (19.3 ng/mL; p = 0.02). This study is the first to link specific colostrum traits with farrowing outcomes in a free farrowing system, suggesting colostrum progesterone, despite its low correlation, may serve as an indicator for prolonged farrowing.