Relationship between embryo recovery rate and uterine lavage fluid composition in postpartum mares

The aim of the study was to determine whether neutrophil numbers (PMN), try psin inhibitor capacity (TIC), lysozyme, N-acetyl-beta -D-glucosaminidase ( NAGase), beta -glucuronidase (B-Gase), total protein, and plasmin in uterin e lavage fluid of postpartum (p.p.) mares, either at the time of foal heat insemination or around the time of arrival of the embryo in the uterus, cou ld be used in predicting conception. Fifteen mares were inseminated within 13 h after the first p.p. ovulation. Uterine lavage fluids were successfull y collected from 9 out of 12 mares before insemination and from all 15 mare s before embryo recovery 7 to 8 days after insemination. The embryo recover y rate was 53% (8/15). Prior to insemination, PMN, TIC and lysozyme levels were elevated in 3/4 mares not producing embryos. However, only 1/5, 1/5 an d 0/5 mares producing embryos had elevated levels of PMN, TIC, and lysozyme , respectively. None of the parameters was significantly different in mares with or without embryos, but lysozyme was the closest to significance (p = 0.07). In both groups of mares, activities of NAGase (p < 0.01) and B-Gase (p < 0.05) were significantly higher in dioestrus than immediately after. ovulation. At embryo recovery, NAGase was higher in mares not producing emb ryos (p < 0.05). The results suggest that a long-lasting inflammation is th e best explanation for low pregnancy rates during the first p.p. oestrus. F urther research is needed to establish whether lysozyme, or possibly TIC, c ould be used in predicting conception at foal heat.