Effect of equine chorionic gonadotropin on glycosidase activity in the reproductive tract of ewes, in relation to ovarian response and embryo yield

•α-mannosidase in uterine fluid & endometrium of eCG treated ewes was higher than controls.•β-NAGASE in uterine fluid & endometrium of superovulated ewes was lower than controls.•α-mannosidase in uterine fluid positively related to embryo yield.•β-N-acetyloglucosaminidase in endometrium related to the number of corpora lutea.•Glycosidases in uterine fluid & endometrium negatively related to blood ovarian steroids. The aim of this study was to investigate a) the effect of equine Chorionic Gonadotropin (eCG), in the dosage used for oestrus synchronization or for superovulation, on the activity of α-mannosidase (α-MAN) and β-N-acetyloglucosaminidase (β-NAGASE) in the genital tract of ewes before maternal recognition of pregnancy and b) the possible relationships among ovarian steroids concentration, glycosidase activity and embryo yield and quality. Twenty-four Chios ewes were treated with progestagen intravaginal sponges for 12 days and eCG [superovulation (SOV), n = 7, 1000 IU; oestrus synchronization (OS), n = 7, 500 IU; controls (C), n = 10, 0 IU] at sponge removal. Ovarian response was assessed and embryos were collected on day 6 of the oestrous cycle, after slaughter. Oestradiol-17β and progesterone concentrations were determined in blood serum samples collected before slaughter using a radioimmunoassay. The activities of α-MAN and β-NAGASE were assayed, photometrically, in uterine horn flushing (UHF) samples, caruncular endometrium (CE) and intercaruncular (ICE) endometrium samples, collected after slaughter. Alpha-MAN activity was higher in the UHF, CE and ICE of SOV ewes, as well as in the UHF and ICE of OS ewes, compared to controls. Beta-NAGASE activity in the UHF and in the ICE of SOV ewes was lower than in C ewes. Alpha-MAN activity in the UHF was positively correlated with the response to superovulation in terms of total recovered structures, embryos or high-quality embryos collected from the ewes. Beta-NAGASE activity in the CE correlated to the number of corpora lutea observed on the ovaries, at the day of embryo collection. Beta-NAGASE activity in UHF and α-MAN activity in the ICE were negatively related to oestradiol-17β concentration in blood serum; β-NAGASE activity in UHF and in ICE was negatively related to progesterone concentration in blood serum. In conclusion, eCG in the dosage used for superovulation and, in a lesser degree, in the dosage used for oestrus synchronization affects glycosidase activity in the genital tract of Chios bre