Faecal concentration of cortisol metabolites in prepartum ewes

This study was performed to determine the endocrinological starting point of parturition in ewes and to study correlations between the viability of offspring and the concentrations of faecal cortisol metabolites in the dam using 11-oxoetiocholanolone EIA (measuring 11,17-dioxoandrostanes). The levels of faecal cortisol metabolites of 10 ewes positive for ovine pulmonary adenocarcinoma (OPA) were compared against 10 negative ewes during the last week of gestation and 12 h after delivery. The mean concentration in the OPA group was higher (500-600 ng/g) than that observed in the control group (150-200 ng/g). The mean cortisol level showed a significant (p<0.05) increase during the last two days of pregnancy in all subjects (OPA and controls). The increase in faecal cortisol metabolites was not significant (p>0.05) in three animals (2 OPA and 1 control); their offspring showed low viability and died soon after delivery. These results underline that the mean baseline faecal cortisol metabolite concentration in ewes does not affect physiological pregnancy while, to ensure viability of lambs, it is essential that the cortisol level increases significantly (90%), regardless of its baseline level.