Effect of energy restriction on serum cortisol and its faecal metabolite (11,17-dioxoandrostan) in pregnant ewes

Abstract

The objective of the study was to investigate the effect of an energy restriction on serum cortisol and its faecal metabolite (11,17-dioxoandrostan) in Chios ewes in late gestation. Twenty pregnant and ten non-pregnant out of 38 randomly selected ewes were detected with ultrasound and were separated into three groups (n=10) on day 105 after mating: normal energy fed pregnant group (NE), restricted energy fed pregnant group (RE), and non-pregnant group (NP). Blood samples were taken on days 117, 130, and 144 of pregnancy and faecal samples were taken twice a week starting on day 106 of pregnancy from both pregnant and non-pregnant ewes. After extraction of serum and faecal samples, concentrations of cortisol and 11,17-dioxoandrostan (11,17-DOA) were measured. A significant decrease in RE was determined only on day 144 of pregnancy (P <= 0.05). Between the two pregnant groups (NE and RE), a significant difference was found only on day 144; at this period, RE had lower serum concentrations. RE had significantly lower 11,17-DOA concentrations in late pregnancy than NE. In pregnant ewes, the levels decreased in a late gestational period. The present data shows that in ewes fed 14.47% crude protein and 8.82 MJ/kg of metabolic energy in late pregnancy, pregnancy toxaemia does not occur. We suggest that the determination of cortisol metabolites in faeces is more objective and safe than that of serum cortisol concentrations.