Stress response to social isolation followed by exposure to a novel object in aged ewes born to undernourished mothers.

ABSTRACT

Fetal programming by subnutrition affects offspring's behaviour, metabolism, and sensitivity to stressors in sheep. The objective was to determine the stress response of ewes born to mothers nutritionally restricted during gestation to social isolation followed by exposure to a novel object. Twenty-six-year-old Corriedale ewes born to mothers who grazed high or low pasture allowances (HPA and LPA groups) from 23 days before conception until 122 days of gestation were used. Ewes were individually isolated in a novel place for 10 min, and 5 min after its beginning, an orange ball was dropped into the test pen. The ewes' behaviours were recorded during the test. Blood proteins, glucose and cortisol concentrations, heart and respiratory rates and rectal and surface temperatures were determined. The number of times looking at the ball tended to be greater in HPA ewes than LPA (6.7 ± 1.0 vs 4.7 ± 0.8, P = 0.08). The LPA ewes had greater serum albumin concentration than HPA ewes (3.2 ± 0.1 g/dL vs 3.0 ± 0.1 g/dL, P = 0.02), regardless of the applied stressors. Overall, the nutritional treatments applied to ewes during their intrauterine development did not modify the stress responses to social isolation followed by exposure to a novel object.