Effects of litter size, sex and periconceptional ewe nutrition on side preference and cognitive flexibility in the offspring

Maternal undernutrition during pregnancy alters the physiology, behaviour and cognitive abilities of the offspring in sheep. Undernutrition restricted to the time around conception alters the physiology of the offspring, but effects on the behaviour and cognitive abilities are unknown. We studied the effects of mild periconceptional undernutrition in sheep on side preference and cognitive flexibility in the offspring. Ewes were well fed (controls) or mildly undernourished from 60 days before until 30 days after mating (PCUN; 10-15% body weight reduction). Offspring were evaluated at 4 and 18 months of age in a left-right choice maze using social and feeding motivation as rewards. We determined side preference, and assessed cognitive flexibility as the ability to improve runs required to reach criterion during two reversal learning episodes. Side preference in the PCUN offspring was close to neutrality in singleton mates (p <= 0.05) and twin females (p <= 0.05) at 4 but not 18 months of age. Twin offspring tended to be more likely to change side preference between 4 and 18 months (p = 0.07). Performance on reversal learning was similar in PCUN and control offspring, but speed of learning improved faster in female than in male lambs (p <= 0.05) at 4 but not 18 months of age. These findings suggest that mild periconceptional undernutrition in sheep can alter behavioural laterality of the offspring, and that singleton/twin status, sex and postnatal age are all important factors to consider in evaluating the effects of prenatal insults on postnatal behaviour. (C) 2009 Elsevier B.V. All rights reserved.