Effects of prenatal undernutrition on emotional reactivity and cognitive flexibility in adult sheep

Abstract

The experiment reported was designed to test two hypotheses: that prenatal undernutrition (a) increases emotional reactivity and (b) impairs cognitive flexibility in sheep. The mothers of one group were fed live weight maintenance requirements throughout pregnancy (control, C) while those of another group were fed 50% of that amount from days 1 to 95 of pregnancy and 100% from then onwards (prenatal undernutrition, PU). At 18 months of age, PU sheep were more active during restraint ( P<0.05) and approached a novel stimulus more slowly ( P=0.02). In response to a sudden stimulus, PU males and C females showed a higher initial level of locomotion compared to C males, which only gradually declined, while PU females started at a high initial rate, changing rapidly to immobility. In a T-maze, PU resulted in a shift of side preferences (laterality) from a general right-bias to neutrality in males and to a left-bias in females ( P<0.05). In the two reversal tasks, C males and PU females had a preference for one side over the other, while PU males showed no preference. In contrast to C males, PU males failed to improve their learning speed from the first to the second reversal ( P<0.05). It is concluded that PU can lead to increased emotional reactivity and changes in side preference in both sexes and impaired cognitive flexibility in males. Undernutrition during pregnancy, therefore, not only affects the welfare of the dam, but also the personality of her offspring.