Exploratory study of the effects of intra-uterine growth retardation and neonatal energy supplementation of low birth-weight piglets on their post-weaning cognitive abilities

Abstract

The present study investigated the effects of intra-uterine growth retardation (IUGR, score 0–3; i.e., “normal” to “severe”) level at birth, and the effects of neonatal energy supplementation (dosed with 2 ml of coconut oil, commercial product or water, or sham-dosed), on post-weaning cognitive abilities of low birth-weight piglets (<1.1 kg). In total, 184 piglets were recruited at weaning (27±0.1 days) for habituation to the test procedures, and were either tested for spatial learning and memory in a T-maze (n=42; 37±0.5 days) or for short-term memory in a spontaneous object recognition task (SORT; n=47; 41±0.3 days). Neonatal supplementation did not affect performances of pigs in the T-maze task or SORT. IUGR3 pigs tended to be faster to enter the reward arm and to obtain the reward in the reversal step of the T-Maze task, suggesting a better learning flexibility, compared to IUGR1 (entry t72.8=2.9, P=0.024; reward t80=3.28, P=0.008) and IUGR2 (entry t70.3=2.5, P=0.068; reward t73.9=2.77, P=0.034) pigs. However, a higher percentage of IUGR1 pigs tended to approach the novel object first (DSCF-value=3.07; P=0.076) and to interact with it more (t40=2.19, P=0.085), relative to IGUR3 pigs. IUGR1 pigs showed a strong preference for the novel object, as they had a greater percentage time difference interacting with the objects when the novel object was presented (t81=−3.41, P=0.013). In conclusion, some low birth-weight piglets are able to perform a spatial task and an object recognition test, but performances in these tests may be modulated by IUGR level.