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.

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.