Background and aims Premature birth interrupts normal growth and may affect postnatal brain development. We hypothesised that prematurity in pigs would affect neuromuscular control and behaviour also beyond the neonatal period.
Methods Caesarean-delivered preterm (n = 44, 90% gestation) and term (n = 33, 100% gestation) piglets were fed parenterally for five days and then enterally with milk-replacer until d26. Time until basic motor skill (BMS) acquisition (eye lid opening, first walk and stand) were recorded, coordination assessed, and locomotion and general exploration were tracked from open field video recordings on d4, d9, d16 and d23. A novel-object recognition test was performed on d24 (assessing both specific exploration and short-term memory), and learning ability was assessed with a clicker-based poke-reward test from d18-d25 in a subset of piglets.
Results BMS acquisition was delayed in preterm piglets (all p < 0.001). Coordination scores were lower in preterm piglets at all ages whereas locomotion and exploration were reduced only on d4 (all p < 0.05). Preterm piglets explored novel objects less (p < 0.001) but short-term memory assessments were not different. Poke-reward performance improved over time in both preterm and term pigs but did not differ significantly between groups, which partly reflects that only clinically healthy preterm piglets could be tested. In preterm piglets, locomotion on d23 was increased (p < 0.01) when parenteral nutrition had been supplemented with enteral nutrition the first five days after birth.
Conclusion Acquisition of neuromuscular control, locomotion and exploration are quantifiable functional neurological endpoints in preterm piglets that may be used to characterise developmental disturbances and nutritional interventions.