Within minutes of birth, tiny piglets must be up on their trotters, competing with their siblings for a place at mum's dining table. But Charlotte Vanden Hole, Peter Aerts, Chris Van Ginneken and colleagues from the University of Antwerp, Belgium, were curious to find out how much control newborn piglets have over their legs at birth and whether their control improves within the first few hours of life.
Being on hand at the birth of seven litters, Vanden Hole, Van Ginneken and Sara Prims intercepted the youngsters immediately after delivery and filmed their first faltering steps as they stumbled along a checkerboard tunnel. However, an hour later, all of the piglets seemed to have better control of their limbs and the team continued filming the piglets’ progress for the first 96 h of their lives.
Rescaling their observations – as if all of the piglets were the same age and size, for comparison – and then analysing how the piglets’ walk developed during the first hours after birth, Vanden Hole, with the help of Jana Goyens and Erik Fransen, found that the piglets’ coordination improved dramatically during the first 4 h, although their movements were not completely coordinated until the age of 8 h. ‘Intralimb coordination does not seem to be fully innate [at birth]’, says Vanden Hole. However, the synchronisation of the footfall pattern did not change from the piglets’ initial steps – it was essentially the same as the adults’. The team also noticed that the youngest piglets kept their feet in contact with the ground for a longer proportion of each stride, while swinging their legs for a shorter period, and Van Ginneken and Aerts say, ‘We propose that during the first hours after birth, the piglet would adopt a means of locomotion that is as energy efficient as possible, because of the limited amount of available energy. One way of accomplishing this is by limiting the swing duration’.
While piglets are remarkably mobile, the circuits that control their movements are not fully developed at birth, although they mature rapidly within the first 4 h of life, allowing newborns to snuffle around their mother in search of milk.