This conclusion was drawn by PhD researcher Marije Oostindjer of the Adaptive Physiology chair group of Wageningen University in an article in last week's Biology Letters. Ms Oostindjer looked for strategies for stimulating the appetites of piglets, many of which do not eat solid food before they are taken from their mothers. After weaning they often do not start eating solid food straightaway, which causes health and welfare problems.

Snacks

Ms Oostindjer offered the piglets a range of different snacks such as chocolate peanuts and cheese cubes - both popular delicacies with pigs. She found that they would more readily try out these snacks in the presence of their mothers. She also noticed that piglets that grew up in a stimulating environment - with turf of wood shavings in the pen for example - ate more of the snacks.

But the most significant factor was the presence of the mother. Piglets that were in with the sow took an average of 15 seconds to start tucking in to the food, while those with no sow in the pen took twenty minutes. What is more, 90 per cent of the piglets in with the sow ate both chocolate peanuts and cheese cubes, as opposed to 75 per cent of those without their mother. The piglets with their mothers also ate slightly more chocolate peanuts.

Learning

The researchers would now like to establish how the sow passes on information about food to her piglets. "Do the pigs learn from seeing what the sow does or by joining in?" "Does the smell of the food and the type of living space play a role?" These are some of the research questions mentioned by Ms Oostindjer. Her research is partially funded by the technology foundation STW. In current pig-farming practice, piglets often cannot imitate their mothers because the sow has a high feeding trough that the piglets cannot reach. And piglets are routinely taken from their mothers at four weeks old.

Litter

So does it help if the piglets stay longer with their mothers? "That is not cost-effective for the farmer," answers Ms Oostindjer. "The sooner the piglets are removed, the more litters the sow can have in a year." 'Living at home' for longer is not strictly necessary as piglets are already able to digest solid food when they are still suckling. "Wild pigs go out with their mothers and eat acorns when they are only a week old." Ms Oostindjer's research may lead to a pigpen design that makes it easier for the piglets to learn from their mothers.