Weaning pigs onto grass

Pigs are generally fed on a diet rich in grains, which means their feed competes with the human food supply chain. Now that grains are scarce and the feed prices are rising, there is a need for alternatives such as silage and root crops. These contain little starch and a lot of fibre, which is good for the bowels and for the immune system. But it does slow the pigs’ growth. And pig farmers do not want that. Yet the cause of the high fibre feed does not seem to be lost yet. If you feed adults pigs on it for a while it seems that they convert a proportion of the fibre into energy. This fermentation is brought about by bacteria in the large intestine of the pigs. Maria Sappok, PhD researcher at Animal Nutrition, wants to know exactly how this works. What goes on in those intestines? She ended up in Wageningen where the Animal Nutrition chair group has developed an in vitro system – a kind of artificial bowel. The hay or silage goes into a bottle with a solution to which Sappok added some pigs’ droppings, which contain the intestinal bacteria that the bacteria break down. During this process gas is formed and by measuring the speed at which this happened she could estimate how well the pig digested the silage. Sappok has improved the in vitro test so much that it is a good imitation of the passage of feed through the pig’s system. It is clear that pigs have difficulty digesting silage but if you get pigs used to raw fodder in the long term, as happens in the organic farming sector, they seem better able to break down the fibres. It is too soon for firm conclusions, however, says Sappok.