Pigs who were given a course of antibiotics as piglets have a less well-developed immune system than those who weren’t. This conclusion has been drawn by animal researcher Dirkjan Schokker. He studied the long-term consequences of antibiotics at Wageningen UR’s Sterksel innovation centre.
Schokker split a litter of young piglets (four days old) and gave some of them an antibiotic used to ward off lung infections. The control group got nothing. He measured the composition of the gut bacteria on days 8, 55 and 176 and the fitness of the pigs’ immune system. Last year Schokker reported that the immune systems of the piglets who didn’t get the course of antibiotics were developing better. As well as the harmful bacteria, the antibiotic had also knocked out the useful gut bacteria that strengthens resistance.
This year he is presenting the long-term effects. On day 55, some four weeks after weaning, when the piglets get solid food instead of milk, there was a wide variation in the gut bacteria in each of the two groups. This meant Schokker couldn’t find a connection between antibiotic use and bacterial composition. But on day 176, just before the pigs were slaughtered, he could. In the control group the diversity of bacteria was greater. Moreover, this group’s immune systems were better developed. The control piglets had substantially more receptors in their intestines that signal and fight harmful bacteria. What’s more, his research shows that an antibiotic that is used to combat lung infections also has an influence on the composition of intestinal bacteria. The manufacturers of this antibiotic state on the packaging that their product has little or no effect on intestinal bacteria, but this conclusion was based on an antibiotics test administered to older piglets. Whereas Schokker, who tested young piglets, did indeed find an effect.
The research supports the policy of using antibiotics sparingly in pig farming. A course of antibiotics like these kills off the good bacteria as well as the bad. Pig farmers would do well to follow up this kind of treatment with a diet that stimulates the growth of good gut bacteria. Such a health cure for piglets is still a distant prospect, but it is being worked on in the Feed4Foodure programme, in which Wageningen researchers are cooperating with the animal feed industry.