Written by Baris Ozdinc
Intestinal nematode worm parasitism is a world-wide problem with impacts on the livestock industry. A recent article in the Economist details this as a major concern of sheep farmers in Australia and New Zealand that causes the sheep to waste away, and, in severe cases, die. Treatment options are far and few between, as excessive use of drugs have caused the evolution of resistance in the nematodes. However, researchers at the University of Western Australia are investigating countermeasures against the worms within the sheep themselves. Dr. Paz’s research group at the University of Western Australia started a breeding program in which they breed nematode-resistant sheep – those with the fewest nematode eggs. This approach works and appears to be an inheriable trait; the resistant-sheep offspring also have fewer nematode eggs. The mechanism behind how this works, though, is not known. To investigate, Dr. Paz’s group compared the fecal microbiome of high-nematode egg and low-nematode egg sheep breeds. Strikingly, the research group identified systematic differences between the gut microbiome of their sheep breeds. The differences were most notable in the faeces from the small intestine where the worms live. In the short intestine, resistant sheep had richer and more diverse bacterial communities than susceptible sheep. According to the research, the resistant sheep’s bacterial populations contain abundant taxa able to ferment carbohydrates and turn them into short-chain fatty acids. Dr. Paz suspects that genetically resistant sheep may be providing an intestinal environment friendly to bacteria which produce short-chain fatty acids that repel worms or compete with them for carbohydrates. Of course, it could also be worms which are affecting the vulnerable sheep’s microbiome. Dr. Paz’s work suggests that probiotic treatment may be a third option to control nematode infestations in the sheep industry, other than drugs and resistance breeding.