Somewhere on the moon battling worms: can rotational grazing do the trick?

Abstract

It is not unlikely that in the future the use of anthelmintic treatment will not suffice for treating nematode infections because of the resistance developed by nematodes. Then, other strategies will have to be followed to deal with nematode burdens. One method to do this is to prevent sheep from getting infected by nematodes by using a rotational grazing system in which sheep graze one area no longer than it takes the worms to develop from an egg to an infectious L3- larvae, with as goal to interrupt the worm cycle.

In this research is tested whether following a rotational grazing programme brings the number of EPG (Eggs Per Gram faeces) of lambs under 100 EPG for N. battus and under 500 EPG for strongylus- type eggs.

The rotational grazing plan that was followed included grazing of a pasture no longer than 14 days and a waiting period before returning to a pasture of at least 2 weeks. The lambs, who were all under one year old, had been administered no anthelmintic treatment shorter than 6 weeks prior to testing.

Concluding can be said that the hypothesis as stated in this research has been proved wrong when it comes to strongylus- type eggs. Most lambs that followed a rotational grazing plan all their life did not have an egg count lower than 500 EPG. As to Nematodirus battus the hypothesis holds true, for only a small percentage of the lambs sampled (6,7%) had counts higher than 100 EPG.

Unfortunately, when trying to explain why the hypothesis is not true for strongylus- type worms, no correlations were found between data found with the McMaster procedure.