Physiological responses to gastrointestinal nematode infection in sheep selected for genetic difference in resistance to 'Haemonchus contortus'

Abstract

The benefit of selection for resistance to gastrointestinal (GI) nematode infection is a lower worm burden. The expectation is that resistant sheep should suffer less production loss due to a reduced parasite infection. Yet, productivity of resistant sheep is comparable to or lower than that of animals carrying a large parasite burden. This research was designed to determine if divergent selection for resistance to 'H. contortus' had produced correlated changes in one or more of the following variables, voluntary feed intake and diet selection, ruminal digestion and nutrient partitioning.