The establishment and survival of Oesophagostomum columbianum in male and female sheep given high and low protein diets

Abstract

Young sheep fed on a low protein (6%) diet were more susceptible to infection with O. columbianum than those on a high protein (18%) diet. Both the number of adult nematodes recovered 56 days after infection, and the fecundity of the female worms prior to autopsy, were greater in the former group. Examinations at the 10th and 56th days after infection revealed a marked reduction with time in the numbers and extent of distribution of macroscopic nodules, associated with the parasite, throughout the intestines; no differences associated with the diet were recorded. Differences in the susceptibility of the host were also associated with the host's sex. Thus the male sheep generally harboured more adult nematodes than the female sheep at autopsy. This effect was most pronounced with the sheep on the low protein diet. The female nematodes which parasitized the female sheep were more fecund than those in the male sheep.