Comparative Resistance of Sheep Breeds to Haemonchus contortus in a Natural Pasture Infection

The objective of the present study was to evaluate the resistance status of three indigenous sheep breeds (Thalli, Lohi & Kachhi) against Haemonchus contortus by natural pasture challenge infection. Following deworming, 15 male lambs of each breed were subjected to selected contaminated pastures in a vicinity of the livestock farms. Between breed variation was assessed on the basis of parasitological, hematological, biochemical and cellular parameters. After nine weeks, 10 lambs of each breed were randomly selected and slaughtered to evaluate the differences in adult worm burden among the sheep breeds. Overall, Lohi sheep performed relatively better in the trial; however difference between breeds remained low. Both significant (P<0.05) and non-significant differences with respect to resistance against haemonchosis were noted at different intervals in all the practiced parameters except fecal egg counts, which showed non-significant difference throughout the trial. This report did not provide the major difference among breeds. This type of study on a large scale could be a model in identification of comparatively resistant sires and incorporation in breeding programs for the improvement of flocks concerning resilience and resistance against nematodes that could lessen dependence upon chemical anthelmintics. © 2010 Friends Science Publishers