Exploitation of Host Resistance: A Promising Alternative Approach to Control Gastrointestinal Nematodoses in Small Ruminant: A Review

Gastrointestinal nematodes (GINs) are the most insidious pathogens causing severe economic losses to the livestock industry. Among GINs Haemonchus contortus is the most pathogenic and predominant parasite of small ruminant livestock. Although the use of chemical anthelmintics is still the corner-stone of control method for GINs, the increasing rate of prevalence of anthelmintic resistance has made it less reliable control option. Anthelmintic resistance together with global demands for chemical residue free animal product has led to search for alternative sustainable control strategies which rely less on chemical anthelmintics. One of such strategy is the exploitation of host resistance against the GINs including H. contortus. The resistance of animals to GINs varies within and between breeds of sheep and goats. Host immune response plays an important role in host resistance but the immune mechanisms responsible for resistance are not fully known. Studies on identification of gene/(s) responsible for host resistance are also being carried out to find out the molecular mechanism of GINs resistance in sheep and goats all over the world. Selective breeding for GINs resistance is the ultimate solution for the problems of anthelmintic resistance. This article reviews the published reports on GINs resistance in relation to immunological response and genetic studies in small ruminants and discusses the prospects for selective breeding of GINs resistance in sheep and goat.