Preliminary association of coat colour types and tolerance to Haemonchus contortus infection in West African Dwarf sheep

Abstract

Reduction in livestock productivity from internal parasites remains a major problem including the roundworm Haemonchus contortus. Treatment is rather expensive in most resource poor regions of the world, and the use of genetically resistant genotypes have been advocated. Our preliminary study investigated the association of coat colour types and tolerance to H. contortus infection in West African Dwarf (WAD) sheep. Twenty-four WAD sheep (12 males and 12 females) representing five coat colour types were orally dosed with 1000 H. contortus third-stage infective larvae, and data were collected over a 3-week period on initial and post-infection body weight (IBW and PIBW), packed cell volume (PCV), total serum proteins (TSP), albumin (ALB), globulin (GLB) and faecal egg counts (FEC). Coat colour was significantly associated with tolerance to H. contortus infection (p<0.05). Brown mouflon (A^mabbSs) sheep showed the highest mean PIBW, PCV and GLB (15.16±1.76 kg, 30.67±3.53% and 31.17±0.54 g/dl), respectively, while brown sheep with extensive white markings (aabbss) had the highest mean TSP and ALB value (73.40±2.02 g/dl and 44.47±0.49 g/dl), respectively. Badger face (A^bfaB-S-) sheep had the least mean values of PIBW, PCV, TSP, ALB, GLB and the highest FEC. There were no significant associations with sex and its interactions with coat colour on post-infection performances of WAD sheep in this study. Our results suggest that brown sheep can tolerate H. contortus infection better than other coat colour types, which may be due to the linkage between coat colour and resistance loci, linkage disequilibrium effects or resulting from pleiotropic effects deserving further study.

Keywords:

• coat colour gene
• tolerance
• Haemonchus contortus
• infection
• sheep