Evaluation of variation in susceptibility of three Ethiopian sheep breeds to experimental infection with Fasciola hepatica

A study was conducted to determine the variation in susceptibility of three Ethiopian sheep breeds (Arsi, Horro and Menz) to experimental infection with Fasciola hepatica. Arsi and Menz breeds of 16 rams each and Horro breed of 14 rams aged between 6 and 8 months were randomly divided into two groups. All rams in the first groups of each breed were infected with 300 viable metacercariae of F. hepatica while those in the second groups were left as controls. Parameters used to assess the level of resistance was fluke egg count (EPG), change in live weight, packed cell volume (PCV) and percentage of adult flukes recovered 18 weeks after experimental infection. The overall mean EPG of Arsi, Horro and Menz sheep breeds was 416.6, 199.1 and 355.7 while the mean number of flukes recovered at the end of the experiment was 107.0 (34.7%), 67.2 (22.3%) and 68.6 (23%), respectively. Based on these factors Arsi breed is (p < 0.05) more susceptible to the effect of F. hepatica compared to other breeds. The EPG, change in live weight and PCV results showed that Horro breed demonstrated better resistance than the rest groups; nevertheless, in terms of adult parasite recovery, no significant difference (p > 0.05) between Horro and Menz breeds was seen. The present results are good indications for the existence of variation in susceptibility of these sheep breeds to infection with F. hepatica. Further studies on genetic basis of susceptibility differences needs to be carried out.