Journal of Veterinary Parasitology

Temperature plays a crucial role in embryonation and hatching of eggs as well as development of infective larvae (L₃) of strongyle nematodes. The present study examines the differences in the rate of egg hatching and development of larvae of Haemonchus contortus subjected to variable temperatures (10 to 40°C) at fixed humidity (55-60%). At 24 h post-incubation, hatching of H. contortus eggs varied significantly (P<0.001) with minimum (0.20%) at 10°C, around 5.0% between 15-20°C and 40°C and maximum (93.08%) at 25°C. At 72 to 120 h post-incubation, >95% hatching was observed with temperature varying between 15 to 25°C. On faecal culture both at 10 and 40°C, the larval (L₃) recovery was almost zero up to 12 days post-incubation. At 25 to 35°C, the larval recovery was around 80 and >90% on day 6 and 9 to 12 post-incubation. The findings suggest that the optimum temperature at which development and translation of exogenous stages of H. contortus occurs is at 25°C.