Development and survival of Haemonchus contortus infective larvae derived from sheep faeces under sub-tropical conditions in the Potohar region of Pakistan |
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| Authors: | Farhana Riaz Chaudary Mazhar Qayyum James E Miller |
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| Institution: | (1) Department of Zoology, University of Arid Agriculture, Rawalpindi, Pakistan;(2) Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 80306, USA |
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| Abstract: | Assessment on the development and survival of Haemonchus contortus larvae was made to evaluate the influence of microclimatic variables viz., relative humidity (%), temperature (°C), rainfall
(mm) and intensity of sunlight (hrs). Pasture plots in a sub-tropical area, Pakistan were contaminated with H. contortus eggs at the start of every month. The plots were sampled on fortnightly basis after contamination for three consecutive months.
The overall pattern indicated the most favorable conditions for survival, development and translation to herbage was during
the wet season from July to October and the least favorable was during the dry season from April to June. Peak infective larvae
(L3) recovery was during the 15–45 day interval for each plot and the lowest number was during the 75–90 day interval. Herbage
was collected in the morning, afternoon and evening and greatest recovery of L3 was in the morning time and least in the afternoon. The number of L3 on pasture was directly related to the pattern of rainfall and relative humidity with a significant (P < 0.05) positive correlation
and temperature and intensity of sunshine were negatively correlated (P < 0.05). The results suggest that pastures can remain
infective for up to 2 months and become relatively clean by 90 days after contamination. Thus, long pasture rest periods,
especially during the high risk wet season, may be a helpful strategy to reduce the infection levels. |
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| Keywords: | Development Survival Haemonchous contortus Infective larvae Sheep Subtropical conditions Pakistan |
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