Yak rearing is considered to be a primary means of livelihood for nomadic people. Heavy infestation by parasites often causes significant loss to them. So far, a few studies have been conducted to determine the prevalence and effect of ecto-parasites in Yak. Thus, a study was conducted by taking 118 yak samples randomly categorised into different age groups during which ecto-parasites were found.
Of 118 samples, 26 (29%) yaks were infested by ticks. The study revealed that mostly ticks are found on the yak’s brisket, fore flank, on the neck region and anterior and posterior thighs. Moreover, the study observed that most of the ticks were found in young, old age and weaker animals probably because they are less resistant or more susceptible to ticks. This could be also because of age difference and different environmental factors while grazing in different ecological zoon. Those tick infested yaks showed clinical symptoms such as weakness, emaciation, restless with pale eyes that lead to anaemia for animals.
The study observed that 58 yaks were mildly infested with lice (65%) which are found to be highly prevalent in yak during winter since lice are more resistant under thick hair coat. The lice highly commonness in weaker animals, particularly to the female old yaks as weaker animals are less resistant to the parasites. The infested yaks were noticed clinically weak, emaciation and less drive to obtain sufficient feeds. Yak lice are mostly apparent under thick coat of neck region, chase floor and shoulder parts. The heavily lice infested yaks are weak and suffers skin irritation and anemia.
About 6% of adult yak were found in manifestation of flea which is found under thick and long hair of yak coats of old age. Number of flea on yak body was very minimal and their clinical symptoms were limited. The study revealed that effect of flea in yaks was not known clearly.
The warble fly (Hypodermosis) affects all age group animals. According to herders, particularly during summer, the warble flies are responsible for causing disease and the most terrifying effect on yaks with skin lesion. The larvae under the skin protrude small swelling which enlarge and causes small holes in skin. As a result, presences of larvae in yak skin can cause loss of appetite and reduce the milk yield. Moreover out of 40 survey interview carried out, 42% of herders stated that consequence of warble flies economically hampers when they make use of their animal skin for Zoedey (Fermented cheese). The skin is used as a packaging or storage materials for processing fermented cheese. Once animal skin is wounded, it is not possible to use for storing and making fermented cheese.
Out of 40, about 25% of herders responded that the infestation of leech (Hirudiniasis) was another ecto-parasite in yak. Leech was observed at an altitude up to 3,000 masl during rainy season causing severe anaemia (heavy loss of blood) in yaks particularly in calves.
Skin scrapping was carried out from the animals showing the symptoms and was visually examined for external parasites such as lice, fleas and ticks. The study confirmed that there was no symptom of yaks severely affected with skin lesion, skin necrosis and dermatitis for detection of mites through microscopic examination. Therefore, this study indicated that in winter, yaks were free from dermatitis, skin lesion and other associated skin diseases.
Reported by Phurpa Tshering, RNR-Extension Centre, Radhi
Photography by Nima Dorji, RNR- Extension Centre, Sakteng
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