In Kashmir during spring (March-May), the valley gets the maximum rainfall, while in summer (June-August), it is the lowest followed by autumn (September-November). During aupumn it is comparatively dry and in winter extending from December to February, there is precipitation in the form of snow and rain. The sheep flocks are reared in lush green pastures during summer. However, they are allowed to graze on village grazing parks during spring and autumn. A number of reports are available on gastrointestinal nematodes in domestic ruminants from other parts especially tropical India (Thaper, 1956; Bali and Singh, 1977; Patnaik et al., 1973; Misra et al., 1974. The present studywas undertaken to obtain a season-wise comprehensive picture of most prevalent gastrointestinal nematodes in sheep in Kashmir valley, to enable the sheepbreeders and veterinarians in planning the prophylactic measures well in advance.

The samples were examined and cultured at Disease Investigation Laboratory, Srinagar. The faecal samples were examined for gastrointestinal nematode infections qualitatively, as per Soulsby (1986). The number of gastrointestinal nematode eggs per gram (EPG) of the faeces was estimated. For identification of the genus, faeces were cultured by standard methodology. Identification was done on the basis of characteristic morphology of the infective stage-larvae, as per Soulsby (1986). A total of 3,652 samples were examined and data were analysed by standard statistical procedures (Snedecor and Cochron, 1967).

Out of a total of 3,652 faecal samples examined, 59.83% were positive for nematodes. The highest incidence (67.14%) was observed in summer followed by 64.87% during autumn season. The difference found between autumn and summer parasitic infections, however, was statistically non-significant. Winter recorded the lowest incidence of 44.31% of nematode (overall) infection. Strongyles had the highest percentage (60.78%) as against Trichostrongylus sp., Haemonchus, Nematodirus and Marshallagia infection in order of 35.56%, 20.73%, 3.66% and 1.37%, respectivelyTable 2.

Strongyles infection showed a descending trend in spring, summer and autumn at 61.72%, 59.77% and 56.00%, respectively but increased during winter season. Trichostrongylus spp. infection also showed a similar trend of descending order up to summer, butHaemonchus spp. infection was highest in summer (33.81 %) with a decreasing trend during autumn, winter and spring at 17.23%, 15.25% and 10.99%, respectively. Nematodirus spp. has almost the same trend i.e. highest in summer and descending trend in other seasonsTable 2.

The increasing trend of infection of Trichostrongylus spp. and Marshallagiav spp. during winter to spring season may be because of the poor managemental practices adopted by the sheep breeders. The sheds are not cleaned regularly during winter, resulting in liberation of ammonia gas and rise in temperature and humidity inside the sheds which favour the development of ova of various nematodes to infective stages. The direct life cycle of nematodes can alsobe one of the reasons which favour infection of nematodes duringwinter season.

The findings are suggestive that these animals were responsible for contaminating the pasture during spring season. The results corroborate with the observations of Dhar et al. (1997).

Haemonchus ova was found to withstand extreme climatic conditions and also survive longer period during winter season (Blood et al., 1994) resulting in mass hatching of ova and high summer infection of pasture (Bhat, 1997).

References