A model for study of lungworm (Dictyocaulus sp.) and gastrointestinal nematode infection in young red deer (Cervus elaphus)

A model of sub-clinical parasitism in young red deer, using concurrent tric kle infections of lungworm (Dictyocaulus sp.) and mixed gastro-intestinal ( GI) nematodes of deer-origin was evaluated. 20 parasite-free deer calves we re artificially reared indoors from 4 days of age. A further five calves we re naturally reared on pasture with their dame, treated with anthelmintic a nd brought indoors at 3-4 months. At 4-4.5 months of age they were individu ally housed and allocated to five groups (n=5). Groups were dosed 3 x per w eek, for 9 weeks with 0, 100 and 500, 200 and 1000 (2 groups), 400 and 2000 infective larvae of lungworm and mixed GI nematodes, respectively, culture d from deer faeces. Liveweight and voluntary feed intake measurements and f aecal and blood samples were taken weekly. In the fourth week following ces sation of trickle infection, deer were euthanased and lung and GI nematodes recovered. Both lungworm and GI nematode infections became patent-at Week 3: of infect ion. Maximum group arithmetic mean faecal egg counts were 100-190 epg. Maxi mum group arithmetic mean-faecal lungworm larval counts were 58-123 lpg. Gr oup arithmetic mean nematode counts at slaughter ranged from 439-806 for GI nematodes and 31-73 for lungworm, respectively. Despite low nematode count s, reduced liveweight gain, voluntary feed intake and serum albumin concent ration, elevated serum pepsinogen, gastrin and globulin concentrations and elevated peripheral eosinophil counts and slight haemoconcentration, but no clinical signs, were observed. The reduction in liveweight gain was relate d to the reduction in voluntary feed intake (r(2)=0.83; p<0.088). Naturally -reared deer had similar liveweight gains, voluntary feed intake and nemato de counts to artificially-reared deer. Thus, methods of infection to produc e concurrent :sub-clinical lungworm and GI nematode burdens for study of su b-clinical parasitism in young deer have been defined. (C) 2000 Elsevier Sc ience B.V. All rights reserved.