Economic impact of gastrointestinal nematodosis in sheep: Enhanced meat production by anthelmintic treatment

A field study involving 4 to 10–month-old sheep (40) of either sex, naturally infected with gastrointestinal nematodes (EPG >300) was conducted for estimating the economic loss, in terms of meat production, due to gastrointestinal nematodosis. The selected sheep were divided into 2 equal groups with a comparable initial mean body weight and they were maintained according to the farmers’ practices. One group was maintained free from gastrointestinal nematodes (negative on quantitative faecal examination) with tactical subcutaneous dosing of ivermectin @ 200 µg/ kg body weight. The other group was left untreated allowing them to harbour the naturally acquired infection. Body weight and quantitative faecal examination of all the sheep under study were recorded at monthly interval for 12 months. The net loss due to reduced meat production in terms of rupees was derived from the final difference in mean body weight between the infected and parasite free groups. The calculation took into account the standard dressing percentage of sheep (50%), cost of treatment per sheep during the entire course of the study and the average rate per kilogram of mutton (Rs 130.00) in the state of West Bengal, India. The mean loss of body weight due to gastrointestinal nematodosis, as recorded, was 3.225 kg with a net per capita loss of 1.613 kg meat production in the infected group during the entire period of the study. The cost of treatment during the entire study period was Rs 14.36/sheep and the resulting net economic loss due to gastrointestinal nematodosis in terms of rupees was Rs 195.33.