Evaluation of growth rates and resistance to nematodes of Deccani and Bannur lambs and their crosses with Garole

Abstract

Sheep rearing is a traditional occupation of about 85 000 shepherd families on the Deccan plateau in theMaharashtra State of India. They rear Deccani (D) sheep which usually bear only single lambs. Prolificacy is animportant trait for the efficiency of meat producing sheep. It was decided to evaluate and utilize Indian sheepgenetic resources with a view to improving the efficiency of sheep production on the Deccan plateau. Acrossbreeding experiment was conducted over 4 years, using rams of the D, Bannur (B) and Garole (G) breeds andD and B ewes with the aim of developing recommendations for the appropriate breed combination of a likelycomposite. It was found that crossing with G reduces live weight and growth rates significantly compared with Dbut lambs sired by G rams were more resistant to naturally acquired gastro-intestinal nematode infections and toartificial challenge withHaemonchus contortusthan those sired by D or B rams. The G breed, being from ahumid environment is, however, not adapted to the semi-arid Deccan plateau. The higher productivity (in terms ofweight of lamb weaned) of twin-bearing ewes compared with those bearing singles was evident even in extensiverearing conditions. The finding of increased resistance to gastro-intestinal nematodes in the G breed, which alsocarries a major gene for prolificacy, highlights the potential for inclusion of G in a composite breed. Negative effectson growth and survival from inclusion of the Garole need to be carefully managed.