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A note on crossbreeding for fat-lamb production in the hot tropics

Published online by Cambridge University Press:  02 September 2010

J. P. Sehgal ,
S. A. Karim ,
Manohar Singh  and
R. M. Acharya
J. P. Sehgal
Affiliation:
Central Sheep and Wool Research Institute, Avikanagar, Rajasthan 304501, India
S. A. Karim
Affiliation:
Central Sheep and Wool Research Institute, Avikanagar, Rajasthan 304501, India
Manohar Singh
Affiliation:
Central Sheep and Wool Research Institute, Avikanagar, Rajasthan 304501, India
R. M. Acharya
Affiliation:
Central Sheep and Wool Research Institute, Avikanagar, Rajasthan 304501, India
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Abstract

To compare the genetic group differences in live-weight gains, efficiency of food conversion (in terms of dry matter, total digestible nutrients, digestible crude protein, digestible energy and metabolizable energy) and physiological responses related to heat balance, a total of 24 male lambs (91 to 180 days old), four each of Malpura, Sonadi, and their crosses with Dorset and Suffolk breeds, were given a ration having a roughage to concentrate ratio of 250:750g/kg and metabolizable energy content of 100MJ/kg dry matter. Live-weight gain per day was higher and the food conversion ratio (the intakes of total digestible nutrients, digestible energy and metabolizable energy per kg gain) was lower in the crossbreds than in the native sheep. The crossbreds had higher respiratory rates (153 per min) than the natives (140 per min) but there was no significant difference in rectal temperature between purebreds and crossbreds. The crossbred lambs in the present experiment grew faster, consumed more food and utilized the food more efficiently than did the native lambs, despite the fact that they dissipated more energy as body heat. It was, therefore, concluded that the crossbreds performed better than the native breeds between 3 and 6 months of age, even though they were not permanently acclimatized to hot environmental conditions.

Type
Research Article
Information
Animal Production , Volume 35 , Issue 3 , December 1982 , pp. 435 - 438
Copyright
Copyright © British Society of Animal Science 1982

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References

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