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The effect of diet and genetic constitution on growth curves and efficiency in rats

Published online by Cambridge University Press:  02 September 2010

Susana Calderari de Lozano
Susana Calderari de Lozano
Affiliation:
Departamento de Ciencias Fisiológicas, Facultad de Ciencias Médicas, Santa Fe 3100, Rosario 2000, Argentina
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Summary

Equations relating biomass to cumulative food ingested ad libitum were defined in rats from weaning to 200 days of age. Two inbred lines of the IIM strain: α, of medium adult weight, and b, of low adult weight, were fed on two different diets, × and Z. The following groups were formed: αX, αZ, bX and bZ. Body weight and food intake were recorded over a 1-day period every second day. For each of the four groups, body weight, W, could be described as a function of cumulative food intake (F) by the equation:

Each exponential term was assumed to measure the behaviour of a portion of the biomass. The first exponential term implied an intense growth and a high initial efficiency, which became effectively zero by about 100 days of age. The second exponential term implied a weak growth and a low but significant efficiency of food utilization. Type of diet influenced level of intake and was important at early ages (<100 days). At 46 days of age, animals of both lines were heavier and more efficient when fed on diet Z. The genetic influence determining final adult weight becomes evident after 46 days of age.

Type
Research Article
Information
Animal Production , Volume 25 , Issue 3 , December 1977 , pp. 381 - 388
Copyright
Copyright © British Society of Animal Science 1977

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References

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