Undesirable changes in weight and body composition often have resulted from selection on weight at specific ages or on weight gain over a particular time interval. These changes have stimulated considerable interest in investigating the possibility of altering the shape of the weight-age growth curve.

Comparisons and concomitant selection of animals is complicated by the dynamic nature of the variables involved in production and efficiency. Feed intake, body mass and body composition change simultaneously in both magnitude and direction as the animal grows and ages. The interpretation of 'merit* of individuals either within a breed or across breeds may change when comparisons are made at different points along the growth plane. Through the application of growth models that describe the total growth curve, either in the weight-time or food intake-time domain, an attempt is made to characterise the phenomenology and aetiology of growth of the animals concerned.

The purpose of this paper is to examine two models of growth used to describe the weight-age and food intake-age relationships of an unselected mouse population, to examine their 'goodness of fit' and the potential for utilizing their characteristic parameters as selection criteria for an alternative approach to selection for growth and efficiency.

A Parratt, J. SF Barker

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 7. Symposia (1), , 405-410, 1982
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