A model was constructed to predict the effect of changes in feeding and growth parameters on biological efficiency (lean tissue produced/food consumed) of the dam/offspring unit, under ad-libitum feeding. In a genetically scaled production system (with all cumulative variables proportional to mature weight (A), and all age variables proportional to A to the power 0.27), biological efficiency of the dam/offspring unit is independent of mature weight. However when time variables are constrained to allow an annual restricted joining (as for most pasture based cattle and sheep enterprises), a 25% increase in mature weight results in an increase in biological efficiency of 4%.
An alternative strategy to increase biological effi change the shape of the growth curve. Results from the an increase in appetite has little effect on biological although it does decrease age at slaughter. A decrease food intake of 253s results in a 143: increase in biologi efficiency, reflecting the importance of the dam food c efficiency of the total production system. An increase food efficiency would result in an increase of 9* in bi efficiency. However, evidence from between species and suggests that there is little genetic variation in food ciency model eff ici in mat cal osts in of 253S ologica breeds ef f ici is to show ency, ure in 1 ency.

J. M Thompson, R. Barlow

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume XI. Genetics of reproduction, lactation, growth, adaptation, disease, and parasite resistance., , 271–282, 1986
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