Protein, lysine and feed intake level effects on pig growth. III. Regression analysis and economic aspects

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Abstract
SUMMARY Data from the experiment described in the first paper of this series were subjected to regression analysis. Lean meat and live-weight gain response to both lysine and crude protein intake was almost linear in period 1 but in later periods little response was evident. Response of live-weight gain to increased energy was continuous though diminishing in the later periods. In periods 1 and 2 lean gains showed positive though diminishing response to energy. In a multivariate regression analysis it was clear especially for younger pigs that the response to dietary lysine for both live-weight and lean meat gains is influenced by the dietary level of crude protein and the energy intake. Separate multivariate analysis for each sex indicated that females are more efficient converters of lysine and energy into live weight and lean meat. Also an interaction between sex and dietary lysine level was suggested. A methodology for an economic analysis taking the joint objectives of total cost of production, speed of grain and quality of gain is established as a basis for design of high profit system of production.