A Method for the Control of Protein and Energy Retentions in Growing Rats

Abstract

A method for the control of protein and energy retentions in the carcass was proposed using rats in this study. Twelve diets were prepared by combining 4 ME levels and 3 DCP levels. Twelve grams of each diet was offered daily to rats. The rats were slaughtered at day 20 of experiment and protein and energy retentions were determined by carcass analysis. Regression equations between nutrient intake and nutrient retention were determined by multiple regression analysis. The relationship between ME and DCP intakes in each equation obtained by setting energy or protein retention in these regression equations to optional values was drawn a figure. This figure shows that energy and protein retentions in the carcass vary in the pattern as suddle point and ridgeline of a mountain with the changes of ME and DCP intakes, respectively. The amounts of ME and DCP intakes required for making energy and protein retentions in the carcass into optional values can be determined by reading the values of ME and DCP intakes corresponding to the intersecting points of both curves of energy and protein retentions. It was confirmed that a method proposed in this study is reasonable by animal experiment.Jpn. J. Zoolech. Sci., 51 (6): [422][423][424][425][426][427][428] 1980 Protein and energy retentions in the carcass are important factors in meat production. It has been established that carcass fat of the animals decreases with the increase of dietary protein or with the decrease of dietary energy1-5) and the simultaneous change in both energy and protein is most effective6-8). It has been also known that as the dietary protein is raised, the lean proportion appears to increase steadily4), but there is a top limit beyond which additional protein will not further increase carcass leanness9).