The Nutrition of Meat-Type Ducks. 11' The Effects of Variation in the Energy and Protein Contents of Diets on Biological Performance and Carcass Characteristics

摘要

In three experiments, ducklings aged 2 or 3 weeks were grown to 8 weeks of age on diets containing nfrom 12 to 25 % crude protein, and from 11 .6 to 15.2 MJ metabolizable energy (ME)/kg 'as fed'. nGenerally the highest growth rates and best feed conversions were observed on diets with the highest nenergy content. A dietary protein content of about 12% was adequate for maximum growth, best nfeed conversion, and the highest protein efficiency ratio. Where comparison could be made, males ngrew faster than females. nME contents of the diet determined by total collection of excreta or its estimation using Cr2O3 nwere in good agreement. ME values for the diets declined as ducklings aged, as did nitrogen balance. nCarcass protein decreased and carcass fat increased as the energy (kJ) to protein (%) ratio nincreased. Dressing percentage tended to increase with increasing dietary energy. Females had nhigher dressing percentages than males. nIt would appear that, for best growth rate and feed conversion, a low protein of 12-13 % and na high energy diet of about 14.0 MJ ME/kg, corresponding to an energy to protein ratio of about n1000, are adequate for ducks grown from 2 to 8 weeks. For maximum carcass lean, and minimum nfat content, a low energy (kJ) to protein (%) ratio of about 600 is desirable. This corresponds to ndietary concentrations of about 15 MJ/ME kg of diet and 24% crude protein.