Selection for 8-Week Body Weight under Different Dietary Protein Levels

A study was conducted to investigate the influence of low dietary protein on the genetic parameter of 6- and 8-week growth in a meat-type randombred broiler stock. Heritability estimates for 6- and 8-week body weight were obtained from the Athens Canadian (AC) randombred population when fed isocaloric diets containing 22%, 18% and 14% protein. Two generations of individual phenotypic selection for 8-week body weight resulted in similar genetic improvement under the 22% and 18% protein diets and little progress under the 14% protein diet. Carcass protein was reduced 0.3% for each 4% reduction in dietary protein. The mean percentages of carcass water, total lipid, and ash values across diets were not significantly different. Protein efficiency ratios indicated greater protein efficiency on the 14% protein diet.