Carcass composition and yield of 1991 vs 1957 broilers when fed "typical" 1957 and 1991 broiler diets.

Whole carcass yield and the yield of parts (i.e., wings, saddle and legs, Pectoralis major, Pectoralis minor, breast skin, rack, abdominal fat pad, heart, and lungs), as well as whole carcass analysis for fat, moisture, and ash, were measured in the 1957 Athens-Canadian Randombred Control (ACRBC) and in the 1991 Arbor Acres (AA) feather-sexable strain, when fed "typical" 1957 and 1991 diets. Using the average of both sexes, the carcass weights of the 1991 birds on the 1991 diets were 4.4, 3.9, and 3.5 times heavier than those from the 1957 ACRBC on the 1957 diet at 43, 71, and 84 d of age, respectively. Birds fed the 1991 diets had significantly heavier carcass weights than those fed the 1957 diets. Hot carcass yield of the AA broiler (mean of both sexes) was approximately 6 to 7% higher at the same age than for the ACRBC. Water uptake in the carcass (following a 60-min immersion in ice water) was approximately 2 to 2.5% higher in the ACRBC than in the AA broiler. Yield of saddle and legs as a percentage of live BW was about 4% higher in the AA than in the ACRBC. Dietary regimen did not affect the yield of saddle and legs. Males had 2 to 3% more saddle and legs than the females. The yield of total breast meat for the AA was approximately 3% higher (mean = 16.9%) than for the ACRBC over both sexes and all ages. Breast yield on the 1991 diets was approximately 1.2% higher for the AA than for the ACRBC. Females had slightly higher breast yield (1%) than males. The AA broiler had consistently heavier fat pads and higher percentage carcass fat at the same age and on the same diet than did the ACRBC. The percentage carcass fat was significantly higher on the 1991 vs the 1957 diet and in females vs males. The male-female difference in percentage carcass fat increased with age. Heart and lung size as a percentage of live BW were lower in the AA than in the ACRBC.