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 le gs, Pectoralis major, Pectoralis minor, breast skin, rack, abdominal f at pad, heart, and lungs), as well as whole carcass analysis for fat, moisture, and ash, were measured in the 1957 Athens-Canadian Randombre d Control (ACRBC) and in the 1991 Arbor Acres (AA) feather-sexable str ain, when fed ''typical'' 1957 and 1991 diets. Using the average of bo th 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 199 1 diets had significantly heavier carcass weights than those fed the 1 957 diets. Hot carcass yield of the AA broiler (xBAR of both sexes) wa s approximately 6 to 7% higher at the same age than for the ACRBC. Wat er uptake in the carcass (following a 60-min immersion in ice water) w as 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% high er in the AA than in the ACRBC. Dietary regimen did not affect the yie ld 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 (xBAR = 16.9%) than for the ACRBC over both sexes and all ag es. Breast yield on the 1991 diets was approximately 1.2% higher for t he AA than for the ACRBC. Females had slightly higher breast yield (1% ) than males. The AA broiler had consistently heavier fat pads and hig her percentage carcass fat at the same age and on the same diet than d id the ACRBC. The percentage carcass fat was significantly higher on t he 1991 vs the 1957 diet and in females vs males. The male-female diff erence in percentage carcass fat increased with age. Heart and lung si ze as a percentage of live BW were lower in the AA than in the ACRBC.