Comparison of the carcass characteristics of steers of different breeds and pre-weaning environments slaughtered at 30 months of age

The carcass composition (dressing-out percentage, kidney and channel fat, fat depth at the 12(th) rib, eye muscle area, and trimmed fat, bone, and muscle weight) of 30-month-old beef-type steers [Angus (71), Beef Shorthorn (28), Galloway (29), Hereford (15), and Red Poll (14)] and dairy-type steers [Friesian (72), Milking Shorthorn (29), Ayrshire (30), and Jersey (29)] were studied over 5 consecutive years. Animals were selected for the trials after weaning and were grazed on pasture with occasional supplementation. The dairy-type steers had lower dressing-out percentages, heavier kidney and channel fat, lower fat depths at the 12(th) rib, and heavier bone weights than the beef-type steers. The difference between bone weight and lean weight was the best linear function of the carcass parameters to discriminate between dairy-type and beef-type breeds. There were significant between-year differences in fat variables and in eye muscle area, but not in bone weight and lean weight. There were positive relationships between the fat variables common to all breeds, and a negative relationship between the fat variables and bone weight and lean weight. The variance of kidney and channel fat and fat depth at the 12(th) rib increased with the mean, and the frequency distributions of bone weight and lean weight showed significant (P < 0.01) skewness and kurtosis.