Estimating total separable lean in beef carcasses by using multiple area measurements of the longissimus dorsi in combination with other measurements

Quality has played the major role in determining the value of a beef carcass for many years. Recently, edible portion or yield of lean meat is obtaining a major role more equal to that of quality in evaluating beef animals. Therefore, a relatively simple and reliable method should be derived for estimating muscling or leanness.

The literature indicates that physical composition of various cuts is highly related to physical composition of the entire carcass. Weights of muscles and bones have been obtained in attempts to develop useful criteria for estimating carcass leanness. Although these methods have proven highly significant in estimating carcass lean, they are time consuming, laborious and costly.

The official grade standards of the United States Department of Agriculture evaluate beef according to conformation, finish and marbling in the ribeye. Objective measurements for estimating yield of closely trimmed wholesale cuts are being studied at the present time in order to classify beef according to cutability.

A limited number of investigations have shown only a small relationship between carcass leanness and area of the Longissimus dorsi muscle at the twelfth rib. This investigation was undertaken to determine whether an average of area measurements taken at the fifth rib, twelfth rib and last lumbar vertebra would give an improved estimate of total carcass lean. Also, the relationship of carcass length, carcass weight and fat thickness over the twelfth rib to pounds of carcass lean was determined.