The quantitative definition of cattle carcasses

Abstract

The possibility of defining quantitatively the carcasses of cattle has been investigated and a procedure evolved, based upon "conformation", "finish", and "quality", which are the features appraised by beef-carcass graders. A series of ratios has been used to define "conformation" with respect to shape rather than to dimensional attributes. For example, length, "meatiness", and compactness, which are attributes of a hind leg, are described by a ratio of which the numerator is the "circumference" measurement at an anatomically fixed point whereas the denominator is a defined length measurement. The trade term "finish" is covered by a percentage assessment of the distribution of subcutaneous fat over the carcass whereas thickness of fat is the mean of two measurements of depth made at points fixed anatomically. The proportion of fat to lean is stated by a ratio of which the numerator is a maximal measurement of the depth of lean meat a t a defined situation and the denominator is the mean depth of subcutaneous fat. Attributes of "quality" are colour of fat, firmness of fat, "marbling", and colour of lean meat. A series of five defined colours has been used to classify colour in a sample of subcutaneous fat rendered by heat. Firmness of fat has been related to a series of iodine numbers of greater or lesser magnitude: firm, medium, soft, and oily fats were found to be classifiable by the reaction of the rendered substance to slight manual pressure exerted through a blunt probe. The degree of marbling was determined from the size relation of a petrol-ether extract to a sample portion of the carcass taken at a defined situation. Colour of lean meat was classified by reference to a series of defined colours which were given distinctive numbers. Quantitative figures from observations may he recorded for examination by statistical methods or they may be transposed as diagrammatic presentations which may be related to trade standards or to market types for the purpose of judging carcass competitions. The procedure may also be used to provide data from which a "fleshing index" can be determined. Examples of all three possibilities are stated. The procedure has been tested on three series of animals, from which measurement errors for individual carcasses were calculated and found to be satisfactorily low. However, it has not yet been adequately tested for the comparison of between-group differences in carcasses, principally because no animals suitable for such a test are likely to become available until experimental conditioning is undertaken. The procedure is, therefore, presented tentatively.