The use of non-carcass parts in the prediction of beef carcass composition on the slaughter floor

Abstract

Ninety-five steers were used to develop a method of estimating the weights or percentages of the four carcass tissues—muscle, bone, fat and connective tissue—while the carcasses were still on the slaughter floor. From an investigation of a number of non-carcass parts it was found that three measurements could be used to estimate all four carcass components. The measurements were (a) short-cut tongue weight; (b) foreshanks weight; (c) hot side weight. Simple and multiple regression equations were developed to estimate the weights of muscle, bone and connective tissue in the chilled side, and the accuracy of the estimates was compared with that of recorded prediction methods. The most useful equations employed short-cut tongue weight and hot side weight to estimate total side muscle weight, and foreshanks weight to estimate both total side bone weight and total side connective tissue weight. Fat weight was estimated from hot side weight and the estimates of the weights of the other three carcass components. This technique was more accurate than the Australian Beef Carcase Appraisal System and Butterfield's equation, both of which use fat thickness measurement at the 10th rib. When fat thickness measurement was included in regression equations, the estimates of muscle weight and fat weight were slightly improved. Advantages of using the 'non-carcass parts' technique are as follows. All four major carcass components are predicted; the carcass components can be recorded as absolute weights or percentages of chilled side weight; chilled side components are predicted whilst the hot side is still on the slaughter floor; no commercial loss occurs in carcass, offals or by-products; all measurements used in prediction are weights; and fat thickness measurements may be included in the prediction. The additional information enables producers to make a more critical assessment of the nutritive performance and genetic progress of their herds.

Use of carcass density for determining carcass composition in beef cattle

“…During the course of the study, the following measurements were recorded: fasted live weight (after restricting the animals to water only for 24 h), hot carcass weight, and chilled carcass weight; fat thickness at the 12th rib and rump Pg fat thickness (Moon 1980), both recorded in Table 1; foreshanks weight (Johnson 1979) which is the weight of both foreshanks, disarticulated at the carpo-metacarpal joint and cleansed of impacted dirt and faeces from sole and inter-digital areas. Twelfth rib fat thickness is the subcutaneous fat thickness measured three-quarters of the distance from the medial to the lateral border of M. longissimus thoracis et lumborum.…”

Prediction of beef carcass composition from organs and tissues of the non-carcass parts

“…Of the two, the intermandibular method, with a lower standard deviation of the mean difference between predicted and actual side fat weight, was slightly the superior predictor. Johnson (1979) demonstrated that the trimmed tongue could be used in multiple regression to predict side muscle weight on the slaughter floor, with an accuracy surpassed only by predictions using the weight of M. biceps femoris or M. longissimus, or combinations of the weights of either of these muscles or shin muscle group, with chilled side weight. In an effort to improve the accuracy of this technique by using entire trimmed muscles from the head, the current study failed to demonstrate any superior predictors, and served only to confirm the relative accuracy and convenience of the variables chosen by Johnson (1979) (trimmed tongue weight, hot side weight and fat thickness at the 12th rib) to predict side muscle weight.…”

“…Johnson (1979) demonstrated that the trimmed tongue could be used in multiple regression to predict side muscle weight on the slaughter floor, with an accuracy surpassed only by predictions using the weight of M. biceps femoris or M. longissimus, or combinations of the weights of either of these muscles or shin muscle group, with chilled side weight. In an effort to improve the accuracy of this technique by using entire trimmed muscles from the head, the current study failed to demonstrate any superior predictors, and served only to confirm the relative accuracy and convenience of the variables chosen by Johnson (1979) (trimmed tongue weight, hot side weight and fat thickness at the 12th rib) to predict side muscle weight. This simple technique, though never used in an Australian abattoir, lends itself to commercial application, since hot side weight and a fat thickness measurement are routinely recorded on the slaughter floor, whilst the tongue may be trimmed in a few seconds, also on the slaughter floor.…”

“…These were the non-carcass parts technique where fat weight is estimated by difference (Johnson, 1979), and the technique utilizing chilled carcass weight plus fat thickness at the 12th rib (Butterfield, 1965) (Table 5). All three prediction equations were derived using data from the current study.…”

“…The removal of such a sample joint may considerably reduce the value of a side of beef. Johnson (1979) introduced a new approach by using non-carcass parts to predict beef carcass composition on the slaughter floor. He used composite organs such as head, tongue, foreshanks and hindshanks, and not the individual tissues, muscle * Present address: Faculty of Veterinary Medicine and Animal Science, Universiti Pertanian Malaysia, Sordang, Selangor, Malaysia.…”