Relationship of beef type and breed to offal composition

Extensive reports of detailed research concerning tissue and excretory shrinkage of beef animals from farm to market have been published. However, few investigations have been made which dealt with the weight losses that occur at the time of slaughter. These losses represent the components of the offal. Since more and more emphasis is being placed upon carcass evaluation and cut-out data as a guide to the selection of meat-type breeding stock, the need for a valid live weight figure becomes critical.

In the determination of dressing percentage and carcass cut-out data, the basis is either the live weight or the carcass weight. The data calculations are not as questionable when based on a carcass weight because only tissue shrinkage is involved and it is relatively minor. However, when these percentages are based on a live weight, the shrinkage due to excretion and offal components such as hide, viscera, and digestive tract can vary widely due to breed, pre-slaughter treatment, and the live weight figure used in making the calculations. The various live animal weights which may be used are: (l1) off-feed weight taken at the farm or feedlot, (2) slaughter or kill weight taken Just prior to slaughtering after the animals have received a prescribed preslaughter treatment, (3) slaughter or kill weight taken without a prescribed pre-slaughter treatment, and (4) adjusted live weight based on a standard viscera percentage. Because of the variations in these weights, the question may arise, "What live weight should be used in determining dressing percentage and carcass cut-out values?"

Many adjustments have been proposed to account for shrinkage due to offal. For example, the National Barrow Show uses a digestive tract standard of 12.5 percent of empty body weight to obtain an adjusted live weight on which to base dressing percent. Recently, emphasis has been placed upon using standard viscera percentages in beef carcass contests. These standards are designed to adjust for the loss in weight due to components of the offal.

The variations in offal components and pre-slaughter treatment have a definite effect upon live weight. If live weight is to be used as a basis for the computation of various carcass improvement criteria, an investigation and report of the offal component percentages certainly is warranted.

The purpose of this study is to provide fundamental knowledge to the animal husbandman about the offal component percentages of beef animals and to elucidate some of the problems facing the establishment of valid offal standards.