An Investigation of the Development of “Quality” Traits in Boran, Bos indicus, Steer Carcasses.

Abstract

The production of high priced carcasses has become associated with the production of fast growing muscular tissue (lean meat) combined, in the final product with the desired proportion of carcass fat. A survey of the literature (Callow 1961, Barton 1959, Ledger 1960) together with information obtained from unpublished grading data, suggests the optimum level of fatness for current tastes is about 28 per cent. As fat is the last of the carcass tissues to be laid down, the time taken to reach this degree of fatness can be used as an index of the rate of maturity for quality carcasses. Because it is economically desirable to produce as great a weight as possible of muscular tissue before the animal becomes over-mature (over-fat) it follows that a good beef producer should be a fast growing but slow maturing (fattening) animal. However, the gross weight of fast grown lean in a carcass of the desired degree of fatness is not the only criterion of carcass worth. Equally important is the distribution of that lean throughout the carcass, for it is clearly advantageous to have a higher proportion of this component in the more expensive joints. On the basis that the above is a reasonable summary of the more important traits involved in the production of high quality carcasses it is proposed to illustrate the part played by them in three herds of Boran, Bos indicus steers considered to represent the first three stages of development from primitive husbandry. These stages of" basic"," intermediate" and" improved" production as they relate to East African beef ranching are described as follows:—(a) Basic production refers to the purchase of immature stock from tribesmen in the extensive, arid" bush" areas for ranch-fattening on grass. In practice these" immatures" are usually between 21 and 3 years old at the time of purchase and are seldom slaughtered before they are four.