Factors affecting subcutaneous fat depth at two sites on beef carcasses

Abstract

Over a 12-month period, fat depths at the P8 rump and 12-13th rib sites were measured on 10968 beef carcasses at 4 Tasmanian abattoirs. All cattle were assigned to 1 of 5 breed types: British beef, dairy, dairy-beef cross, beef cross, and European and European cross. Dairy-beef cross and European breeds were excluded from the analysis because of small numbers. Sex and age (dentition) were recorded. As the data set was unbalanced and no single relationship between P8 rump and 12-13th rib sites applied, models describing the relationship between fat depths at the 2 sites were developed for subsets of the data. These showed that breed type, sex, age, season, and carcass weight all affected the relationship between fat depths at the 2 sites. In general, British beef and beef cross cattle could be considered as 1 group, but dairy cattle were different. In the former group, for the no-teeth age class a seasonal and sex effect was evident, giving rise to 4 models, 1 for each of the steer and heifer groups in winter-spring and summer-autumn. For the no-teeth dairy cattle there was no sex effect and all seasons were pooled to form an overall model. For older cattle (2, 4, and 8 teeth) there was significant monthly variation, and few overall models could be developed. In addition, the relationship between fat depths at the 2 sites was generally independent of carcass weight in older cattle. The analysis revealed that within the subcutaneous fat depot the relationship between sites for fat depth can be influenced by a range of variables.