Fat - rib fat thickness and distribution
Rib fat thickness is the measured depth of subcutaneous fat over the quartered rib site between the 5th and 13th ribs. Rib fat thickness may vary between sites and typically increases towards the head (5th rib). Rib fat is a better indicator of yield than the P8 site. It is measured when the carcase is chilled and quartered, as opposed to P8 fat being measured on the hot carcase on the slaughter floor.
A covering of fat is needed to protect the high value primal cuts from rapid chilling, which can cause toughening, and to enhance eating quality and appearance. MSA has a minimum requirement of at least 3mm of rib fat. Each market specifies an optimum fat depth that suits their customer requirements.
Fat distribution is important for both yield and quality. The key requirement for all beef markets is to have adequate cover over the high-value cuts along the loin (back) and rump.
Fat distribution is affected by the genetics and nutrition of the animal. Higher boning yield results from moderate to heavy muscled animals grown consistently to produce adequate and even carcase fat.
MSA requires carcases to have adequate fat coverage over all major primals. An area of inadequate fat distribution greater than 10cm x 10cm will result in an ungraded carcase.
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