89 Meat Science Perspective, Carcass Composition, and Grid Marketing: Have we Made any Advances?

Abstract

Abstract Throughout recorded history of beef cattle improvement, the pendulum of cattle type has swung from large, old and extremely fat to extremely short in stature and overfinished to extremely tall in stature and lean to moderate in size and overfinished. During all of these transitions, the underlying growth principles of muscle, fat, and bone have remained constant. As animals age, muscle growth, as well as independent accumulation of water and protein increases at a decreasing rate whereas fat growth increases at an increasing rate. Beef carcass grading records reported by USDA indicate that percentage of Prime and Choice grade carcasses increased consistently from 62.9% in 1956 to a peak of 97.7% in 1987. Beginning in 1988, a notable decline in percentage of Prime and Choice began that plateaued from 1997 to 2007; USDA records indicate that Prime and Choice percentage was the lowest in history in 2006 at 59.0%. Since 2007, percentage of carcasses grading Prime and Choice has again steadily increased to 80.7% in 2021. Concomitantly, percentage of carcasses with yield grades of 4 or 5 has increased from a recent low of 1.3% in 1997 to 16.2% in 2021 – the highest percentage of overfinished cattle since records began. The recent improvement in quality is primarily the result of an industry paradigm shift from marketing of live animals and selling beef as a commodity to the marketing of carcasses and selling beef as premium branded products. Cattle feeders have been incentivized to market cattle as carcasses rather than live animals primarily due to the economics associated with carcass transfer. Carcass transfer is the proportion of live animal gain that is retained as carcass gain – this value increases at a decreasing rate during the finishing period and typically ranges from 75 to 85% of live animal gain. Our current yield assessment metric was developed in the late 1950s and is representative of cattle of that period, not modern cattle. The yield grade estimates 40% of the variation in cutability of beef-type cattle carcasses and 0% of the variation in cutability of dairy-type cattle. Opportunity exists to improve beef carcass yield estimation. The goal of our beef production system is to provide domestic and foreign customers with premium quality products that meet their expectations for palatability. Objective shear force values indicate that steaks from the rib and loin have continued to become more tender during the last 3 decades.