CHEMICAL-COMPOSITION OF ANGUS AND HOLSTEIN CARCASSES PREDICTED FROM RIB SECTION COMPOSITION

Seventy-four small-framed Angus and sixty-nine Holsteins were used to evaluate the classic Hankins and Howe equations for predicting percent ages of water, protein, and lipid of steer carcasses varying in weight and breed type. Animals were fed either corn grain or corn silage die ts, housed inside or outside, and slaughtered at one of five predeterm ined weights within breed. Soft tissues from a carcass side and the fr om the 9-10-11th rib section were separated from bone, and the percent ages of water, protein, and lipid were measured. The Hankins and Howe equations predicted .81 +/- .181 percentage units more (P < .001) wate r and .99 +/- .213 percentage units less (P < .001) lipid than was mea sured in the carcasses. The residual difference for protein depended o n breed anddiet (P < .028) and decreased .22 +/- .078 percentage units for each percentage unit increase in predicted protein. During develo pment of equations from our data, no statistical difference was found between Angus and Holstein in the relationship of carcass water to rib water. The relationship of carcass protein to rib protein had a lower (P < .1) intercept with a steeper (P < .055) slope for Angus than for Holstein steers, whereas for lipid there was no difference between th e slopes, but Holsteins had one percentage unit more (P < .038) carcas s lipid than Angus at the same percentage rib lipid. These results con firm that composition of the 9-10-11th rib section can be used accurat ely to predict carcass composition with minor adjustments for breed ty pe.