Potassium Concentration in Bovine Muscle as Influenced by Carcass Location, Breed, Sex, Energy Intake, Age and Shrunk Body Weight

Abstract

Potassium (K) levels were measured in six muscle categories comprising the entire carcass musculature of 36 cattle. Equal numbers of Angus and Holstein bulls, steers and heifers were fed three levels of a high corn ration in a 2 × 3 × 3 factorial design with two observations per cell. The least variability in K content for the weighted mean of total muscle and for individual muscles was found when expressed on a fat-free wet (FFWTK) basis and the most on a dry matter (DMK) basis. Although protein and potassium are both intracellular components, the expression of K per unit protein (PRK) was highly variable, indicating levels of these two components are not closely related. Animal to animal variability existed within breed × sex × energy combinations (P<.05). For all methods of expressing K concentration, differences (P<.01) were found among the six muscle categories. However, for the weighted mean K level in total muscle, the coefficient of variation for all 36 animals was only 2.43% for K expressed as FFWTK. This is because muscle to muscle variability within animal is greater than animal to animal variability within muscle. Holsteins had higher (P<.05) K than Angus in all six muscle categories and in total muscle except when expressed on a fat-free dry (FFDMK) basis. Sex and energy intake effects were minor and were reduced or eliminated when differences in fat content were removed. Correlations between K and age or weight were negative for each muscle category and total muscle. Correlations of K with age were stronger than those with weight indicating age decreases K more than weight. Age was correlated (P<.05) with total muscle K for all methods of expressing concentration except PRK.