Chemical Composition of Necrotic Fat Lesions in Beef Cows Grazing Fertilized “Kentucky-31” Tall Fescue

Abstract

The chemical composition .of necrotic fat lesions from two groups of beef cows grazing fertilized tall fescue (Festuca arundinacea Schreb.) was compared with that of normal fat tissue from the same cows and with results reported in die literature. Sample group one consisted of 68 normal fat samples and 37 necrotic fat samples from a group of nine cows, and sample group two consisted of 51 normal fat samples and 56 necrotic fat samples from a group of eight cows. Necrotic fat lesions were found in abdominal fat depots, but not in subcutaneous fat or pericardial fat depots. Crude protein (percentage of wet tissue) for normal vs necrotic fat was 1.5 vs 4.1 (P<.01, group 1) and 2.4 vs 5.1 (P<.01, group 2). Ash was .3 vs .7 (P<.01, group 1) and .2 vs .7 (P<.01, group 2). Ether extract was 91.9 vs 47.7 (P<.01, group 1) and 88.3 vs 53.8 (P<.01, group 2). Cholesterol (mg/g of ether extract) was 4.1 vs 12.0 (P<.01, group 1) and 3.2 vs 9.5 (P<.01, group 2). The long-chain fatty acid composition of the ether extracted fraction of all samples was similar. The amount of fatty acids tended to be greater in the residue fraction not extracted by ether from necrotic fat than in the residue from normal fat. The molar proportion of stearic acid was greater in the necrotic fat residue than in normal fat residue and the proportions of oleic and palmitoleic were less. The concentrations of calcium, magnesium, potassium, and sodium were 21.8 (P<.01), 4.7 (P<.01), 1.1, and 2.6 (P<.01) times greater, respectively, in necrotic fat samples than in normal fat samples. The localization (abdominal fat depots) and composition of necrotic fat lesions for those cows grazing fertilized tall fescue were similar to results reported by others for ruminants.