The chemical composition of cattle skin.

Abstract

Skin samples taken from the midsides of Hereford, Angus, and Shorthorn cattle of the same age were analysed for water, crude protein (N x 6.25), and fat contents. Water and crude protein contents were calculated as percentages of fat-extracted fresh skin and fat-extracted dry skin respectively. Breed differences in Chese components were small and not significant. Mean values obtained for all cattle were: water, 69.84¦S.E. 0.16; crude protein, 100.68¦S.E. 0.29. When fat content was calculated as a percentage of total dry matter, Angus cattle had a significantly lower skin fat content than Shorthorns and Herefords, the mean values for each breed being: Shorthorn 7.40¦S.E. 0.88; Hereford, 5.51 ¦S.E. 0.57; Angus, 3.72¦S.E. 0.26. The difference between values for Herefords and Shorthorns was not significant. At slaughter, rib cuts were collected from each beast and dissected into bone, muscle, and fat. The correlation coefficient between the percentage of fat in dry skin samples with the percentage of dissected fat tissue in fresh rib cuts was +0.18 (not significant). In a group of Hereford cattle the effect of plane of nutrition on skin composition was investigated. The percentages of water and crude protein present in skin were almost unaffected by plane of nutrition. However, the absolute contents of water and crude protein increased in animals fed to either gain or lose weight. The percentage of fat in skin increased when animals were gaining weight and decreased when they were losing weight. It is concluded that analyses of skin samples are not likely to be useful in predicting body composition of cattle.