Equations for postnatal chemical composition of the fat-free empty body of sheep and cattle

Abstract

SUMMARYRegression analysis was used to examine the relationship between the weight of water, protein and ash (kg) and fat-free empty body (FFEB) weight (kg) in data from six published and one unpublished experiment conducted in this laboratory. The analysis involved 201 sheep divided into 12 groups which were either in positive growth, weight stasis, weight loss or compensatory growth prior to slaughter. Each of the relationships between water, protein or ash and FFEB was linear and could be expressed by a common slope. Small (though statistically significant) differences in intercept were found between treatments. The following overall equations provide a simple description of the data:water (kg) = 0·721 FFEB + 0·37, R.S.D. 0·18,protein (kg) = 0·215 FFEB - 0·22, R.S.D. 0·16,ash (kg) = 0·055 FFEB - 0·07, R.S.D. 0·09.Published data for cattle were also examined and corresponding equations are:water (kg) = 0·701 FFEB + 3·59, R.S.D. 2·6,protein (kg) = 0·234 FFEB - 2·00, R.S.D. 2·3,ash (kg) = 0·060 FFEB - 0·71, R.S.D. 1·8.It is suggested that these equations could be used in computer simulation models of growth to calculate FFEB gain (or loss) from nitrogen balance.