Prediction of the energy value of ewe milk at early lactation

Abstract

This study was conducted in order to develop equations for the prediction of ewe's milk energy content via milk composition. Twenty-four multiparous Chios breed ewes were examined in a eight-week study that started at parturition. Animals were fed in groups (12 ewes), with two, highly concentrated (forage to concentrate ratio 30:70 DM), rations differing in undegradable protein (UP) content. The following equations are proposed: (i) when fat content (F; g/kg) is the only variable: EV_L(kJ/kg)=39×F+2090 (SE 0.30 kJ/g), (ii) when total solids (TS; g/kg) is the only variable: EV_L(kJ/kg)=33×TS–1222 (SE 0.26 kJ/g) whilst the following equation is proposed when solids non fat content (SNF; g/kg) is an additional known variable: EV_L (kJ/kg)=39×F+36×SNF–1990 (SE 0.27 kJ/g). Fat corrected milk (FCM) yield can be calculated by the following equation: Y (FCM 6%; kg/d)=L (kg/d)×0.472+0.0088×F (g/kg)], where L is milk yield.