Prediction of the Energy Value of Cow's Milk

The quantification of lactation response requires that various yields of milk of various chemical compositions be equated to a common term. Although the gross energy value is the most common characteristic to which all organic substances can be reduced, its direct measurement is expensive. As a consequence, a study was made of the relationships among the energy value and the concentrations of total solids, solids-not-fat (SNF), fat, protein, lactose, and ash in 600 two-and seven-day composite samples of milk from 42 Holstein cows and ranging from 1.6 to 6.4% fat. An analysis of 21 different combinations of milk components showed that the most practical equation for the accurate prediction (C.V. = 1.3%) of the energy value of milks having a wide range of chemical composition is :