Prediction of the Energy Value of Cow's Milk,

Abstract The quantification of lactation response requires that various yields of milk of various chemical compositions he 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: Energy (kcal/lb) = 41.84 (% fat) + 22.29 (% SNF)−25.58. From this, the following equation was derived to compute the solids-corrected milk (SCM) yield containing 340kcal of energy per pound: SCM (lb) = 12.3 (F) + 6.56 (SNF)−0.0752 (M); where F, SNF, and M are expressed as pounds of fat, solids-not-fat, and milk, respectively. This equation predicted the milk energy output of cows producing low-fat milk effected by dietary means as accurately as that of normal milk. The Gaines 4% FCM equation underestimated by as much as 15% the energy output in milk containing less than 3% of fat.