Factors affecting the shape of the lactation curve in cattle

Abstract

SUMMARY: The lactation curve in cattle has been explained by the expression y_n = An^be^-cn where y_n is the average daily yield in the nth week, and A, b, and c are constants. In general, in a sample of 859 Friesian lactations recorded during 1964–65 daily yield was depressed during the winter months (18·8% in January) and stimulated during the spring (14·7% in May) to an extent which was independent of the stage of lactation. Winter calvers on the other hand tended to produce more in total lactation than spring calvers (14·5% for animals calving in November as opposed to those calving in April).Using a suitable technique it is possible to predict month by month output from a cow, or herd, accurately enough to furnish a basis for forward planning.