A note on the repeatability of parameters of the lactation curve in cattle

Abstract

SUMMARYA study of 1567 lactations of 336 Friesian cows in 10 herds has been undertaken to establish to what extent the shape of the lactation curve varies between parities, cows and herds, and to assess the importance of variations in seasonality from year to year, with particular reference to herd production forecasts.In general, cows calving the same parity at the samé time of year showed similar curves, modified only by total yield and abnormal seasonality of production. Production forecasts based on month/parity subclasses are therefore adequate, provided due account is taken of extréme variations in weather conditions or forage growth.