Live Weight Changes, Feed Consumption, Milk Yield and Energy Balance in Dairy Cattle during the First Period of Lactation

Abstract

Abstract The purpose of this study was to estimate any breed differences and to investigate the interrelationships between live weight changes, feed consumption, milk production in kg energy corrected milk (kg ECM) and the therefrom calculated energy balance with emphasis on the first part of lactation. Altogether 508 lactations were studied for 153 cows from the same herd in first to fifth lactation of the following Swedish dairy cattle breeds: Swedish Red and White (SRB), Swedish Friesian (SLB), reciprocal F1-crosses of the two breeds, and Swedish Jersey (SJB). The gamma function (Y n=an b·ecn) was fitted to each animal's records in order to derive secondary traits from the functions. A Mixed Model Procedure was used to estimate breed and parity effects and variance components. The average goodness of fit to the function, as assessed by the R 2 value, was best for milk production data, followed by feed consumption, while lower R 2 values were obtained for live weight changes and especially for energy ba...