Physiology of milk production and modelling of the lactation curve.

Abstract

Abstract Lactation is defined as the combined processes of synthesis, secretion, and excretion of milk, starting at calving and continuing until natural or induced drying off in the lactating female. Milk production follows a common pattern in several mammalian species known as a lactation curve. A typical lactation curve starts at day four after calving, reaching peak yield in early lactation, followed by a daily decrease in milk yield (persistency) until the lactating female is artificially dried off, or the lactation comes to a natural end. Mathematical models have been applied to lactation curves to provide information in relation to lactation curve parameters, providing valuable information for herd management and breeding decisions. Therefore, the aim of this study was to review the most used mathematical models for the prediction of dairy production curves. The importance of modelling lactation curves is to predict the yield for each day with the minimum possible error, to be able to elucidate the underlying pattern of milk production in the presence of local variation associated with the effect of the environment. The usefulness of any model of adjustment to the lactation curve depends on its capacity to mimic the biological process of developing milk production and to adjust the factors that affect it. Furthermore, these models can only be used to adjust productive records adequately, or to provide a biological understanding of the lactation process.