Lactation curves as a tool for monitoring the health and performance of dairy cows - a mini-review

According to the estimation of FAO, worldwide milk production increased from 694 million tons in 2008 to 914.3 million tons in 2020. Currently, animal breeding for high milk yield continues. However, some authors consider high milk productivity the main reasons of milk quality and health deterioration, including fertility. Therefore, monitoring of animal physiological state and productivity becomes especially important. Lactation curve modeling is one of the most effective methods for predicting component milk composition, yielding capacity and animal health. It is a tool for early diagnostics of certain diseases, which can help reduce treatment costs and improve the disease course prognosis. Thus, predicting the evolution of milk yields is an important stage of management and breeding decisions; it is widely used for diagnostic purposes. The article provides a brief overview of mathematical methods for modeling lactation curves (for milk yield, percentage of fat, fat yield and protein). Classic Wood’s model (P.D.P. Wood, 1967), Ali and Schaeffer (T.E. Ali and L.R. Schaeffer, 1987), Wilmink parametric models (J.B.M. Wilmink, 1987) and models based on the machine learning algorithms are considered here. It should be mentioned that there is no universal model for describing lactation curves. Most attention is paid to Wood’s model used for constructing lactation curves described by A.S. Emelyanov (1953). This equation application for prediction milk yield curves and milk components has shown good prediction accuracy. In this study, it was found that most of the models are unstable under decreasing input data that makes their use almost impossible for farms unable to accurately collect data of the lactation activity on a regular basis. It is shown that deviations of the observed milk yield from a prediction made by a well-fitted model are clear indicator of animal’s diseases and can be used to prevent and detect udder diseases such as mastitis.