The effect of calving season and stage of lactation on the milk protein concentration of Queensland dairy farms

Abstract

A number of factors are known to affect milk protein concentration, including breed, environment, management practices, disease status, stage of lactation, age, parity and nutrition of the dairy cow (De Peters and Cant 1992). A combination of, or an interaction between these factors, can significantly affect milk protein concentration. Calving season has also been found to affect the lactation curve of milk protein concentration (Garcia and Holmes 2001, White 2001). This effect is likely to be an important issue in Queensland due to the year-round calving pattern, which is primarily a relationship between the seasonal changes in the nutritive value of pastures and stage of lactation. The aim of the on-farm monitoring program conducted over a 12-month period in Queensland was to identify the main factors and interactions that affect milk protein concentration. The study is part of a Dairy Research and Development Corporation (DRDC)-funded national project, also being conducted in Western Australia using a similar data collection and analysis protocol.