The amount and composition of milk produced by dairy cows appears to be more regulated by internal, annual biological rhythms than by environmental factors. A new study released by Penn State University found peak yield, fat concentration and protein concentration occurred in winter months, when days are shorter, and lowest in summer months, when days are longest. And the amplitude of the rhythms were greater in the north and declined depending how far south herds were located. A researcher involved in the study noted that being more precisely aware of their cows’ rhythms allows dairy farmers to better judge the effectiveness of management strategies.
Although researchers have long recognized an annual pattern of milk composition in dairy cattle – with higher milk fat and protein concentrations observed during the winter and lower levels occurring in the summer – the rhythms of milk yield and composition previously have not been well quantified, according to the research.
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