Biological Rhythms Govern Milk Production In Dairy Cows

The amount and composition of milk produced by dairy cows appears to be more regulated by internal, annual biological rhythms than by environmental factors such as heat and humidity, according to Penn State researchers who studied more than a decade of production records from herds across the country.

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 quantifie...