Milk production responses to turnips fed to dairy cows in mid lactation

Recently, many dairy farmers in Victoria have grown turnips as a summer fodder crop for lactating dairy cows. This paper reports on a 1 month experiment in which cows were individually fed indoors, and milk yield responses to feeding combinations of turnips and barley were measured. Forty cows in mid lactation were evenly allocated to 5 treatment groups. The control group were offered a basal diet of pasture hay and pasture silage which is similar to that available on many Victorian dairy farms during summer. Cows in the other 4 groups were offered the basal diet and various combinations of turnips and/or barley. Marginal milk responses from barley, turnips and a 50:50 mixture of turnips and barley were 0.62, 0.49 and 0.59 L/kg dry matter of supplement eaten. Milk composition of all groups was similar. Despite diets differing greatly in the proportions and physical form of dietary constituents, the mean milk production of each group was accurately predicted by their mean dry matter intake. Measurement of plasma minerals (calcium, magnesium, sodium, potassium and phosphorus) and rumen fluid pH showed that dietary treatments caused some significant (P < 0.05) differences but all values were within the normal range. In this experiment, the milk production responses from barley, turnips and combinations of barley and turnips were similar. Since the cost of turnips is generally about half that of barley, it is concluded that turnips are an economic alternative to barley as a feed supplement for summer milk production.