The project aimed to investigate whether the response in drinking water intake at group level and individually was equal for potassium and sodium salts, how large the response in milk urea content was and what opportunities there are to use drinking water intake for estimating feed intake in dairy cows.
Water intake can be recorded at reasonable cost on dairy farms. There is a strong linear relationship between mineral intake, water intake and milk urea concentration. If dietary mineral content is taken into account, it may be possible to estimate dry matter intake from water consumption. Individual water and feed intake will be recorded in 120 cows over 2 years at every visit to feeding stations and water bowls. Treatments will be applied for four periods of 5 days with sodium and potassium added in the forage. The study will assess: the water intake response of individual cows to altered mineral intake; whether sodium and potassium are always additive with respect to water intake, urinary output and milk urea concentration; whether the effect on milk urea concentration is constant across lactation stage and feeding level; and whether deviation in drinking pattern of individuals gives early indication of heat or illness.