Mjölkureahalten som mått på vom-mikrobernas kväveförsörjning och kons miljöbelastning

Abstract: The aim of this literature study was to analyze how milk urea concentration is working as a measure of the nitrogen supply to rumen microbes and indicator of the environmental load. Questions included in this literature study were how to improve the dairy cattle nitrogen efficiency and what correlations there are between milk urea, nitrogen efficiency and crude protein content in the feed. Effects on the reproduction from high ration protein content are also addressed. Dairy cattle are today fed with large proportions of protein which could lead to high expenditure of feed and environmental pollutions. The nitrogen can be lost to the environment by different pathways; leaching, denitrification or by emission to the air. High crude protein concentration in the feed will increase milk urea and decrease the nitrogen efficiency. The nitrogen that’s not used by the rumen microbes is exuded as urea. Urea diffuses easily from the blood to the milk and is used by advisers as a tool for assessing rumen protein balance. Milk is easily sampled and the sampling is not stressful for the cow and doesn’t create additional work for the farmer. Milk urea concentrations can have large variations for many reasons. This is important to consider when the test milking is performed. The fertility is decreasing with high percentage of protein in the feed. The cows become more difficult to get pregnant. The quality of the sperms and the ova is decreasing. Milk urea is a good and a useful tool for evaluation of the nitrogen support of rumen microbes and environmental strain.