Feeding measures to reduce nitrogen excretion in dairy cattle

Feeding measures with a potential to improve N efficiency in dairy cattle husbandry were studied at two levels of undegradable protein balance (OEB). In each of the two experiments, two simultaneous Latin squares were conducted, each with three treatments and three lactating Holstein cows. Decreasing the OEB of the diet improved N efficiency and resulted in lower N excretion per kg milk. To avoid a negative effect of the decreased OEB on the production results, spreading the concentrate intake (as TMR or in five meals) seemed to be most promising, although only few significant effects were found. The use of protected protein sources or the addition of clinoptilolite were not successful in improving N-efficiency. The rather well balanced mixed basal diet and the large variation between animals seem to have hampered the assessment of such significant influences.