The effect of concentration and form of dietary nitrogen on the utilization and excretion of nitrogen by lactating dairy cows

Abstract

Three total mixed rations containing differing sources and levels of protein were fed to 18 lactating cows in a 3 x 3 Latin square design with the objective of quantitating nitrogen losses for specific feeding regimes. Feeding a total mixed ration containing 12.3% crude protein reduced the amount of nitrogen excreted and increased the proportion of dietary nitrogen secreted in the milk. The diet supplemented with corn gluten meal resulted in high blood urea nitrogen levels and higher losses of nitrogen in the urine. It was concluded that diet formulation impacts on nitrogen wastage.