Effect of dietary protein level on nitrogen excretion in dry cows

Nitrogen (N) utilisation in dairy cattle is generally low and thereby results potential downstream ammonia nitrous oxide emissions as well nitrate leaching. Despite this, only few studies have investigated N excretion dry cows. The objective of the present study was to examine effect protein level diet on cows subsequently develop a simple equation predict based nutrient intake parameters. In addition, aim investigate whether crude (CP) concentration sufficient fulfil requirements Twelve Danish Holstein were fed two total mixed ration (TMR) diets both containing grass-clover maize silage, but with different ratios rapeseed cake dried sugar beet pulp vary CP, 111 135 g/kg DM, respectively. Cows randomly allocated one dietary treatments 2 × Latin square design six replications early late period, lasting for weeks. periods, first eleven days used adaptation, while last three sampling recording. Feed water recorded daily, blood, faeces urine samples collected analysed N, nutrients other compounds. Faecal output not affected by increased CP level, whereas urinary diet, indicating that excess mainly excreted urine. Thus, appears be strongly correlated A DM seems meet cows, underpinning reducing manipulation. Using Lucas principle, equations predicting urine, respectively, established matter (DMI) intake, considered reliable proxies during period.