EFFECT OF DIET ON MILK ALLANTOIN AND ITS RELATIONSHIP WITH URINARY ALLANTOIN IN DAIRY-COWS

The present study examined the effects of diet on the concentration an d excretion of allantoin in milk and the relationship between allantoi n in milk and urine of dairy cows. Results are reported from three exp eriments. In Experiment 1, four diets with two different protein perce ntages and two different rumen degradabilities were fed to 12 cows in a continuous trial. In Experiment 2, four diets with different protein balance values in the rumen were fed to four cows in a 4 x 4 Latin sq uare design. In Experiment 3, four diets with different contents of co ncentrate and fat were fed to four cows in two incomplete 2 x 2 Latin squares. The excretion of allantoin N in milk increased as dry matter intake increased (Experiment 1) and as the concentrate in the diet inc reased (Experiment 3). In Experiments 1 and 3, the excretion of allant oin in milk was correlated with its concentration in milk and with its excretion in urine. In the three experiments, allantoin excretion in milk was closely correlated with milk yield. The amount of allantoin s ecreted in milk represented a small proportion (0.63 to 1.34%) of the total excretion in urine and milk. The proportion of allantoin secrete d in milk was negatively correlated with the urinary excretion of alla ntoin in Experiments 2 and 3 and positively correlated with the excret ion of allantoin in milk in Experiment 1. In Experiments 1 and 2, the proportion of allantoin excreted in milk was not constant but increase d as milk yield increased.