Studies on the Protein-Assimilating Action of Zeranol in Holstein Steers, Especially on Total Nitrogen Amount

Abstract

Eight Holstein steers 4.5 months, on the average, of age were divided equally into two groups. In each animal of one group, 2 pellets of a zeranol preparation were buried subcutaneously at the root of the ear. The other group served as an intact control. Each animal was placed in a metabolic cage for 3 consecutive days to collect all the feces and urine discharged, which were examined for the total nitrogen amount discharged by the micro-Kjeldahl method.
As a result, average D.G. for the whole experimental period was 0.94kg for the medicated group and 0.84kg for the control group. The difference in average D.G. between the two group was the largest over a period from 10 to 20 days of experiment, when average D.G. aws 1.26 kg for the medicated group and 0.89kg for the control.
When the total amount of nitrogen deposition was determined and expressed with an index which was regarded as 100 at the time of beginning of the experiment, it was 168.5 and 135.7 in the medicated and the control group, respectively, 20 days and 174.6 and 138.2, respectively, 40 days after the beginning of the experiment. These results lend support to a conclusion that the zeranol preparation has a proteinassimilating action.