Concentrations of ammonia, urea and nitrate nitrogen in urine of dairy cattle in the university herd
2001
Okamoto, M. (Rakuno Gakuen Univ., Ebetsu, Hokkaido (Japan)) | Ishihara, M. | Izumi, K.
Urine samples were collected from 79 dairy cows (63 lactating, 4 dry and 12 heifers) at 13 hours after the last feeding to determine the pH value and concentrations of urea nitrogen, ammonia nitrogen and nitrate nitrogen. The pH ranged from 8.14 to 8.63, and the average was 8.41 =+- 0. 095. Average concentrations of urea and ammonia nitrogen were 5465 =+- 1606 mgL sup(-1) and 140.8 =+- 38.0 mgkg (sup-1) , respectively. In 24 of the cows, nitrate nitrogen was detected, and the concentration was ll.5 =+- 8.6 mgkg sup(-1) . A close positive correlation was found between the concentration of urea nitrogen and that of ammonia nitrogen. Nitrate content of dry matter in the ration was less than 400 mgkg sup(-1) , and nitrate consumption by the cows was less than 8 g per day. This was considered to be safe level. The correlation coefficient between nitrate nitrogen consumption and the urinary concentration of nitrate was 0. 135. In the frequency of disorders within the last year, no difference was observed between the cows in which nitrate was found in the urine and the other cows. However, the days open were considerably greater in the cows with nitrate detected in the urine than in the other cows (111.8 vs. 93.7; p<0.05) .
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