On the amino acids in the urine of dairy cows fed urea as the sole or partial source of nitrogen

Abstract

Abstract. The urinary amino acids in free and bound form were determined quantitatively in dairy cows fed urea and ammonium nitrogen as the sole (0-cows) or partial (ULP-cows) source of nitrogen. For comparison, amino acid determinations were performed also on the urine of cows on ordinary silage-cereals feed and pasture feed (NorPcows). The total amount (mg/1 urine) of the free amino acids was the smallest with 0-cows and the highest with NorP-cows on pasture feeding. The difference was mainly due to glycine .which was found in significantly higher (P < 0.001) amounts with NorP-cows on pasture feeding. The proportion of glycine in the total identified free amino acids was 9.7 ± 9.0 % with 0-cows, 13.5 ± 5.1 % with ULP-cows, 7.7 ± 3.4 % with NorP-cows on indoor feeding and 56.4 ± 21.0 % with Nor P-cows on pasture feeding. The corresponding figures for glutamic acid, which was quantitatively the most important amino acid with 0-and ULP-cows, were 36.5 ± 29.6 %, 19.8 ± 19.2 %, 5.7 ± 4.0 % and 3.9 ± 2.1 % of the total free amino acids. Besides the identified amino acids, there were a number of unidentified amino acid derivatives in the free amino acid fraction in all the feeding groups.The total amount of amino acids freed by hydrolysis was the lowest with 0-cows. The proportion of glycine of the amino acids of the hydrolysate was 48 % with 0-cows, 66 % with ULP-cows and 84 % with NorP-cows.

Nitrogenous constituents in the urine of cattle, sheep and goats

“…Taurine was the second most abundant amino acid in the cattle urine (on average 17% of the total a-amino-N in the form of free amino acids), though with much higher values in the urine of cows fed maize silage and concentrates (3 1 YO) than in the urine of cows that were grazing (2.4%). Again, this is consistent with the data of Kreula and Ettala (1977). In the cattle urine, about 25 other amino acids were identified but none accounted for more than 5 % of the total N as free amino acids.…”

“…In the cattle urine, glycine was the dominant free amino acid (Table 4), though there was a difference between two cows that were grazing (57 and 91 YO glycine N of the total N in the form of free amino acids) and three fed maize silage and concentrates (3&35Y0 as glycine N). This difference between grazing animals and those fed silage and concentrates is consistent with data reported by Kreula and Ettala (1977). Taurine was the second most abundant amino acid in the cattle urine (on average 17% of the total a-amino-N in the form of free amino acids), though with much higher values in the urine of cows fed maize silage and concentrates (3 1 YO) than in the urine of cows that were grazing (2.4%).…”

“…Most amino acid N transported in the blood stream to the kidneys is absorbed there and, partly for this reason, the amino acid composition of urine shows little relationship to that of the diet (Kreula and Ettala 1977). In the cattle urine, glycine was the dominant free amino acid (Table 4), though there was a difference between two cows that were grazing (57 and 91 YO glycine N of the total N in the form of free amino acids) and three fed maize silage and concentrates (3&35Y0 as glycine N).…”