Studies on the nitrogen compounds of the faeces of dairy cows fed urea as the sole or partial source of nitrogen

Ettala, Terttu; Kreula, Matti

doi:10.23986/afsci.72012

Cited by 2 publications

(3 citation statements)

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“…In the faeces of 0-and ULP-cows the content of those amino acids which had the lowest labelling in the rumen bacteria and protozoa (His, Pro, Arg and Gly) was smaller than in the faeces of NorP-cows (Ettala and Kreula 1979). However, the amino acid compositions of the rumen microorganisms, with the exception of the proportion of diaminopimelic acid, were very similar, being independent of the type of feed (Syväoja and Kreula 1979).…”

Section: Resultsmentioning

confidence: 98%

“…1972, Ettala and Kreula 1976. However, the composition of the protein of the milk produced by 0-and ULP-cows is similar to that of cows (NorP-cows) on normal protein-rich feed (Syväoja 1971).…”

Section: Introductionmentioning

confidence: 98%

“…The daily ration of urea given to the cow was 204.7 g and the total nitrogen 373 g. Complete details of the feeding have been published (Virtanen 1966, Virtanen et ai. 1972, Ettala and Kreula 1976.…”

Section: Methodsmentioning

confidence: 99%

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Incorporation of 15N and 14C into amino acids of bacterial and protozoal protein in the rumen of the cow on urea-rich feed

Syväoja

Kreula

1979

AFSci

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Abstract. The utilization of the non-protein nitrogen and carbon of feed by rumen microorganisms for the synthesis of protein was studied by administering [U-14 C] sucrose and 15 NH 4 C1 to a cow on urea-rich, low-protein feed. By studying the labelling of the protozoa and bacteria and the amino acids isolated from them at intervals up to 48 hours afterwards, it was found that the bacteria synthesized amino acids from nonprotein nitrogen much more rapidly and effectively than the protozoa. Also the labelling of the carbon in the amino acids of the bacteria was more rapid than in the protozoa.In both protozoa and bacteria there was intracellular storage of [ l4 C] sucrose.Of the bacterial amino acids the most vigorous 14 C labelling was found in Glu, Arg, Lys, Val and Ala and the weakest labelling in Gly, His and Ser. Of the protozoal amino acids Ala, Asp, Glu, Leu and Lys had the highest labelling and Pro, Gly, His and Phe the lowest. In the bacterial protein the labelling of Pro and Arg was ten times that of the corresponding protozoal amino acids, and Asp, Ser and Ala four times.After the 15 NH 4 C1 dose the half-life of 15 N in the rumen fluid was estimated to be 3.3 h. Labelled ammonium nitrogen was about 11 -l5 % of the bacterial nitrogen and 2-3 % of the protozoal nitrogen after 1 h. Of the protozoal amino acids Ala, Glu, Val, Asp and Met had the most vigorous labelling, and of the bacterial amino acids Glu, Asp, Ser, He and Tyr. The slowest incorporation of ammonium nitrogen was into His, Pro, Arg and Gly in both bacteria and protozoa. The labelling of the bacterial amino acids was approximately 7 8 times more vigorous than that of the protozoal amino acids. The labelling of Ala was only 4 times, and that of Val, Met and Glu 5 times more vigorous than with protozoal protein. The pathway of histidine synthesis seemed to be restricted in both bacteria and protozoa and therefore may be a limiting factor in protein synthesis, particularly in cows fed urea as the sole source of nitrogen.Of the 14 C and 15 N label given, 12.9 and 9 % respectively was secreted in the milk during the first 3 days; over the same period the 14 C and 15 N excreted in the faeces plus urine accounted for 16.9 and 44.3 % respectively of that administered.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%