Metabolism of Biuret and Urea by Sheep

Farlin, S. D.; Brown, Richard E.; Garrigus, U. S.

doi:10.2527/jas1968.273771x

Cited by 12 publications

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“…The inhibition of ammonia production from urea in sheep rumen fluid is evidence for the action of a urease, and agrees with the findings of Bainter (1967) who used goat contents, and of Jones (1968) and Brent, Adepoju & Portela (1971) who used bovine rumen contents or preparations from them. On the basis of experiments with [l*C]urea, Farlin, Brown & Garrigus (1968) suggested that there was significant non-hydrolytic metabolism of urea in rumen contents, but further experiments (Brookes et al, 1972) showed that urea was completely metabolized hydrolytically.…”

Section: Discussionmentioning

confidence: 99%

“…No similar situation exists with regard to ureolytic activity; although a number of different species of ureolytic bacteria have been isolated, there is no proof that such bacteria are widespread in rumen contents or that any of them are a major source of rumen urease activity. Indeed, it has been suggested that ruminal urea may not be hydrolysed by the enzyme urease (Farlin, Brown & Garrigus, 1968), or that the total activity is produced by summation of the relatively small activities of a large number of species of m e n bacteria (Muhrer & Carroll, 1964). The known species of ureolytic rumen bacteria are considered later, in the Discussion.…”

Section: Introductionmentioning

confidence: 99%

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Urease Activity in the Rumen of Sheep and the Isolation of Ureolytic Bacteria

Cook¹

1976

Journal of General Microbiology

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S U M M A R YUrease activity in the sheep rumen varied with the diet of the sheep, but appeared to be largely or entirely present in the small bacterial fraction. Screening of over 1000 strains of rumen bacteria isolated on different media showed that urease activity was apparently confined to species of Staphylococcus, Lactobacillus casei var. casei and KZebsieZZa aerogenes. Consideration of the numbers in which these occurred and their activities suggested that the bacteria could not be responsible for the total rumen urease activity. By enrichment culture a ureolytic strain of Streptoc o c m faecium was isolated. This had a higher urease activity than the other bacteria and occurred in higher numbers in the rumen. It could live with other bacteria in the rumen of a gnotobiotic lamb in numbers, and with a urease activity, comparable with those in the normal sheep rumen. The other properties of the bacterium also suggested that it would grow and produce urease in the rumen, but was unlikely to retain its urease activity after isolation. It was concluded that this bacterium was the main source of rumen urease in roughage-fed, and probably other, sheep.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Urease Activity in the Rumen of Sheep and the Isolation of Ureolytic Bacteria

Cook¹

1976

Journal of General Microbiology

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“…There is some evidence for incomplete hydrolysis of urea entering the rumen, based on the finding that less than 25 yo of an injection of [14C]urea into the rumen was recovered as 14C0, in respired gases (Farlin, Brown & Garrigus, 1968), suggesting that urea N may be incorporated into nitrogenous compounds in the rumen without entering the ruminal ammonia pool. However, there was no evidence of direct incorporation into bacteria of urea breakdown products more complex than ammonia since the enrichment of bacterial N in the rumen was not greater than the enrichment of ruminal ammonia N at the same time (Fig.…”

Section: Continuous Infusion Of [*Sn]urea and [14cc]urea Gicen Togethmentioning

confidence: 99%

Dynamic aspects of ammonia and urea metabolism in sheep

1972

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I. To obtain a quantitative model for nitrogen pathways in sheep, a study of ammonia and urea metabolism was made by using isotope dilution techniques with ['SN]ammonium sulphate and [Wlurea and [14C]urea.2. Single injection and continuous infusion techniques of isotope dilution were used for measuring ammonia and urea entry rates.3. Sheep were given 33 g of chaffed lucerne hay every hour; the mean dietary N intake was 23.4 gjd.4. It was estimated that 59 yo of the dietary N was digested in the reticulo-rumen; 29 yo of the digested N was utilized as amino acids by the micro-organisms, and 71 % was degraded to ammonia.5. Of the 14'2 g N/d entering the ruminal ammonia pool, 9.9 g N/d left and did not return to the pool, the difference of 4'3 g N/d represented recycling, largely within the rumen itself (through the pathways : ruminal ammonia + microbial protein + amino acids --z ammonia).6. Urea was synthesized in the body at a rate of 18.4 g N/d from 2.0 g N/d of ammonia absorbed through the rumen wall and 16.4 g N/d apparently arising from deaniination of amino acids and ammonia absorbed from the lower digestive tract. 7.In the 24 h after intraruminal injection of [15N]ammonium salt, 40-50 % of the N entering the plasma urea pool arose from ruminal ammonia; 26% of the lSN injected was excreted in urinary N.8. Although 5-1 g N/d as urea was degraded apparently in the digestive tract, only 1.2 g N/d appeared in ruminal ammonia; it is suggested that the remainder may have been degraded in the lower digestive tract. 9. A large proportion of the urea N entering the digestive tract is apparently degraded and absorbed and the ammonia incorporated in the pools of nitrogenous compounds that turn over only slowly. This may be a mechanism for the continuous supply to the liver of ammonia for these syntheses.10. There was incorporation of 16N into bacterial fractions isolated from rumen contents after intraruminal and intravenous administration of [15N]ammonium salts and [lSN]urea respectively. 11. A model for N pathways in sheep is proposed and, for this diet, many of the pool sizes and turn-over rates have been either deduced or estimated directly.

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confidence: 99%

“…While urea is physiologically important to nitrogen metabolism in ruminants, it is also economically important to ruminant feeding. However, the microbial aspects of urea metabolism are not well understood, either regarding numbers relative to total rumen bacteria or whether the ureolytic bacteria are widespread in rumen contents, or even whether bacteria are the major source of rumen urease (Farlin et al, 1968).Strain GPC 589 T was isolated from the rumen fluid of a penned cannulated sheep that had been fed on a diet of hay and grass with water ad libitum. The anaerobic culture technique of Hungate (1950) was used with oxygen-free CO 2 as the gas phase and incubation at 37 u C. Initially, a fresh rumen fluid sample (0.5 %, v/v) was enriched for 48 h (Cook, 1976) in medium GM comprising (w/v): Bacto casitone (0.5 %), Bacto yeast extract (0.5 %), KH 2 PO 4 (0.25 %), Na 2 HPO 4 (0.25 %), CH 3 .…”

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confidence: 99%

Howardella ureilytica gen. nov., sp. nov., a Gram-positive, coccoid-shaped bacterium from a sheep rumen

Cook¹,

Riley²,

Murdoch³

et al. 2007

International Journal of Systematic and Evolutionary Microbiology

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In the ruminant herbivore, primary digestion of the food is carried out by the micro-organisms of the rumen. For many of the ruminal bacteria, ammonia is the major nitrogen source. Urea is present in ruminant saliva and diffuses into the rumen through the rumen wall and, as urea is rapidly hydrolysed in the rumen (Pearson & Smith, 1943), it is an important source of ammonia especially in the recycling of nitrogen in the rumen. While urea is physiologically important to nitrogen metabolism in ruminants, it is also economically important to ruminant feeding. However, the microbial aspects of urea metabolism are not well understood, either regarding numbers relative to total rumen bacteria or whether the ureolytic bacteria are widespread in rumen contents, or even whether bacteria are the major source of rumen urease (Farlin et al., 1968).Strain GPC 589 T was isolated from the rumen fluid of a penned cannulated sheep that had been fed on a diet of hay and grass with water ad libitum. The anaerobic culture technique of Hungate (1950) was used with oxygen-free CO 2 as the gas phase and incubation at 37 u C. Initially, a fresh rumen fluid sample (0.5 %, v/v) was enriched for 48 h (Cook, 1976) in medium GM comprising (w/v): Bacto casitone (0.5 %), Bacto yeast extract (0.5 %), KH 2 PO 4 (0.25 %), Na 2 HPO 4 (0.25 %), CH 3 . COONa (0.1 %), mannitol (0.2 %), MgCl 2 . 6H 2 O (0.05 %), sodium thioglycollate (0.075 %) and resazurin (0.0001 %), pH 7.0; autoclaved at 103.5 kPa for 15 min. Filter-sterilized urea (0.2 % w/v, final concentration) was added to cooled medium. The enrichment was maintained by overnight subculturing (0.1 ml) in 8 ml medium G (mannitol-free GM) in Hungate tubes. An ureolytic Gram-positive coccus Abbreviation: ECL, equivalent chain-length.

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Metabolism of Biuret and Urea by Sheep

Cited by 12 publications

References 0 publications

Urease Activity in the Rumen of Sheep and the Isolation of Ureolytic Bacteria

Urease Activity in the Rumen of Sheep and the Isolation of Ureolytic Bacteria

Dynamic aspects of ammonia and urea metabolism in sheep

Howardella ureilytica gen. nov., sp. nov., a Gram-positive, coccoid-shaped bacterium from a sheep rumen

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