scholarly journals Passage rate and total clearance rate from the rumen of cows fed on grass silages differing in cell-wall content

1995 ◽  
Vol 73 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Marlou W. Bosch ◽  
Marianne Bruining
Keyword(s):  
Organic Matter ◽  
Crude Protein ◽  
Growth Stages ◽  
Passage Rate ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
The Mean ◽  
Voluntary Intake ◽  
Rate Limiting ◽  
Different Growth Stages

Four non-lactating, rumen-fistulated cows were fed ad lib. on two grass silages (first cut (FC) and second cut (SC)) harvested at different growth stages, resulting in different crude-protein (CP) and neutral-detergent-fibre (NDF) contents (FC, 152 g CP/kg, 515g NDF/kg and SC, 210 g CP/kg, 442 g NDF/kg). Voluntary intake and rumen contents, total as well as organic matter were higher for silage FC. Fractional passage rate from the rumen, calculated from the logarithmic decline in Cr-NDF rumen pool, was higher for silage FC (0·0395/h and 0·0446/h for silages SC and FC respectively). When fractional passage rates from the rumen were calculated by dividing the intake of indigestible organic matter by the mean rumen poo! of this fraction, the same differences between silages were found, although the actual levels were much lower (0·0258$sol;h and 0·0300/h for silages SC and FC respectively). The results from the present experiment suggest that disappearance rate from the rumen of particles with a size between 1·25 and 0·071 mm is the rate-limiting step in the control of rumen fill.

The digestibility and voluntary intake of six varieties of Panicum

1971 ◽  
Vol 11 (48) ◽  
pp. 18 ◽  
Author(s):  
DJ Minson
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
Nutritional Value ◽  
Growth Stages ◽  
Dry Matter Digestibility ◽  
Digestible Organic Matter ◽  
Guinea Grass ◽  
Voluntary Intake ◽  
Different Growth Stages ◽  
Selection Of

The digestibility and voluntary intake of P. coloratum CV. Kabulabula, P. coloratum var. Makarikariense CV. Burnett and C.P.I. 13372, P. maximum var. trichoglume CV. Petrie Green Panic, P. maximum cv. Coloniao guinea grass and Hamil were measured with sheep in metabolism pens. Each grass was cut eight to ten times at different growth stages and times of the year. Varieties differed (P<0.01) in their dry matter and organic matter digestibility but the maximum mean difference between varieties was only 2.8 and 3.4 per cent respectively. There were large differences in voluntary intake between grasses. P. maximum cv. Hamil had a voluntary intake 50 and 27 per cent greater than P. coloratum cv. Kabulabula when both had p dry matter digestibility of 50 and 60 per cent respectively. Voluntary intake of digestible organic matter of P. maximum CV. Hamil was 26 per cent higher than that of P. coloratum CV. Kabulabula. The higher intake of P. maximm occurred despite its having higher silicon percentages than P. coloratum. It was concluded that because of the biased relation between intake and digestibility selection of grasses on the basis of digestibility determinations alone could be a misleading guide to their nutritional value.

scholarly journals Monosaccharide transport into lactating-rat mammary acini

1982 ◽  
Vol 204 (2) ◽  
pp. 493-501 ◽  
Author(s):  
L C Threadgold ◽  
H G Coore ◽  
N J Kuhn
Keyword(s):  
Plasma Membrane ◽  
Cytochalasin B ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Monosaccharide Transport ◽  
Rat Mammary Gland ◽  
The Mean ◽  
Rate Limiting ◽  
Rate Of Consumption ◽  
Uptake And Release

The uptake and release of 3-O-methyl-D-[3H]glucose at 37 degrees C by acini, prepared from lactating-rat mammary gland with collagenase, was inhibited by glucose, phloretin, cytochalasin B, HgCl2 and low temperature. Uptake and phosphorylation of 2-deoxy-D-[3H]glucose, studied in greater detail, could be ascribed to a specific, saturable, inhibitable, process of apparent Km 16 mM and Vmax. approx. 56 nmol/min per mg of protein, plus a non-specific, non-inhibitable process that was monitored with [14C]fructose. The mean rate of uptake of 5 mM-2-deoxyglucose (16 nmol/min per mg of protein) was similar to the rate of consumption of 5 mM-glucose, suggesting that transport was a rate-limiting step in the overall metabolism of glucose. This accords with evidence for a glucose gradient across the plasma membrane.

Ornithine Decarboxylase Activity in Cultured Endothelial Cells Stimulated by Serum, Thrombin and Serotonin

1978 ◽  
Vol 39 (02) ◽  
pp. 496-503 ◽  
Author(s):  
P A D’Amore ◽  
H B Hechtman ◽  
D Shepro
Keyword(s):  
Endothelial Cells ◽  
Ornithine Decarboxylase ◽  
Decarboxylase Activity ◽  
Aortic Endothelial Cells ◽  
Ornithine Decarboxylase Activity ◽  
Rate Limiting Step ◽  
Bovine Aortic Endothelial Cells ◽  
Limiting Step ◽  
Rate Limiting ◽  
Serum Serotonin

SummaryOrnithine decarboxylase (ODC) activity, the rate-limiting step in the synthesis of polyamines, can be demonstrated in cultured, bovine, aortic endothelial cells (EC). Serum, serotonin and thrombin produce a rise in ODC activity. The serotonin-induced ODC activity is significantly blocked by imipramine (10-5 M) or Lilly 11 0140 (10-6M). Preincubation of EC with these blockers together almost completely depresses the 5-HT-stimulated ODC activity. These observations suggest a manner by which platelets may maintain EC structural and metabolic soundness.

Dynamics of hepatic and peripheral insulin effects suggest common rate-limiting step in vivo

Diabetes ◽  
1993 ◽  
Vol 42 (2) ◽  
pp. 296-306 ◽  
Author(s):  
D. C. Bradley ◽  
R. A. Poulin ◽  
R. N. Bergman
Keyword(s):  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone

1979 ◽  
Vol 44 (3) ◽  
pp. 912-917 ◽  
Author(s):  
Vladimír Macháček ◽  
Said A. El-bahai ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrochloric Acid ◽  
Dilute Hydrochloric Acid ◽  
Base Catalysis ◽  
General Base ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Rate Limiting ◽  
Kinetics Of

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.

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