Rumen

Because feed comprises over 80% of the cost of producing and fattening cattle, the maximum utilization of ever increasingly expensive rations is of upmost importance (179). Monensin under the trade name of Rumen sin (Elanco Products) was introduced in 1976 at a recommended level of 30 ppm in cattle feed. Lasalocid having the trade name Bovatec (Hoffmann-LaRoche, Inc.) was marketed some years later. 

C. S. Stewart, T. Acamovic, FI. Gurung and A. S. Abdullah, in Manipulation of Rumen Microorganisms , Faculty of Agriculture, Alexandria University, Alexandria, Egypt, 1992, p. 150. T. Acamovic, in Developments and Ethical Considerations in Toxicology, ed. M.I. Weitzner, The Royal Society of Chemistry, 1993, p. 129. 

R. E. Hungate, The Rumen and its Microbes, Academic Press, New York, 1966. 

R. E. Elungate, The Rumen Microbial Ecosystem, ed. P. N. Elobson, Elsevier Applied Science, London, 1988, pp. 1-19. 

K. Ogimotoand S. Imai, Atlas of Rumen Microbiology, Ja.pan Scientific Societies Press, Tokyo, 1981. C.G. Orpin, J. Gen. Microbiol, 1975, 91, 249. 

Cross-contamination between animal species may be a factor in the spread of resistance. Flint and Stewart " showed that a rumen strain (46/5) of the Gram... 

In the Slimmer of 1989, Rutland Water, the largest man-made lake in Western Europe and which supplies potable water to approximately 500 000 people in the East of England, contained a heavy bloom of Microcystis aeruginosa. By the end of the summer, a number of sheep and dogs had died after drinking from the bloom and concentrated scum. Analysis revealed that the cyanobacterial bloom material was toxic to laboratory mice, and that rumen contents from a poisoned sheep contained fivemicrocystin variants.Microcystins were detected in waters used for recreation in Australia at concentrations greater than 1 mg per... 

The ability to identify and quantify cyanobacterial toxins in animal and human clinical material following (suspected) intoxications or illnesses associated with contact with toxic cyanobacteria is an increasing requirement. The recoveries of anatoxin-a from animal stomach material and of microcystins from sheep rumen contents are relatively straightforward. However, the recovery of microcystin from liver and tissue samples cannot be expected to be complete without the application of proteolytic digestion and extraction procedures. This is likely because microcystins bind covalently to a cysteine residue in protein phosphatase. Unless an effective procedure is applied for the extraction of covalently bound microcystins (and nodiilarins), then a negative result in analysis cannot be taken to indicate the absence of toxins in clinical specimens. Furthermore, any positive result may be an underestimate of the true amount of microcystin in the material and would only represent free toxin, not bound to the protein phosphatases. Optimized procedures for the extraction of bound microcystins and nodiilarins from organ and tissue samples are needed. 

FIGURE 7.28 Giraffes, cattle, deer, and camels are rmninant animals that are able to metabolize cellulose, thanks to bacterial celln-lase in the rumen, a large first compartment in the stomach of a ruminant. 

Pantothenic acid is found in extracts from nearly all plants, bacteria, and animals, and the name derives from the Greek pantos, meaning everywhere. It is required in the diet of all vertebrates, but some microorganisms produce it in the rumens of animals such as cattle and sheep. This vitamin is widely distributed in foods common to the human diet, and deficiencies are only observed in cases of severe malnutrition. The eminent German-born biochemist Fritz Lipmann was the first to show that a coenzyme was required to facilitate biological acetylation reactions. (The A in... 

Hungate, R. The Rumen and Its Microbes Academic Press New York and London, 1966. 

The Rumen Ecosystem Hobson, P. N., Ed. Elsevier Applied Science London and New York, 1988. 

Metges, C, Kempe K. and Schmidt, H.-L. 1990 Dependence of the carbon-isotope contents of breath carbon dioxide, milk, serum and rumen fermentation products on the 8 Cvalue of food in dairy cows. British Journal ofNutritim 63 187-196. 

Three animal studies were located regarding distribution of endosulfan in animals following dermal exposure (Dikshith et al. 1988 Hoechst 1986 Nicholson and Cooper 1977). Endosulfan was detected in the brain (0.73 ppm), liver (3.78 ppm), and rumen contents (0.10 ppm) of calves that died after dermal exposure to a dust formulation of endosulfan (Nicholson and Cooper 1977). Following a single dermal application of aqueous suspensions of 0.1, 0.83, and 10.13 mg/kg C-endosulfan to male Sprague-Dawley rats, low concentrations of endosulfan (ng/g levels) appeared in the blood and tissues (other than skin at and around the application site) after 1 hour (Hoechst 1986). The concentrations of endosulfan in the blood and tissues increased with the time of exposure and were proportional to the dose applied. The liver and kidney appeared to sequester radiolabel relative to the concentrations of radiolabel in the blood or fat. Endosulfan levels were approximately 10 times higher in the liver and kidney than in the fat, blood, and brain throughout the study (Hoechst 1986). 

Acetic 2 Major end product of carbohydrate fermentation by rumen organisms ... 

In mminants, whose main metabohc fuel is short-chain fatty acids formed by bacterial fermentation, the conversion of propionate, the major glucogenic product of rumen fermentation, to succinyl-CoA via the methyhnalonyl-CoA pathway (Figure 19—2) is especially important. 

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