Rumen fermentation

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. 

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. 

Hungate RE. 1976. The rumen fermentation. In Schlegel HG, Gottschalk G, Pfennig N, editors. Microbial production and utihzation of Gases. Gottingen Goltze. p 119-24... 

One product of the rumen fermentation, methane, is of no value to the ruminant. The major fermentation products used by the ruminant are the short-chain fatty acids, acetate, butyrate and propionate. Acetate and butyrate can be used for energy, but propionate is most useful for the synthesis of protein. If the fermentation could be shifted to reduce methane, acetate and butyrate production and to increase the propionate, the feed efficiency and growth rate could improved. 

Monensin was tested in a rumen fermentation assay at the Lilly Laboratories, and it was found to produce the desired shift in the fermentation (9). Monensin has been licensed in the U.S. for use in beef cattle for improved feed efficiency, where it is administered at 5 to 30 g/ton in a complete feed. In this application, the rate of growth is not increased, but the cattle consume about 10% less food. It is also licensed for increased rate of weight gain in cattle weighing more than 400 lb. and on pasture, where it is fed in a supplement at a rate of 50 to 200 mg per head per day. Lasalocid and salinomycin have also been licensed for use in cattle. 

Three broad groupings, of the antibiotic substances presently used in animal production, include (a) broad-spectrum antibiotics, including penicillins and tetracyclines, which are effective against a wide variety of pathogenic and non-pathogenic bacteria (b) several narrow-spectrum antibiotics that are not used in human medicine and. (c) the ionophore antibiotics, monensin. lasalocid and salinomycin Monensin and lasalocid are used as rumen fermentation regulators in beef cattle, and the three ionophores are used as coccidiostats in poultry production. The ionophores. which are not used in human medicine, were first introduced in the 1970 s and account for most of the increase in antibiotic usage in animal production since the 1960 s. 

The most widely used and researched growth promotant of this type is the polyether antibiotic monensin (63). Monensin, at levels of 33 p.p.m. in feed, has been shown to increase efficiency of feed utilization in both sheep and cattle fed a variety of rations by up to 12%. Slaughter and carcass analysis data indicate that the main effect of the compound is to increase the efficiency of dietary energy retention in the carcass. Its mode of action is thought to be related to its ability to increase the molar proportion of propionate, at the expense of acetate and butyrate, produced in rumen fermentation probably by an effect on the relative microfloral populations. Theoretically this should make more energy available to the animal. 

In vitro rumen fermentation of the heated alfalfas showed (Table V) a decrease in organic matter digestibility (OMD) which was of the same order of magnitude as the increase in NDIN, suggesting that the NDIN fraction was resistant to microbial attack at rumen pH (6.9). The addition of HCl-pepsin to give a pH of... 

Table V. In vitro rumen fermentation of heated alfalfa...

Bhatta, R., Krishnamoorthy, U. and Mohammed, F. (2001) Effect of tamarind (Tamarindus indica) seed husk tannins on in vitro rumen fermentation. Animal Teed Science and Technology 90(3—4), 143-152. 

Investigations in which the transfer of CLA to milk fat in dairy cows was examined showed that supplementation of mixed isomers of CLA resulted in a dramatic reduction in milk fat secretion (Loor and Herbein, 1998 Chouinard et al., 1999a, b). Decreases of up to 50% in milk fat yield occurred and the effects were reversed when supplementation was terminated. Furthermore, effects were specific for milk fat with the yield of milk and other milk components being relatively unaffected. Initial investigations were of short duration (<7 days) and the CLA supplement was infused abomasally as a convenient experimental method to avoid possible alterations during rumen fermentation. However, subsequent long-term studies (20 weeks) demonstrated that the reduction in milk fat synthesis was... 

Diet-induced MFD has been the subject of extensive research, especially over the last 50 years (see reviews by Davis and Brown, 1970 Palm-quist et al., 1993 Bauman and Griinari, 2001). Many theories have been advanced to explain diet-induced MFD, however, most have been found inadequate to explain the cause and mechanism of this phenomenon (Dor-eau et al., 1997a Bauman and Griinari, 2001, 2003). A shift in rumen fermentation is clearly involved and the occurrence corresponds to a marked increase in the trans 18 1 content of milk fat (Davis et al., 1970 Griinari et al., 1998). While VA is generally the principal trans 18 1 isomer in milk fat, a key development was the discovery by Griinari et al. (1998) that the change... 

Freidinger RM, Veber DF, Hirschmann R, Paege LM. Lactam restriction of peptide conformation in cychc hexapeptides which alter rumen fermentation. Int. J. Pept. Protein Res. 1980 16 464 70. 

Formate as an Intermediate in the Bovine Rumen Fermentation, J. Bacteriol (1970) 102,389-397. 

Because the presence of CLA in the human diet is reliant on ruminant products, this chapter first addresses the synthesis of CLA in ruminants. The presence of CLA in ruminant milk and meat is related to rumen fermentation and its synthesis by microorganisms through the process of biohydrogenation (BH) of dietary unsaturated fatty acids. Thus, the effect of diet and processes within the rumen is reviewed. The role of endogenous synthesis of CLA in mammalian tissues has been discovered, and this will be discussed also first as it contributes to the occurrence of CLA in ruminant products and second the significance of endogenous synthesis as a source of CLA in humans and other species. 

Nagalakshmi, D., Sastry, V. R. B., and Pawde, A. (2003). Rumen fermentation patterns and nutrient digestion in lambs fed cottonseed meal supplemental diets. Anim. Feed Sci. Technol. 103,1-4. 

Figure 1. Time course of the rumen fermentation. Solid lines show nitrogen in the solids fraction for 5 g/liter glucose (solid circles) and for 5 g/liter sugar beet pulp (open circles). The high initial value for sugar beet pulp represents its protein content as received.

From the slope of the curve for addition of sodium carbonate to the rumen fermentation of starch, one can estimate tht the net rate of acid formation is equivalent to 36 millimoles of acetic acid per liter per hour. If a level of no more than 0.2% acid must be maintained in the rumen fermentor, then the exchange rate across the membrane must be at least one liter per hour or half of the total reactor volume each hour. This is well below the observed exchange rate of 20 liters per hour. 

In view of the encouraging results obtained by feeding alder sawdust to beef cattle, as was reported earlier, it seemed worthwhile to develop methods of treatment mat would make the cellulose in low quality roughages more available to rumen microorganisms. In order to assess the merits of various physical and chemical treatments of wood and wood by-products, in vitro rumen fermentation tests were conducted and the extent of availability of nutrients to the microorganisms studied. 

Methods. The effect of various NaOH levels and dilutions on cellulose digestion was determined by use of an in vitro rumen fermentation... 

Ipharraguerre, I.R. J.H. Clark D.E. Freeman. Rumen fermentation and intestinal supply of nutrients in dairy cows fed rumen-protected soy products./. Dairy Sci. 2005, 88, 2879-2892. 

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