Rumen digestion

Guo D, Chen F, Wheeler J, Winder J, Selman S, Peterson M, Dixon RA. 2001. Improvement of in-rumen digestibility of alfalfa forage by genetic manipulation of lignin O-methyltransferases. Transgenic Res 10 457-464. 

When a feed material contained more than 10% starch, the level of FOM was reduced to take into account the starch fraction that escapes rumen digestion. The multiplication coefficient used for FOM was 0.6 for maize, sorghum and rice, and 0.8 for peas, faba beans, potato pulp, whole potatoes, full fat and extracted rice bran, maize germ meals, maize bran and cassava. A value of 0.95 was used for all the other feed materials containing more than 10% starch. 

Doran, M.P., Laca, E.A., Sainz, R.D., 2007. Total tract and rumen digestibility of mulberry foliage (Morus alba), alfalfa hay and oat hay in sheep. Animal Feed Science and Technology 138, 239-253. 

As investigations have revealed the mechanisms of rumen digestion, attempts have been made to alter the patterns of digestion in ways that should improve the nutrition of ruminants. The primary approach has been to modify the microbial population in order to suppress undesirable processes (e.g. methane production see Section 8.4 and Chapter 11) or stimulate desirable processes (e.g. microbial protein synthesis). A secondary approach has been to protect nutrients from rumen fermentation in order that they should be digested in the small intestine. Changing the bacterial... 

The second type of supplement required for straw is one that provides the animal with additional protein that is not degraded in the rumen (digestible undegradable protein see Chapter 13). This often stimulates intake (see Chapter 17) and ensmes a... 

Although tannins appear to protect protein from microbial attack in the rumen, their ultimate effects on ruminant nutrition may depend upon how available this bypass protein is to the animal. According to Price and Butler (1980), the same factors that cause tannins to have a deleterious effect on monogastric nutrition, will presumably be important in the post-rumen digestive tract. If the tannin-protein complex does not dissociate in the abomasum or intestine, there will be no benefit to the animal from the protein having been protected in the rumen. If it does dissociate, the liberated tannin may damage the intestinal tract or form new complexes at some point with endogenous proteins. 

RdNDF rumen digestible neutral detergent fibre. 

Splanchnic release of ketogenic nutrients could be predicted (Loncke et al, 2008a, Loncke, 2009 Table 2) from two major dietary predictors the rumen fermentable organic matter (RFOM) intake and its content in rumen digestible neutral detergent fiber (RdNDF) plus an animal predictor the... 

The net splanchnic release of L-lactate could be predicted either from RFOM intake and the RdNDF concentration in RFOM themselves predictors of propionate and L-lactate-NPA, or from rumen digestible starch (to predict L-lactate-NPA) and energy balance (able to predict both net hepatic uptake and release of L-lactate). These predictions will still require improvement to solve the remaining high discrepancy between predicted-observed values. 

Sauvant, D. and D. Mertens, 2008. Use of meta-analysis to build a mechanistic model of responses of rumen digestion to dietary fiber in cattle, hr Modeller s Meeting of the ADS A. Can. J. Anim. Sci. 

Clapperton, J.L., 1974. The effect of trichloroacetamide, chloroform and linseed oil given into the rumen of sheep on some ofthe end-products of rumen digestion. Br. J. Nutr. 32 155-161. 

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