Fiber Digestion (Rate & Extent) Effect

Rate of Fiber Digestion

The rate of fiber digestion is impacted by factors such as the forage species, maturity of the forage, particle size of the forage, level of grain in the diet, and whether the forage is fed dry as with hay or ensiled as with haylage. Forage particles must first be solubilized before they can be digested, so a fresh grass or a haylage is digested more rapidly than a hay of the same species and maturity. Additionally, forage particles are usually digested from the inside to the outside, because the outside of forages have a waxy cuticle layer that make bacterial attachment difficult. This is one of the reasons why alfalfa, which may have more lignin than a grass, but which is hollow-stemmed, and breaks apart easily during the chewing process, may have a more rapid digestion than a grass which is flat and must be broken into sections for bacteria to attach. Amaferm has been shown to accelerate both the rate and extent of fiber digestion through increased growth of the rumen fungus Neocallimastix frontalis EB188, thus functioning like a prebiotic in stimulating the activity of fungi that break lingo-cellulose bonds leading to enhanced bacterial digestion.

 Specific research information can be found by clicking on the links below:

Rate

Fondevila et al.,  1990

Newbold et al.,  1991

Varel et al.,  1993

Chang et al.,  1999

Chiou et al., 2000

Extent of Fiber Digestion

The extent to which a fiber is digested is determined by the rate of digestion and the amount of time the forage stays in the rumen or cecum. As a result, increasing the surface area of the forage available for bacterial attachment either through reducing the particle size by grinding or increasing the growth of the fungi that break lingo-cellulose bonds can both lead to increased digestion. The rate of passage of solids is affected by the level of feed intake, with a higher feed intake increasing the rate of passage. Additionally, smaller feed particles have a faster rate of passage, which means that they stay in the rumen or cecum for a shorter amount of time. Generally, forage particles pass out at a rate of 1 to 6% per hour, or .25 to 1.5 times per day. When very mature forages are fed, they need to be physically broken down and they form a mat layer in the rumen or cecum. In many cases, the space that the mat layer takes up actually reduces an animal’s feed (and energy) intake, because this very indigestible portion of the diet takes up space that a more digestible feed could occupy. Varga and Kolver, (1997) reported that only 30 to 80% of the cellulose in a forage may be digested, leaving a considerable portion of the potentially digestible fiber unused. In vitro studies have shown the addition of Amaferm to increase NDF and ADF degradation of certain feedstuffs (Beharka and Nagaraja, 1993). Furthermore, Gomez-Alarcon et al. (1990) reported a 36% improvement in NDF digestibility and a 41% improvement in ADF digestibility when Amaferm was fed.

 Specific research information can be found by clicking on the links below:

Extent

Van Horn et al.,  1984

Wiedmeier et al.,  1987

Gomez-Alarcon et al.,  1990

Westvig et al.,  1991

Beharka and Nagaraja,  1993

Chen et al., 2004