Include forages with high fiber concentrations and long particles. Forages vary greatly in fiber concentration and particle size, and long fibrous particles distinguish forages from other feed ingredients. Therefore, the forage content of diets can be reduced if forage with higher fiber concentrations and longer particles are used. For instance, a diet formulated using a forage containing 50% NDF can contain 20% less forage to provide the same forage NDF concentration compared with a forage containing 40% NDF, because more fiber is provided per unit forage weight. However, it is also important to consider digestibility of forage NDF; increasing forage NDF by delaying harvest will decrease the rate and extent of NDF digestion, which will decrease the energy supply to microbes and to the animal. Across cuttings and maturities, NDF concentration is poorly related to digestion characteristics of NDF for alfalfa, so it is possible to purchase or select forage with both high NDF content and high NDF digestibility. Corn hybrids with high NDF and high NDF digestibility exist and can be selected when land is limited for forage production. Forages can be compared for NDF digestibility by in vitro rumen fermentation or by evaluating the lignin concentration as a percent of NDF; within a forage type, digestibility of NDF decreases as lignification of NDF (%lignin/%NDF) increases.
Less forage also is needed in the diet if forage is long or coarsely chopped. Fibrous particles of finely chopped alfalfa or corn silage are not as effective in forming a rumen mat as are longer particles from coarsely chopped forage. Addition of coarse fiber as chopped hay also increases rumen mat consistency and rumination time and decreases passage rate of wet corn gluten feed. The length and concentration of long particles required in diets is not constant and depends on their digestion characteristics as well as characteristics of other diet ingredients
Avoid rapidly fermented feeds.Rapidly fermented feeds containing sugars and starch should be limited. It is important to consider the fermentability of all diet ingredients when feeding low forage diets because most forage alternatives are more fermentable than forages and are also less effective at stimulating chewing. Limiting rapidly fermented feeds such as finely ground high moisture corn and molasses will reduce the risk of acidosis.
Manage to avoid slug feeding. Diets with less coarse fiber require less chewing during eating and can be consumed more quickly, resulting in larger meals before satiety occurs. Although this might be desirable to increase feed intake in some situations, it also can result in ruminal acidosis if fermentation acids cannot be absorbed quickly enough, and the buffering capacity of ruminal contents is greatly exceeded. Overcrowding and feeding for no weighback increase competition among animals and encourage slug-feeding and should be avoided when feeding minimum forage diets.
Include dietary buffers. Although efforts should be made to reduce fermentability by limiting highly fermentable feeds, and to reduce slug-feeding by providing adequate bunk space, inclusion of buffers makes sense as another way to reduce risk of acidosis.
Limit NFFS with high fat content.Concentration and availability of poly-unsaturated fatty acids might limit inclusion rates for some NFFS such as whole cottonseeds and distiller’s grains because of potential milk fat depression. Limitations depend on fatty acid concentration and composition of the NFFS and other dietary ingredients.
Source: Mike Allen, Jennifer Voelker, Michigan State University Extension