Physical fractionation of grains and legume seeds and their nutrient supply estimated from rumen degradation kinetics and end product formation determined in vitro.
01 / 2001 - 12 / 2007
METIS Wageningen Universiteit en Researchcentrum
Information on the conversions and the type of nutrients supplied by different feed fractions that differ in degradative behaviour in the rumen is mainly based on in situ incubations in the rumen. This method divides major feed fractions like starch, proteins and cell walls in a washout (TWF), a non-washout(NWF) but degradable (D) and an undegradable (U) fraction. Much information is available on the degrative behaviour in the rumen of starches, proteins and cell walls present in the D fraction, but this is not the case for the components in the W fraction. Besides it has become apparent (Lopez et al., 1994; De Boever et al., 1995, 1997; Madsen et al., 1995) that the TWF partly consist of soluble components (SWF) and partly of insoluble small particles. Their degradative behaviour is not known, but the fraction of insoluble small particles may resemble more the D fraction than the S fraction. In order to seperate, determine and characterise the insoluble washout (TWF) and soluble (SWF)fractions, alternative methods have to be developed. A new method of fractionating feeds that mimics the washout procedure with nylon bags, combined with an in vitro system, in which gas production is measured continuously (Davies et al., 2000) loos promising and suitable. With this approach different fermentation characteristics of the NWF, TWF and SWF can be determined and evaluated. the objectives of this study are: 1. To fractionate and characterise rumen degradation kinetics of these fractions in grains (barley, corn, sorghum) and legume seeds (faba beans, peas, lupins). 2. To determine the chemical composition of these fractions by wet chemistry and by Near Infrared Reflectance Spectroscopy (NIRS). 3. To determine the fermentation kinetics and the fermentation end products of these fractions in vitro with the cumulative gas production technique. 4. To study the effects of some feed processing methods on fermentation characteristics of these grains.