For measuring the nutritive value of ingredient using in vitro trail, should the ingredient used alone in the in vitro trail or mixed with the whole diet then used for the trial?
Here's a nice article: J Dairy Sci. 2000 Oct;83(10):2289-94. The classic in vitro digestibility method is the old Tilley and Terry method J. Brit. Grassland Soc. 18:104-11, 1963. One caveat of terminology typically is that nutritive value refers to the chemical composition of the ingredient. So measuring nutritive value typically involves wet chemistry proximate analysis, NIRS, etc. An in vitro procedure won't give you information about the chemical composition, just the digestibility.
It depends on your goals and the type of animal you have in mind. For ruminants, with an in vitro trial you evaluate how much of the sample is lost (solubilized) in an incubation process with rumen fluid or cellulases, plus a pepsin treatment. This is known as in vitro digestibility and it is typically measured for the dry matter or the organic matter. A combined determination of digestible organic matter as percentage of the dry matter (DOMD) is used to estimate the metabolizable energy content of forages for ruminants.
If you are interested in evaluate an ingredient, you should try the ingredient alone. Otherwise you’d be evaluating a diet.
Hope this helps…
A rough assessment of the composition of feed or feed components may be done by the socalled Weende analysis. Crude protein, fat, ash, fiber, etc... is referred to fresh and dry matter in g/kg. An enhanced analysis gives more detailed information on fiber composition (neutral detergent, acid detergent, and lignin) and is known as the Van Soest analysis. Additional analyses for starch, saccharose, elements,... are frequently offered by laboratories for feed analysis.
These analyses however can not tell you about actual digestibility of your material. This might be done by other methods like mentiioned by the colleagues above!
They need to know more information to help. However this literature costs
. Greetings!
Sorry, the reference is: Méthodes d'évaluation et de contrôle des matières premières Picard M., Leon A.
In : Sauveur B. (ed.). L'aviculture en Méditerranée. Montpellier : CIHEAM, 1990. p. 71-79. (Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 7). Aviculture en Méditerranée, 1987/11/05-07, Belgrade (Yugoslavia). http://om.ciheam.org/om/pdf/a07/CI901581.pdf
Other: British Journal of Nutrition (1989), 61, 689-698
An in vitro method for studying digestion in the pig
2. Comparison with in vivo ileal and faecal digestibilities
BY H. GRAHAM, w. LOWGREN AND P. WMAN
Referring to your question - if you wish to do a Weender analysis it is essentail to know about the nutritional value of the entire diet, including your ingredient of interest. In this case, you should analyze the diet without your component as control. The other possibility is analysing your ingredient alone and the basic diet alone. You can calculate the nutritional values of various mixtures afterwards.
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