The objective ofthis experiment was to evaluate estimates of concentration of indigestible drymatter (iDM), indigestible neutral detergent fiber (iNDF) and indigestible aciddetergent fiber (iADF) in samples of cattle feed and feces processed at differentparticle sizes (1-, 2-, and 3-mm) using bags made from nylon (50 μm),F57 (Ankom®), and non-woven textile (NWT - 100 g/m2)in a in situ evaluation procedure. Eight samples of concentrates, sevensamples of forages and two samples of cattle feces were used. The samples wereput in the bags according to a ratio of 20 mg of dry matter/cm2 ofsurface by using three bags of each textile for each size of particle, totaling405 bags, which were submitted to ruminal incubation for 264 hours. The contentsof indigestible compounds in the samples were evaluated sequentially. Blankbags were used for microscopic evaluation of textile physical integrity andfor evaluation of the physical resistance. The presence of contaminants causedhigh variability of results of iDM, indicating that its using as internal markershould not be recommended. By using the textiles F57 and NWT, similar estimatesfor contents of iNDF and iADF were obtained whereas by using nylon (50 μm),the concentration of iNDF was underestimated, possibly because of loss of particlesdue to its porosity. Nylon presented loss of resistance in all analytical stages,expanding its probality of rupture, especially after extraction with acid detergent.For in situ evaluation of indigestible compounds, it is suggested grindingsamples in 2-mm screen sieves.
