The Effects of Indigestible Neutral Detergent Fiber (iNDF) of Alfalfa Hay and Corn Silage on Ruminal Degradability of Ration Fiber in Sheep

Two experiments were carried out to evaluate the effects of indigestible neutral detergent fiber (iNDF) of ration for estimation of rumen degradability of fiber in sheep. In experiment 1, to determine feed iNDF, four ruminal fistulated Zel ewes were used. Three grams of alfalfa hay, corn silage, barley grain, wheat bran, ration 1 (including alfalfa hay and concentrate), and ration 2 (including corn silage and concentrate) in four replications were put in nylon bags and incubated in the rumen for 288 h. In experiment 2, the ruminal degradation of dry matter (DM), NDF, iNDF and potential digestible NDF (pdNDF) of alfalfa hay, corn silage, in both ration 1 and 2, were determined with in situ method using four ruminal fistulated Zel ewes. Rumen disappearance of DM at 0 and 2 hour incubation time and NDF at 96 hour incubation time in ration 2 were higher. The soluble, slowly degraded fractions, and rate of degradation in rations 1 and 2 were 28.93 and 25.93%; 50.40 and 46.26%; 2.36 and 3.19 %/h for DM; 11.81 and 11.74%; 61.37 and 46.32%, and 1.74 and 2.33 %/h for NDF, respectively. The iNDF content in alfalfa hay, corn silage, barley grain, wheat bran, ration 1 and 2 were 30.74 ± 3.02, 16.84 ± 2.14, 4.77 ± 1.48, 11.75 ± 2.29, 21.32 ± 0.77, and 11.42 ± 0.91% of DM, respectively. The results showed that despite the similarities in NDF content in both rations, differ-ence in the iNDF content could affect on degradability in rumen.