Determination of indigestible neutral detergent fiber and other newly identified parameters of fiber digestibility in fibrous feedstuffs of a dairy farm

The study was conducted to evaluate indigestible neutral detergent fiber (iNDF) and other related parameters of fiber digestibility of alfalfa hay, corn silage, wheat straw, beet pulp, and wheat bran of a dairy farm. Using two cannulated non-lactating Holstein cows and in situ method, undigested neutral detergent fiber (uNDF) after 288 h was measured as indicator of iNDF. Then with evaluating the kinetic of fiber digestibility in several time points, the rate and extent of NDF digestibility (NDFD) were measured according to newly-developed equations. The measured NDFD was used for estimation of total tract NDF digestibility (TTNDFD). Alfalfa hay had a greater amount of lignin as well as greater rate of NDF digestion than corn silage and wheat straw. Alfalfa hay and wheat straw, compared with corn silage, had a greater amount of uNDF and lower NDFD and TTNDFD. In spite of having relatively similar amount of NDF, the beet pulp and wheat bran had lower amounts of lignin and uNDF, while greater rate and extent of NDF digestibility as well as TTNDFD than forages. Overall, the considered fibrous feedstuffs showed a considerable variation in uNDF, NDFD, and TTNDFD that must be considered at the time of use.