Effect of dietary indigestible neutral detergent insoluble fiber (iNDF) content on nutrient digestibility, fermentation, ingestive behavior and performance of dairy cows

Abstract

Neutral detergent fiber (NDF) has been widely studied since the initial effort proposed by Peter Van Soest in quantifying and categorizing carbohydrates in the 1970s and 1960s. The knowledge on dietary NDF is critical for ruminant nutrition as the NDF fraction consists of the slow fermentation portion of feeds with the potential of filling the rumen and limiting dry matter intake. In addition, NDF is composed of a digestible and an indigestible fraction (iNDF), but these fractions largely vary among feeds and within the maturation stages. Studies have suggested that the iNDF dietary content can influence dry matter intake, feeding behavior, milk production and composition, and ruminal fermentation in dairy cows. However, there is still a gap in literature regarding the importance of knowing and considering the NDF dietary content at the time of formulation. Therefore, the aim of this study is to evaluate increasing levels of iNDF in the diet of dairy cows on intake and apparent total-tract digestibility of nutrients, sorting index, rumination time, feeding behavior, ruminal fermentation, excretion of purine derivatives, milk production and composition. The hypothesis of this study is that the increase in iNDF dietary concentrations would reduce animal performance by impairing nutrient intake and digestibility in a dose dependent manner.