Effect of insoluble neutral detergent fiber (indigestible NDF) content of the diet on intake, productive performance, nutrient digestibility of dairy cows

• Grant number: 23/13590-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): January 01, 2024
• Effective date (End): December 31, 2024
• Field of knowledge: Agronomical Sciences - Veterinary Medicine
• Principal Investigator: Francisco Palma Rennó
• Grantee: Ana Caroline Silvério Vitor
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Neutral detergent fiber (NDF) has been widely studied since the initial effortproposed by Peter Van Soest in quantifying and categorizing carbohydrates in the 1970sand 1960s. The knowledge on dietary NDF is critical for ruminant nutrition as the NDFfraction consists of the slow fermentation portion of feeds with the potential of filling therumen and limiting dry matter intake. In addition, NDF is composed of a degradable andan undegradable fraction (uNDF), but these fractions largely vary among feeds and withinthe maturation stages. Studies have suggested that the uNDF dietary content can influencedry matter intake, feeding behavior, milk production and composition, and ruminalfermentation in dairy cows. However, there is still a gap in literature regarding theimportance of knowing and considering the NDF dietary content at the time offormulation. Therefore, the aim of this study is to evaluate increasing levels of uNDF inthe diet of dairy cows on intake and apparent total-tract digestibility of nutrients, sortingindex, rumination time, feeding behavior, ruminal fermentation, excretion of purinederivatives, milk production and composition. The hypothesis of this study is that theincrease in uNDF dietary concentrations would reduce animal performance by impairingnutrient intake and digestibility in a dose dependent manner.