Indigestible internal markers for the estimation of digestibility of diets containing co-products

Abstract

The aim was to evaluate the indigestible neutral detergent fiber (NDFi) and indigestible acid detergent fiber (ADFi) as internal markers to estimate the digestibilities of feedlot beef cattle diets with grounded corn, soybean hulls or corn germ meal. Twenty seven Nellore steers were confined and distributed in three different treatments with grounded corn, soybean hulls or corn germ meal. The NDFi and ADFi percent were quantified after 144h of in vitro incubation of ingredients, earts and faecal samples. The markers intake did not differ when the byproducts soybean hulls and corn germ meal replace partially the grounded corn, probably due to the digestive similarity between that feeds. The means of dry matter (59.9 vs 59.8%), crude protein (54.4 vs 54.3%), neutral detergent fiber (52.2 vs 51.8%) and acid detergent fiber (40.4 vs 40.9%) digestibilities estimated by NDFi and ADFi were similar, respectively, without any relation with the ingredients used. It was concluded that the NDFi and ADFi provided similar digestibility coefficients in diets with 40% of concentrate, even though the introduction of ingredients rich in fiber in partial substitution of grounded corn.