Effects of the inclusion of increasing proportions of citrus pulp, corn or barley to a high quality pasture on the in vitro fermentation

Abstract

The aim of this work was to evaluate the effect of inclusion of increasing proportions (from 0 to 100%) of citrus pulp, corn or barley to high quality pasture on in vitro fermentation. The in vitro gas production technique was used and the gas volume data were fitted to a simple exponential model with lag time. The effect of the proportion of the concentrates was studies using PROC MIXED of SAS® including as fixed the concentrate, the proportion into the substrate and the interaction among them. Since interactions concentrate*proportion were significant, linear and quadratic regression analysis were performed to describe the impact of increasing the proportion of each concentrate in the substrate using PROC GLM of SAS®. Increasing concentrate proportion enhanced the gas volume (mL/g OM incubated) and decreased the production rate, in different ways according to the concentrate included. Lag time increased up to the maximum level of inclusion of the cereals, but citrus pulp increased the lag time until 48% of inclusion.  Increasing the proportion of different concentrates into the substrate caused similar behaviors of the potential gas production and the gas production rate, even though with own characteristics according to the concentrate included. Although citrus pulp does not affect ruminal microbiota adhesion at the same extent as cereals, it could replace them in the supplementation of high quality pastures producing similar effects in the rumen.