In vitro and in vivo nutrient digestibility in sheep of rations with and without residue from the extraction of tamarind pulp

Abstract

<p>This study evaluated the digestibility of nutrients by, and parameters associated with, <em>in vitro </em>fermentation using different inocula (sheep ruminal fluid and feces) as well as the <em>in vivo </em>digestibility in sheep that were fed rations with 50% concentrate containing either no (0%) residue from the extraction of tamarind pulp (RETP) or 15% RETP. To determine the <em>in vitro </em>digestibility (<em>IV</em>D) of nutrients, two sheep, weighing 40.38 ± 2.10 kg, were used as inoculum donors. To determine the <em>in vivo </em>digestibility of nutrients, we used four sheep and a 3×2 factorial experimental design, with three methods of digestion of nutrients and two experimental rations (0% and 15% RETP). The variables were subjected to analysis of variance and the variables that showed differences at 5% probability were further analyzed using the Tukey test at 5% significance. The <em>IV</em>D using different inocula did not significantly differ (p&gt;0.05) from the <em>in vivo </em>digestibility in sheep for dry matter (DM), organic matter (OM), and neutral detergent fiber (NDF). The different methods for determining nutrient digestibility did not affect (p&gt;0.05) the digestibility of DM, OM, crude protein (CP), NDF, and acid detergent fiber (ADF) in rations with 0% and 15% RETP. However, the <em>IV</em>D of CP for rations containing 0% and 15% RETP incubated with both inocula was lower (p&lt;0.05) than the CP digestibility <em>in vivo</em>. The <em>in vivo </em>digestibility of ADF for rations containing 0% and 15% RETP was higher (P&lt;0.05) than the <em>IV</em>D using sheep ruminal fluid and feces as inocula. The pH values and concentration of ammonia nitrogen (NH3-N) after <em>in vitro </em>incubation for 24 h and the <em>in vivo </em>assay were not different (p&gt;0.05) for the rations containing 0% and 15% RETP, but the pH and NH3-N of both fermented and rumen contents differed (p&lt;0.05) depending on the inocula used and the <em>in vivo </em>assay. In summary, the digestibility of DM, OM, and NDF can be determined by the <em>in vitro </em>fermentation method using the ruminal fluid or feces of sheep as inocula in rations containing 0% or 15% RETP. However, <em>in vitro </em>fermentation is not a suitable method for the determination of pH and NH3-N concentration.</p>