Effects of the inclusion of glycerin in diets containing 30 or 70% roughage on feed disappearance and digestibility

Abstract

The objective of this study was to evaluate in vitro nutrient disappearance and in vivo nutrient digestibility of cattle diets containing 70 or 30% roughage, with and without glycerin supplementation. Four Nellore cattle were used in the study based on a 4 × 4 Latin Square design in a 2 × 2 factorial arrangement. Inclusion of glycerin and roughage proportion did not affect the nutrient disappearance of each ingredient (P > 0.05). Regardless of the inclusion of glycerin, a reduction in the proportion of roughage led to an increase (P < 0.05) in DMDis (64 vs. 72%), NDFDis (41 vs. 54%), and ADFDis (31 vs. 44%) of the total rations. Inclusion of glycerin resulted in an increase (P < 0.05) in DMD (70 vs. 62%) and a reduction (P < 0.05) in CPD (32 vs. 38%) and STD (82 vs. 74%). The diet containing 30% roughage led to higher (P < 0.05) DMD (67 vs. 65%) and CPD (35 vs. 33%) in comparison with the 70% roughage diet, but did not differ (P > 0.05) in STD (78%). Inclusion of glycerin at 20% of the total DM increased the utilisation of dietary DM without affecting the fibrous fraction of the diet. Glycerin supplementation in diets containing 70% roughage improves neutral detergent fibre digestibility. Key words: INDF. Glycerol. Ingredients. In vitro. In vivo. Total ration. ResumoO objetivo deste estudo foi avaliar o desaparecimento in vitro de nutrientes e a digestibilidade in vivo de alimentos para bovinos contendo 70 ou 30% de forragem, com e sem suplementação de glicerina. Foram utilizados quatro bovinos Nelore num delineamento quadrado latino 4 × 4 em um esquema fatorial 2 × 2. A inclusão de glicerina e forragem não afetou o desaparecimento de nutrientes dos ingredientes (P > 0,05). Independentemente da inclusão de glicerina, uma redução na proporção de forragem provocou um aumento (P < 0,05) na DesMS (64 vs. 72%), DesFDN (41 versus 54%) e DesFDA (31 vs. 44%) das rações totais. A inclusão de glicerina resultou em um aumento (P < 0,05) na DMS (70 contra 62%) e uma redução (P < 0,05) na DPB (32 vs. 38%) e DAM (82 versus 74%). A dieta contendo 30% de forragem proporcionou maior (P < 0,05) DMS (67 vs. 65%) e DPB (35 versus 33%) em comparação à 1 Drs. em Zootecnia, Universidade Estadual Paulista, FCAV, Jaboticabal, SP, Brasil.