This study investigates the methane and carbon dioxide gas production, dry matter degradation, and final pH values obtained during the in vitro incubation of corn grain, soybean hulls, citrus pulp, corn silage, and crude glycerin. Experiments were performed using a randomized block design with four incubation periods. Each period featured four replicates per ingredient and four blanks, totaling 16 repetitions per ingredient. The lowest total amount of produced gas (37.96 mL gincubated DM-1) and the lowest final pH value (4.95) were obtained for crude glycerin (P < 0.05), which, however, exhibited the highest (P < 0.05) DM degradation. Citrus pulp produced the largest amount (P < 0.05) of CH4 per gram of incubated DM (13.56 mL g-1). However, when methane production was expressed per gram of degraded feed, the ingredients with lower degradation values, such as soybean hulls and corn silage, produced more CH4 per gram of degraded DM. Citrus pulp and corn grain produced more (P < 0.05) CO2 per gram of incubated DM. However, per gram of degraded food, citrus pulp produced the largest amount of CO2 (P < 0.05). Crude glycerin and corn grain produced less methane (per gram of degraded feed) than citrus pulp, soybean hulls, and corn silage. Differentiation of ingredients based on their methane production ability is important to express methane production per unit degraded food mass.

In vitro fermentation of corn silage using rumen fluid buffered or not and different sample amounts.Ciência Rural, v.45, n.12, dez, 2015. 2229In vitro fermentation of corn silage using rumen fluid buffered or not and different sample amounts

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.