PSXIV-12 In vitro gas production and fermentation parameters in diets with increasing levels of natural zeolites for feedlot cattle.

Abstract The use of natural feed additives to reduce methane (CH4) production through manipulation of ruminal fermentation patterns and improve animal performance has increasingly been evaluated. One of these strategies may be the use of Natural Zeolites (NZ), such as glauconite. This study aimed to evaluate in vitro dietary supplementation with levels of NZ on rumen fermentation patterns and dry matter digestibility (DMD). In the experiment, a basal diet (50% concentrate: 50% forage) was incubated without additive (control) and with natural zeolite (1 or 2 % of DM) for 24 h to assess their effect on ruminal fermentation, feed degradability, and gas and methane production using a semi-automatic system of in vitro gas production (GP). The GP was determined using the Ankom® RF Gas Production System (Ankom Technology, NY, USA), by incubating 0.5 g of samples (ground to 1 mm). Eight analytical repetitions (8 bottles/ treatment) and four blank bottles (rumen fluid and buffer solution) were used. The pressure of GP in all bottles at each measuring time was converted into volumes to calculate the total accumulative gas produced through 24 h. After this time, methane concentration was determined using a gas chromatograph., a gas sample was taken for methane analysis, a sample was taken for short chain fatty acid (SCFA) analysis, and DM was performed on the final residue from the bottles to estimate the disappearance of DM. Methane concentration was determined using a gas chromatograph. All data were analyzed as polynomials using SAS. Significant effects were adopted when P ≤ 0.05 and tendency was reported when 0.05 < P ≤ 0.10. The inclusion of NZ did not affect the VFA proportion (P ≥ 0.15). The inclusion of NZ in the diet linearly increased the rumen pH (P = 0.02), but not effect ruminal ammonia concentrations (P ≥ 0.21). The experimental treatments did not affect the DM digestibility (P ≥ 0.11), total gas (P ≥ 0.19), and methane production (P ≥ 0.43). In conclusion, the addition of NZ not affect in vitro dry matter digestibility and, at the same time, increasing rumen pH without affecting gas production, including methane.