PSXI-12 Effects of Flint corn with or without high concentration of amylase and particle size on in vitro fermentation parameters, gas production and methane emission

Abstract The objective of this trial was to evaluate the fermentation parameters, gas production and dry matter (DM) disappearance in vitro of two corn hybrids with two particle sizes. A 2 × 2 factorial design study was carried out to evaluate two types of Flint corn with or without high amylase concentration (Enogen flint or Tropical Flint, respectively), and two particle sizes (1.5 or 2.5 mm). Incubations were carried out for a total period of 24 h using the automatic gas pressure system (ANKOM, RF). The ruminal liquid was combined with buffer in a 1:4 ratio respectively and each bottle received 150 mL of this mixture plus 1.5 g of DM corn sample. At the end of the 24-h period, 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. Data were analyzed using SAS Proc Mixed (9.4). There was no interaction effect between corn hybrid and particle size for the variables evaluated. Enogen Flint corn increased the proportion of propionate (30.7 vs. 28.1 mM/100 mM; P = 0.03) and reduced isovalerate (1.23 vs. 1.65 mM/100 mM; P = 0.01), and acetate:propionate ratio (1.85 vs. 2.11; P = 0.04), with no effect on the other fermentation variables evaluated. The particle size affected the pH of the fluid, with lower pH observed when using 1.5 mm particle size (6.64 vs. 6.70; P < 0.01). Regarding the disappearance of DM, Enogen Flint corn increased disappearance compared with Tropical Flint (80.8 vs. 77.5%; P < 0.01), and the 1.5 mm particle size also resulted in an increase in DM disappearance (81.9 vs. 76.4%; P < 0.01), with no interaction between the factors studied. (P = 0.80). Corn hybrids did not affect total gas production and methane production. However, the 1.5 mm particle size increased the total gas production (117.5 vs. 103.2 mL/24 h; P < 0.01), with no effect on methane production. In conclusion, Enogen technology optimizes the rumen fermentation process and increases corn dry matter degradability, and 1.5 mm particle size of the corn grain also increases degradability.