57 Effects of particle size and heat treatment on in situ and in vitro digestion of dry-rolled Enogen® Feed Corn.

摘要

Enogen Feed Corn (EFC; Syngenta Seeds, LLC) has amplified expression of heat-stable amylase. Our objectives were to evaluate impacts of particle size and heat treatment on digestibility of EFC using a 4 x 4 x 3 factorial treatment arrangement. Mill-run corn (CON) and EFC were ground in a Wiley Mill through 9-, 6-, and 4-mm screens. CON and EFC were then blended to produce mixtures of 0, 33.3, 66.7, or 100% EFC. Duplicate samples were heated in a forced-air oven to internal temperatures of 50, 75, or 100ºC, and a non-heated control also was used. dry matter disappearance (14 h; ISDMD) was measured in triplicate using 6 fistulated steers. gas production (IVGP) and volatile fatty acid (VFA) profiles were measured in duplicate after incubating for 24 h at 39ºC using fermentation bottles equipped with pressure sensing modules (ANKOM Technology, Macedon, NY). Production of VFA was measured by gas chromatography. There were no 2- or 3-way interactions ( > 0.10). ISDMD, IVGP, and concentrations of propionate and butyrate increased linearly in response to decreasing particle size ( < 0.01). ISDMD responded quadratically to heating ( < 0.01), with grains heated to 75ºC yielding the greatest and 100ºC yielding the least ISDMD. Heating did not impact IVGP or VFA ( > 0.16). ISDMD and IVGP increased linearly in response to increasing proportions of EFC (Table 1), but VFA production was not affected by proportion of EFC. Enogen Feed Corn is more susceptible to degradation by ruminal microbes compared to non-Enogen corn, but absence of a quadratic response suggests that its impact on other dietary components is minimal.