Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2010
Publication Date: 7/11/2010
Citation: Hoffman, P.C., Esser, N.M., Shaver, R.D., Coblentz, W.K., Scott, M.P., Bodnar, A.L., Schmidt, R. 2010. Influence of Inoculation and Storage Time on In Vitro Gas Production of High Moisture Corn. Journal of Dairy Science. 93:725. Interpretive Summary:
Technical Abstract: The hydrophobic prolamin (zein) proteins, which encapsulate high moisture corn (HMC) starch, are altered by genetic-maturity origin and fermentation. The effect of protein alteration on in vitro digestibility of HMC has not been thoroughly investigated. To assess influences of protein alteration, as effected by inoculation and storage time, on in vitro gas production of HMC, quadruplicate samples of two random HMCs (A and B) containing 25.7 and 29.3 % moisture were ground (± 900 um), inoculated (I) with or without 500,000 cfu/g of LB500 (Lallemand Inc., Milwaukee, WI) ensiled, and stored for 0, 15, 30, 60, 120 and 240 d. The HMCs were re-ground through a 4-mm screen, inoculated with rumen fluid from two cannulated cows fed 35 % concentrate. Samples were incubated for 36 h in an in vitro gas production (GP) system fit with wireless transponders. Total, 0-12, 12-24, and 24-36 h GP was evaluated with lag (h) and fractional rate (h-1) estimated using a segmented non-linear model. Total GP of A, AI, B and BI were modestly altered by storage time and HMC (A vs. B). Larger alterations of 0-12 h GP (% of total) were observed for A, AI, B and BI, with 0 and 240 d GP at 52.0, 52.0, 59.4, 59.5 and 58.6, 60.2, 71.9 and 71.6 %, respectively. Fractional rates of digestion were faster for corn B, and increased with storage time but were not affected by inoculation. Fractional rates were best correlated (r = -0.64, 0.58, 0.62, -0.70, 0.64) to pH, acetate, lactate, prolamin and NH3-N contents of HMC and 0-12 h GP was best correlated (r = -0.73, 0.77, 0.72) to pH, lactate and NH3-N. Lag times were shorter (1 h) for HMC B but lag time was not influenced by storage time or inoculation. Gas production pools, fractional rates and lag time were poorly correlated to ADF, NDF, ADF-CP and NDF-CP. Data suggest genetic-maturity origin and storage time alter in vitro gas production of HMC.