Abstract #M270

# M270
Eeffect of different heat processing methods on both morphological changes of starch granules and degradability of barley grain.
S. Shirmohammadi*1, A. Taghizadeh1, G. A. Moghaddam1, A. H. Khani1, 1University of Tabriz, Tabriz, East Azerbaijan, Iran.

The aim of this study was to evaluate the effect of different heat-processing methods on both morphological changes of starch granules and degradability of barley grain. Treatments included 1) control: whole barley grain with no processing(WBG), 2) roasted: roasting for 5min at 130C° (RBG), 3) microwave irradiated: microwaved for 2min at 1200W(MBG), and 4) steam flaked: moisturized for 30 min on direct steam flow of boiling water and flaked just after moisturizing (SBG). To evaluate degradability by treatments, a gas production technique and an in situ method were utilized. For estimating post-ruminal digestibility, a modified 3-step method was adopted. Scanning electron microscopy (SEM) was used to identify morphological changes and also as a new method for explaining digestion kinetics. Cumulatively produced gas was recorded at 2,4,6,8,12,16,24,36,48,72, and 96 h of incubation. Kinetics of digestion were estimated using the model of Gp = A(1 − e−ct). The in situ method used for determination of ruminal digestion kinetics. Two bags were incubated in the rumen of 3 wethers fitted with a rumen cannula. Incubation times were 0,2,4,8,12,16,24,36, and 48 h. Degradation kinetics of DM were calculated using the model of y = a + b(1 − e−ct). In vitro intestinal disappearance of ruminal DM residue after 12 h of incubation was estimated using a modified 3-step procedure. Different heat-processing methods increased (P < 0.05) cumulative gas production, being 179.9, 190.2, 200.6, and 211.8 mL/g of DM for WBG, RBG, MBG, and SBG respectively. Disappearance of DM increased (P < 0.05) from 70.9% for WBG to 74.8%, 79.5%, and 84.2% for RBG, MBG, and SBG, respectively. Extent of intestinal disappearance of DM was greatest for SBG and least for WBG. All these results were evident by the ratio of holes to starch granule surface using SEM. Heat-processing can be used not only to make greater use of grain in the rumen but also can be used to improve postruminal digestibility.

Key Words: barley grain, scanning electron microscope, gas production technique