Factors In Relation To Physical Processing And Variety Influencing Starch Gelatinization And In Vitro Rumen Fermentation Characteristics Of Corn Grains

Three in vitro gas production experiments were conducted using the procedure described by Menke et al. (1979) to investigate the effect of steam conditioning time, processing method and corn variety on the gelatinization of starch and ruminal fermentation characteristics of corn grains.In experiments 1, various steam conditioning time (0, 15, 30, 45 and 60 min) of pre-steam-flaking high oil corn (PSFHC) were selected to determine the effect of the steam conditioning time on the gelatinization of starch and ruminal fermentation in vitro. The result showed that steam conditioning time had a significant influence (P<0.05) on gelatinization of starch, fat content, maximum gas production, gas volume produced from 48h fermentation, gas producing rate, starch degradability, NH3-N concentration in 12h and 24h fermentation medium. However, no difference in the DM degradability , pH and total VFA was obtained for 12h and 24h (P>0.05). So it is more obvious to use gelatinization and starch degradability combined with gas production to reflect fermentation status than fermentation parameter. There was high consistency between gelatinization and starch degradability and gas production(R2>0.9). Best effect was obtained with 45min pre-steam-flaking.In experiments 2, Best conditioning time of PSFHC, micronized high oil com, extruded high oil corn and popped high oil com were compared with uncooked high oil corn to evaluate the effect of different processing on the gelatinization of starch and ruminal fermentation. The result showed that between processing had a significant differences (P<0.05) on gelatinization of starch, DM content, fat content, starch content, maximum gas production, gas volume produced from 48h fermentation, gas producing rate, starch degradability and NH3-N concentration in 12h and 24h fermentation medium. With contrast, no difference in DM degradability, pH and VFA was obtained for 12h and 24h (P>0.05). It indicated that processing can improve feeding value of high oil corn .In experiments 3, Effect of corn varieties on the gelatinization of starch and ruminal fermentation. It's concluded that there was significant difference (P<0.05) between three kinds of corn on gelatinization of starch, starch content, maximum gas production, gas volume produced from 48h fermentation, gas producing rate, DM degradability and starch degradability. Cau 108 is better than high oil corn and high quality protein corn, however there was no significant difference (P>0.05) in fermentation parameter (pH, NH3-N,VFA). It came to an conclusion that variety didn't change the fermentation style.