Study On The Effects Of Processed Corns On Ruminal Fermentation, Intestinal Digestion And The Synchronization Of Energy And Nitrogen Release In Lactating Cows

Combined with In Vitro, In Sacco, and In Vivo techniques, this paper studies the effects of processed corns on ruminal fermentation, intestinal digestion, the synchronous metabolism of energy and nitrogen, and production performance of lactating cows, in order to provide the theoretical base for ruminal fermentation manipulation, ration formulation and the effective utilization of nutrients by ruminants. 4 parts are included as follows:Part 1. Study on the dynamic degradation regularity of processed corns and common-used feedstuffs in the rumen3 health Chinese Holstein lactating cows with permanent ruminal cannulas were selected as experimental animals. Cows were fed at the ratio of concentration to roughage 55:45, to investigate the starch, OM and CP degradabilities of processed corns (expanding, toasting, pelleting, rolling and roasting) and common-used feedstuffs (corn, wheat bran, soybean meal, flaxseed meal, cottonseed meal, hay and corn silage). The result shows that the ruminal degradabilities of starch, OM and CP are affected by different processing methods. Expanding and pelleting methods significantly increase the starch degradability(P<0.05), while that of toasting and roasting apparently decrease the starch degradability(P<0.05). The sequence of starch degradability is expanded corn>elleted corn>rolled corn>control corn>roasted corn>toasted corn(140℃,35min). As for the expanded corn, the starch degradability decreases linearly as the temperature rises from 130℃ and 140℃ to 150℃; There's a linear relationship between expanding temperature and starch degradability; the regression equation is Y=-0.211X+106.26 (r2=0.9876,N=3). Treated by different temperature and time, the ruminal starch degradability decreases to some degree by toasting processing. As the temperature rises and time prolongs, the starch degradability decreases gradually. The lowest degradability is found under the condition of 140℃,35min. The major factors affecting ruminal starch degradability may include the rapidly degraded fractions (S) and the degradation rate (Kd) of slowly degraded fractions (D). The result also shows that the ruminal degradation regularity of starch, DM and CP of common-used feedstuffs are different. As to energy feedstuffs, wheat bran has higher starch and CP degradabilities than that of control corn, while OM degradability is insignificant between them. As for protein feedstuffs, starch, OM and CP degradabilities of soybean meal are higher than that of flaxseed meal and cottonseed meal; starch and OM degradabilities of flaxseed meal are higher than that of cottonseed meal, but protein degradability is lower than that of cottonseed meal. As to the roughage, starch, OM, CP degradabilities are higher than that of hay.Part 2. Determination of the effects of processed corns on intestinal digestibility by BIF technique.The intestinal digestibility of ruminal non-degradable residues of processed corns (after 12h culture) was studied by BIF technique. The result shows that the best culture condition is as follows: 0.5g BIF/0.5g feed, McDougall buffer, pH 7.0, Ca2+ concentration 680um, 39℃and 8h. Processing methods affect the intestinal digestibility to some degree. Expanding significantly increases the intestinal digestibility(P<0.05), but toasting, pelleting rolling and roasting have no significant effect compared with control corn(P>0.05). Combined with the result in Part 1, 130℃ expanding and 140℃,35min toasting are relatively better processing methods in this experiment.Part 3. The effects of different bypass starch diets on ruminal fermentation, nutrients utilization, lactation performance and blood indices in lactating cows.3 above-mentioned lactating cows were selected as experimental animals with the ratio of concentrate to roughage 55:45. A 3×3 Latin Square design was used to study the effects of 3 diets (expanded, roasted and control corn diets) on ruminal fermentation, nutrients utilization, lactation performance and blood indices in lactating cows. Expanded and ro...