| Four ruminally cannulated Limousin × Luxi beef cattle were chosen for this study. Nylon bag technique were used to evaluated the degradation characteristics of twenty-four kinds of cattle feeds and a 4×4 Latin square design were used to investigate the influence of four different diets contained two types of cereal(wheat, W or Maize, M) and two types of forage(Leymus chinensis, LC or sweet potato vine, SP) on rumen fermentation.The result showed that: in terms of wheat and its by-products, when the degradability towards stability, the black flour needs 24 h, wheat and wheat bran 36 h, and wheat germ 48 h. The degradation rate of black flour and wheat germ were highest, the effective rumen degradability of DM and OM were above 85%, the effective rumen degradability of NDF and ADF were70%~80%. The degradation rate of wheat,wheat middings and wheat bran were lower. The degradation rate of DM and OM were more than 60%, the effective degradation rate of CP were above 70%, and the wheat middings was 86.15%, which was the highest in wheat and its by-products. The degradation rate of NDF and ADF were about 30%,while wheat was about 50%.In term of maize and its by-products, the corn germ meal degrade faster than others, when the degradability tends towards stability, it needs 36 to 48 h. The degradation rate of CP and ADF in corn gluten feed and ADF in the corn gluten meal tends to stability after incubating in rumen for 48 hours. the effective rumen degradability of DM and OM in maize and its by-products are all between 55% and 65%. The effective degradation of CP in corn gluten feed and corn fiber feed are the highest, 86.27% and 88.76%,corn distillers lowest, 45.67%, other products between 50% to 70%. The effective degradation of NDF in maize is the highest, 71.71%, followed by corn gluten meal, is 61.26%,corn gluten feed is the lowest, 27.65%, the others between 35% to 45%. The ADF degradation in corn gluten meal is highest for 78.78%.In term of oil-cake feedstuff, when incubated in rumen for 48 h, only the degradability of NDF and ADF in rapeseed meal reaches stable while other are significantly increased(P < 0.05)within 72 h. Among all oil-cake feedstuff, the effective degradation rate of DM, OM, NDF and ADF in soybean meal are highest, which are 66.56%、65.20%、56.39% and 52.26% respectively. The highest effective rumen degradability of protein in rapeseed meal were 68.07%. The effective degradability of NDF and ADF in peanut meal and NDF in rapeseed meal are all above 30%, others are all lower than 30%. The effective rumen degradability of DM, OM, CP, NDF, ADF in solvent rice bran meal are the lowest, which are 46.96%, 45.46%, 45.12%, 18.29% and 12.67% respectively.In term of the residue products, when incubated in rumen for 36 h, the degradability of DM, OM, CP and NDF in bean dregs and CP, NDF in white distillers’ grains reach stable,while the NDF and ADF in cassava dregs and ADF in white distillers’ grains need 48 h. The effective rumen degradability of DM, OM, CP and NDF are all above 60% while brewer’s grains are all lowest, cassava dregs and white distillers’ grains centered.In terms of forage, when incubated in rumen for 48 h, the degradability of DM, OM and CP in peanut vine and CP in corn silage and alfalfa reach stable. the degradability of corn silage are the highest, followed by alfalfa and peanut vine and the Leymus chinensis is lowest.The result showed that: significant variability in ruminal p H with the WSP diet was more pronounced on which p H dropped from 6.81(before the dietary changes) to 6.57 by d 10(P = 0.03). The Ammonia(NH3-N) and total volatile fatty acid(TVFA) concentrations of the cattle fed the LC were decreased(P < 0.05) after diet changes and then increased to values similar to that before changing. However, the TVFA concentrations of the cattle fed the SP had the opposite trend. Mean ruminal p H were not affected by the treatments(P > 0.05). the NH3-N concentrations of the cattle fed the diet contain wheat are significantly higher than that of diet contained maize. The cattle fed WSP diet had greater(P < 0.05) butyrate and total VFA concentrations than others. The average NH3-N concentrations and the ratio of acetate to propionate were affected by cereal and the average p H values, concentrations of acetate, butyrate and total VFA were affected by forage(P < 0.05), No Cereal × Forage interactions were detected among all ruminal fermentation characteristics(P> 0.05)In conclusion, the degradability of feeds were all increased with the passage of incubation time, but different feeds differ greatly in degradability and degradation rate. The type of cereal and forge had apparent effects on ruminal fermentation characteristics, but no interactions were observed. |
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