| The aim of this study was to investigate the effects of Rumen-Protected Glucose(RPG) in diet on Performance and serum biochemical indicators of postpartum dairy cows. It was to develop the glucose microcapsules whose protection efficiency in rumen is the highest by using fluid bed granulation technique. The experiment was divided into three parts:Experiment 1:Screening of Coating MaterialsEthylcellulose, polyacrylic acid resin IV and chitosan were chose to be used for coating materials. These materials were sensitive to p H. The effects of coating with different concentrations were evaluated by sensory indicators under the condition of the same process to screen out the most appropriate coating concentration. The results showed that the appropriate concentration of Ethylcellulose, polyacrylic acid, resin IV and chitosan can make the production successedly. The particles of these microcapsules were uniformity and the coating was integrity and these microcapsules were enough dried and not easy to be adhered.Experiment 2:Production and the Assessment of Protective Effect of RPGUsing technology of fluidized bed, RPG was separately coated with three kinds of p H sensitive material. The three kinds of RPG named EC-M, IV-M and CS-M. The stability of these RPGs was tested by the methods of digestion in vitro and rumen nylon bags. The results showed that the release rate of EC-M was the lowest. The release rate of EC-M was 9.5%~15.52% and 11.82%~35.69% when it was incubated in artificial saliva and the buffer solution( p H = 6. 6) for 2 h~24 h. With the increase of cultivation time, the rumen degradation of all the products decreased. After incubating for 2~24 h in the rumen,the three kinds of RPGs degradation rate were increased, but the release rate of EC-M was still the lowest, ranged from 26.68%~48.62%.The effective rate of RPC reached 57.42 %( k=0.03). Compared with the other two wall materials, the RPG produced by the EC-M can ensure high stability.Experiment 3:Effects of RPG in Diet on Performance, Serum Biochemical Indicators and Nutrient Apparent Digestibility of Postpartum Dairy Cows28 healthy Dairy Cows at the period of prenatal 21 d with similar body condition were randomly divided into 4 groups, 7 Dairy Cows per group. The control group(group IV) was fed a basal diet. Group I, group II and group III were fed a basal diet supplemented with 200 g, 300 g and 400 g RPG form the first day of postpartum, respectively. The experiment lasted for 28 days. The results showed that :(1)The postpartum weight of the group I, group II, group III and group IV were 61.99 kg, 43.2kg, 42.83 kg and 62.66 kg, respectively. Compared with group IV, group II, group III the lose of weight was significantly different(P<0.01).(2) Group II and group III milk yield is 26.68 kg?d-1?cow-1 and 26.84 kg ? d-1 ? cow-1, respectively, which significantly higher than the group IV that is 24.49 kg ? d-1 ? cow-1(P<0.01) and were not significant with groups IV milk yield of 25.66 kg ? d-1 ? cow-1(P>0.05).(3) The control group improved milk protein and lactose content, but the difference among these groups was not significant(P>0.05).(4) Compare to the control group, the experimental group increased the serum glucose concentration, decreased serum non-esterified fatty acids and β- hydroxybutyrate concentration. Especially, group III difference compared with the control group was significant, which reduced by 18.45% and 52.11%, respectively(P<0.01).(5)Adding rumen protection glucose microcapsules had no effect on digestibility of dietary nutrients.In conclusion, A new product of RPG was made by coating technology with ethylcellulose,and itseffective passing rate in rumen of RPG was 57.42%. Postpartum cow fed with RPG could reduce the amount of weight loss, improve milk yield, increase glucose concentrations in serum, and decrease non-esterified fatty acids and β- hydroxybutyrate concentrations. It was recommended that 300g~400g RPG per head per day was the optimum supplemental level during the postpartum period. |
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