| Three Holstein dairy cows fitted with permanent ruminal cannulas were used in this study. Different ratio of ruminal biodegradable nitrogen and ruminal fermentable organisms (20, 25, 30, 35) were used as substrates to determine the corresponding effect on synchronization index. And study the effect of the different synchronization index diet on rumen fermentation pattems and microbial protein synthesis in the rumen with fermentation experiment in vitro. A randomized experiment was carried out to study the effect of energy-nitrogen synchronization index in diet on the productive performance, blood biochemistry indicators ,digestion and metabolism of nutrients and microbial protein synthesis in the rumen of dairy cows. The results of the study showed:1. At first make different ratio of RDN/FOM formulas diets according to the characteristics of cows feed degradation .Study the degradable quantities of nitrogen and organism in every four hours'time with the experiment in vitro. Calculating the synchronization index with the degradable quantitiy datas of nitrogen and organism.The SI of different ratio of RDN/FOM diets 20,25,30,35 were 0.66,0.72,0.55,0.88 respectively.There was not obvious relationship between RDN/FOM and SI.2. Effect of different SI substracts on fermentation pattems were investigated.The highest pH was in 0.72 group.But both the fluctuation range of pH and the average level of it were in the normal range of fermentation in vrtro. With the increase of treatment as 0.66,0.72,0.55,0.88, The NH3-N concentration in rumen increased from 17.34mmol/l to 23.81mmol/l. When the SI was 0.66, microbial protein synthesis yield was highest.The acetate concentration increased as the ratio of RDN/FOM increased in the respective treatment group,the highest was in 0.55 group, and lowest in 0.88 group. The propionate concentration was highest in 0.66 group, and lowest in 0.88 group. The percent of acetate increased, butyrate decreased with the increase of RDN/FOM in the substrate. The percent of propionate was highest in 0.66 group,and lowest in 0.72 group. The proportion of acetate and propionate was close to 3:1.3. After feeding four different synchronization index diets on 16 cows in early lactating period with the same parity and similar body weight from Yang Zhou University Experimental Farm. The average milk yielding per cow had no significant changes(P>0.05). From the milk ingredients, the milk fat percentage had no apparent difference in the four groups fed on different diets, while the milk protein and NFS had increased significantly when fed SI as 0.66,0.55(P<0.05).And the highest is 0.66. The effects of dietary SI ratio on the blood biochemistry indicators such as ALP,CRE,TG,ST/LT,ALB,LDH,A/G,TCO2,ALT,CHO had no significant changes(P>0.05).But the BUN concentration increased with RDN/FOM increasing, difference was significant(P<0.05). The highest TP and GLU concentration was in the group SI=0.88, lowest in the group 0.55,difference was significant(P<0.05). The highest ratio of A/G was in the group 0.66. difference was significant(P<0.05). All of the blood biochemical indexes were in the normal range after feeding four different synchronization index diets. The highest digestibility of DM,OM,ADF were all in 0.66 group,highest digestibility of CP was in 0.88 group, highest digestibility of NDF was in 0.55 group.The highest digestion efficiency of CP was 0.72 group. The best energy efficiency treatment group were 0.66 and 0.72.In this study the method of Urinary Purine Derivatives estimating rumen microbial protein production was used to caculating microbial protein synthesis .When collectting complete urine,the most microbial protein production was in the 0.88 group.But when collecting sample urine,the most treatment group was 0.55. And there was no obvious relationship between synchronization index and microbial protein synthesis. Considering the second experiment'result,found that when the SI was 0.66,we can get the diets'best utilization efficiency and the best productive performance of animals. |
