| Three xuhuai white goats fitted with permanently ruminal cannlas were used in a 4x3 latin square design to evaluate the effects of roughage to concentrate ratio(R:C ratio) diet on dynamic changing rules of ruminal internal environment parameters and bacteria and protozoa composition. 4 different diets varied in R:C ratios among 10:0, 8:2, 6:4 and 4:6; The study also determined the effect of 4 diets on l5N-ammonium sulfate utilization by mixed ruminal bacteria in vitro; 6 kinds of bacteria were isolated and pure cultured from rumen contents of goats, the ability of inorganic nitrogen utilization and physiological characteristics were also identified. The results showed that: 1.Decreased R:C ratio decreased ruminal pH. pH decreased from 6.37 to 5.86 if R:C ratio varied from 10:0 to 4:6. pH in 10:0 group was much higher than that in 8:2, 6:4 and 4:6 groups (p<0.01), no clear differences were detected among 8:2, 6:4 and 4:6 groups (P>005).2.Lower R:C ratio increased ammonia-N(NH3-N) concentration. NH3-N concentration increased from 8.37 to 13.71 mg·l00ml-1 if R:C ratio decreased from 10:0 to 4:6. 8:2, 6:4 and 4:6 groups increased NHs3N concentration to a large extent compared with 10:0 group (P<0.01).3.Ruminal pH decreased to the lowest point after eating 1~3 hours, then increased until the next time' s eating. Similarly, NH3-N concentration increased to the highest point after eating 1 ~2 hours, then decreased until the next time' s eating. 4.The highest acetic acid concentration was observed in 8:2 group, much higher than in 10:0, 6:4 and 4:6 groups (P<0.01). Acetic acid concentration decreased orderly in 10:0, 6:4 and 4:6 groups; On the other hand, butyric acid concentration increased orderly in 10:0, 8:2, 6:4 and 4:6 groups; Propionic acid concentration were 15.09,15.75mmolL-1 respectively in 8:2 and 4:6 groups, much higher than that in 10:0 and 6:4 groups (P<0.01). The highest level of total volatile fatty acids(TVFA) was observed in 8:2 group (68.48mmol/L), much higher than that in other three groups. Acetate/propionate(C2/C3) ratio decreased orderly when R:C ratio decreased from 10:0 to 4:6. Except 10:0 group, there were no clear differences among 8:2, 6:4 and 4:6 groups.6.Various R:C ratio diets showed different influences on total nitrogen(TN) content of bacteria, while diets had negligible effects on TN content of protozoa and fat content of bacteria and protozoa.7.Comparison of bacteria amino acid(AA) from different groups indicated differences for 4 out of 17 AA measured, they were lysine(Lys), cystine(Cys), glutamic acid(Glu) and histidine(His) respectively. Protozoa were found to be different for 1 out of 17 AA measured, it was valine(Val).8.In vitro, pH and NH3-N concentration rapidly decreased in first 8 hours' incubation, then the speed of decrease became slow in later incubation times. At the end-point of the incubation (24 hours), bacteria isolated from 8:2, 6:4 and 4:6 groups had much higher biomass compared with 10:0 and blank groups, and the same trend was observed in the 15N-enrichment of bacteria. There was 547.43 μ g 15N in medium solution, and the amount of l5N-incorporation into bacteria at the incubation end-point was 120.44 μ g.9. 6 kinds of bacteria from rumen contents of goats were obtained. In physiological-biochemical characteristics test, the tested bacteria had different abilities of inorganic nitrogen utilization; 2 out of 6 kinds of bacteria were G+ coccus, others were G- bacillus; 5 out of 6 kinds of bacteria were facultative anaerobic bacteria; All of bacteria were tolerant to pH4.5-10.0 and the highest temperature 45 ; The behavior and reaction of mice were normal, had no toxicity symptom after mice were given bacteria liquids of high dose by oral administration; The preliminary identify result of 6 kinds bacteria was that: one for Cellulomonas flavogensis, one for Actinobacillussuis, one for bacteroides, three other kinds of bacteria species were not confirmed yet.
|
PDF Full Text Request