纳豆芽孢杆菌在奶牛瘤胃和十二指肠存活规律

Survival of Bacillus subtilis natto in rumen and duodenum of Holstein dairy cows

通过体内外试验研究纳豆芽孢杆菌(Bacillus subtilis natto,BSN)在奶牛胃肠道存活规律及停留时间。试验1:经过滤的荷斯坦奶牛瘤胃液或十二指肠液加入BSN菌液(芽孢含量为105cfu/mL),对照组不添加;将处理好的发酵液于39℃厌氧培养,瘤胃液检测发酵0、6、12、24、48和72 h挥发性脂肪酸浓度和芽孢数,十二指肠液检测发酵0、1、2、3、4、5和6 h芽孢数。试验2:选取7头瘘管牛随机分成2组,处理组(4头)通过瘤胃瘘管投放100 mLBSN菌液(芽孢含量为108cfu/mL),对照组(3头)不投放;投放后6、12、24、48和72 h采集瘤胃液、十二指肠液和粪样。BSN在瘤胃液发酵过程中芽孢数呈先增高后降低的趋势,发酵24和72 h的存活率分别为191.3%和175.9%,并促进了丙酸和丁酸的产生(P<0.05),减少了乙酸、异丁酸和异戊酸的产生(P<0.01)。BSN在十二指肠液中发酵1 h内芽孢数有上升的趋势(P>0.05),发酵3 h后急剧降低,发酵1、3和6 h的存活率分别为159.2%、121.4%和35.7%。体内试验结果表明瘤胃、十二指肠和粪便中的芽孢数均随投喂时间的延长而逐渐降低,48 h后各位点均很难检测到芽孢。总之,BSN能耐受奶牛瘤胃液环境,并能影响瘤胃发酵,在十二指肠液的耐受时间约为3 h,但不能在奶牛胃肠道中定植。

Experiments in vitro and in vivo were conducted to evaluate the survival of B. subtilis natto （BSN） in the gastrointestinal tract of Holstein dairy cows. In experiment 1 ： the two treatment groups were strained rumen fluid and duodenum fluid inoculated with BSN at 10^5 cfu/mL level,and control group was strained rumen fluid or duodenum fluid without BSN inoculantions,all three groups were incubated in vitro at 39 ℃. Changes of BSN spore counts and volatile fatty acid in rumen fluid were monitored at 0,6, 12,24,48 and 72 h. Changes of BSN spore counts in duodenum fluid were monitored at 0,1,2,3,4,5 and 6 h. In experiment 2 ： 7 cows were randomly assigned to two groups. Four cows were infused with 100 mL BSN culture （108 spores/mL） into rumen through rumen cannula,and the other three cows did not receive infusion. Rumen fluid,duodenum fluid and eces were collected at 6, 12,24,48,72 h after the infusion. The results of rumen fermentation showed that spores increased in the first 24 h,and then decreased. The survival rate of BSN was 191. 3% and 175. 9% at 24 h and 72 h, respectively. In addition, BSN increased the concentration of propionate and butyrate in rumen fluid （P〈0.05）, but reduced the concentration of acetic acid, isobutyric acid and isovaleric acid（P〈0.01）. The results of duodenum fermentation showed that spore counts tended to increase in the first 1 h （P〉0.05）,and then decreased gradually,decreased sharply after 3 h. The survival rate of BSN was 159.2%, 121.4% and 35.7% at 1,3 and 6 h, respectively. The results of in vivo experiments indicated that spore counts continued to decrease in rumen,duodenum as well as feces and almost cannot be detected at 48 h after infusion in all of the location. In conclusion, BSN spores have the ability to survive in rumen and alter rumen fermentation. BSN spores are able to survive in duodenum fluid up to 3 h. However,the spores cannot permanently colonize in the gastrointestinal tract of Holstein dairy cows.