不同硒源对泌乳牛瘤胃发酵及瘤胃微生物区系的影响

Effects of Different Selenium Sources on Rumen Fermentation and Rumen Microflora of Lactating Cows

试验旨在研究高羊毛氨酸硒(SeHLan)和亚硒酸钠(SS)对泌乳中期荷斯坦奶牛瘤胃发酵及瘤胃微生物区系的影响。选用健康的泌乳日龄(181±18)d、日产奶(33.88±3.44)kg/d、(3.25±1.27)胎的荷斯坦泌乳奶牛32头,随机分成2组,每组16头,分别饲喂添加SS、SeHLan的全混合日粮(饲粮中硒实测值分别为0.47 mg/kg和0.46 mg/kg),预试期2周,正试期9周。试验结束前的最后一天,每组选取6头体况良好且健康的奶牛,在晨饲后4 h通过口腔真空抽取瘤胃液,并测定氨态氮、挥发性脂肪酸以及瘤胃微生物区系情况。结果表明:瘤胃液pH、氨态氮浓度、总挥发性脂肪酸及各酸的比例、乙酸/丙酸均不受硒源的影响(P>0.05);2组奶牛的瘤胃微生物多样性指数无显著差异;门水平上,2组奶牛瘤胃中的优势菌门无显著差异,均为厚壁菌门(Firmicutes)、拟杆菌门(Bacteroidetes)、糖化菌门(Saccharibacteria)、放线菌门(Actinobacteria)、软壁菌门(Tenericutes)和变形菌门(Proteobacteria);属水平上,2组奶牛瘤胃中的优势菌属均为普雷沃氏菌属_1(Prevotella_1)和解琥珀酸菌属(Succiniclasticum),其含量两组间差异不显著;但SeHLan组糖化假丝酵母菌属(Candidatus_Saccharimonas)含量高于SS组(P<0.05),毛螺菌科NK4A136群(Lachnospiraceae_NK4A136_group)含量低于SS组(P<0.05)。由此可见,与饲喂SS相比,饲喂SeHLan对泌乳中期荷斯坦奶牛瘤胃发酵参数、微生物丰富度以及主要优势菌门和优势菌属无显著影响,但在属水平上检测到2种具有显著差异的功能性细菌。

This experiment studied the effects of selenohomolanthionine and sodium selenite on rumen fermentation and rumen microflora of lactating cows.Thirty-two healthy lactating Holstein cows(lactation age 181±18 d,milk yield 33.88±3.44 kg/d,parity 3.25±1.27)were randomly divided into 2 groups,with sixteen cows in each group,and fed total mixed ration supplemented with sodium selenite or selenohomolanthionine which measured selenium contents in the diets were 0.47 mg/kg and 0.46 mg/kg,respectively.The trial lasted eleven weeks,including two weeks preliminary experiment period and nine weeks experiment period.On the last day before the end of the trial,six cows in each group which had good and healthy condition were selected.Rumen fluid was collected by oral intubation 4 h after morning feeding,and ammonia nitrogen,volatile fatty acid and rumen microflora were determined.The results showed that pH,ammonia-nitrogen concentration,total volatile fatty acid and ratio of each acid,and acetic acid/propionic acid were not affected by selenium source(P>0.05);There was no significant difference in rumen microbial diversity indices between the two groups;There was no significant difference in dominant phylum in the rumen of cows at the phylum level between two groups,all of which were Firmicutes,Bacteroidetes,Saccharibacteria,Actinobacteria,Tenericutes and Proteobacteria.The dominant bacteria in the rumen of cows in the 2 groups at the genera level were Prevotella_1 and Succiniclasticum,and their contents showed no significant difference between the two groups.However,the content of Candidatus_Saccharimonas in SeHLan group was significantly higher than that in SS group(P<0.05),and the content of Lachnospiraceae_NK4A136_group was significantly lower than that in SS group(P<0.05).In summary,compared with sodium selenite,selenohomolanthionine had no significant effect on rumen fermentation parameters,microbial richness,main microbiota at the phylum and genera levels of Holstein cows in mid-lactation,but two functional bacteria with significant difference were found at the genera level.