Effects of alfalfa flavonoids extract on the microbial flora of dairy cow rumen.
OBJECTIVE
The effect of flavonoids from alfalfa on the microbial flora was determined using molecular techniques of 16S ribosome deoxyribonucleic acid (rDNA) analysis.


METHODS
Four primiparous Holstein heifers fitted with ruminal cannulas were used in a 4×4 Latin square design and fed a total mixed ration to which alfalfa flavonoids extract (AFE) was added at the rates of 0 (A, control), 20 (B), 60 (C), or 100 (D) mg per kg of heifer BW.


RESULTS
The number of operational taxonomic units in heifers given higher levels of flavonoid extract (C and D) was higher than for the two other treatments. The Shannon, Ace, and Chao indices for treatment C were significantly higher than for the other treatments (p<0.05). The number of phyla and genera increased linearly with increasing dietary supplementation of AFE (p<0.05). The principal co-ordinates analysis plot showed substantial differences in the microbial flora for the four treatments. The microbial flora in treatment A was similar to that in B, C, and D were similar by the weighted analysis. The richness ofTenericutesat the phylum level tended to increase with increasing AFE (p = 0.10). The proportion ofEuryarchaeotaat the phylum level increased linearly, whereas the proportion ofFusobacteriadecreased linearly with increasing AFE supplementation (p = 0.04). The percentage ofMogibacterium,Pyramidobacter, andAsteroleplasmaat the genus level decreased linearly with increasing AFE (p<0.05). The abundance ofSpirochaeta,Succinivibrio, andSuttonellaat the genus level tended to decrease linearly with increasing AFE (0.05<p<0.10).


CONCLUSIONS
Including AFE in the diet of dairy cows may alter the microbial composition of the rumen; however its effect on nutrient digestibility remains to be determined.
College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China.|Institute of Animal Husbandry and Veterinary, Jiangxi Academy of Agricultural Sciences, Nanchang 330200 China.
Jinshun
J
Zhan
College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China.|Jiangsu Joint Institute of Technology of Profession of Huai'an Bio-engineering Branch, Huai'an 223200, China.
Mingmei
M
Liu
College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China.
Caixia
C
Wu
College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China.
Xiaoshuang
X
Su
College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China.
Kang
K
Zhan
College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China.
Guo Qi
GQ
Zhao
Alfalfa; Dairy Cow; Flavonoids; Microbial Flora