The characterization of lactic acid producing bacteria from the rumen of dairy cattle grazing on improved pasture supplemented with wheat and barley grain.
OBJECTIVE
To identify and characterize the major lactic acid bacteria in the rumen of dairy cattle grazing improved pasture of rye grass and white clover and receiving a maize silage and grain supplement with and without virginiamycin.


RESULTS
Eighty-five bacterial isolates were obtained from the rumen of 16 Holstein-Friesian dairy cows. The isolates were initially grouped on the basis of their Gram morphology and by restriction fragment length polymorphism analysis of the PCR amplified 16S rDNA. A more definitive analysis was undertaken by comparing the 16S rDNA sequences. Many of the isolates were closely related to other previously characterized rumen bacteria, including Streptococcus bovis, Lactobacillus vitulinus, Butyrivibrio fibrisolvens, Prevotella bryantii and Selenomonas ruminantium. The in vitro production of L- and/or D-lactate was seen with all but five of the isolates examined, many of which were also resistant to virginiamycin.


CONCLUSIONS
Supplementation of grain with virginiamycin may reduce the risk of acidosis but does not prevent its occurrence in dairy cattle grazing improved pasture.


CONCLUSIONS
This study shows that lactic acid production is caused, not only by various thoroughly researched types of bacteria, but also by others previously identified in the rumen but not further characterized.
Hernandez
J D
JD
School of Animal Studies, The University of Queensland, Gatton, Australia.
Scott
P T
PT
Shephard
R W
RW
Al Jassim
R A M
RA
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D001419:Bacteria / Q000235:genetics / Q000302:isolation & purification*; D002417:Cattle; D019587:Dietary Supplements; D002523:Edible Grain; D005260:Female; D029902:Medicago; D006109:Poaceae; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012417:Rumen / Q000382:microbiology*; D012434:Secale; D014908:Triticum; D014769:Virginiamycin / Q000008:administration & dosage
D000900:Anti-Bacterial Agents; D012336:RNA, Ribosomal, 16S; D014769:Virginiamycin