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Tracking bacteria though the gut of beef cattle


The bacteria from cattle feces are important in agricultural systems. They help cycle nutrients, emit gaseous, sometimes odorous, compounds, contribute to the animal’s health by impacting the immune system status, and serve as a source for zoonotic pathogens and antibiotic resistant bacteria. The forage and grain fed to animals is converted, throughout the length of the gastrointestinal tract, into the material deposited in the cow pat. While the bacteria in the rumen and feces are well studied, little is known about the bacteria that populate the rest of the gastrointestinal tract, or how the bacterial communities change along the way, despite their critical role in turning feed into feces.

In a paper recently published in Agricultural and Environmental Letters, researchers report on a study characterizing the bacteria at 16 sites along the entire length of the beef cattle digestive system, including 11 sites where both the tissue and the ingesta are examined.

Close up images of tissue from Cow gastric chambers

The team found that in most instances 50-80% of the bacteria in any gut compartment could be attributed to the neighboring, upstream compartment, meaning that 30-50% of the bacteria were “new” for each compartment. The one exception was the ilium, part of the small intestine, which shared only 11% with its upstream neighbor. Overall, the four-chambered stomach of the animal was the place along the gastrointestinal tract with the largest diversity of bacteria.

Although the microbial composition the feces remains a research priority for food safety, and environmental quality, and soil health, the possibility exists that the bacterial community structure, and ultimately function, of fecal bacteria are influenced by the other, in-line GIT microhabitats. This DNA sequencing study provides additional resolution to the outstanding work of early culture-based efforts to characterize the microbial flora of cattle.

Read the full open access article in AEL.