Dr. Penner presented “Progress in the gut: What we know about ‘gut health’” to lead off the symposium. He highlights using rumen acidosis as a model for gut health, focusing on key structures and how paracellular permeability is maintained or dysregulated, absorptive function, and microbiology. He notes that rumen acidosis affects other parts of the gut besides the rumen. (4:52)

Dr. Laarman wrapped up the symposium with “Gut health in ruminants: Where to from here?” He agrees with Dr. Penner that we need to look beyond the rumen at all other gut organs. His group has researched rumen acidosis in calves and how it’s linked to hindgut acidosis and pH dynamics. Calves behave very differently from cows in this model. Gut health begins from birth and is the whole tract, not just the rumen. (7:35)

Work in Dr. Penner’s lab showed that inducing inflammation in the mammary gland actually tightened permeability in the GI tract, which was opposite of their initial hypothesis. Dr. Baumgard’s lab found similar results in a heat stress model, and Dr. Laarman echoes that his group has also found this result. The panel discusses possible mechanisms of action. Dr. Penner explains that diet may also have an influence on gut permeability. (11:01)

The panel talks more about what we know and don’t know about gut health. We probably know which regions of the gut are most likely to be affected by challenges, what those impacts are, how fast those gut changes occur, and how nutrient absorption can be affected by challenges. The group hypothesizes that pH alone does not have a negative effect, but if low pH occurs at the same time as other signals or molecules, then pathology happens. Dr. Laarman shares some of the observations his group has made with calves, which withstand low pH that would kill a mature cow if she experienced it. (18:40)

Guests talk about some of the reasons why we know less about ruminant gut health compared to monogastric species. They also visit about the microbiome and how perhaps what the microbiome is doing and producing is more important than who all is present in the microbiome. (23:44)

Panelists share their take-home thoughts. (29:33)

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