This episode was recorded at the 2025 Florida Ruminant Nutrition Symposium.

Dr. Baumgard begins with an overview of his presentation, “Importance of gut health to drive animal performance and health.” He notes the metabolic and inflammatory fingerprint of all stressors is essentially the same, indicating they likely all emanate from the gut. Overall, we’re gaining a better understanding of how typical on-farm stressors negatively influence gut barrier function. He thinks the most likely mechanism of leaky gut is the immune cell known as a mast cell. When an animal or human is stressed, the enteric nervous system releases corticotropin-releasing factor, which binds to the mast cell, the mast cell degranulates, and the former contents of the mast cell (TNF-alpha, proteases, histamine, etc.) causes the gut to become leaky. (4:20)

Once the GI tract barrier becomes compromised, antigens like lipopolysaccharide (LPS) can infiltrate, stimulating the immune system. Immune activation causes loss of appetite much like any other infection. The gut heals fairly quickly upon removal of the stressor(s), and the gut can also acclimate to stress such that the early stages of a stress event are more severe than later stages. Strategies to combat leaky gut remain scarce, and there is no silver bullet. There are a variety of dietary strategies to target the gut permeability issue itself. Another approach would be to bind pathogens or curb their proliferation at the membrane of the small intestine. (7:06)

Dr. Neiehues asks if an antihistamine would work on gut mast cells the way it does in other body systems. Dr. Baumgard isn’t sure that’s ever been looked at, although there have been some studies in pigs using a product targeted to prevent mast cell degranulation. Dr. Nelson wonders if we should interfere in some of these processes because they’re obviously there for a reason. Panelists discuss stress events related to parturition and transition, particularly for first-calf heifers. Dr. Baumgard notes that stacking stressors on top of one another compromises an animal’s ability to tolerate stress. (9:28)

We know stress can cause ulcers in humans and horses - what about ruminants? Dr. Baumgard thinks it is likely that it’s happening, but we aren’t looking for it. Few animals who die on-farm do receive a thorough postmortem exam. It could also be that these types of insults to the gut are not visible to the naked eye. (19:11)

Dr. Nelson asks what makes some cows, despite all the challenges, able to be up and milking 150 pounds a day in no time after calving. What makes them unique? Dr. Baumgard lists some possibilities, including lower pathogenic inflammation than other cows, less tissue trauma damage to the uterus during calving, and lower sensitivity to immune activation. The panel disagrees with the notion that high-producing cows are stressed. (23:16)

Dr. Niehues and Dr. Baumgard trade stories of experiments where cows maintained production even with high stress and inflammatory markers. The panel goes on to discuss subclinical infections and their impact on transition cows. Dr. Nelson notes there are retrospective datasets where cows who had metritis showed decreased feed intake even before calving. Dr. Baumgard feels that the decrease in intake has been incorrectly assumed to be the cause of the metritis. He says the decrease in intake is often around two weeks before calving and he doesn’t think it’s a coincidence that at the same time, the mammary gland is initiating lactogenesis. He hypothesizes the mammary gland is causing an immune response, resulting in a decrease in intake. Dr. Nelson wonders if measuring somatic cell counts of colostrum would show any differences in mammary gland inflammation during this prepartum period. (29:18)

Panelists share their take-home thoughts. (42:02)

Please subscribe and share with your industry friends to invite more people to join us at the Real Science Exchange virtual pub table.

If you want one of our Real Science Exchange t-shirts, screenshot your rating, review, or subscription, and email a picture to anh.marketing@balchem.com. Include your size and mailing address, and we’ll mail you a shirt.

This episode was recorded at the 2025 Florida Ruminant Nutrition Symposium.

Dr. Bach gives an overview of his presentation, highlighting that buffers make the rumen resistant to a decrease in pH while alkalizers immediately increase rumen pH. He prefers magnesium oxide, an alkalizer, over sodium bicarbonate, a buffer. Both are effective, but sodium bicarbonate requires a larger amount, thus taking up more room in the diet. The magnesium oxide must be of high quality and soluble in the rumen. (3:40)

Dr. Richards asks if we should use magnesium oxide more as a first line of defense against acidosis. Dr. Bach notes that the very best strategy is to avoid using either additive by making a proper ration balanced in terms of amount and rate of degradation of starch. But there are many constraints in the field, so he recommends using magnesium oxide before sodium bicarbonate. For the magnesium oxide to be effective, it must be solubilized in the rumen to magnesium hydroxide, and solubility can be tested in a variety of ways to determine quality. (7:35)

The panel discusses the impact of magnesium oxide in place of sodium bicarbonate on DCAD and which DCAD equation(s) should be used for calculations. Dr. Bach recommends removing sodium bicarbonate from rations containing less than 1% of the ingredient. It will have little effect on the rumen, but make room in the ration. The panel explores how this can impact farm-level economics. (12:39)

Dr. Bach also mentions probiotics and their impact on rumen function. In vitro studies have shown a wide variety of modes of action and positive results. Extrapolating in vitro doses to the cow often results in unsustainable amounts of the additive needing to be fed. Applied studies at the cow level have yielded inconsistent results. (23:29)

Scott asks how long Dr. Bach has been making the case for pulling sodium bicarbonate out and putting magnesium oxide in, and what kind of pushback he has received. Dr. Bach gives some of the reasons farmers have given for not wanting to make this management change. He also notes that farmers who do make the switch do not tend to go back to sodium bicarbonate. (25:18)

Dr. Bach and Maimie discuss grass silage diets and grazing diets with high amounts of moisture and how best to combat acidosis symptoms with those. In diets like this, where you’re not trying to make room for energy, sodium bicarbonate can be a good choice. Dr. Richards chimes in with questions about the ratio of the two ingredients; Dr. Bach indicates the ratio doesn’t mean much to him. (26:16)

Panelists share their take-home thoughts. (33:27)

Please subscribe and share with your industry friends to invite more people to join us at the Real Science Exchange virtual pub table.

If you want one of our Real Science Exchange t-shirts, screenshot your rating, review, or subscription, and email a picture to anh.marketing@balchem.com. Include your size and mailing address, and we’ll mail you a shirt.

This episode was recorded at the 2025 Florida Ruminant Nutrition Symposium.

Microbial protein has always been Dr. Frikins’ main interest. It’s the most important and consistent source of protein for the cow, with a very high amino acid content. Histidine is the only exception, but bypass protein sources high in histidine complement microbial protein well. Our assessment of microbial protein is all based on prediction models. In his presentation, Dr. Firkins talked about what we can do to have consistently high microbial protein production and how to make the best use of the models. He touched on starch and fat content as two areas of focus, emphasizing a balanced diet to achieve a balanced supply of microbial protein. (5:36)

Dr. Firkins notes that about 90% of the bacteria in the rumen can’t be cultured, and there is great diversity in the rumen. There’s a core group of bacteria that almost every cow has that are really good at their job because they’ve been co-selected along with the cow for fiber digestion. The panel discusses how much the microbiome changes over time, host interactions with the microbial population, and inoculation of calves at birth and weaning. (8:47)

Dr. De Souza and Dr. Faciola talk about starch associative effects and their impacts on fiber digestibility, how sugars impact the rumen and butyrate production, and the importance of butyrate in de novo milk fat synthesis. Dr. Frikins hypothesizes that when sugars improve fiber digestibility, the sugar stimulates how fiber digesters do their job. Some studies have shown an increase in rumen pH when sugars are supplemented, which may be part of the mechanism of improved fiber digestibility. However, he doesn’t recommend using sugars when there is a lot of starch in the diet. (13:38)

Dr. Faciola and Dr. Firkins discuss some of the finer points of the dietary starch and fiber digestibility relationship. What are you replacing when you add more starch? What is the proper amount of effective fiber in higher-starch diets? On the other hand, if you decrease starch a little bit, there might be more room for fat. Well-managed cows with adequate effective fiber can probably handle more starch. Dr. Firkins underlines that starch is more digestible than fiber and thus supports microbial protein, but an optimum level is desirable, perhaps 28-20%. (20:37)

The panel talks about microbial growth efficiency and the energy-spilling mechanisms some bacteria have. Some models suggest that starch-digesting bacteria have higher maintenance energy requirements. The group then pivots to methane production and available feed additives marketed to reduce methane. Dr. Firkins notes that there is quite a bit of variability in the additives. He emphasizes that if we’re using these products, we need to know and measure what’s in them and have them be consistent. This is challenging due not only to variability in product, but also rumen adaptation. Dr. Firkins also reminds the audience that improving the cow’s efficiency in general in a variety of ways will lead to a smaller environmental footprint. This can range from improving reproductive efficiency to understanding differences in the microbiome of cows who emit more or less methane and trying to shift microbial populations to those with lower emissions. (23:12)

Dr. De Souza and Dr. Firkins discuss fatty acid supplementation and fiber digestion relationships. Dr. Firkins explains that in the microbiology literature, it's common to culture bacteria in a simple or complex medium, then add yeast culture. Interestingly, the yeast culture contains a lot of palmitic acid, which has been shown to improve fiber digestibility. He suggests the cell membrane of the bacteria is very critical. When fat supplementation depresses fiber digestibility, he suspects it’s disrupting the bacterial membrane. Dr. De Souza recommends 1-2% palmitic acid in the diet for optimal results. (33:58)

The panel touches on the importance and relevance of in vitro fermentation work, why histidine is the limiting amino acid in microbial protein, and Dr. Firkins’ passion for protozoa. (43:08)

Panelists share their take-home thoughts. (53:40)

Please subscribe and share with your industry friends to invite more people to join us at the Real Science Exchange virtual pub table.

If you want one of our Real Science Exchange t-shirts, screenshot your rating, review, or subscription, and email a picture to anh.marketing@balchem.com. Include your size and mailing address, and we’ll mail you a shirt.