Ruminant Nutrition and Health

Acidosis

Acidosis is fundamental to many other problems discussed in the lecture.
Epidemiological evidence suggests a definite relationship between acidosis and liver abscesses.

Liver Abscesses

Liver abscesses are the leading cause of liver condemnation in the United States.
Older data from point 14 by Brown and Lawrence suggested 14% abscess rate. Newer data suggests it's closer to 20%.
Increased numbers of dairy by beef crossbred cattle being fed may contribute to the higher incidence of liver abscesses. They have approximately two times higher incidence than native beef cattle.
Beef on dairy cross calves are raised like a dairy calf, and early life experiences and feeding practices could be a factor.
An Iowa State study found a higher incidence of liver abscesses when calves were fed high starch starter diets compared to higher fiber diets.
Holsteins have lower rates than dairy beef crosses in recent data.
Economically, liver abscesses cause about a billion dollar loss to the beef industry.
Elanco scoring system for liver abscesses:
- 0: No abscesses
- A- :Minor abscesses, one or two small abscesses
- A: A few more abscesses
- A+: Severe, multiple active abscesses
- A+ with adhesions: Liver adhered
Scarring of liver tissue is being tracked.
There is no knowledge of the timeline for how long it takes for an abscess to resolve.
Ultrasound technology is not very accurate yet for detecting liver abscesses in live animals. but there may be improvement in the future.
Considering interventions to resolve abscesses before slaughter if detected early enough.
Doctor DG Nagarajio, Kansas State University, is an expert on liver abscesses.
Fusobacterium necroform (particularly subspecies necroform) is the predominant causative agent.
Trupyrella pyogenes a secondary organism, usually isolated with Fusobacterium, may not be very infective alone.
Recent years, salmonella has been isolated, but there’s not much evidence it can cause liver abscess.
Recent paper out of the folks at the Bureau Group at West Texas A A and M Festival Group concluded that about 75% of abscess samples are probably hemesobacterium, but there's around 25% are a couple of other genuses, bacteroides being one of those.
Bacteriodis typically is, other parts of the digestive tract besides the rumen might be a site where we could get bacterial entry into the bloodstream
Gut is leaky of varying degrees; bacteria found in blood samples of healthy animals. So it's not the gut is this barrier to keep bacteria from getting into the body.

Fusobacterium necrophorum

Fusobacterium necrophorum is a gram negative rod and is ubiquitous.
There are two subspecies found in the rumen: Necrofrum, subspecies necrofrum, and subspecies fundyliform
There's very little evidence that fundyliform causes liver abscess. It is still isolated in the liver abscess itself. Subspecies fundyliform is probably not causing abscess.
Fusobacterium varium a different species, potentially can cause liver abscesses.
All these bacteria use lactic acid as a substrate.
Fusobacterium is pH sensitive if the pH gets too low, it actually starts decreasing. There's this window in there, probably around the sera range, you've got more lactate that would stimulate these, though you get much lower pH than that, and it actually goes away.
Fusobacterium adheres to various outer membrane proteins.
Trupyrella pyogenes is often found with Fesobacterium in blood liver abscesses and foot rot abscesses, but it needs to be in combination with fusobacterium.
It has virulence factors, and all of them is the primary one.

Traditional View vs. Recent Findings

Traditional dogma: Fermentable carbohydrates (starch, glucose) cause irritation/erosion of ruminal epithelium, allowing bacteria like Pneumonia bacterium to enter the bloodstream and cause liver abscesses.
Recent findings challenge this view. Whether ruminitis is necessary for liver abscesses is an open question.
Acidity in the rumen is involved, as liver abscesses are less common in grazing animals.
Increasing roughage level in finishing diets can reduce abscesses, but it's not economical.
Key linkage: Bacteria that cause liver abscesses (predominantly Fusobacterium) thrive in an acidic environment, especially with lactate.
Dr. McDaniel published paper in 2024 on the model system that we developed showing we could develop a model that would consistently give us around 40% consistently gotten around 40% of them.
McDaniel compared using acylactic cycling, he had a low starch control, so he kinda had a control diet without any infusions, low starch control.
Showed an acrofuram pyogenes, salmonella, carrots all at once.
In one study there was a slight bump with addition of salmonella. More work needs to be done.
Paper reading this morning, and that's the only one I've looked at really, but they found about twenty five percent of the abscess samples actually had bacteroides in it.
They are using very cross calves now, very big cross calves, so potentially fairly high incidence, which maybe helps the model out a little bit, and they're also using pretty high doses of salmonella.
The acetic cycling and the high starch diet are not required. What's really critical is the dose of fusion bacteria. Don't know how circumstances some animals get a large enough dose to cause liver abscesses. The model system will help solve this.

Control of Liver Abscesses

Typically controlled with antibiotics, predominantly tylocin.
Concern about antibiotic resistance development.
Preventative measures are important.
Roughage level: Increasing roughage decreases liver abscesses.
Bunk management: Probably doesn't relate to liver abscesses.
Probiotics: No proven effect on liver abscesses based on current knowledge.
Tylosin: Very effective, can cut the incidence of liver abscesses in half.

Bloat

Bloat occurs when an animal cannot expel gas.
Fema flow is a frothy type of blood (where the ruminal contents are very frothy).
Eruption issues can be inhibited when you get something on the cardia.
Contractions in the rumen push gas out through the esophagus.
Cattle get rid of gas primarily through the mouth and nostrils.
$27 \%$ of all fetlock mortalities were associated with digestive disorders, of which $96 \%$ were diagnosed off of bloat.
Inhibition of the rotation is caused by a couple of Renaudid, strep bovis and Trebepella, Bray antii.
Grain type, grain processing, any type of high rate of fermentation is going to promote load. Wheat is a provocative grain.

Polioencephalomalacia (PEM)

Also known as cerebral cortical necrosis.
Can occur in both grazing and feedlot animals.
It is a neurological disorder.
Symptoms: Blindness, incoordination, muscle tremors, seizures.
More common in younger animals.
Two types: related to thiamine, and from excessive sulfur intake
The bacteria in the room make thiamine, so it's usually not a problem. But if you get something weird going on in the room and that actually destroys that thiamine, like a thiamine ace.
High dietary sulfur is the other thing, venereal is going give the ammo fiber. It helps, it actually is kind of a, and thiamine has this soothing effect almost to the nerves that helps in cases like this.
There is a relationship probably between high sulfur and diamond.
High grain diets probably induce more thiaminease, or maybe a decrease thiamine supply in other ways.
The sulfate ion itself can destroy thiamine
There is potentially some evidence of a lower thiamine tyrophosphate concentrations in the brain brains of cattle that have sulfur induced polyp.
Treatment: Thiamine injections (10 milligrams per kilogram of body weight, three or four times daily), limited success

Laminitis

Related to subacute renal acidosis in dairy cattle.
Acid production causes histamine production, leading to systemic effects like laminitis.
It is a major cause of lameness in dairy cattle.
Effect: Vascular constriction, hemorrhaging in the foot.
Organic sources of zinc, like zignothione, show some benefit.
Foot rod is kind of related to laminitis. Injury to the area here between not used very much for this purpose because you have to see higher levels than the FDA allows.

Urinary Calculi

It can be.
Only seen in steers because they have a much smaller urethra.
What you do when you have the problem is you make a steer into effort.
Concentrate diets tend to have lower water intake per unit of seed than grain diet or forage diets.
Salt can increase water intake.
Urine acidifiers (ammonium chloride, 43 grams per day in a Fiedmont steer) prevent stone formation.