Better Understanding of the Gut Health Challenge

Each year, tens of thousands of young calves are received at feedlots and the challenges begin. Pre-receiving environment and management, health status, weather and feed quality can all influence on the calves’ start. Hospital pens are prepped, medical supplies ordered and pen riders are prepared to start working with calves that begin to have health issues and fall behind.

Many of the health issues at the onset of the feedlot phase are opportunistic and magnify themselves due to the fact that the calf’s system has been lowered to a point of little defense to these health challenges. This defense primarily hinges on gut health. Because nearly 80 percent of the calf’s immune system is located in the gut, a compromised gut will compromise overall health and immune status.

One of the factors that can have a significant impact on gut health is mycotoxins, particularly those produced by Fusarium and Penicillium molds. These molds can produce mycotoxins that can not only decrease dry matter intake (DMI) and weight gain, but also can have a significant impact on rumen function and gut health.

Molds and the Mycotoxins They Produce

Fusarium: DON, 3-AcDon, 15-AcDon, DON-3-Glucoside, Nivalenol, Fusarenon X, T2, HT2, DAS, Neosolaniol, Fusaric Acid

Penicillium: Patulin, Mycophenolic Acid, Roquefortine C, Penicillic Acid, Wortmannin

Mycotoxins produced by Fusariums can decrease DMI, lower gain, impact rumen function, reduce microbial protein, cause gut irritation with poor gut wall integrity and diminish immune response. Penicilliums can impact rumen function by altering microbial concentrations, decreasing DMI and gain and producing digestive disorders and lower immune response.

According to the 2015 Alltech North America Harvest Analysis recently conducted, corn silage is showing a greater percentage of samples with Fusarium and Penicillium-produced mycotoxins. More than 86 percent of the corn silage samples analyzed to date for the 2015 crop are at a high risk to calf health and performance. Corn grain is at a slightly less risk but can bring Fusarium-produced mycotoxins into the TMR.

It is often stated that mycotoxins do not pose a serious risk to beef cattle because they can break down the mycotoxins in the rumen. Beef cattle do have the ability to break down mycotoxins, but their system will not be able to break down higher levels and significant amounts of complex mixtures of mycotoxins. The mycotoxins are broken down by protozoa.

Protozoa do many things from a nutritional standpoint such as break down fiber, cellulose, starch, etc. If protozoa are working to break down mycotoxins, they are not available to perform nutritional tasks. Each separate mycotoxin requires specific protozoa to decompound and many times, particularly in younger, more immature cattle, these required protozoa are not present in an adequate concentration to be effective in controlling mycotoxins. In many cases, once these protozoa attack mycotoxins, their populations are reduced and very difficult to restore.

Once in the lower gut, Fusarium mycotoxins will remove the mucin layer, which is the protective covering for the gut wall. Fusarium will then begin to ulcerate the gut wall, and villi will become irritated and broken. This provides pathogens a direct opening to the bloodstream, so that a lower pathogen level now becomes a more significant level.

The lowering of immune response is the lowering of the calf’s ability to fend off opportunistic health challenges. These calves may also not respond as well to vaccinations and normal health treatment protocols. This is shown when calves require multiple health treatments and need second and third pulls or spend extra time in the hospital pen.

Calf challenges such as these can be improved when a proper management program is put into place. Feedstuffs and total mixed rations should be analyzed for mycotoxins, through a program such as the Alltech 37+® mycotoxin analysis. The laboratory can detect for more than 38 individual mycotoxins and identify mycotoxins that are conjugated or “masked.”

Some common practices for dealing with a mycotoxin issue in feed:

1. Eliminate the suspected source of the mycotoxin (e.g., silage, haylage, whole cottonseed, almond hulls, etc.).

2. Add mold inhibition products (i.e., use of fungicides or mold inhibitors on the total mixed ration or corn silage).

3. Use mycotoxin sequestering agents in the feed. In many cases, the use of sequestering agent products results in the clinical and/or subclinical symptoms disappearing, and begins the progression of the affected animals or herd returning to normal.

Most mycotoxin problems go undiagnosed due to lack of perseverance or a lack of records and analyses that may be used for diagnostic purposes. The management team at the feedlot must be willing to cooperate with each other. One of the most important factors is good recordkeeping. Feed and ingredient analysis records are of the utmost importance in determination of the cause and source of a case of mycotoxicosis.

Finally, feedlot managers should consider what is going on in the gastrointestinal tract. Any damage done to the GI tract by molds and mycotoxins may alter the beneficial microflora and immune system enough to make an animal more susceptible to infection by pathogenic organisms. It may be beneficial to feed a prebiotic and probiotic to help restore the gut and optimize performance.

If the immune system has been compromised, the herd’s diet may need to be adjusted to help restore maximum immune function. It may be necessary to adjust vitamin and trace mineral levels for a period of time. Products like organic trace elements, selenium yeast, higher vitamin E levels and the addition of additional yeast culture to the diet should be considered.