2015 Corn Silage – Test Again

As dairy producers begin to steadily feed out their 2015 corn silage, nutritionists might want to take a proactive approach by testing their clients’ feed bunks to see what risks may be present. Since Alltech’s 2015 North America Harvest Analysis, additional testing through the Alltech 37+® mycotoxin analysis is now indicating type A trichothecene mycotoxins are on the rise.

According to Dr. Max Hawkins, Alltech Mycotoxin Management team nutritionist, type A trichothecenes, composed of T-2, HT-2, diacetoxyscirpenol and neosolaniol, have shown an increase in levels present from 33.18 parts per billion (ppb) in September to 86.38 ppb in February (as illustrated by the trend line in Figure 1). Type A trichothecenes are now present in 46 percent of all samples of corn silage.

“The levels are higher than in years past, and exactly why that may be is difficult to identify. There may be many causes,” said Hawkins.

Type A trichothecenes are produced by Fusarium molds. Fusarium molds require moisture levels at or above 70 percent humidity as well as oxygen and a temperature range that can include cool days and nights to cool nights and hot days. Corn plants stressed from insect damage or birds, plant disease, wind and hail are always a concern for mold proliferation. Corn silages that are drier, poorly packed and allow greater oxygen penetration are also at a greater risk.

The Alltech 37+ mycotoxin analysis tested 239 corn silage samples from Sept. 1, 2015, to March 8, 2016. The average sample contained 5.28 mycotoxins. The Risk Equivalent Quantity, or the risk represented by all of the mycotoxins present, is at higher risk in 59.1 percent of all corn silage samples with another 17.7 percent at a moderate risk.

“Over 75 percent of corn silage presents an increased risk to dairy cows,” said Hawkins. “This contributes to the complexity of the mycotoxin mixture that is included into total mixed rations (TMRs) and can lead to increased mycotoxin impact on cow health and performance.”

Type B trichothecenes and fusaric acid were present in more than 90 percent of the samples, while fumonisins have been found in over 70 percent of the samples. The levels of these mycotoxin groups have remained relatively constant at a moderate-to-high risk since harvest. Type A trichothecene toxins, however, have shown a steady increase since January.

In the dairy cow, type A trichothecenes first affect the rumen where they are partially metabolized. Rumen adsorption may be increased by rumen acidosis. When cellulolytic bacteria activity decreases, protein synthesis is reduced.

The ingestion of type A trichothecenes can cause reduced feed intake, slower weight gain, decreased milk production, digestive disorders (vomiting and diarrhea), acute hemorrhagic enteritis, reproductive failure, increased mortality, hemorrhages (stomach, heart, intestine, lung, bladder, kidney), edema, dermatitis, immune suppression, abomasal and ruminal ulcers and death. Serum immunoglobulins and complement proteins are lowered in calves receiving T-2 toxin. Also, a reduction in white blood cell and neutrophil counts in calves can be observed after exposure to these types of toxins.

“The increasing level of type A trichothecenes, along with the steadily higher level of type B trichothecenes and fusaric acid, creates a combination of mycotoxins that can easily increase the risk of corn silage that is being included into the TMR,” Hawkins said.

JPW Nutrition recently utilized Alltech’s 37+ mycotoxin analysis program to test corn silage and TMR samples for some of their customers in the Midwest. The results indicated type B trichothecene toxins were most prevalent; however, type A trichothecene mycotoxins were also showing up. Jason Prins, a nutritionist with JPW Nutrition, wasn’t surprised the analysis found type A trichothecenes, as he had observed issues with stomach linings being excreted and gut health challenges on the dairies.

“From a reproduction, immune response and gut health standpoint, we need to know what type of mycotoxins are having an impact. Finding out which types of mycotoxins are present in the feed allows us to make adjustments in the diet accordingly,” said Prins. “For our clients, we have found that it is better to be proactive than reactive with these issues.”

Figure 1 - Type A Trichothecenes Risk in Corn Silage