As we approach the final stretch of winter, this past year’s harvest may seem like an eternity ago. However, as dairy producers begin to feed out the 2015 crop, they may want to consider testing for mold and mycotoxins.
A wet spring and a late dry season obstructed the quality of the 2015 North America crop, generating inconsistencies in plant growth and putting dairy cows and calves at higher risk for mycotoxin exposure.
Our annual study surveyed 116 North American corn silage samples from across the U.S. and Canada from September to November 2015, testing for mycotoxin contamination to determine the risk posed to ruminant animals. The analysis found an average 5.6 mycotoxins per sample, with 71 percent of samples testing at higher risk to dairy cows and 87 percent at higher risk to calf performance.
The harvest analysis revealed multiple mycotoxins present in 2015 corn silage, showing the greatest risk for Type A trichothecenes, fusaric acid and Type B trichothecenes. Even at low levels, these mycotoxins can impact herd health and performance as Type B Trichothecenes and fusaric acid act synergistically, increasing overall toxicity.
Also present this year were Penicillium mycotoxins, commonly known as storage toxins. Found in more than 41 percent of samples, Penicilliums can have a strong impact on rumen health, altering microbial protein and affecting rumen and gut health, which can result in altered production.
TMRs often contain more than one fungal species, contributing to a complex mixture of mycotoxins and unresolved health issues in the herd. Dairy producers need to observe herd health indications such as reduced feed intake, reproductive disorders, laminitis, mastitis, impaired liver function and poor response to vaccination programs, which can all be attributed to ingesting mycotoxin-contaminated feed.
Scientific literature shows that at higher risk levels to dairy cows, cows may produce 1.34 pounds (0.61 L) milk per day less when consuming mycotoxins. Additionally, milk somatic cell count (SCC) may increase by 48.8 percent.
With this loss in performance and considering current milk prices, producers could see an estimated reduction in profitability per cow at $67.27 over one lactation.
The risk is often greater for calves, as 80 percent of calves’ immune system is located within the intestine. Calves are considered the most sensitive animal species, with a less developed immune system; they are more susceptible to the impacts of mycotoxins. This can also be compounded by the health status and the stress level of calves during weaning.
Even at low levels, mycotoxin contamination in feed can affect calf health through:
- Impaired immune function
- Increased susceptibility to bacterial and viral diseases
- Decreased dry matter intake
- Reduced growth rate
- Distressed gut health and immune response
- Added opportunistic infections with poor treatment response
All of these symptoms can result in lost performance and increased health costs. Decreased growth rate in heifer calves can have a negative impact on first-lactation performance.
Most mycotoxin problems with calves often go undiagnosed because the dairy doesn’t follow a complete investigation. One of the most important factors is good record-keeping at the dairy. Documentation of production, breeding and treatment are extremely valuable in this situation. Feed and ingredient analysis records are of the utmost importance in determining the cause and source of a case of mycotoxicosis.
It is important for producers to be proactive rather than reactive and to remember that any intervention strategies should improve the rumen flora and reduce the bioavailability of mycotoxins.
However, when producers suspect mycotoxins are present, testing feed samples prior to feedout through a laboratory is the best way to determine what risk is already prevalent and what actions need to be taken.
The use of a mycotoxin-mitigating substance (or sequestering agent) in the feed could help reduce or prevent the negative effects mycotoxins have on the animal and additionally improve rumen function and gut health and integrity.
The most effective agents are those that can help combat the risk of multiple mycotoxin contamination, as more than 97 percent of the feed samples tested have been contaminated with multiple mycotoxins.
If the risk from the forage and grain has been reduced by inclusion rate and proper management, the amount of sequestering agent required will be lower but will still be needed. If left unchecked and uncontrolled, it is not a matter of if mycotoxins will cause issues in herd health, but when.
Winter temperatures and environments can compromise gut health in dairy herds, especially calves, and can be a challenge to overcome. Molds and mycotoxins, colder temperatures, decreases in air movement and birds migrating indoors can distress the immunity of dairy herds.
Dairy calves are often the neglected species when it comes to addressing mycotoxin issues; however, long-term multi-toxin exposure can impede the pre-ruminant’s start to life and impair the animal’s immunity throughout her life cycle. PD
Max Hawkins holds a Ph.D. in animal science from the University of Tennessee and currently serves as a nutritionist on the Alltech Mycotoxin Management Team. Email Max Hawkins.
