Mycotoxins can be a problem in feed this year
Mycotoxins in feed pose a real threat to the health of a herd, causing anything from a minor drop in yield to death. That's why farmers should decide whether to actively do something to minimise the risk now.
The summer weather this year with lukewarm temperatures, high humidity and occasional heavy showers means a considerable risk of fungus attack in the fields, and thus of mycotoxins in feed.
Mycotoxins are a form of toxin produced by various fungal species. We are familiar with the Fusarium fungus in maize, which produces the mycotoxin Zearalenon, or ZEN. But Deoxynivalon (DON), is also a typical mycotoxin, along with a number of others.
There are several crops in the risk zone, especially maize.
“As I see it, maize fields represent the biggest risk, because we do not traditionally spray them,” says John Snede, a Vilomix consultant. Spraying will not remove the threat of fungus attack, but it will minimise it, along with the risk of mycotoxins occurring in feed.
There is increased risk of Fusarium in crops planted on unploughed land, and where plant residue is left from last season.
Variation in stacks
Whether a field attacked by fungus will give problems with mycotoxins when the crop is used for feed cannot be seen. And when the crop is in a stack, it will still be impossible to see whether it will give problems with the naked eye.
“Vilomix performed analyses during the winter on the 2019 maize silage crop and TMR rations at a number of farms. 9 out of 11 samples taken had some content of various toxins. Some samples contained a single type, while 5 of them contained multiple toxins. Mycotoxin content was found in 7 out of 8 samples from TMR rations. 3 of those contained more than one type of mycotoxin,” explains Snede, adding that analyses can actually be taken from a single stack that will show a toxin content of 125-130 units, whilst others will be over 4,000 units.
“Which goes to show that the results depend to a large extent on where a sample was taken from in a stack,” says Snede.
If samples are taken at points with a high level of occurrence, the overall analysis can give an unrealistically high indication of scope, while it is also possible to have an analysis result showing low figures, yet still experience major problems.
This means that there can certainly be areas with no problem in a stack, while there can be other areas that will have massive problems with mycotoxins.
“You also find that two or more mycotoxins can enhance each other with a synergy effect, so that 2+2 no longer gives 4, but 10,” Snede adds.
Many mycotoxins can be seen in a traditional analysis, but not all.
Because one of the ways that plants protect themselves against fungal attack is to envelope a mycotoxin, often binding it with sugar. That prevents the mycotoxin being detected in an analysis, and it will not be released until it is in a cow’s digestive system. When the toxin has bonded with sugar, it is known as a DON-3-glucoside.
“Up to 45% of the occurrences of DON in grain analyses can be in the form of DON-3-glucosides, giving no chance of detecting it before it can cause problems for the animal,” says Snede.
There can be a number of symptoms of toxins present in a herd.
Falling feed intake, falling milk production, bad skin and hide condition, cows in poor condition, deteriorating reproduction, high and fluctuating cell counts and sporadic fatalities.
“The symptoms vary a lot from herd to herd and for individual cows. We also see some in which the symptom is displaced abomasum or something else entirely,” states Snede, who also finds that some time can elapse from when the herd owner notices that there is something wrong until he discovers that mycotoxins are the problem.
Small doses accumulate in the body
There are enormous differences in how cows are affected by mycotoxins in feed.
Some experience no problems, others react immediately.
“Some cows will react even at a very low level. They can be under some sort of pressure, such as high yield cows, or one that has just been through a hard calving. In common with us, they can react very differently.
Snede often finds that customers call in March and April with suspected cases of toxin poisoning.
“They've usually started using their stack in November, and the process takes a few months. Even if there is a low level of mycotoxins in feed, they can accumulate in the cow over a period of time before the animal suddenly deteriorates,” he explains.
Toxin binders can help
Some sow herds consistently use toxin binders in feed, but not so many regular cow herds.
Snede believes that every farmer ought to decide whether they want to make a difference.
“I often recommend letting cattle decide themselves whether they have problems with mycotoxins. This can be done by adding toxin binder for a while, and noting if there is any change. If not, you can take the toxin binder out of the feed, and then look for a reaction,” explains Snede, adding that a low dose of toxin binder can be given as a form of insurance.
“It costs 40-50 øre per cow per day, and if a drop in production is avoided, not much of an improvement is needed to pay for the toxin binder,” he points out.
If the cow copes with the problem itself
You can also opt to do nothing, leaving the cow to manage on its own, but that will still incur some form of cost,” states Snede.
“When the cow neutralises toxins, it costs energy that could otherwise have been used to produce milk. The cow’s immune system will also be put under strain, to which the cow may react with a high cell count,” explains Snede.
It’s the liver that neutralises mycotoxins, but the liver has plenty of other things to do, including energy conversion and maintaining the mineral balance, including the Ca balance.
“That puts extra strain on the cow,” says Snede.
“As I see it, maize fields represent the biggest risk, because we do not traditionally spray them,”
John Snede, a Vilomix consultant.