The negative effects of mycotoxins on pig performance, health and fertility are frequently seen across the UK.
Yet despite this, the risk of mycotoxin exposure continues to be underestimated, with new data showing mycotoxins in bedding straw are adding to those found in many feeds.
Dr Gustavo Cordero, AB Vista’s global swine technical manager, says that initial studies have shown that pigs in straw-based systems can consume substantial amounts of bedding straw during rooting behaviour.
He says: “With the moulds and fungi that infect cereal crops producing over 300 different mycotoxins, it is no surprise that mouldy bedding straw can heighten mycotoxin exposure.”
Moulds produce mycotoxins as a defence mechanism when exposed to stress, such as pressure and heat. Rooting behaviour is, therefore, likely to disperse any clusters of mycotoxins within the straw and increase the risk of ingestion by penmates.
“Of all the production livestock species, pigs are considered to be the most susceptible to the negative effects of mycotoxins,”Dr Cordero adds.
“Thefusarium-derived mycotoxins fumonisin (FUM) and zearalenone (ZON), for example, are acutely toxic to pigs, but are much less damaging for poultry.”
The risk to the pig depends heavily on the level of contamination, the types of mycotoxins present and the age of the animal.
The cumulative combination of mycotoxins is also important, as low levels of several can act additively.
Dr Cordero says the effects of mycotoxicosis in breeding herds can be ‘disastrous’, with the impact of reduced fertility, still births and low piglet viability having significant implications for herd profitability.
“If the problem extends to the growing and finishing herds, then poor feed intakes and the subsequent drop in growth rates will further reduce output,” he says.
One of the biggest challenges is the non-specific nature of mycotoxicosis symptoms, making it difficult to diagnose, and resulting in treatment often being delayed.
Adding to this is the susceptibility of pigs to many of the common mycotoxins, so at a minimum any mycotoxin strategy needs to provide protection from the most toxic, which for pigs are ZON, FUM and Deoxynivalenol (DON).
“Both the breeding herd and growing pigs are commonly housed on bedding straw,” Dr Cordero says. “And with recent dry sow studies showing bedding straw can contribute up to 25 per cent of the pig’s daily feed intake, it is worrying that the mycotoxin risk is not always considered.”
Analysis of 71 straw samples by Micron Biosystems in 2019 showed that 80.3 per cent contained one or more mycotoxins, with 14.1 per cent being contaminated with three or more.
Of particular concern was the high prevalence of DON (63.4 per cent), HT2 toxin (32.4 per cent) and T2 toxin (22.5 per cent).
“Of the different straw types, barley had higher levels of contamination – 85.7 per cent of samples versus 66.7 per cent for wheat straw – suggesting that it may be the higher risk overall,” Dr Cordero adds.
“When you then consider the risk presented by common pig feeds, the mycotoxin load can be substantial.
“For example, previous studies have shown that over 50 per cent of common pig feed ingredients in the UK present a high mycotoxin risk.
“It is so important to have the right management and remediation strategies in place if herd health and performance are to be optimised.”
A key component in managing mycotoxin risk is to ensure feedstuffs and bedding straw are not exposed to moisture, which creates ideal conditions for mould growth. Having suitable storage facilities capable of keeping both straw and feed dry is essential, whether the moisture comes from high humidity, leaking roofs or yard run-off.
“Check straw regularly and remove any that is damp or discoloured,” says Dr Cordero. “As with feeds, some batches will be more susceptible to mycotoxin contamination, so it can be worth testing multiple samples to get an indication of the level of risk.
“And if the use of poor quality straw is unavoidable, then you should definitely be using mycotoxin remediation measures,” he adds.
According to Dr Cordero, more and more pig units are now including a mycotoxin remediator as routine protection against potential lost production from mycotoxin contamination.
One option when looking to diagnose a suspected mycotoxin problem is to add a mycotoxin remediator to the feed and monitor the results.
A clear performance response within three weeks is indicative that mycotoxins are present in significant volumes.