Over three quarters of feeds are likely to contain mycotoxins and endotoxins, which pose a particular risk to Jersey cows and could provide a hidden drain on herd performance if unaddressed.
The Jersey breed could be more susceptible to endotoxins and increasing mycotoxin challenge, highlighting the need for farmers to put preventative measures in place.
Volac’s testing of feed samples in the UK through its Mycocheck service indicate that mycotoxin risk is increasing. In 2024, 78.9% of all samples tested positive for one or more mycotoxins, rising to 93.5% of samples in 2025.
Mycotoxins are produced by certain moulds which grow on bought-in feeds and silage. These invisible toxins have wide-ranging effects including reduced feed efficiency, suboptimal fertility and problems such as lameness, mastitis and raised somatic cell counts due to their impact on the cow’s immune system.
Endotoxins are components found in the cell walls of certain bacteria, such as E coli. These trigger an immune response in the animals, causing inflammation, which has a large energy requirement and so diverts this energy away from milk production and other important processes.
Peter van der Vegt, Volac’s global lead for technical services, says all breeds are at risk from these toxins, but Jerseys could be even more susceptible.
“Jersey cows can be more susceptible, primarily because they are higher-producing, smaller-bodied animals that often experience greater metabolic stress compared to larger breeds,” he explains. “Any stress can have a detrimental impact on immune response, making it harder for them to fight off any challenge from mycotoxins or endotoxins.”
For example, Jerseys have been found to suffer from a higher prevalence of ketosis (19%) than Holsteins (14%). Jerseys also tend to be more susceptible to Milk Fever with risk increasing with parity and higher levels of milk production.
“As Jerseys tend to produce higher fat milk, the energy demand per litre is also higher which can intensify metabolic stress. Cows low in energy balance will also be more susceptible to endotoxins,” Peter adds.
Peter highlights that just because silage doesn’t look mouldy, it doesn’t mean there isn’t a mycotoxin problem, and the figures suggest most farmers will be affected.
“With over three-quarters of feed samples containing mycotoxins and endotoxins creating an unseen drain on productivity, farmers face a serious profitability challenge. Because these challenges are often invisible, farmers may not realise they have a problem, but with such high prevalence, they are very likely to be impacted,” he adds.
Heat stress
Heat stress, which can occur at ambient temperatures as low as 18C, particularly if humidity is high, also means cows are less able to cope with mycotoxin and endotoxin challenge. This highlights the need to put mitigation strategies in place ahead of any hot period.
Doing so could have help prevent the spike in lameness and mastitis often seen several months after a period of heat stress and likely linked to endotoxin challenge, Peter says.
“When a cow is under heat stress, she eats and ruminates less, which reduces saliva production,” he explains. “Panting also produces more carbon dioxide which further reduces her buffering capacity. She’s also more likely to binge eat when the environment cools. All these increase rumen acidosis risk.”
Acidosis causes a decrease in rumen pH leading rumen bacteria to die. Gram negative bacteria release components of their outer cell walls, called lipopolysaccharides (LPS), which are endotoxins. Stress also leads to gaps opening between the cells lining the intestine and this can result in an influx of LPS into the bloodstream.
“LPS can settle in soft tissues like the hoof and teats resulting in lameness and mastitis. At the same time, the immune system kicks into gear to try and get rid of the LPS, diverting energy away from milk production,” Peter explains.
The gaps between cells lining the intestine which are caused by stress also raises the risk of mycotoxins entering the blood stream.
Peter says it’s possible to reduce the impact of heat stress and protect the cow from endotoxin and mycotoxin challenges. This stems around optimising cow comfort and cooling cows (see tips for lowering the impact of heat stress box). Focus should also be paid to providing cows with a consistent, well balanced, easily accessible ration to lower acidosis risk.
He also urges farmers to incorporate a mycotoxin remediator and endotoxin binder into the ration in advance of hot periods so cows are better able to cope (see mycotoxin remediator box).
Peter believes taking a preventative approach will benefit staff time and herd performance. “Cows in need of your attention take up most of your time, so ultimately if you can have less mastitis, less lameness, it will free up time to spend elsewhere managing the herd,” he says.
Tips for lowering the impact of heat stress
Provide 10cm of water space per cow.
Invest in fans / cow cooling.
Ensure fan maintenance is up-to-date – it takes 30% more energy and produces 30% less wind if fans are dirty.
Avoid feed that has heated and could be at increased risk of mycotoxins.
Provide plenty of feed space and push up regularly to optimise intakes.
Speak to a nutritionist about adapting the diet in response to heat stress. This may mean raising the energy density.
Incorporate Ultrasorb R into the diet at a maintenance rate of 10g per cow per day.
UltraSorb R supplied in the UK and Ireland is UltraSorb R 3.0 and is exclusively supplied through Trident MicroNutri.
The role of a myctoxin remediator and endotoxin binder
Using a triple-action mycotoxin remediator and endoxtoxin binder can help protect cows from the negative impact of toxins produced by moulds and bacteria in feed.
UltraSorb R is added to rations at the point of feeding and covers a broad spectrum of mycotoxins and endotoxins, including newly emerged toxins identified through Volac’s Mycocheck feed sample testing service. It contains specially-selected minerals to bind various mycotoxins and endotoxins; plus biological active agents to transform and detoxify/degrade the harder to bind mycotoxins, such as DON and ZON, into safe forms. Yeast components also help to support gut health.
“By protecting herd health, evidence points to the inclusion of Ultrasorb R in feed rations delivering an extra 1-2 litres of milk per cow per day. That’s equal to a 5:5:1 return on investment at a milk price of 32p/litre,” Peter explains.
Where dairy farmers identify a particular mycotoxin/endotoxin problem, UltraSorb R can be added to feed rations at a dose of 20g/cow/day. In low-risk situations when targeting sub-clinical effects, a lower maintenance dose of 10g/cow/day can be used.
References Chandler, T.L, et al, 2018. Journal of Dairy Science. Predicting hyperketonemia by logistic and linear regression using test-day milk and performance variables in early-lactation Holstein and Jersey cows
Chiwome B, et al, 2017. The Journal of the South African Veterinary Association, A study of the indicence of milk fever in Jersey and Holstein cows at a dairy farm in Beatrice, Zimbabwe.