Mitigating the threat mycotoxins pose on milk margins

Author: Beth Gardner, InTouch Feeding Specialist – North of England

In the absence of having much control over milk prices, dairy farmers are having to be extra careful with farm inputs and super proactive with any challenges that might hinder milk yields.

Mycotoxins should be top of the agenda

Farmers are producing more milk than ever before, and with fewer cows. UK milk yield has increased from 7,000 to 8,500 litres since 2010 (UK milk yield | AHDB). With higher-yielding cows needing more feed, the chance of mycotoxin exposure has also increased.

More specifically, early laboratory sampling as part of the Alltech 2023 European Harvest Analysis is indicating a high risk of mycotoxins across UK silages this year. This confirms what we would anticipate from such a wet start and end to the silaging season. Previous results from these analyses have found that Penicillium and type B trichothecenes mycotoxins pose the greatest risk to ruminants from forages.

Source: Alltech, 2023

That said, it is really important to understand that this high risk of mycotoxins is not necessarily a given for every farm and all silages.

Mycotoxins are naturally occurring toxins produced by certain moulds (fungi) that can grow in or on plants such as grasses and various varieties of corn. There are over 500 mycotoxins. Some are visible as mould, but some cannot be seen by the naked eye.

Mycotoxins are not retained in the rumen long enough to be degraded by the rumen microflora, so they can remain intact for adsorption within the gut wall, the liver and immune cells. They are increasingly evidenced as having a toxic effect on protein synthesis and therefore cell growth, impacting overall health and productivity.

So the mycotoxin threat to calves, heifers, and lactating, transition and dry cows needs to be taken very seriously.

Testing, observation, mitigation and planning are the four components to an effective mycotoxin management strategy.

1. Test silages ahead of using them

Effective mycotoxin risk management starts with understanding the ongoing risk, so that we can try to stop the impact taking hold in the first place.

With Alltech’s technological advances in testing and monitoring, we are now able to keep tabs on even the more subtle problems occurring from even low levels of mycotoxins.

Detailed analysis

Alltech 37+® mycotoxin analysis provides a comprehensive picture of mycotoxin contamination in a total mixed ration (TMR), grass, maize, or wholecrop silages and concentrates. This independent laboratory-based testing service can detect up to 54 individual mycotoxins. All mycotoxin test data can then be stored in one integrated platform to enable farmers to implement the most informed mycotoxin control strategies quickly.

Real-time analysis

Alltech 37+ provides the most detailed analysis, but intermittent on-farm testing is needed to keep results updated between Alltech 37+ analyses. Alltech® RAPIREAD™ is a portable test device with the latest mobile that enables on-farm identification and analysis of the risk of six key mycotoxins within minutes, providing a helpful estimate of overall mycotoxin levels.

The cost of these tests are low relative to the cost of feeding mycotoxins, so they are recommended standard practice for any farm system.

2. Watch out for what your cows are telling you

When dairy cows ingest mycotoxins through feed, the impact on health and performance may not be immediately observable. Instead, indicators can build up over time.

All farm operators should keep an eye out for these ten warning signs:

1. Visible moulds in forage and feed

Moulds like Penicillium, Aspergillus and Fusarium are often found in grass and maize silage and are common mycotoxin producers. All these moulds start white and only develop colour as they become older.

White to red or pinkish moulds are typically Fusarium, or field-borne, moulds.
Blue-green moulds are typically Penicillium, which is often storage-related but can occur in the field during certain weather conditions.
Olive-green to yellow moulds are typically Aspergillus, which is very common in drier climates.

To identify different mould types, download Alltech’s quick guide.

2. Heating behind the clamp face

Heating is a natural result of the fermentation process that occurs in the silage clamp at ensiling. Poor management causes air to be sucked into the silage directly behind the clamp face. This allows dormant yeasts, moulds, and bacteria to flourish, and one of the associated risks is mycotoxin production.

3. Reduced intakes

Gastrointestinal issues resulting from poor rumen health caused by mycotoxins can lead to reduced feed intake and even feed refusal. This will immediately impact on milk yield and will diminish body condition relatively quickly too.

Deoxynivalenol (DON) is the proper name for the most-often-detected Fusarium mycotoxin commonly referred to as vomitoxin. In cattle, DON is typically associated with reduced feed intake and lower milk production

4. Loose and/or inconsistent dung

A significant telltale sign of poor gut health is loose and/or inconsistent dung (e.g., intermittent diarrhoea, sometimes with bloody or dark manure).

5. Physical indicators

Indicators may include swollen hind legs, arched backs and even cracks showing separation of the hooves from the feet.

6.Lethargy

Studies have shown that an intake of fumonisins can cause cows to become fatigued. You will notice longer-than-normal laying times, resistance to standing, listlessness, and a dull appearance.

7. A sudden drop in milk yield

One of the most critical impacts that mycotoxin contamination can have on your farm is suboptimal milk production. If you see a sudden or temporary milk loss in your herd, it could be the result of contaminated feed.

8. Higher somatic cell counts

The somatic cell count (SCC) results from the bulk milk tank are a good indicator of the general state of the udder health of the dairy herd. Somatic cells in milk consist mainly of white blood cells produced by the cow to destroy the bacteria that enter the udder and cause mastitis; these cells also repair damaged udder tissue. Somatic cells are always present in milk, but when an infectious agent enters the udder or the udder is damaged, the number of somatic cells shed by the individual cow increases.

Mycotoxins are a significant threat to the cow’s natural immunity, with the ability to cause both immune stimulation and immunosuppression, depending on the mycotoxin type and concentration. This can result in cows being more susceptible to disease, leaving them unable to tackle the bacterial challenges that lead to a high somatic cell count.

9. A drop in reproductive performance

Decreased fertility, abnormal oestrus cycles, swollen vulvas, vaginitis, reduced milk production and mammary gland enlargement are the most common symptoms reported in cattle.

A change in the oestrus cycle can manifest in various forms. Prolonged, skipped or irregular heats are commonly associated with zearalenone. While these abnormal oestrus changes are not exclusively specific to zearalenone toxicity, feed-related causes should be investigated when increases in abnormal oestrus cycles are observed on-farm. However, reproductive changes may also be due to the indirect effects of other mycotoxins on animal health. For instance, trichothecene mycotoxins, such as deoxynivalenol and T-2/HT-2 toxins, have been associated with lower pregnancy rates in dairy cows.

10. Increased incidence of laminitis and mastitis in the herd

Mastitis usually occurs in response to an intramammary bacterial infection but can also be the result of intramammary mycoplasmal or fungal infections. Tissue damage and the increased somatic cell counts caused by mastitis infection can block the tiny milk ducts in the udder, resulting in lower production when the milk-secreting cells above the blockage are dried off.

Another aspect that should be considered is the higher incidence of lameness on dairy farms feeding rations contaminated with mycotoxins. Aflatoxin has been found to have negative effects on the sensitive hoof lamina, leading to costly foot issues.

Download our warning signs poster

3. Plan your mitigation programme

Careful clamp management and mould removal

Reducing exposure to mycotoxins is key. If feedstuffs are shown in testing to contain high levels of mycotoxins, it may be necessary to remove contaminated silage from rations, particularly for groups of animals with high inclusion and increased susceptibiltiy to disease.

Visible moulds on feedstuffs — often seen at the edges of silage clamps or on the outsides of bales — should be discarded. The time taken to get across the face of a silage clamp should also be taken into account. Ideally, the clamp face should be moved across every three to four days, especially during warmer weather. The clamp face should also be kept clean and compacted; defacers and/or shear grabs are best designed for this management.

Inclusion of a mycotoxin binder in the diet

When mycotoxins are found to be present in any feed, farmers are advised to include a mycotoxin binder into the TMR.

Mycotoxin binders work by a process of adsorption, in which the carbohydrate components of yeast and algae cell walls bind to the mycotoxins that have been consumed, removing them from the animal’s digestive tract before they have a chance to cause toxicity.

Mycosorb A+ is a broad-spectrum binder which has been proven to address the multi-mycotoxin challenge, including Penicillium toxins the most common toxin found in forages and TMRs, based on results of Alltech 37+ mycotoxin testing.

Unlike the mode of action of clay-based binders, Alltech Mycosorb A+ does not bind with other essential nutrients, including vitamins.

The Alltech Mycotoxin Matters customer portal can be accessed online 24/7 by nutritionists to view up-to-date risk levels of mycotoxins in your area, taken from real samples submitted of 2023 feedstuffs. To access this tool, contact your local Alltech representative.

4. Plan for the next silaging season

Finally, think ahead to your next growing season. 95% of mycotoxins are found to be produced in the field, and this risk can be influenced by various factors: a delayed harvest, slow or delayed filling of silos, inadequate packing and sealing of clamps, slow feedout across the silage face, and damaged clamp covers. Each of these risks can create a conducive microclimate for mould proliferation and mycotoxin production (Whitlow and Hagler, 2005).

Here are six top tips to have at your fingertips for the next silage season:

Ensile the crop at the right stage of maturity. Older crops are more vulnerable to attack in the field from fungal pathogens.
If cutting is delayed, adjust the cutting height to 7.5–10 cm from the base of the stem. The bottom of the stem poses the highest risk of diseased material and has lower digestibility and nutritive value.
Wilt rapidly and immediately to prevent a warm, humid environment, which encourages the growth of yeasts and moulds.
Compact the clamp well, rolling each layer no thicker than 15 cm to achieve a high target density of 750 kg/cm of fresh matter.
Use side sheets, oxygen barrier films and top sheets, then apply top weight to keep air out.
Consider clamp management, perhaps investing in equipment and/or reducing the widths of clamp faces.

Testing is crucial to understand the threat of mycotoxins in your silages before they have a chance to impact on your milk yields.

If your cows are showing signs of facing a burden of mycotoxins from your silages or TMR, it is important to remediate quickly using a mycotoxin binder.

Our team of InTouch Feeding Specialists are on hand to help you do just that.