HealthyLife
Programme for Sustainable Dairy Farming
The impact of mycotoxins on health and performance of dairy cows
HealthyLife
Programme for Sustainable Dairy Farming
The impact of mycotoxins on health and performance of dairy cows
Assessing the risk of contamination of dairy rations with mycotoxins is difficult, but that doesn’t mean the problem doesn’t exist!
Assessing mycotoxin risk in dairy feeds has always been challenging. Most cases dairy cows are fed with Total Mixed Ration (TMR) containing silages, grains, and by-products. Although mycotoxins in TMR and high-fiber ingredients can be analysed, test methods are costly and not practical for routine analysis. On the other hand, more practical and affordable tests, such as ELISA and Lateral Flow Devices, are not particularly suitable for testing high-fiber ingredients. This problem can be solved by combining rapid tests that are practical for testing mycotoxins in ingredients with low amounts of fiber with mould counts and mycotoxin analysis for ingredients with high levels of fiber and for TMR.
Making a correct assessment of the risk of contamination with mycotoxins in combination with understanding the consequences of their presence and negative effective effects in dairy cows is very important to prevent problems with health, performance and fertility of dairy cows and problems with residues of aflatoxins in milk.
Traditionally, there are the so-called “big 6” mycotoxins (Aflatoxins, Zearalenone (ZEA), deoxynivalenol (DON), T-2 toxin, Fumonsins and Ochratoxin A (OTA)), sometimes also referred to as "AFOZET mycotoxins", that are associated with several mycotoxin problems in dairy cows. More recently, new groups of mycotoxins, the so-called silage mycotoxins have been identified[108,109,110]. Lastly, there are the Endophytes, moulds that grow inside plants and can cause problems in gazing dairy cows. These silage mycotoxins and Endophytes can be different from the “big 6” mycotoxins and hence understanding the presence and negative effects of these silage mycotoxins and endophytes in dairy cows is very important.
Table 1 shows which feed ingredients can contain the various AFOZET mycotoxins of dairy cattle and what the effects of mycotoxins in dairy cows can be.
Mycotoxin/s | Source | Negative effects of chronic toxicity |
Aflatoxins | Grains, protein sources, by-products, silages | Poor rumen fermentation, reduction of feed intake, milk yield, feed efficiency and reproduction capacity, poor response to vaccines, lowered disease resistance, liver toxicity, kidney toxicity, increased incidence of lameness and mastitis, increased somatic cell counts. |
Zearalenone | Grains, protein sources, by-products, silages, hay | Reduced feed intake, reduced milk yield, abortions, abnormal estrus cycle, vaginitis, sterility, increased number of services per conception, increased incidence of retained placenta. |
DON | Grains, protein sources, by-products, silages, hay | Reduced milk yield, poor rumen fermentation, reduced microbial protein synthesis, increased somatic cell counts. |
T-2 toxin | Grains, protein sources, by-products, silages, hay | Feed refusal, reduced milk yield, hemorrhagic gastroenteritis, diarrhea, blood in the faeces, abomasal and ruminal ulcers, poor immunity, absence of oestrus. |
Fumonisins | Corn, corn by-products, corn silage | Reduced feed intake, milk yield, feed efficiency, and reproduction capacity, liver toxicity, kidney toxicity, poor immunity. |
Ochratoxin A | Grains, protein sources, by-products, silages | Not a serious problem but when rumen health is compromised, it can cause performance and health issues. |
Ergot toxins | Small grains, grass, hay | Reduced feed intake, milk yield, and reproduction, increased incidence of abortion and retained placenta, reduced prolactin levels, rough hair, necrosis of extremities like tail, ear and hoofs. |
Tremorgens (fumigaclavine A and B) |
|
Anorexia, diarrhea, reduction of thriftiness, irritability. |
Silage Penicillium mycotoxins (Ochratoxins, penicillic acid, citrinin, roquefortine C, mycophenolic acid, patulin) | Corn silage, wheat silage, alfalfa silages | Reduced VFA synthesis, poor milk yield, poor rumen health, kidney toxicity, increased incidence of mastitis, ruminitis and laminitis, increased somatic cell counts. |
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Aflatoxins can cause problems with health fertility and performance of dairy cows at high concentrations, but as they are very toxic for humans, tolerance levels in milk are relatively low. Aflatoxins in dairy cows are mainly related to problems with rejection of milk due to concerns about safety for human consumption. Thus, if there is an aflatoxin risk, particularly aflatoxin M1, a Hazard Analysis Critical Control Points (HACCP) approach will be required.
The symptoms caused by mycotoxins are mainly related to poor rumen fermentation, systemic immune activiation leading to poor immunity, hormonal imbalance and sometimes liver and kidney toxicity, all leading to poor health, performance and reproduction. There are many other causes for these types of problems, as a result, recognising a problem with mycotoxins isn’t always easy.
Are dairy cows able to deal with mycotoxin toxicity?
Figure 1: Factors with a negative impact on detoxification of mycotoxins in the rumen.
The risk of mycotoxins is much bigger in dairy cows than in monogastric animals because the chances of exposure to mycotoxins through various ingredients is much higher (see Figure 1). There is no doubt that microbes in the rumen of the cows, particularly protozoa, can help to lower mycotoxin toxicity, particularly in case of a challenge with ochratoxin A (OTA). Some mycotoxins can however have a negative effect on the ability of rumen flora to detoxify mycotoxins. Next to that, modern dairy cows do have an increased passage rate of feed through the rumen, leaving less time for microorganisms to detoxify. In case of sub-acute ruminal acidosis (SARA), the number of protozoa in the rumen declines, having a negative effect on the ability to detoxify mycotoxins. As a result, the awareness of farmers, nutritionists, and veterinarians that mycotoxins indeed are a significant challenge to dairy cows is increasing.
Compared to poultry and pigs, it has always been difficult to assess mycotoxin risk in dairy feeds. Most dairy cows are fed a Total Mixed Ration (TMR) containing forages, grains (including high moisture grains), protein meals, by-products and sometimes green grass or hay. Two methods to measure mycotoxin levels in feed exist. Next to that, the risk of mycotoxin contamination can be indirectly assessed by mould analysis of high moisture ingredients and TMR. Out of the 2 methods available for mycotoxin analysis, rapid mycotoxin analysis is recommended for raw materials having less than 15% moisture and low fiber content. Mould analysis is recommended for raw materials or TMR with more than 15% moisture and high fiber content.
Both HPLC and LC-MS/MS methods can be used to measure mycotoxins in TMR and high-fiber ingredients, but these methods are not practical due to the time consumed to obtain results as well as the high cost per sample analysis.
Rapid mycotoxin tests, such as ELISA and Lateral Flow Devices (including Mycomaster), are excellent for testing important mycotoxins rapidly and at an affordable cost. Unfortunately, these tests are not particularly suitable for testing high-fiber ingredients.
Mould analysis of dairy feed ingredients and TMR
The alternative to measuring mycotoxin levels in feed with expensive tests is mould analysis. Depending on the extent of information needed, further identification of mould species is possible in some commercial labs. Such identification helps in understanding whether the mould identified can produce mycotoxins and if yes, which types of mycotoxins potentially can be present (see Table 2).
Mould | Potential mycotoxins |
Aspergillus | Aflatoxins, ochratoxins |
Fusarium | DON, T-2 toxin, fumonisins, zearalenone |
Penicillium | Ochratoxins, penicillic acid, citrinin, roquefortine C, mycophenolic acid etc. |
Mucor/Cladosporium | Non-mycotoxin producing molds |
Table 2: Moulds and mycotoxin relationship. Mycotoxins produced by Penicillium species in silages are highly volatile and hard to analyze by conventional methods.
Because there is no cheap and practical way to measure the levels of mycotoxins in a TMR or high-fibre feed ingredient for dairy cows, the alternative is to combine two methods. Ingredients with a low amount of fibre should be analysed for mycotoxins using a rapid mycotoxin test such as the Mycomaster, whereas mould analysis should be used to assess mycotoxin risk of the total TMR or ingredients with high fibre content (see Table 3).
Lastly, there is the option to test feacal samples of dairy cows for moulds. This method is not very accurate, as the presence of moulds only indicates there has been a problem in the recent past and also, it does not provide any information as to where the mycotoxin contamination is coming from, but is is a simple method that can be used to find out if a mycotoxin problem is a likely or unlikely cause of problems with health, performance and fertility in a dairy herd.
Rapid Mycotoxin Analysis | Mould Analysis |
Grains | Silages/high moisture grains |
Protein Meals | Hay/grass |
Grain by-products | TMR |
Concentrate |
|
Table 3: Diagnostic tools for understanding total mycotoxin risk in ruminants
Rapid Mycotoxin Analysis | Mould Analysis | Rapid Mycotoxin Analysis | Mould Analysis | Mould Analysis |
Total Mould Count | cfu/g | 104-105 | 105-106 | >106 |
Aflatoxins | ppb | 5-10 | 10-15 | 15-20 |
DON | ppb | 450-900 | 900-1800 | >1800 |
T-2 toxin | ppb | 50-75 | 75-100 | >100 |
Zearalenone | ppb | 50-150 | 150-250 | >250 |
Fumonisins | ppb | 2000-3000 | 3000-4000 | >4000 |
Table 4: Mycotoxin and mould guidance values for TMR for dairy cows. Aflatoxins recommendations are based on FDA regulation and the values are much lower for EFSA regulation.
How to manage problems with mycotoxins in dairy cattle?
Reducing animal exposure to mycotoxins in feed is key. Identifying contamination can help to reduce exposure. Moulds can already grow and produce toxins when the crops are still on the field. High humidity, temperature and un-seasonal rains during crop growth and harvesting can increase mould prevalence and mycotoxin risk in dairy feed ingredients. Contamination and growth can however also occur during storage.
Robust mycotoxin risk management programme should comprise many actions, including:
Conclusions
Irrespective of the source and the type of mycotoxins, overall health, performance, and reproduction of dairy cows are significantly affected by poor quality raw materials and TMR. This impact has increased in recent times as rumen health and the immune system of high yielding dairy cows is relatively compromised. The risk of mycotoxin exposure is much higher in dairy cows as compared to monogastric animals and hence an integrated approach should be in place when procuring raw materials, producing feed and silages, and rearing dairy cows. In terms of milk quality, aflatoxin M1 residues in milk is a global concern and that requires HACCP-like approach as the problem ends in compromising human health.
Problems with mycotoxins in dairy cattle are not always easy to recognise
The moulds that produce mycotoxins are sometimes visible when crops are harvested, but the mycotoxins themselves are invisible. Thus, mycotoxins will only be found in animal feed if it is being analysed. Yet, even if the feed is being analysed, there is still the risk of sampling error and “masked” mycotoxins, conjugates of mycotoxins that are formed by plant metabolism and cannot be detected with standard methods.
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The moulds that produce mycotoxins are sometimes visible when crops are harvested, but the mycotoxins themselves are invisible. Thus, mycotoxins will only be found in animal feed if it is being analysed. Yet, even if the feed is being analysed, there is still the risk of sampling error and “masked” mycotoxins, conjugates of mycotoxins that are formed by plant metabolism and cannot be detected with standard methods.
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SELKO LACTIBUTE
Adding Selko LactiBute to the ratio increases milk production while increasing fat and protein levels at the same time. This results in an increase of Energy Corrected Milk of 0.85-1 kg per head per day.
SELKO INTELLIBOND
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Selko TOXO® is a mycotoxin mitigation product that contains bentonite, which has strong binding capacity for aflatoxins, ergot toxines and LPS, in combination with glucose biopolymers which maintain gut tight junctions to reduce the translocation of mycotoxins into blood stream. Selko TOXO-XL® combines this with purified β-glucans that improve the immune function of dairy cows.
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