When the relevance of mycotoxin mitigating strategies in dairy farms was discussed in the past, the focus was on managing aflatoxin B1 in the final feed to avoid a high carry-over rate of AFM1 into milk and thus protect human health. In recent years, however, the health of the dairy cow itself and its maintenance have become increasingly important.
Product Manager Toxin Management
Biochem
Even if ruminants are less sensitive to the effects of mycotoxins than monogastric animals thanks to a certain microbial detoxification in the rumen, this protection may not be sufficient in all cases:
• The feed of dairy cows leads to a high exposure to a broad spectrum of mycotoxins, especially through the various silages (Fink-Gremmels, 2008). As the dry matter intake is also very high, dairy cow feed obviously carries a high qualitative and quantitative risk for the uptake of mycotoxins.
• The degradation of mycotoxins is reduced when feeding with high energy density due to a shortened passage time or, for example, in the case of deoxynivalenol (DON) with reduced rumen pH (Debevere et al., 2020). It can therefore be assumed that intensive feeding is associated with a reduced detoxification of mycotoxins overall.
• When some mycotoxins are degraded, the degradation product can sometimes be even more harmful than the original toxin. For example, the degradation of zearalenone (ZEA) leads, among other things, to the formation of α-zearalenol (Seeling et al., 2005), which is 60 times more estrogenic than zearalenone itself.
As a result, there is a real risk that larger quantities of mycotoxins may escape ruminal detoxification and lead to symptoms similar to those of monogastric animal species. The most frequently reported clinical signs are reduced milk yield, an altered milk quality, which is particularly evident in reduced milk fat, increased somatic cell count (SCC) or partly reproductive disorders.
There is a wide range of variations in the assessment or determination of critical contamination levels. While in scientific trials with an artificial contamination by purified mycotoxins, very high quantities appeared to be necessary to trigger such symptoms, field reports point to reduced health and performance even at levels far below the EFSA guidance values when feeding naturally contaminated raw materials (Whitlow et al., 2008). In the following, several field trials are presented that show from different perspectives how low to moderate levels of field contamination can have a negative impact on dairy cow performance and health and how an efficient broad spectrum toxin binder (B.I.O. Tox®Activ8, Biochem) can prevent these adverse effects.
FIELD TRIAL I
The first field trial was conducted as an on-off design on a German dairy farm with about 1,180 lactating Holstein Friesian cows. Farm production data had shown a clearly negative tendency from spring onwards, reaching a low point in June. The mycotoxin DON was first detected in the milk and then also in TMR together with ZEA. Subsequently, the toxin binder (TB) was added to the TMR of the lactating cows by a premixture, resulting in a dosage of 20 g/head and day in the Start group and 25 g/head and day in the High Yield group for a period of two months. Meanwhile, mycotoxin levels in the milk as well as the development of performance parameters were monitored. Table 1 provides an overview of all results before and at the end of the trial period.
During the trial period, all parameters were improved. Considering the on-off character of the trial, these parameters certainly may also be influenced by other environmental factors like the varying quality of feed ingredients. The daily maximum temperatures monitored from June till end of trial period did not show extreme or strongly deviating conditions and are unlikely to have had a decisive influence on the performance as well as the average lactation day of the herd, which was nearly the same.
The clear reduction of DON-derivates in the milk with no change in the contamination of the TMR suggests that TB is effective in reducing the bioavailability of DON. This factor may have contributed decisively to the stabilization of performance and health issues during the trial period.
After the successful stabilization of the performance parameters, the trial farm discontinued the use of the TB in October. However, after about two months, parameters started to deteriorate, and the milk analysis again showed an elevated DON level. Hence, the farm started reusing TB and parameters stabilized again, including the DON level below the guidance value. Figure 1 shows the development of DON levels in milk and TMR.
FIELD TRIAL II
The next field trial took place on a Czech dairy farm with about 500 Czech Simmental cows. The aim was to test the influence of the TB on milk yield, milk ingredients and SCC under a moderate field contamination with mycotoxins. The TMR analysis showed contamination with 700 ppb DON and 190 ppb ZEA and the farmer, being used to higher inclusion rates for such products, insisted on double the recommended dosage of 25 g to 50 g TB per cow and day. The product was used for a duration of 8 weeks and the results of the monthly milk testing, which records milk yield, ingredients and SCC, were used for the evaluation.
Figure 2 shows the temporal development of the parameters over the test months (green bars) as well as 4 months before and one month after product application (grey bars). Under the use of the TB, milk yield increased while SCC was reduced compared to the months without product use. Taking into account the milk fat and protein contents monitored in parallel, it was also possible to calculate the energy corrected milk (ECM), showing as well a clear economical advantage for the farmer. After deducting the product costs, the farm was left with an average additional income of more than 100 € per day.
FIELD TRIAL III
The positive results obtained in Germany and Czeck Republic were confirmed by a further field experience on a dairy farm in Northern Ireland. The farm with around 200 Holstein Friesian lactating cows faced an unusual drop in performance, which was accompanied by an increased SCC and mastitis incidence as well as a reduced appetite in the cows. The mycotoxin analysis of the TMR revealed only a low contamination of approx. 200 ppb DON and the cows received a dosage of 25 g TB per head and day over an observation period of eight weeks.
Table 2 provides an overview of the temporal development of performance parameters.
Milk yield was once again increased, while the SCC was reduced under the use of TB. Due to the positive impact also on milk ingredients, the profitability of the farm was particularly improved with the strongly increased ECM. Even considering the additional costs for the TB, the farm ended up with an average of over 300 € more income per day. In addition, the cows’ appetite normalized, and the incidence of mastitis was clearly reduced.
FIELD TRIAL IV
The last field trial presented in this series aims to show another, completely different facet of the clinical appearance of mycotoxins. It was conducted on a French dairy farm with about 70 lactating Montbéliarde cows and 20 heifers of the same breed with regular access to pasture grazing. Farm reproduction data showed a clearly reduced fertility compared to the previous reference period. This was accompanied by an increased prevalence of ovarian cysts and endometritis as well as cows not expressing heat behaviour or showing heat signs out of oestrus. The TMR analysis revealed an average contamination with ZEA of 13 ppb and DON of 447 ppb. However, other, undeterminable mycotoxins could have been ingested during grazing. Consequently, the TB was added to the TMR with a dosage of 50 g/head/day during the first month, followed by a dosage of 20 g/head/day for the following four months. The reproductive health was assessed by the scanning technician who screened the animals for gestation after artificial insemination (AI).
Figure 3 shows the historical development of the AI index (artificial insemination done/ fertile insemination, AI/FI) before and during the trial period considering also the fertility level before the problems began.
The reproductive parameters show a clear improvement during the trial period, especially concerning the insemination success. During the third period, where the TB was added to the TMR, the AI index was clearly decreased again. Concerning the heifers, the AI index was improved even more significantly. In parallel with the fertility parameters, the urogenital health parameters monitored by the scanning technician were similarly improved. After the trial period, the farmer kept using the product at a daily dosage of 20 g per cow and day.
SUMMARY & CONCLUSION
The different types of field trials introduced here demonstrate that mycotoxins can have significant impacts on the health and productivity of dairy cows under field conditions. Particularly in the presence of DON, a reduced milk yield and milk fat were observed. Increased SCC is also one of the frequently observed problems. Apart from this, reduced fertility, especially promoted by ZEA, can be another costly consequence.
Efficient toxin binders, such as the product applied in these field trials, are specific strategies against this environmental stress factor. They safely neutralize a relevant negative component in the environment of dairy cows and thus not only preserve health and performance, but also the profitability of dairy farms.
References
1. Debevere, S.; Cools, A.; De Baere, S.; Haesaert, G.; Rychlik, M.; Croubels, S.; Fievez, V. (2020). In Vitro Rumen Simulations Show a Reduced Disappearance of Deoxynivalenol, Nivalenol and Enniatin B at Conditions of Rumen Acidosis and Lower Microbial Activity. Toxins, 12, 101. https://doi.org/10.3390/toxins12020101
2. Fink-Gremmels, J. (2008). Mycotoxins in cattle feeds and carry-over to dairy milk: A review. Food Additives & Contaminants: Part A, 25(2), 172–180. https://doi.org/10.1080/02652030701823142
3. Seeling, K.; Dänicke, S.; Ueberschär, K. H.; Lebzien, P.; Flachowsky, G. (2005). On the effects of Fusarium toxin-contaminated wheat and the feed intake level on the metabolism and carry over of zearalenone in dairy cows. Food Additives & Contaminants, 22(9), 847–855. https://doi.org/10.1080/02652030500163708
4. Whitlow, L. W., and W. M. Hagler. (2008). Mold and mycotoxin issues in dairy cattle: effects, prevention and treatment. Adv Dairy Technol 20: 195-209.
About Dr. Cornelia Becker
After her veterinarian studies in Hungary, Dr. Cornelia Becker worked as a vet for large animals for about 18 years, focusing especially on pig production and animal nutrition. She also gained experience as a special consultant in one of the leading mineral feed mills of Germany. In 2019, she joined Biochem as an R&D Product Manager for Toxin Solutions.
