1. Mycotoxins can be very pocketed throughout a load of feed. How is this treated as part of a feeding trial?
In the different in vivo studies presented, mycotoxins were added to the feed to reach a given contamination corresponding to a specific challenge level investigated complying with regulatory limits (low dose, chronic levels). Mixing was performed by specialized feed processing groups and analysis of the mycotoxin content was performed on composite sample of every feed used after mixing. The concentration of mycotoxin was within 10% of expected concentrations. Full mycotoxin profile was also evaluated on the control feed to account for any residual natural levels of toxins. For other studies performed with naturally contaminated feed, the approach used a highly contaminated diets that was diluted down using clean feed to reach the challenge levels investigated. Again, thorough mixing was performed, and every final treatment evaluated for its mycotoxin final content compared to control.
Yes, different clays have different binding affinities to different mycotoxins. Clays constitute a vast family of inorganic materials (phyllosilicates) that possess different colour, textures, density, opacity, refractive index, intralamelar structures (mode of stacking of the crystal sheets, the nature of bonding and the type of cation in the lattice in different clay minerals, e.g. kaolinite, montmorillonite, illite), slacking and swelling properties. For aluminosilicates, the silica-alumina ratio can range from 1:2 to 1:8. Clays have strong cation-exchange properties and are able to trap many trace elements. They have reportedly a good adsorption property toward AFB1 but are limited for other mycotoxins. Adsorption for those can vary according to their physical/chemical properties. Clay tend to be used at high inclusion rate, which could have an impact on other important constituents of the diet. Finally, clay, if not sourced properly, can also be contaminated with heavy metals, dioxin and PCBs as well as radionuclei, as they are mined products subjected to environmental and industrial contaminations. Proper quality control is needed when clay materials are used.
DON production is generally dependent on temperature (temperate climate < 25°C). Moisture is not necessarily affecting trichothecene production. Water availability is key for Fusarium growth (0.960-0.980). pH can also affect production - acidic pH favouring DON production.
If this relates to the mycotoxin analysis, most toxins are quite resistant to temperature and won’t degrade in normal drying condition. However, some of them such as neosolaniol or some ergot alkaloids, could be affected. As such, drying at high temperature is not recommended for submitting a sample unless the bulk feed undergoes the same process. For sample submission, it is rather recommended to vacuum pack the sample and refrigerate. Freeze drying could be also applied. Samples could be run as is. Reports should provide humidity level of the samples in that case for proper expression of the mycotoxin concentration results. Silage samples are generally further freeze dried when received in the laboratory to facilitate grinding and particle size reduction before extraction, and mycotoxin values are then reported per dry weight.
5. Don is a problem in South Africa. What anti-mycotoxin strategies can be used to reduce potential Don toxicity?
As presented, in the animal system both detoxification and binding could be used as mitigation strategies.
Risk Equivalency Evaluation is proper to our evaluation and dependent on the threshold of risk used. Risk assessment can be performed when samples are submitted to our laboratory based on the evaluation of the presence of 54 mycotoxins.
7. Are grazing dairy herds at less risk from mycotoxins than TMR herds? Is there any research on the mycotoxin risk purely from pasture?
Mycotoxins could be found in grass. Grass samples are run through our laboratory. For animal pasture, other issues can be of concern especially coming from endophytes exposure that are producing ergot alkaloids (ergovaline, ergotamine…). Some of those are part of the toxins that we are investigating in our feeds. For grass silage, it appears that often the toxin present are storage toxins, showing that most of the mycotoxin produced is synthesized during the storage phase and coming from Penicillium, Aspergillus and other emerging toxins. Fusarium toxin could still be detected but in lesser amounts.
8. Hot-spot occurrence and continued accumulation of toxins are real issues when it comes to testing - what is the real value of mycotoxin testing?
If good agricultural practices are used, very little accumulation of toxin is happening as the rhizobiome and soil microbiome are able to handle and detoxify those toxins. Many enzymes sourced for detoxification are coming from soil microbial samples. However, because of environmental concerns, tillage for examples is not used as much as before, which is positive in terms of CO2 trapping but detrimental for mycotoxin accumulation. As such, mycotoxin accumulation trends might potentially be seen especially in the last couple of years of implementation of such programs. Crop rotation is then probably another approach to minimizing this accumulation. Mycotoxin testing is always advisable since patterns of contamination are always changing and different feed matrices have different fingerprints of contamination. Evaluating the mycotoxin content in final feed is providing a good insight into the mycotoxin management at the farm or feed mill, and potentially can provide insight into eventual problems observed at the animal level. It becomes also an appropriate decision tools for implementing corrective measure or using a mitigation approach such as a binder. Of course, the number of samples will be always the limiting factor to a proper mycotoxin evaluation. In this context, mitigation strategies such as the use of an adsorbent is advisable as a prevention approach (basal inclusion level) as well as when hot spot of contamination occurs (higher inclusion level).
9. You mentioned the impact of environmental temperature change on mycotoxin contamination level. What new risks can we expect with this phenomenon?
As demonstrated by the predictive work performed at Cranfield University (P. Battilani et al, 2016), prospects are on a change of the mycotoxin production profile with for example in that study an increase of the AFB1 contamination risk in Europe by an increase of +2-5C. It will be interesting to see if there is also a change in the population of different mycotoxin families, and the balance between those.
From the analysis across countries and continents, it appears that in final feedstuffs, contamination profiles are not region specific. The trading of ingredients across the planet is inducing increased chances to see unsuspected mycotoxin patterns, but also decrease the differences between patterns of contamination across regions. Contamination of pastures is however very much region specific, as locally sourced, with for examples issues relate to sporidesmin in New Zealand or lupinosis in Europe. For these issues, some product specificity could be interesting to pursue. For the rest of the mycotoxins, even for emerging ones, they could be found in all regions. As such, a large spectrum product is probably the most practical approach to the mycotoxin mitigation globally.
As demonstrated by the latest in vivo work looking at a specific DON challenge, using validated biomarkers such as DON concentration and its corresponding metabolite DOM-1 in urine, YCWE was able to decrease their concentration showing efficacy against DON contamination issue.