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Functional Additives

   

Three combined strategies guarantee success in mycotoxin control

 
Dian Schatzmayr 

Biomin Innovative Animal Nutrition GmbH, Austria

 


Numerous strategies are evolving for control of mycotoxins, some clearly being more practical and effective than others. Novel approaches combining different strategies that counteract mycotoxins through diverse biological and dietary interventions show greatest promise.


Mycotoxins are toxic chemical products formed by fungal species that colonize crops in the field or after harvest and thus pose a potential threat to human and animal health. In farm animals, a mycotoxin-contaminated diet may lead to substantial economic losses due to feed refusal, poor feed conversion, diminished body weight gain, immune suppression, interference with reproductive capacities and residues in animal products. Even though recommended agricultural practices have been implemented to decrease mycotoxin elaboration during crop growth, harvesting and storage, the potential for significant contamination still exists. According to the Food and Agriculture Organization (FAO), at least 25% of the world's crops are contaminated with mycotoxins. The significance of these unavoidable, naturally occurring toxicants to human and animal health, the increase in mycotoxin regulations and global trans-shipment of agricultural commodities highlight the need to provide successful counteracting strategies.


Certain treatments have been found to reduce levels of specific mycotoxins. However, no single method has been developed that is equally effective against the wide variety of mycotoxins which may co-occur in different commodities. Moreover, detoxification processes that appear effective in vitro (i.e. in the lab) do not necessarily retain their efficacy when tested in vivo (i.e. in feeding trials).


In the course of several extensive research projects involving scientists from all over the world, the Austrian company Biomin developed a unique, continuously improved concept to successfully deactivate agriculturally relevant mycotoxins present in feed. This year, the fourth Mycofix® Plus product generation is launched which is based on three different mycotoxin-counteracting strategies: (1) elimination of the toxin (= absorption), (2) elimination of the toxicity (=biotransformation) and (3) elimination of toxin-related effects.

 


Elimination of aflatoxins


The most well-known approach to detoxification of mycotoxins involves the use of nutritionally inert adsorbents with the capacity to tightly bind and immobilise mycotoxins in the gastrointestinal tract of animals, thus reducing their bio-availability. In several independent scientific studies, hydrated sodium calcium aluminosilicates (HSCAS) have proven to be the most promising adsorbents. Mixed into feed they markedly diminish aflatoxin uptake by the blood and distribution to target organs, thus avoid aflatoxin-related diseases and the carryover of aflatoxins into animal products. Unfortunately the efficacy of these adsorbing substances is quite limited against zearalenone (ZEA), ochratoxin A (OTA) and fumonisins (FUM) and totally ineffective for trichothecenes such as deoxynivalenol (DON), T-2 toxin and diacetoxyscirpenol (DAS).


However, adsorption is not only economically feasible today, but in the first place a well-established and scientifically proven approach to prevent aflatoxicoses in farm animals. The efficiency of aflatoxin-adsorption mainly depends on the chemical properties of the adsorbent used. In the course of the Mycofix® Plus product development and its continuous improvement several screening studies were carried out in cooperation with Austrian universities in order to find the best adsorbents with regard to aflatoxin-deactivation and safe application. A synergistic blend of minerals was designed that as part of Mycofix® products guarantees maximum, pH-independent activity at an inclusion rate as low as 0.5 kg/t without removing essential nutrients from the diet (see figure 1).

Fig. 1: Aflatoxin-adsorption capacity of Mycofix® Plus. Left side: 99-100% adsorption at pH 6.5 (intestinal conditions). Right side: 98-99% adsorption at pH 3.0 (gastric conditions).

 

 

Biotransformation of trichothecenes, ZEA and OTA


In the course of extensive research activities in the field of biological detoxification (1988 - 2004), Biomin found a unique practical method to successfully counteract less- and non-adsorbable mycotoxins. "Biotransformation", which can be defined as the enzymatic degradation of mycotoxins leading to non-toxic metabolites, has been successfully applied in Mycofix® products since 1991. Continuous research finally led to the most recent development of patented microbial supplements able to detoxify all kinds of trichothecenes, zearalenone and ochratoxin A.


A safe bacterial strain (Eubacterium sp.) was found to have trichothecene-detoxifying activity and was named Biomin® BBSH 797 after the research team that discovered it in July 1997: Binder, Binder, Schatzmayr and Heidler. During its metabolism BBSH 797 produces specific enzymes that eliminate toxicity of trichothecenes by selective cleavage of their toxic 12,13-epoxy group. Both, in vitro and in vivo, efficacy of the strain was scientifically proven (see figure 2 and table 1).

 

 

 

Tab. 1: Scientific feeding trials with piglets (45 days) and broilers (36 days), University of Veterinary Medicine, Vienna, Austria. Mean values.

 

 

Initial weight [kg]

Final weight

[kg]

FCR

p

 

Piglet trial, 2.5 ppm DON

Control group

6.66

16.43a

2

£0.001

Trial group (+ BBSH 797)

6.76

23.62b

1.62

 

 

Broiler trial, 10.5 ppm DON

Control group

36.4

1.26a

1.92

£0.05

Trial group (+ BBSH 797)

36.4

1.44b

1.87

 


In the course of a several-year research project, the feed additive Biomin® MTV was developed and patented. The live yeast species contained was named Trichosporon mycotoxinivorans after its unique property to "eat" and thus detoxify both, zearalenone and ochratoxin A (lat.: vorans = eating, devouring).


Incubation experiments with the strain and subsequent cell culture studies at the University of Utrecht in the Netherlands proved successful degradation of 1 ppm ZEA (figure 3). Additional in vitro studies with OTA-concentrations as high as 5 ppm revealed a complete detoxification within max. 1 hour (figure 3). Feeding trials carried out at the universities of Godollo in Hungary (piglets) and Maribor in Slovenia (broiler) showed that the negative influence of OTA on performance of animals could be totally neutralized by addition of T. mycotoxinivorans (table 2).


Being part of Mycofix® products, both Biomin® BBSH 797 as well as Biomin® MTV guarantee success in the fight against less- and non-adsorbable mycotoxins.

 

 

 

Tab. 2: Scientific feeding trials with piglets (39 days) and broilers (42 days). Mean values (p ï‚£ 0.05). Negative control: no toxin, no additive; Positive control: no toxin, + additive; Toxin group: + toxin, no additive; Trial group: + toxin, + additive.

 

 

Negative control

Positive control

Toxin group 

Trial group

 

Piglet trial, 0.5 ppm OTA

Final weight [kg]

32.65

33.1

30.78

33.81

ADWG [g]

457.7a

465.5a

379.8b

476.7a

 

Broiler trial, 1.0 ppm OTA

Final weight [g]

2129a

2150a

2065b

2148a

Mortality [%]

4

2

20

4

 


Elimination of toxin-related effects


The total number of mycotoxins is not known, but toxic metabolites of fungi potentially could number in the thousands. The number of mycotoxins actually known to be involved in diseases is considerably less, but even this number is difficult to asses due to the diversity of their effects on animal systems.


Natural intoxications by mycotoxins often are more complex than can be related to those experimental studies utilizing one mycotoxin. Therefore, natural responses may be the cause of two or more toxins. The immune system, for instance, is not only a key target of the major classes of mycotoxins, but also of ergot and fescue alkaloids, citrinin, patulin and gliotoxin, to name a few. Hepato-toxic effects are not exclusively attributed to aflatoxins, ochratoxins and fumonisins, but also to sporidesmin (New Zealand, Australia: facial eczema), rubratoxins and phomopsins (Australia, New Zealand, South Africa, USA: lupinosis). All of them will produce significant liver damage when given to animals.


Finding successful detoxification strategies for agricultural relevant mycotoxins is not an easy task; several years of intense research were necessary to develop methods described above. However, finding respective strategies for minor classes of mycotoxins, that might act synergistically and contribute to various mycotoxicoses, is probably impossible. Thus, Biomin adopted a different method for non-adsorbable and non-degradable toxins.


Since 2001, Mycofix® products are provided with a blend of scientifically studied and carefully selected plant and algae extracts that are able to eliminate toxin-related effects such as immune suppression, liver-damage or inflammation (see table 3).


Herbs for the immune system are general immune-system-stimulators (immunostimulants). They increase resistance by mobilizing "effector cells" which act against all foreign particles rather than just one specific type. The immune-stimulating extracts incorporated into Mycofix® products were selected using different in vitro test systems. Numerous preparations of plant and algae origin were compared in a macrophage activation assay. Macrophages (figure 4) are one of the major cells of the unspecific immune system responsible for consuming invading microbes (i.e. for phagocytosis of pathogens). Thus, substances which are able to enhance the activity of macrophages lead to enhanced phagocytosis activity and subsequently to a strengthened immune system. A synergistically acting blend of plant and algae extracts finally gave the best results (figure 5). Immune stimulating effects of these substances were further confirmed in a lymphocyte proliferation test.

 

Tab. 3: Scientifically described effects of various plant extracts.

 

Effect

Active constituents

References1

Stimulation of immune system

polysaccharides, alkaloids

Goel V et al.(2002); Keplinger H et al.(1994); Mungantiwar AA et al.(1999); O¡¯Neill W et al.(2002) ; Rossi V (1993); Sohni YR et al.(1996); Wagner H (1985); Wenigmann M (1999); Williams L et al.(1997)

Liver protection

flavo(no)lignans

Agarwal R et al.(1994); Gujral D et al.(2002); Handa S et al.(1990); Hruby K et al.(1992); Letteron P et al.(1990); Rastogi R et al.(2000, 2001); Salmi H and Sarna S (1982); Trivedi N and Rawal U (2001)

Anti-inflammatory activity

flavonoids, triterpene saponines, carotinoides

Blumenthal M et al.(1998); Della Loggia R et al.(1994); Glowania HJ et al.(1987); Leung A and Foster S (1996); Shipochliev T et al.(1981); Weiss RF (1988); Zitterl-Eglseer K et al.(1997)

         1Details available on request
 

 


The liver protecting effect of plant derived substances contained in Mycofix® products was scientifically proven in a broiler feeding trial carried out at the National University of Colombia. A total of 144 chicks were fed a commercial starter mash ration which contained the hepato-protective additive and/or two hepato-toxic substances, pyrrolizidine alkaloids and aflatoxin B1 (200ppb). A clear difference (52.5 g) in body weight gain was observed between the toxin and the trial group (see table 4). Feed intake as well as relative liver weights followed a similar trend indicating that the investigated additive completely overcame the adverse effects caused by the hepato-toxic substances.

 

Tab. 4: Scientific broiler feeding trial (21days) with liver protecting substances. Control group: no toxin, no additive; Toxin group: + toxin, no additive; Trial group: + toxin, + additive.

 

 

Control group

Toxin group 

Trial group

Final weight gain1[g]

594.5 ¡À 33.4

566.5 ¡À 58.0

619.0 ¡À 49.1

Total feed intake1[g]

835.2 ¡À 23.6

786.5 ¡À 92.8

842.3 ¡À 95.7

Relative liver weight2[g/kg]

28.2 Â¡Ã€ 4.2

32.4 ¡À 2.8

30.2 ¡À 2.8

      1 values are means ¡À S.D. of 4 replicate pens per treatment
      2 values are means ¡À S.D. of 10 liver weights per treatment

 


Conclusion

 

The combination of three strategies described above guarantees success in mycotoxin control. Live bacteria and yeast strains expressing specific mycotoxin-degrading enzymes offer a unique natural way of providing these activities in the digestive tract of animals. With BBSH 797 and T. mycotoxinivorans Biomin was the pathfinder of this successfully working technology.


In Mycofix®, the combination of bio-transformation and adsorption ensure an effective control against all agriculturally relevant mycotoxins taken in with contaminated feeds. Selected plant and algae extracts that counteract effects of non-degradable and non-adsorbable toxins complete the product.


In the course of several-year research projects numerous in vitro and in vivo studies have proven the superiority of Mycofix® to commercially available mycotoxin binders.

 

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