Animal Nutrition Severely Affected by Mycotoxins: Can Mycotoxins be Managed?11 March 2016
Mycotoxins are highly toxic secondary metabolic products of molds. Mycotoxin producing molds damage crops which can cause great economic losses at all levels of food and feed production.
Moreover, many of the mycotoxins interact with digestibility of nutrients, impair health, cause diseases and death in humans and animals which consume contaminated food or feed products. At the moment, there are more than 400 known mycotoxins. Those of most concern can be divided into six major categories: aflatoxins, trichothecenes, fumonisins, zearalenone, ochratoxins, and ergot alkaloids. From the nutritional point of view mycotoxins interact with lipid, protein, carbohydrate, and vitamin nutrition. Diets high in lipid have a mortality-sparing effect against mycotoxins and, if high in unsaturated fatty acids, a growth-sparing effect. Some mycotoxins causes a lipid malabsorption syndrome coupled with decreased digestive enzymes and bile salt excretion, a decreased synthesis of fatty acids, and impaired transport. Deficiencies of vitamins A, D, or riboflavin make animals more sensitive to mycotoxins while a thiamin deficiency has the opposite effect. Interaction with vitamins E and K has not been clearly demonstrated as yet. Mycotoxins increase the protein requirements of animals and apparently alter the enzymes that regulate glycogen catabolism and neogenesis (Hamilton, 1977).
Swine is the most sensitive animal species, how can farmers recognize typical mycotoxicosis symptoms?
Mycotoxins may cause various toxic effects or mycotoxicosis. Symptoms caused by mycotoxin contamination depend on the level and type of mycotoxin, but also on several factors such as animal species, sex, environment, nutritional and health status and other toxic entities. However, they are not transmissible between animals and contaminated feed is mostly the cause. Diagnosis of mycotoxicosis is often very difficult because the effects of mycotoxins in animals are diverse, varying from specific to unspecific symptoms like immune suppression, diarrhea, hemorrhages or reduced performance.
The most frequently co-occurring non-specific symptoms of mycotoxin contamination in fattening pigs and piglets is decreased feed intake or feed refusal - very typical for deoxynivalenol (DON) contamination - and diarrhea. We know that DON is able to compromise several intestinal barrier functions, including a decreased surface area available for nutrient absorption and potentiation of intestinal inflammation. Both feed refusal and diarrhea might contribute to decrease daily weight gains and worst FCR in growing pigs.
Zearalenone is the mycotoxin most detrimental to swine and somewhat to ruminants with serious effects on the breeding stock. Young gilts and piglets are most sensitive. Toxicity results in the reddening and swelling of the vulva, increased size of mammary tissue, straining with subsequent rectal and vaginal prolapse, as well as pseudo-pregnancy and false heat. The piglets of affected sows may experience depressed piglet growth in utero, early embryonic mortality and be born with splayed legs. Fertility problems surface at 100 to 200 ppb. Zearalenone also produces swelling of the prepuce in boars.
The splay leg syndrome is the major congenital cause of lameness in suckling piglets. It is characterized by a temporarily impaired functionality of the hind leg muscles immediately after birth, resulting in inability to stand and walk. Etiology and pathogenesis of splay leg syndrome is complex and remain still poorly understood. Infectious factors might be also involved in etiology. Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) cause late term reproductive failure in sows, which is characterized by increased number of stillbirth, weak, light weight and splay-legged piglets (Papatsiros et al., 2012). Exposure of piglets to another Fusarium mycotoxin - fumonisin B1 (FB1) increased the risk for PRRSV disease (Bane et al., 1992). Various management and genetic factors have been connected with the etiology of splay leg syndrome, such as the farrowing induction, low birth weight, short gestation lengths, slippery floors and breeds (e.g., Large White and Landrace pigs) (Ward, 1978). Moreover, nutrition can play a role to pathogenesis, as choline or methionine deficiency in sow diets are correlated with the presence of slay leg syndrome. Some researchers supported that one cause of splay leg was a deficiency in the sow’s diet of choline and methionine which are essential for normal myelin production (Kornegay and Meacham, 1973). Finally, nutrition also is involved in etiological factors and especially the zearalenone toxicity. The contamination of feed in sows with more than 4 ppm zearalenone can result in increase in the number of piglets born with splay leg (Kanora and Maes, 2009).
All these negative effects will result into worse health status and productivity of pigs and other animal species. The question is: Can these negative effects be prevented?
Raw materials, the most important source of mycotoxins
The best practical way to control mycotoxin levels is to use rapid test kit systems for analysis of mycotoxins in raw ingredients which are not in silos yet. Different rapid test kit systems are validated for different mycotoxins and commodities and offer very quick and effective way of raw material screening before they enter the feed mill. Once the levels are known every feed mill can estimate quality of its raw ingredients in terms of mycotoxin contamination and can effectively and more precisely (dosage adjustment) apply mycotoxin deactivator during production of feeds.
Finished feed contains mixture of mycotoxins
Another strategy of mycotoxin risk management is to test mycotoxins presence in finished feeds. This method has some advantages and disadvantages. The most important advantage is that as every raw ingredient will bring its own mycotoxins into the finished feed and by only testing some raw ingredients by rapid test kits we can miss some important raw ingredients which inclusion is not high (5-10%) and which can still cause significant contamination of finished feed.
Since the 1960’s, many analytical methods have been developed for the testing of mycotoxins in human food and animal feeds due to the concern of toxicity for human health. Among them, the methods of thin-layer-chromatography (TLC), enzyme-linked immunosorbent assay (ELISA) and immunosensor-based methods have been widely used for rapid screening, while high-performance liquid chromatography (HPLC) with fluorescence detection (FD) and mass spectrometry detection (MS) have been used as confirmatory and reference. Accredited laboratory service is required for this step. The most important disadvantage is that analysis of finished feed takes usually quite long time and in the point when the results are finally known the feed has been already fed to the animals a long time ago.
Mold inhibitors – effective against mold but not mycotoxins
Storage mycotoxin contamination (ochratoxins, aflatoxins) can be prevented by keeping temperature and moisture content in silos low while grain is regularly aerated. In case perfect storage conditions cannot be guaranteed usage of mold inhibitor is highly recommended. Unfortunately, already produced mycotoxins (etc. trichothecenes) cannot be destroyed by any mold inhibitor.
Effective mycotoxin management
The final possible step in mycotoxin management is the application of a mycotoxin deactivator. These products work strictly in vivo and will not counteract or mask mycotoxin in stored feed or raw ingredients. These products deactivate the toxins directly in the gastrointestinal tract of animals, based either on adsorption of those mycotoxins with suitably located polar functional groups, or biological degradation (bio-inactivation). NUTRIAD specially developed feed additives which protect animals from mycotoxicoses by adsorption, bio-inactivation, organ, immune and antioxidant system support and represent an optimal solution for mycotoxin management for farm animals. NUTRIAD mycotoxin deactivators do not interact with vitamins, minerals or medication in vivo. It is highly recommended to apply effective mycotoxin deactivator which offers an opportunity to significantly improve animal health, performance, productivity and profit impaired by mycotoxins. Depending on the target performance different mycotoxins can be less or more problematic. Therefore, using different products for different animal groups become a rational trend.
Radka Borutova, Business Development Manager, Nutriad International, Belgium.
Bane D.P., Neumann E.J., Hall W.F., Harlin K.S., Slife, R.L.N. 1992. Relationship between fumonisin contamination of feed and mystery swine disease-a case-control study. Mycopathologia; 117, 121–124.
Hamilton, PB. 1977. Interrelationships of mycotoxins with nutrition. Feed Proc. 36:1899-902.
Kanora A. and Maes D. 2009. The role of mycotoxins in pig reproduction: a review. Veterinarni Medicina, 54, 2009 (12): 565–576.
Kornegay E.T. and Meacham T.N. 1973. Evaluation of supplemental choline for reproducing sows housed in total confinement on concrete on in dirt lots. J. Anim. Sci.37:506-509.
Papatsiros V. 2012. The splay leg syndrome in piglets: A Review. American Journal of Animal and Veterinary Sciences 7 (2): 80-83.
Ward, P. 1978. The Oxford companion to Spanish literature. 1st Edn., Clarendon Press, Oxford, pp: 629.