This article is aimed at briefly reviewing the toxic effects of mycotoxins aflatoxins, trichothecenes, zearalenone and fumonisins in the growth performance of poultry. The discovery of hepatotoxic and carcinogenic properties of some lineages of Aspergillus flavus and A. parasiticus for turkey in England in the 60’s, followed by the determination of the chemical structure of their toxic components - the aflatoxins (AFL) - brought a new focus and paved the way for the modern mycotoxicologic research. From 1986 to January of 2000, 15,600 food samples, mostly for animal consumption, were submitted to aflatoxin analysis at the Laboratory for Mycotoxicologic Analysis (LAMIC-UFSM, Brazil). Among the corn samples tested, 41.9% were positive for aflatoxins. In field outbreaks o aflatoxicosis, the most prominent feature is the low absorption of nutrients, leading to the appearance of particles of feed in the feaces. Paleness of the legs and mucosas is also often observed in broilers and laying hens.Diets deficient in riboflavin and colecarciferol (vitamin D) may significantly increase the susceptibility of broilers to AFLs, resulting in a poor growth performance. The adverse effects of AFLs are more intense during the initial periods of growth, i.e. when the animals are fed AFL-contaminated food during the first 21 days of life. The level of stress has also been shown to enhance the toxic effects of AFLs, by reducing the toxic threshold and leading to a reduction in growth and egg production. The main mycotoxins belonging to the trichothecenes group are toxin T-2, deoxynivalenol (DON) and diacetoxyscirpenol (DAS), produced by several fungi species of the genera Fusarium. Fungi belonging to the Fusarium genus also produce zearalenona and fumonisin. Among the Fusarium mycotoxins, only toxin T-2 is a severe pathogen for poultry, causing oral lesions and immunodepression. The fumonisins can affect the growth performance of broilers at doses as low as 75ppm. In contrast, no toxic effects of zearalenona and DON have been demonstrated for poultry. The method of choice to prevent food contamination with mycotoxins is to avoid fungal growth, narrowing the quality control of the grains in the farm or during storage/transportation. Alternative methods such as antifungic drugs or adsorbents may also be used with success. Monitoring grains before or as they enter the food industry is the key point in a mycotoxin control program. This can be accomplished through a systematic and consistent mycotoxicologic analysis of grain samples already received at the plant or to be purchased.
mycotoxins; poultry; toxic effects; aflatoxins; trichothecenes; zearalenone; fumonisins; control
