ReviewFusarium mycotoxins: Effects on reproductive function in domestic animals—A review
Introduction
Fusarium mycotoxins are secondary metabolites produced by several species of Fusarium molds that occur naturally worldwide in cereal grains and animal feed. Fusarium mycotoxins are endowed with both acute and chronic aspects of toxicity and have shown to cause a broad variety of toxic effects in animals. Spontaneous outbreaks of Fusarium mycotoxicoses have been reported in Europe, Asia, Africa, New Zealand, and South America. Moreover, chronic intake of these mycotoxins is reported on a regular and more widespread basis due to their global occurrence [1]. The main classes of Fusarium mycotoxins with respect to animal health and production are trichothecenes such as deoxynivalenol (DON) and T-2 toxin (T-2), fumonisins, and zearalenone (ZEA) [2]. Exposure to these mycotoxins has been linked to reproductive disorders in domestic animals. The current review is intended to provide a comprehensive summary of identified reproductive effects of Fusarium mycotoxins in domestic animals.
Section snippets
Zearalenone
In cycling sows, ZEA causes several reproductive dysfunctions including nymphomania, pseudopregnancy, ovarian atrophy, and changes in the endometrium. ZEA causes sterility in sows by inciting a malfunction of the ovary [3], [4]. The oocyte dies in the Graafian follicles, and despite signs of estrus, there is no ovulation. ZEA acts similarly to estradiol in inhibiting the release and secretion of FSH, thus depressing the maturation of ovarian follicles during the preovulatory stage [3], [4]. The
Zearalenone
In young boars, ZEA was reported to reduce weights of testes, spermatogenesis, serum testosterone, and libido [42], [43], [44]. No adverse effect on the reproductive potential of mature boars was described at ZEA levels normally found in contaminated feed and capable of causing severe reproductive problems in female swine [45]. Dietary exposure to 1 mg/kg of ZEA for 55 days appeared not to adversely affect spermatogenesis in mature boars [46]. A lack of effect of a diet containing ZEA on
Effects of Fusarium mycotoxins on placenta and fetus
The mammalian placenta works like a selective barrier, and, depending on the number and the permeability rate of layers by which it is composed, it differently regulates the transport of substances and metabolites from the mother to the fetus. The passage of substances through the placenta is also influenced by others factors such as the dimension of contact surface between placenta and uterine mucosa and the different characteristics of the maternal and fetal vascular system [65]. Despite the
Effects of Fusarium mycotoxins on puberty/sexual maturity
Although puberty is an important landmark in the productive life of an animal, the effects of Fusarium mycotoxins on puberty attainment do not seem to have received enough attention as reflected by the paucity of information. In a recent study carried out by Gutzwiller et al. [84], the continuous intake of 2 mg DON and 0.4 mg ZEA/kg diet beginning shortly before puberty had no effect on the age at the first observed estrus in gilts. This finding confirms the observation of Friend et al. [85]
Conclusions
The major Fusarium mycotoxins, DON, T-2, ZEA, and FB1, have been indicated to have systemic effects in most mammalian species studied. In vitro, these mycotoxins have direct effects on ovarian cells, altering oocyte maturation, inhibiting granulosa cell proliferation, and differentiated functions such as gonadotropin-supported steroid production. However, the mechanism by which various Fusarium mycotoxins may interact to alter ovarian cell functions is unclear. In vivo, Fusarium mycotoxins can
Competing interest
All authors disclose any actual or potential conflict of interest including any financial, personal, or other relationships with other people or organizations within 3 years of beginning the submitted work that could inappropriately influence, or be perceived to influence, their work.
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