The pig industries main aim is to maximize the quantity of quality meat produced per sow per year while maintaining sow condition and health. In the breeding herd, the animal performance is directly related to the reproductive performance of the sows latter to be measured by the number of weaned piglets per sow per year. The objective of pig producers in breeding herds is to increase this number while providing finishing herds piglets with good growth rates and carcass traits.

If it is true that genes are crucial in determining fertility, performance and carcass traits - thus corroborating the importance of genetic breeding programs - one should never forget that environmental factors will influence the way genes are expressed. Environmental factors manipulating gene’s expression include diet, physical activity, infectious agents, chemicals, ultraviolet radiation and even emotions. A palatable diet guaranteeing the animal’s nutrient requirements in its different stages which does not pose threats to the animals ingesting it is crucial for the animal production’s success.

Swine fertility

Mycotoxins are included in the toxic substances that often occur in animal feeds, posing a serious menace to animals ingesting them and acting directly and indirectly on pig fertility.

Reproductive failure, abortions, poor rearing ability and litter size are the cause for 45 % and 59 % of female pigs culled, in all parities and in gilts and second parities respectively. A high culling rate related to breeding problems has a big impact on the profitability of pig producers. A direct and important correlation can be made between mycotoxin-contamination and fertility problems; data collected in five Swedish pig farms showed that 85 % of all sows presented zearalenone in the bile liquid. Furthermore, the level of this mycotoxin in the bile liquid was significantly higher in farms having fertility problems in comparison with control farms.

Because of its multiple origins and high economic impact, reflected by decreased animal performance and increased culling rates, reduced fertility is one of the most complex and puzzling problems dealt by swine producers.

Mycotoxins and direct consequences on swine fertility

Zearalenone and T-2 toxin were shown to have direct impacts on animal fertility.

• Zearalenone
  
  

  Zearalenone is produced by fungi of the Fusarium sp., especially Fusarium graminearum and Fusarium culmorum. Although zearalenone (ZON) represents a relatively low toxicity to animals, this mycotoxin is well known due to its interference with the endocrine system. Zearalenone is the number one regarding its negative effects in fertility and swine are the animals that are most affected by it. The resemblance between zearalenone and the primary female hormone, estrogen, misleads the cells’ estrogen-receptors causing hyperestrogenism and impaired fertility. Concentrations of zearalenone such as 1 to 30 ppm are related with infertility and other problems such as anoestrous, pseudo pregnancy, swollen and reddened vulva, mammary gland enlargement and vaginal and rectal prolapse. Moreover, other problems may also occur, such as disrupted placental and piglet development, resulting in decreased litter size and diminished viability of neonates. It is important to bear in mind that not only female animals are negatively affected by this mycotoxin, but also boars. A depression of serum testosterone, testicles’ weight and spermatogenesis, along with feminization and suppressed libido can be observed in boars fed ZON-contaminated diets. Clinical signs in females involve reddened teats, swollen and reddened vulva and splay legs can be observed in newborn piglets, thus suggesting placenta and/or milk transfer from the female pigs.
  
  

• Trichothecenes - T-2 toxin
  
  

  T-2 toxin (T-2) is a part of the type A-trichothecenes, a family of mycotoxins produced by Fusarium sp. fungi, especially F. graminearum, F. culmorum and F. sporotrichoides. This trichothecene is known to inhibit protein synthesis. Its biological mode of action may be the explanation why this fusariotoxin is responsible for fertility problems in swine. T-2 has caused drastically decreased conception rates, infertility (repeated return to estrus), decreased litter size and reduced weight of piglets.

To continue reading this article click here