Sow fertility has a paramount effect on farm profitability. The number of pigs produced per sow per year defines the production cost per pig and other key metrics. The key to success is to sustain reproductive indices such as litter size, farrows per year and productive days at a high level.
Several parameters, such as management, genetics, nutrition, health status, and anti-nutritional factors, all affect herd fertility. Among the latter, mycotoxins are a major anti-nutritional factor known to affect reproduction—and pigs are particularly susceptible to the negative effects of mycotoxin exposure. (Watch ‘What is a Mycotoxin’).
Mycotoxins impair herd fertility
Zearalenone, T-2 toxin and ergot alkaloids are mycotoxins that are known to have a number of direct negative effects on pigs that contribute to herd infertility, as shown in Figure 1.
Zearalenone mimics estrogen, disrupts hormones
Among mycotoxins, the most notorious for its effects on reproduction is zearalenone (ZEN). ZEN blocks normal synthesis of hormones. It resembles the estradiol molecule and competes with the latter for estradiol (estrogenic) receptors. This estrogenic effect causes disturbances of the endocrine system, hypothalamic-pituitary-ovarian axis and suppresses the follicle-stimulating hormone (FSH) secretion in ovaries.
Deoxynivalenol (vomitoxin) lowers feed intake and alters immune response
Deoxynivalenol (DON) in feedstuffs compromises feed intake and may cause vomiting (Diekman and Green, 1992). In addition, DON inhibits protein synthesis and alters immune system response. It has been shown that DON causes reproductive effects by targeting oocyte and embryo development (Pestka et al. 2004, Alm et al. 2006).
The effects of DON and its relationship to reproduction in pigs has a more indirect effect. Feed intake reduction results in low nutrient availability and poses a threat on some metabolic pathways of the reproductive system.
In addition, any potential dysfunction of vital organs with a key role in metabolism such as liver and spleen would have an adverse effect on health. When health is compromised, animals’ metabolic priorities change. The immune response becomes the priority and consequently nutrients are allocated there, instead of the reproductive system (Kanora and Maes, 2009).
The DON + ZEN combination compromise follicle development, oocyte maturation, and embryo development
Deoxynivalenol and Zearalenone are both Fusarium toxins produced by mainly by F. graminearum, F. culmorum, and F. roseum (Tiemann and Dänicke, 2007). Due to the fact that they are produced by the same species of fungi, they can and often do contaminate the same crop at the same time (co-occurrence). For the latest information on mycotoxin global occurrence, check out the BIOMIN Mycotoxin Survey.
This co-occurrence is dangerous because the interaction between mycotoxins can have synergistic (amplified) effects: negative consequences that are greater than expected from single mycotoxins alone, and are of great concern in livestock health and productivity. Research has documented the negative combined effects of deoxynivalenol and zearalenone on fertility, as shown in Figure 2.
In vitro studies on porcine oocytes have shown that presence of ZEN, DON or combination of them compromise the development of oocytes and they lose the ability to mature (Figure 3). This may compromise embryo survivability, pregnancy continuation and further birth weight. In addition, DON has the most potent effects on embryo development after fertilization, resulting in abnormal and reduced numbers of blastocysts.
Figure 3. Exposure to estradiol, ZEN, DON, ZEN+DON, significantly reduced the percentage of oocytes that reached the MII (metaphase II) stage and increased significantly oocytes nuclear abnormalities (Malelinejad et al., 2007)
DON and ZEN trial design
A recent trial contacted by BIOMIN and the University of Berlin evaluated the reproductive parameters of sows in the presence of DON and ZEN over a long-term period (three cycles). Sows were allocated in three different groups:
- One group with no contaminated feed
- A toxin group that received contaminated feed with DON at high levels and ZEN at medium levels
- A trial group that received similarly contaminated feed as the toxin group and Mycofix® Plus
The presence of mycotoxins impaired several reproductive and performance parameters, as shown in Figures 4 and 5.
The most common index used to assess reproductive performance is weaned piglets per sow per year.
Farrowing rate and wean to estrus interval both affect the former index. The presence of mycotoxins, especially ZEN, increased the returns to heat and decreased farrowing rate.
Feed intake affected sows’ body condition at weaning and milk yield. Consequently, underweight sows needed more days to come in estrus after weaning.
This decreased the number of farrows, and depleted weaned piglets produced per sow per year. In addition, milk yield could compromise litter growth and weaning weights, resulting in lower weights to slaughter or/and more days in feed.
On the piglet side, the presence of mycotoxins compromised piglet quality. The percentage of underweighted piglets (< 1.2 kg) increased, implying a negative effect of mycotoxins on embryo development and maternal nutrition.
We could assess that the negative effect on piglet quality accompanied with a depletion of milk yield that resulted in higher pre-weaning mortality and lower weaning weights.
However, a sound recovery was observed with the application of Mycofix®.
Mycotoxin co-contamination of raw materials is more common than single mycotoxin contamination. Mycotoxins act in a concerted manner against the animal, affecting multiple tissues, organs and functions. In the case of sow fertility, DON and ZEN can be particularly harmful. Mycofix® offers a safe and effective way to overcome multiple mycotoxin contamination and protect sow reproductive performance.