Description of Problem
The term ‘antinutritional factor’ typically refers to secondary metabolites such as phytate, nitrates or tannins, which are produced by a variety of plants as a defense mechanism against attack by insects, pathogens and herbivores (Saad, 2016). These compounds can cause adverse effects on mineral transport, hormone regulation, feed utilization, health or production when consumed. Although not considered a mainstream antinutritional factor, mycotoxins are a type of secondary metabolite, in this case produced by certain mold species. Similar to classic antinutritional factors, mycotoxins can disrupt endocrine function, impact mineral and nutrient transport or utilization, and interact with other organisms to compromise health and performance (Antonissen et al., 2014; Keci et al., 2019; Weaver et al, 2020a; Yuan et al., 2022). As such, mycotoxins fit into most, if not all, of the functions described for antinutritional factors (Table 1).
Table 1. Comparison of production and effects of antinutritional factors and mycotoxins.
| Attribute | Antinutritional Factors1 | Mycotoxins |
|---|---|---|
| Producing organism | Plants | Fungi |
| Produced on crops pre-harvest | ✓ | ✓ |
| Produced on crops post-harvest | – | ✓ |
| Naturally occurring | ✓ | ✓ |
| Secondary metabolite | ✓ | ✓ |
| Provide protection/adaptation for producing organism | ✓ | ✓ |
| Impacts nutrition or endocrine functions | ✓ | ✓ |
| Lowers bird performance or health | ✓ | ✓ |
- 1
-
“✓” checkmark indicates an agreement with the attribute; “-“ indicates that this category does not have this attribute.
Mycotoxins are of importance because while the prevalence, type and concentration may vary from year to year, or region to region, they are a common contaminant of feedstuffs worldwide. Furthermore, mycotoxins are likely to co-occur in a single feedstuff or a complete ration, thereby increasing the challenge to the bird. Recent publications report that multiple mycotoxins are the norm, for example with corn grain in the United States containing an average of 4.8 mycotoxins (Weaver et al., 2021) and European corn an average of 6 mycotoxins (Koletsi et al., 2021). Furthermore, samples routinely analyzed by the Alltech 37+ Analytical Laboratory (Nicholasville, KY) show not only a presence of multiple mycotoxins but also a high prevalence of emerging mycotoxins (Fig. 1). Emerging mycotoxins do not fall within the traditional group of mycotoxins, for example aflatoxin or deoxynivalenol (DON), and are classified as those that are neither routinely determined nor legislatively regulated (Chiminelli et al., 2022). Additionally, they may be considered emerging as they can now be identified with advancements in laboratory techniques and they appear to have frequent and increasing mycotoxin presence in agricultural commodities. Many of these emerging mycotoxins are produced by Fusarium molds, but others such as those produced by Alternaria species are also of interest and importance. Analysis of 5,593 corn grain samples globally from January 2023 to May 2024 revealed an average of 6.7 mycotoxins per sample, with emerging mycotoxins being the most prevalent group appearing in 31.4% of samples (Fig. 1). Notably, these results also showed that the prevalence of seven of the key emerging mycotoxins has increased on average 6.6% between 2018 and 2024 (Fig. 2), underscoring the growing significance of these compounds in poultry feed safety.
Fig. 1. Mycotoxin prevalence based on the relative occurrence (%) of mycotoxins in 5,593 global corn grain samples analyzed between January 2018 and May 2024 for 54 mycotoxins by ultra-high performance liquid chromatography with tandem mass-spectrometry (Alltech 37+ Analytical Laboratory, Nicholasville, KY).
Fig. 2. Increase in the overall occurrence rate of emerging mycotoxins (beauvericin, enniatin A/A1, enniatin B/B1, fusaric acid and moniliformin) in 5,593 global corn grain samples analyzed between January 2018 and May 2024 for 54 mycotoxins by ultra-high performance liquid chromatography with tandem mass-spectrometry (Alltech 37+ Analytical Laboratory, Nicholasville, KY).
Symptoms of mycotoxin intake by poultry
Ingestion of mycotoxin contaminated feed may result in both direct and indirect responses in the bird. Early signs of mycotoxin intake could include changes to performance such as reduced feed intake or gain, poor feed conversion, lower egg production or altered egg quality (Kolawole et al., 2020; Weaver et al, 2020a). Similar to antinutritional factors, mycotoxins have also been shown to impact mineral status. For example, increasing concentrations of DON lowered the calcium to phosphorus ratio of the femur and tibiotarsus of broiler chickens (Keci et al., 2019). Additionally, Wang et al. (2006) reported a higher incidence of leg problems when a multi-mycotoxin contaminated diet was fed to broilers. Mycotoxins can also interfere with endocrine functions contributing to hormone disfunctions. Zearalenone, in particular, has been shown to significantly reduce the levels of follicle-stimulating hormone and progesterone in laying hens (Yuan et al., 2022).
Mycotoxins may affect organ health, with the gastrointestinal tract being one of the first and most impacted. Various types of mycotoxins are shown to alter protein synthesis within the intestinal villi which can cause lesions and reduced villi growth, leading to poor nutrient digestion and absorption (Li et al., 2022). Mycotoxins may reduce the number of goblet cells in the intestine that in turn impacts the mucus layer, as well as weaken tight junctions between cells (Weaver et al., 2020a; Li et al., 2022). This damage can impact the health of the bird, making it more susceptible to secondary infections (Antonissen et al., 2014). As such, secondary symptoms including an increase in diseases, wet manure, poor vaccination response, and greater mortality rates may be observed.
Although the role of emerging mycotoxins in poultry is less widely discussed, there is a historical database of research documenting the potential implications on performance and health. Bacon et al. (1995) described the presence of the emerging mycotoxin, fusaric acid (FA), on embryo livability without or with the presence of fumonisin B1 (FB1). After injecting these mycotoxins alone or in combination into egg yolks, FA and FB1 individually increased embryo mortality after 21 days, but the harmful effects were even more pronounced when combined. As such, the presence of the emerging mycotoxin FA with FB1 could result in greater responses within the bird. Another emerging mycotoxin example, moniliformin (MON), can be produced by numerous Fusarium species and can be highly toxic for poultry (Broomhead et al., 2002; Sharma et al., 2012). Consumption of MON by birds may result in heart damage, respiratory distress, muscular weakness and immune suppression.
Managing mycotoxins
To effectively combat mycotoxins, the first step is to detect the mycotoxin risk present which can be accomplished through a variety of detection methods such as lateral flow technology, enzyme linked immunosorbent assays, or liquid chromatography tandem mass-spectrometry (Weaver et al., 2020b). The use of analytical technologies that not only detect but also quantify mycotoxins, allows for the best understanding of risk which can help producers to make informed decisions about feed quality and safety. Data from mycotoxin analysis can also be used to better track mycotoxin risk over time and correlate mycotoxin risk with bird health and performance challenges, guiding effective management strategies.
Another step to be employed for managing mycotoxins is the use of adsorbents that reduce the uptake of mycotoxins into the animal (Weaver et al., 2022). There are a variety of potential adsorbent materials available globally, with some of the most widely used being inorganic clay minerals and yeast-based additives. One type of adsorbent commonly used in poultry production to minimize mycotoxin effects is yeast cell wall extract (YCWE, Alltech, Inc.). To assess the overall effects of using YCWE during mycotoxin challenges, several meta-analyses have been published. Meta-analysis assessments are valuable as they allow for the synthesis of multiple individual trials into one overall quantifiable conclusion (Sauvant et al., 2008). For example, a recent meta-analysis with broilers synthesized a collection of 25 trial references and reported that the use of YCWE during mycotoxin challenges could result in significantly higher gain, better efficiency, lower mortality and smaller carbon footprint of production compared to consumption of mycotoxins alone (Weaver et al., 2022). Similarly, a meta-analysis published on laying hens showed that hens fed YCWE during mycotoxin challenges had significantly greater egg production and heavier egg weights than hens fed mycotoxins without YCWE (Weaver et al., 2024).
Overall, mycotoxins can have a presence in all commodities globally. These mycotoxins can result in negative effects to the health and performance of birds, which could impact the profitability and sustainability of poultry operations. However, by understanding both mycotoxin risk and mycotoxin mitigation, producers can better manage mycotoxins and reduce their ‘antinutritional’ effects on bird performance and health.
Conclusions and applications
- 1.
Mycotoxins are globally present in feedstuffs and finished feeds and should be considered a threat to feed safety and quality.
- 2.
Mycotoxins have actions similar to antinutritional factors, leading to both direct and indirect losses associated with animal health, performance and profitability.
- 3.
Emerging mycotoxins are an important category of mycotoxins with high prevalence rates and potential to negatively impact bird health.
- 4.
Assessment of mycotoxin presence in feedstuffs and feeds is a first step in mycotoxin management, although quantifying this risk and linking it to potential bird performance and health challenges is also important.
- 5.
Management strategies that directly reduce the risk from mycotoxin exposure within the bird, such as YCWE, are available to the industry which have the potential to support performance, health, profitability and sustainability.
Source: Science Direct
