How to Protect Your Layers and Breeders from Trichothecene Mycotoxins

Photo: aprilfoto88

Mycotoxin contamination in feed is a major concern for poultry producers. BIOMIN GmbH, a world leader in mycotoxin research, has published many articles about mycotoxins, their mode of action, and management of the risk they present. Mycotoxins are toxic secondary metabolites produced by fungi either in the field or under post-harvest storage conditions. Research shows that 95% of mycotoxins are already present in the field. Mycotoxins can negatively affect gut health and thus decrease animal performance and immune status.

Poultry genetics have drastically evolved so that now, poultry producers expect high rates of growth for broilers and long life cycles with intensive metabolism for layers and breeders. Mycotoxin contamination of feed, even at low levels, can compromise these performance criteria. The synergistic effects of more than one mycotoxin contaminating feed can reduce the livability and productivity of the birds even more.

Mycotoxins and necrotic enteritis

Broiler studies from Ghent University (Antonissen et al, 2014) have demonstrated that deoxynivalenol (DON) is a predisposing factor for the development of necrotic enteritis (NE). Contamination of the diet with DON at concentrations below the EU maximum guidance level of 5,000 mg/kg feed, significantly increased the number of chickens with NE. Nowadays, the effects of trichothecenes (e.g. DON and T2-toxin) and fumonisins (e.g. FB1) on gut permeability are well known. Mycotoxins reduce enterocyte proliferation and mucus production, allowing clostridia development and pathogens like E.coli and salmonella to cross the fragile gut wall, leading to infections.

Ochratoxin is able to damage the kidneys, but more importantly, it affects thymus, spleen and fabricius bursa tissue (Huff et al., 1974, and Chang et al., 1981) which reduces antibody production, especially the production of IgA, IgG and IgM (Dwivedi and Burns, 1984). Birds are pushed to high rates of production, leaving them more exposed to local pathogens, and more sensitive to infections at all levels.

Vertical transfer

Mycotoxin exposure can be aggravated in breeders as research has shown that the vertical transfer of mycotoxins to eggs is possible. This can have a huge impact as even low levels of DON transferred to fertile eggs can affect normal chick development (Bergsjo et al., 1993 and Prelusky et al., 1987). A low but continuous exposure to ochratoxin can also lead to accumulation in eggs, which will subsequently affect the development of the embryo (Fuchs et al., 1988). Chi et al. (1978) showed that T2-toxin and its metabolites could be transferred to the egg (yellow and albumin), therefore risking the development of the embryo. Ingesting feed contaminated with zearalenone (ZEN) may result in residues being found in egg yolks, which may affect human health and viability of chick progeny (Allen et al., 1981). Aflatoxins and their metabolites have been found in poultry meat and eggs in various studies. Aflatoxins accumulate in the genitals and are transferred to the egg and offspring (Barnard, 2008).

Two solutions to the mycotoxin problem

The ubiquitous nature of mycotoxins makes it difficult to predict contamination levels. However, even low levels of contamination, which might not be detected by standard rapid testing kits, can have a negative impact. Mycotoxin binders and deactivators help to avoid such deleterious effects. The advantage of using a mycotoxin deactivator is that both absorbable mycotoxins like aflatoxins, and non-absorbable mycotoxins like DON, T2 and ZEN can be controlled. First, the mycotoxin is absorbed, and second it is biotransformed using enzymes. To certify this process as safe for both animals and humans, BIOMIN submitted a comprehensive dossier to the European Food Safety Authority (EFSA). In 2013, BIOMIN received registration for adsorption with an aluminosilicate (bentonite E558) for absorbable mycotoxins like aflatoxins, and registration for Biomin® BBSH 797—a component of Mycofix® for non-absorbable mycotoxins like DON (only licensed for pigs)*.  In 2017, BIOMIN received registration for the 5th generation of its Mycofix® product for all species. The registration was based on the same approved registration for binding with bentonite and BBSH for all trichothecenes. This 5th generation product also includes another registered enzyme called fumzyme for the biotransformation of fumonisin.

Mycofix® in practice

A trial was conducted in Switzerland to test the efficacy of BBSH on layer breeders, under official authorization; the results were very positive for both mortality and hatchability. Nowadays, mortality in layers or breeders is economically significant considering that a normal layer breeder produces 300 eggs over a 70-week period, and a layer produces more than 350 eggs in 80 weeks. This fact is even more considerable for high quality eggs produced by semi-range or free-range farms where the value per unit is significantly higher. The trial was conducted in three phases as shown in Table 1.

Table 1: Trial phases

Phase   Start date   End dateDiet content
12-3/6/2014 14/09/2015 No mycotoxin binder or deactivator
228/05/201509/05/2016Mycofix® BBSH included during production cycle
324/05/201609/05/2017Mycofix® BBSH included during rearing and production periods

Mortality, egg number and hatchability were compared, and mycotoxin prevalence was checked during the last phase. Mortality was below standards and egg production was above breed standard guidelines. Mycotoxin contamination levels were checked periodically throughout the final phase. Low to medium levels of B-Trichothecenes, and medium to high levels of ZEN were found. Flocks in the final phase were fed diets containing Mycofix® BBSH at 1kg/ton for the whole cycle. According to the data, recorded hatchability was good and above standards. Egg production results are shown in Table 2.

Table 2: Egg production results

Eggs per henTotal eggs
Brown NickWhites
Phase 3 – all Mycofix® BBSH284.9283.42896000
Phase 2 – part Mycofix® BBSH282.0266.92763310
Phase 1 – no Mycofix® BBSH273.0260.02739940

Egg production increased by 9% for white layers and 4.3% for brown nick hens over the three-year period. This is extremely significant considering the same production conditions. This net improvement in productivity was due to the control of the mycotoxin risk, even at low to medium levels, which reduced the subclinical, negative effects of mycotoxins on the immune system and egg development and laying.

Figure 1. Egg production results
Figure 1: Egg production results

Figure 1 shows that even with the mycotoxin contamination during the third phase, the birds were still able to produce more eggs per hen than the previous two phases, despite a slight increase in mortality.

Hatchability also improved in the third phase compared to the first phase, as shown in Figure 2.

Figure 2. Hatchability results
Figure 2. Hatchability results

In the third phase of the trial, Mycofix® Plus BBSH was applied during the complete cycle, while in the second phase it was only applied during production and in the first phase, it was not applied at all. The rearing period is crucial for the development of the pullets’ immune system and reproductive organs. A stressful vaccination plan is applied while they are growing adding further developmental pressure and perhaps explaining why hens may loose productivity after peak when challenged with field viruses and other pathogens. Even when mycotoxin contamination is low, synergistic mycotoxin-pathogen effects can still take place, highlighting why a mycotoxin risk management plan is so crucial for the future success of flocks.

* Biomin® BBSH 797 is the trade name for a feed additive containing viable cells of an unnamed bacterium (DSM 11798). The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) produced an opinion on the safety and efficacy of this additive when used with pigs concluding that the additive itself did not raise any safety concern. It was confirmed that the additive could detoxify the trichothecene, deoxynivalenol (DON), producing a less toxic de-epoxy metabolite. Chickens and turkeys for fattening and laying hens showed no adverse effects when the additive was added to diets at 1000 times the recommended dose. Consequently, the additive is considered safe for these species/categories when used at the recommended dose of 1.7 x 108 colony-forming units (CFU)/kg complete feed. This conclusion is extended to all avian species. The use of the additive in feed for all avian species is not expected to introduce concerns for consumers, users or the environment not previously considered. (© 2017 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.) Another enzyme produced by an inactivated bioprotein detoxifies ZEN into a non-toxic metabolite called ZOM 1.