How mycotoxins influence your layer pullets’ egg production potential

The global layer industry is expected to produce over 94 million tons of eggs in 2024, a 1.3% increase from last year (OECD-FAO Agricultural Outlook 2023-2032). Eggs will continue to be in high demand for human consumption as they possess the optimal balance of protein, energy, and vitamins. The genetic potential of current layer breeds could produce over 400 eggs in 100 weeks per year, but subclinical challenges from mycotoxins is one aspect preventing birds from achieving their potential.

To prevent the effects of mycotoxins, they must be adsorbed or deactivated. Clays and other materials with adsorption capacity are only effective for adsorbable mycotoxins like AFLA. Mycotoxins such as FUM, DON, ZEN, OTA and T2 are poorly adsorbed and require different strategies for mitigation such as enzymatic degradation. The main feed ingredients in a layer diet —corn, wheat, soy, and by-products— are often contaminated by various mycotoxins. Common mycotoxins affecting poultry include: aflatoxins (AFLA), zearalenone (ZEN), trichothecenes (DON, T2), fumonisins (FUM) and ochratoxin A (OTA). Even at low levels, mycotoxins predispose birds to nutritional and health challenges.

The effects mycotoxins have on layers include:

• poor feed conversion and body weight gain
• immunosuppression
• fatty liver syndrome
• damage to reproductive organs
• skeletal issues
• visible lesions

These effects have a direct impact on the flock’s disease responses, uniformity, and bone health. The quality and quantity of eggs produced can also decrease. The rearing period (0 to ~ 18 weeks) is the time which mycotoxin risk management provides the greatest insurance to health and performance programs since chicks are more susceptible than laying hens to the subclinical and clinical challenges from mycotoxins (Qing et al., 2022).

Rearing period is crucial

The focus of the rearing period is to invest in good health and nutrition of the pullet with the expectation that this allows her to meet or exceed the high production expectations as a layer (Hy-line® Technical Update, 2016). This means setting birds up with good muscular-skeletal growth, gut development, and immunity. The return on investment (ROI) during rearing is high, as the volume of feed needed is low, but the benefits of the birds reaching their genetic potential are great. Effective mycotoxin risk management at this time offers a high ROI as the feed investment is relatively short but the long-term benefits of reducing the risk and impact of (sub)clinical challenges from mycotoxins can be seen throughout production.

Three important components of good pullet development which mycotoxins can affect are:

• Uniform body weight gain
• Skeletal development
• Stress management (transfer, vaccines, disease)

Uniform body weight gain

Pullets may not reach expected body weight if there is inadequate nutrition due to formulation errors, overcrowding, improper feed particle size, or feed refusal due to poor quality or mycotoxins (Hy-line® Technical Update, 2016). Mycotoxins cause reduced body weight due to the damage in the bird’s intestinal tract and liver (Tomaszewska et al., 2021, Carvalho Martins et al., 2023). Low levels of FUM disrupt the intestinal barrier and damage the liver, altering nutrient absorption and predisposing the pullets to gastrointestinal challenges later in production (Tomaszewska et al., 2021). The combined toxicity of OTA and AFLA reduces body weight and average daily gain, increases feed conversion, while also causing inflammation in the liver (Qing et al., 2022). Pullets with lower body weights have a reproductive tract with fewer and smaller egg follicles in development, influencing how they will come into lay and the egg size they will produce (Celliers, 2020).

Skeletal development

Skeletal bone in the pullet is 95% formed by 3 months of age while the medullary bone is developed from 3-4 months of age- both of which have direct impact on the egg production and persistency (Celliers, 2020). Low levels of FUM cause negative structural changes and development of pullet bone and bone tissue, increasing the risk of bone fractures during lay (Tomaszewska et al., 2021). This can also affect eggshell quality, as the bone acts as a reservation for the key nutrients needed to make the eggshell. Maintaining calcium absorption will support the pullets for better performance during lay (Grignon Dumoulin, 2016) and can impact eggshell quality, particularly during late lay (one of the main factors in being able to extend the laying cycle to 100 weeks).

Stress management

Pullets are regularly handled during the rearing period to check flock body weights, uniformity, administer vaccinations, and collect blood for health monitoring (Grignon Dumoulin, 2020). The regular body weight and uniformity checks ensures the producers that nutrients are being properly utilized and offer the additional benefit for a physical check on the bird to examine bone and muscle development, feathering, and if oral lesions are present. Inability to overcome environmental and microbial stressors can be caused by mycotoxins like AFLA, FUM, OTA, DON and T2 because of their impact on immunomodulation (Bhuiyan et al., 2021, Hou et al., 2022, Qing et al., 2022, Carvalho Martins et al, 2023). The birds are then less responsive to vaccines and more susceptible to disease. It has been shown that vaccine efficacy is reduced in pullet flocks when mycotoxins are found in their feed (Hou et al., 2022; Carvalho Martins et al, 2023).

Protecting your birds

Mycotoxin prevention starts with analyzing your feed. This can indicate which mycotoxins could be affecting your birds and give guidance to the producers on which mitigation strategy would be the best investment. If at the farm, you are seeing oral lesions or impaired feathering, which can be checked for during weight checks (Wyatt et al., 1975). If expected body weights or vaccine titers are not met or there is increased incidence of failure to thrive, mycotoxins should be considered.

Preventing challenges during lay like thin eggshells, cracked eggs, and bone fractures can start with incorporating mycotoxin risk management as an integral part of the health and nutrition plan for your pullets.

To protect birds from the negative effects of mycotoxins, they must be adsorbed or deactivated. Clays and other materials with adsorption capacity are only effective for adsorbable mycotoxins like AFLA. Mycotoxins such as FUM, DON, ZEN, OTA and T2 are poorly adsorbed and require different strategies for mitigation such as enzymatic degradation. The addition of a mycotoxin deactivator has been shown to support body weight gain and vaccine efficacy (Danicke et al., 2002).

Mycotoxin risk management will help protect your pullet nutrition and health investment, support your pullets going into lay and safeguard your return on investment.