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Mycotoxin management in laying hens

 

Laying hens are very sensitive to mycotoxins in feed. The length of the rearing period (70 weeks or more) and the increasing use of food industry products and byproducts containing high levels of mycotoxins expose them to chronic mycotoxins that can have serious health and economic impacts.

More than 500 mycotoxins have been characterized in the last 50 years, the most dangerous for laying hens are aflatoxins, ochratoxins, vomitoxin (DON), T-2 toxin, zearalenone, and fumonisia, this danger is further increased by the ability of these mycotoxins to act synergistically producing additive toxicity and further complicating diagnosis.

Several research centres are working on the determination of critical thresholds of mycotoxins in food for different animal species. This is a difficult task since the levels determined assume an individual action of each mycotoxin, which is rarely the case. Added to this is the presence of masked mycotoxins that are not detectable by routine analysis and whose effect is again accentuated on the feed ingested.

The table below shows the risk levels of some mycotoxins according to their concentration in the feed for laying hens.

 

 

Concentration ppm (ug / kg of feed)

Mycotoxins

Low risk

Moderate risk

High risk

Aflatoxins

20

40

80

Ochratoxins

25

50

75

Trichothecenes B

500

1000

1500

Trichothecenes A

30

65

100

Fusaric acid

1000

2000

3000

Group of zeralenones

250

500

750

Fumonisins

5000

7500

10,000

Alkaloids pin

750

1500

3000

 

Mycotoxins negatively affect the performance of laying hens through a decrease in egg production and egg mass, weakening of the eggshell, weakening of the eggshells, and a decrease in immunity.

The effects on egg production and weight can be explained by the negative impact of mycotoxins on feed consumption, liver function and the integrity of the hen's gastrointestinal tract.

The effects on the immune system, through the decrease in antibodies and the destabilisation of cell integrity, makes birds more vulnerable to infectious diseases. Causing higher morbidity and mortality, the explanation for which may remain unknown and enigmatic by the breeder.

The negative effects of mycotoxins on bones are mainly due to their action on vitamin D . Some mycotoxins can also affect the functioning of skeletal muscle leading to weakness of limbs.

Mortality is therefore increased due to hunger (the hen can no longer move around and stand up to eat), dehydration and trampling. Hens are reared early for reasons of low productivity.

Concerning the quality of the egg, the integrity of the shell is frequently affected by mycotoxins. As a result, nutrient losses are observed. The risk of bacterial contamination is increased and the shelf life of eggs is reduced. Mycotoxins can also affect the shape, texture and cleanliness of eggs.

The main effects on shell quality of some mycotoxins and their mode of action can be summarised in the table below.

 

Mycotoxin

Mode of action

Aflatoxins / Cyclopiazonic Acid

Reduces the availability of minerals (Ca, P and Zn), vitamins (A and D) and the functions of the parathyroid hormone.

T-2 toxin, DAS, DON

Reduces the surface density of the shell. Damage the kidneys, and reduce the Ca-fixing proteins.

Zearalenone

The imitating effect of estrogen disrupts the localization of the carbonic anhydrase enzyme in the shell.

Ochratoxins

Reduces kidney damage

Citrinine and Patulin

Reduction of Ca content in the eggshell, change in shape of the egg.

Fumonisins

Reduces the weight of the shell.

 

Regarding the economic impact of mycotoxins in a laying hen farm, a recent study conducted by ALLtech in partnership with the University of Guelph, Canada, showed that dietary mycotoxins induced a 6% decrease in egg production. In a farm with a capacity of 100,000 laying hens, losses per day were estimated at 6,000 dhs. The management of mycotoxins in feed for laying hens relies heavily on prevention. The use of HACCP principles to control mycotoxins is strongly recommended in feed factories and on-farm manufacturers. Factors such as grain moisture and water activity, temperature and relative humidity of the environment must be controlled.

Ventilation of storage bins and frequent cleaning of plant equipment are also practices that should be adopted to minimize mycotoxin production.

In conclusion, laying hens are sensitive to mycotoxins because of their long exposure period. The non-specific symptoms and the subtle nature of the mycotoxin challenge justify implementing mycotoxin prevention steps throughout the production chain, rather than waiting for the devastation to occur.