Most laying hens, due to the high volume of egg production and the resulting metabolic pressures, are affected by fatty liver metabolic disease to varying degrees. By learning treatment or prevention strategies for this syndrome, the negative effects on reduced egg production, poor shell quality, and mortality in breeding farms can be prevented.
What is fatty liver:
The nutritional needs of laying hens vary at each stage of life. Therefore, poultry are managed based on their growth stage, feed intake, and weight gain. The mechanism of fat synthesis and metabolism is influenced by external factors such as diet, environment, etc., as well as internal and inherent mechanisms of the bird’s body.
During the peak production period, the laying hen’s diet is high in energy. Consequently, the bird stores excess body fat in the abdominal cavity, under the skin, around the intestines, around the heart, ovaries, oviduct, and most importantly, in the liver. With increased fat accumulation in the liver, this fat deposition leads to softening of the liver and causes significant damage to laying hens.
Major reasons:
– Improper feeding with high energy
(Excessive energy consumption in rations and lack of ration balance cause excess energy to be available for fat synthesis by the liver over a long period, followed by obesity and increased fat infiltration in the liver.)
– Increased estrogen or hormonal factors
(Estrogen is secreted more during puberty and stimulates the liver to store more fat for egg yolk synthesis. When the bird begins egg production, the liver size increases in response to increased estrogen levels.)
– Heat stress
(The highest incidence of the disease occurs in the warm seasons of the year. High ambient temperature reduces energy requirements. Birds cool their bodies by breathing. Also, increased abdominal fat due to excess energy consumption can interfere with normal breathing and cooling of the bird.)
– Mycotoxins or fungal toxins
(The use of rapeseed meal in the diet increases the prevalence of fatty liver.)
Symptoms of fatty liver in laying hens:
Affected flocks usually chronically lose their appetite, become lethargic, and in acute cases, the bird’s skin is yellow and easily identifiable.
Clinical signs:
– Decreased performance and egg production
– Weakened eggshell
(One of the important functions of the liver is to activate vitamin D. Due to the increase in serum calcium levels in affected hens (which indicates interference in the formation of 1,25-dihydroxycholecalciferol), this process is disrupted, leading to shell damage.)
-Shortening of peak production or failure to reach peak production
– Increased water consumption in the coop
– Diarrhea (watery stool)
– Reduced feed efficiency
– Swelling of the face and abdomen
– Paleness in the bird’s skin area
– Decrease in egg production
– Gradual increase in mortality in the flock
– Obesity beyond the usual level
– Yellow crown and beard
– Sudden death of the bird
Mortality in normal laying hen farms is not more than 6%, but in cases of fatty liver involvement, the mortality rate in the shed exceeds 20%.
Histopathology:
Microscopic examination reveals that the liver cells are swollen due to the presence of fat, and there is a high probability of bleeding in the liver tissue. Stored fats are also present as vacuoles in the cytoplasm of liver cells. In fact, the accumulation of fat in the liver weakens the integrity of blood vessels and leads to bleeding in this tissue.
Necropsy Signs
In the necropsy of affected birds, we observe weight gain, pinpoint hemorrhages, and the deposition of large amounts of fat in the liver, abdominal cavity, under the skin, intestines, muscles around the heart, and stomach. Fatty deposits in the liver also cause blockage of capillaries, paleness, and liver failure. With increased fat deposits in the oviducts, hens experience significant pressure during production, leading to rupture and internal bleeding of the liver.
Prevention Strategies for Fatty Liver in Laying Hens
– Energy level appropriate for the stage of production
– Replacing carbohydrates in the diet with supplemental fats, as these fats prevent the formation of fatty acids.
– Keeping poultry away from any kind of stress, especially heat stress.
Calcium deficiency in laying hens is often associated with fatty liver, which can be prevented by adding calcium and vitamin D.
– Use reliable toxin binders to control mycotoxins and protect the liver.
– Use fat-burning nutrients:
These substances are feed compounds that improve fat metabolism and facilitate the transfer of fats from the liver. Methionine, choline, vitamin B12, carnitine, etc. are essential for proper liver function and fat metabolism.
– Use enzymes in poultry feed:
Because they provide more energy from a certain amount of diet, they prevent excessive pressure on the liver.
Last word
Management, strengthening daily production and creating a suitable environment are the most important preventive measures to prevent fatty liver in laying hens. In general, providing a standard system and ensuring a clean, hygienic environment, proper temperature and humidity, regular disinfection, maintaining good ventilation and avoiding the accumulation of toxic gases in poultry houses are the most important preventive measures for fatty liver.
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Treatment of fatty liver in laying hens
Laying hens have different nutritional needs at each stage of life. Therefore, the amount of feed consumed is controlled according to their growth. Also, prevent the weight gain of hens or the energy level of the diet, and when the flock is affected by fatty liver, the negative effects of fatty liver can be minimized by nutritional and management methods.
Nutritional method of treating fatty liver in laying hens
The most important nutritional method to reduce the complications of fatty liver is a balanced protein-to-energy ratio. In fact, feed with less energy and more than 6% fiber is consumed.
Food rations should be formulated based on the species and production rate of the bird. So that it can control the energy-to-production ratio within a reasonable range. The ratio of energy to protein in the laying hen’s diet varies according to the ambient temperature and the percentage of laying. Reducing the amount of energy in the diet less than the bird’s needs also causes fatty liver due to increased stress on the liver. Because it is much easier to supply the required energy from fat to form the yolk than from carbohydrates.
Management solutions for treating fatty liver in laying hens
In addition to nutritional methods, with proper management, the negative effects of fatty liver can be minimized in the flock. Improving the quality and balance of the diet, adjusting and checking the size of the mill screen, the size of the feed particles, providing adequate space, adjusting the ambient temperature and reducing stress in the flock by reducing the additional activities of workers, the noise of the equipment can minimize the vibrations in the hall and reduce the stress transferred to the chicken.
Suitable additives for the treatment of fatty liver in laying hens
Usually, the prevalence of fatty liver in laying hen flocks is high in summer. The use of suitable additives such as minerals (selenium, etc.), amino acids (choline, methionine, betaine), fatty acids, etc. helps to improve liver function.
Digestive system improving additives such as probiotics, prebiotics, enzymes, etc. can prevent liver damage by reducing the effects of inflammation, strengthening antioxidant effects, improving digestion and absorption of nutrients, preventing the presence of toxins and strengthening defense barriers.
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https://www.thepoultrysite.com/articles/fatty-liver-haemorrhagic-syndrome
