Occurrence: Worldwide. Species affected: Chickens- commercial layers and broiler breeders. Age affected: laying hens (usually early in production).

Causes: Excessive consumption of high energy diets, where exercise is restricted in cages or overcrowded breeder houses. It may be compounded in hot weather.

Effects: Straining during oviposition, sudden drop in egg production, thin-shelled eggs, cage layer fatigue, weak, rubbery legs and depressed sternum and rib cages. Hens are overweight with large pale combs and wattles covered with dandruff.

Chickens (commercial layers and broiler breeders) can develop this chronic disease. In laying hens, FLHS usually occurs early in production. It is caused by excessive consumption of high-energy diets, where exercise is restricted in cages or overcrowded breeder houses. It may be compounded in hot weather.

There is an over consumption of feed, positive energy balance and excessive fat deposition. It usually occurs because of too low calcium in layer diet when birds are just coming into production. Birds in cages overeat to achieve increased calcium requirement. Elevated serum calcium and cholesterol in affected chickens may be due to a hormone imbalance. Diets high in rapeseed meal may aggravate the condition.

Signs include straining during oviposition, sudden drop in egg production, thin-shelled eggs, cage layer fatigue, weak, rubbery legs and depressed sternum and rib cages. Hens are overweight with large pale combs and wattles covered with dandruff.

Lesions include internal haemorrhage, and a fatty, friable, haemorrhagic liver. Haematomas (blood tumours) are dark red to brown within the parenchyma (specific cells within the organ).

Large amounts of fat in the abdominal cavity and around the viscera can be seen.

Postmortem lesions (enlarged, yellow, haemorrhagic liver) are characteristic. The fat content of livers exceeds 40% dry weight. Hepatocytes are distended with fat vacuoles, varying sized haemorrhages and organising haematomas.

It simulates aflatoxicosis.

Lower calorie intake, increase calcium during the onset of lay. And avoid animal fat in the diet increase choline and methionine levels in feed.

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