Fatty liver syndrome is a condition that affects only hens, primarily caged layers. It is a metabolic or nutritional disease and is characterised by general obesity with an enlarged, fatty liver that becomes soft and easily damaged. Mortality rates vary and death is often caused by internal haemorrhage due to rupture of the liver.
The principal cause is thought to be excessive calorie intake, but it may also be related to exposure to the mycotoxin aflatoxin, calcium deficiency and/or stress. An incorrect protein:energy balance may also be to blame. Some strains of laying hen appear to be more susceptible. The higher producing hens appear the be the birds within a flock that are most affected. Fatty liver syndrome has been seen in conjunction with cage layer fatigue.
The principal causes of fatty liver syndrome are related to feed ingredient quality or inappropriate feed formulation. Unless caused by aflatoxin or calcium deficiency, the main treatment for this condition is to reduce the amount of dietary energy consumed. If aflatoxin is involved, the contaminated feed must be replaced. If a calcium deficiency is suspected, adding large particle calcium to the diet is recommended, as this allows the hen to select an increased calcium intake without over-consuming the energy component of the diet. Some farmers add choline chloride to feed as a treatment, however effects are variable. If a complete layer ration is being fed, addition of vitamins can be of benefit. However, control of body fat is the only successful remedy for this condition and is best accomplished by regulation and reduction of total energy intake.