Fatty Liver Syndrome in Laying Hens—An Attempt to Review

Abstract

SummaryFatty Liver Syndrome (FLS), also described as Fatty Liver Haemorrhagic Syndrome (FLHS), is a metabolic disorder in laying hens, characterised by an excessive accumulation of fat, with an aberrant fatty-acid composition in the liver. The liver structure is affected and numerous capillary bleedings (haemorrhages), varying in size, may be observed in the liver tissue. Mortality generally remains on a low level and is caused by a fatal internal bleeding due to a rupture of the liver capsule in hens still producing. Egg production may fall with 30 per cent with a few weeks.The accumulation of fat in the liver is probably a consequence of a too intensive “de novo” synthesis of fat from carbohydrates. Factors, frequently mentioned as the causes of FLS, are either energetic overconsumption, or breeding on a high egg production level. The surplus of energy available, resulting from overconsumption and possibly inducing an intensified “de novo” synthesis of fat, may be reinforced by the restricted movement of hens in batteries and by high temperatures.A common method to control FLS is raising the concentration of lipotropic compounds (choline, inositol, vit. B12, vit. E) in the diet. A number of successful treatments with this method, especially in the field, have been reported. The recovery was not always complete however, fall backs have been reported and also negative results, especially in experiments under controlled circumstances. This must therefore not be regarded as a reliable and adequate control measure.Reduction of the energy intake, either by feed restriction, or by lowering the ME-content of the diet, seems a more reliable method to reduce the liver fat content. In several experiments this method was a success. A similar effect may be obtained by offering the hens more opportunity to move.A number of trials have indicated, that an increase of the fat content in the diet may favourably effect the liver fat content, especially if fats, rich in linoleic acid, are used. As the physiological background of this phenomenon is not known yet and this method has not been tested on FLS in the field, more research on this point is required.