Effects of rapeseed meal on laying hens (Gallus domesticus) in relation to fatty liver-haemorrhagic syndrome and egg taint.

Fatty liver-haemorrhagic syndrome (FLHS) occurred in the controls and was modified in hens that received a diet containing 10 per cent rapeseed meal. This diet increased the extent and severity of the hepatic haemorrhage without affecting the reticulin content of the liver but decreased the body weight and liver lipid levels and so weakened the correlation between these parameters and haemorrhage score found in FLHS. Plasma aspartate transaminase and beta-glucuronidase activities tended to increase with the score. The rapeseed meal diet also produced thyroid hypertrophy and since this was greater in the hens that produced tainted eggs and was positively correlated with the trimethylamine (TMA) content of the eggs it was postulated that rapeseed meal goitrogens may be involved as secondary factors in producing the disturbance in TMA metabolism that causes the egg taint. This abnormality was associated with a reduction in the soluble protein content of the liver, which reflected a decrease in TMA oxidase activity, but was not related to hepatic haemorrhage, steatosis or reticulolysis, or to lipid levels and the activities of lysosomal enzymes and transaminases in the plasma.