The occurrence of liver haemorrhages was compared when diets containing 30 or 40 per cent rapeseed meal (RSM) or 30 per cent soybean meal (SBM), with and without experimental additives, were fed to in-lay hens of a commercial egg-producing strain for 12 weeks. The incidence of haemorrhages was significantly greater when the birds were maintained on the basal (unsupplemented) RSM diet than on the equivalent SBM diet. Haemorrhages were either small and infrequent, minute and multiple as in
peliosis hepatis, or large enough to
rupture the liver
capsule. They might be recent or old and encapsulated, sometimes both varieties affecting the same specimen, and they occurred in any part of the liver. Histologically, hepatocyte
necrosis and
reticulin derangement were not detected in livers without gross haemorrhages and even in those with haemorrhages these abnormalities were only seen closely adjacent to haemorrhages or to foci of eosinophilic fibrinoid. In some instances there was sinusoidal
ectasia. Separate additions of 50 g dried skimmed milk
powder, 0.5 g
zinc oxide, 0.25 g
ferrous sulphate or 2.0 mg
selenium (as
sodium selenite) kg-1 to the basal RSM diet did not significantly modify the incidence of haemorrhage.
Ferrous sulphate slightly reduced goitrogenicity. Supplements of 2.2 mg
menadione and 1.0 g
sodium phenobarbital kg-1 RSM diet induced slight reductions in the number of cases of liver haemorrhage or their severity, indicating that the multifunction
oxidase system may be involved in rapeseed hepatotoxicity. The addition of 0.5 g
methimazole kg-1 to the basal SBM diet induced severe
colloid goitre but did not induce liver haemorrhage. Both
thiouracil (0.5 g kg-1 diet) and
beta-aminopropionitrile (0.5 g and 2.5 g kg-1 diet) when added to the basal SBM diet induced liver haemorrhages which did not differ in incidence or histological appearance from those induced by RSM. Hyperplastic goitre was caused by
thiouracil.
Intrahepatic cholestasis induced by
sodium taurolithocholate,
bilirubin and
alpha-naphthylisothiocyanate and
extrahepatic cholestasis induced by bile duct
ligation resulted in hepatocyte
necrosis but not gross liver haemorrhages. Spontaneous deaths due to conditions other than liver haemorrhages were significantly more numerous in RSM-fed than SBM-fed hens.(ABSTRACT TRUNCATED AT 400 WORDS)