The effects of rapeseed meals from brassica napus varieties and the variety tower on the production and health of laying fowl

1. A diet containing rapeseed meal (200 g/kg) prepared from Brassica napus varieties grown in Britain fed to laying hens consistently depressed egg production when compared with a similar diet containing soyabean meal. Deaths from liver haemorrhage, greatly enlarged thyroid glands and a “ fishy “ taint in eggs from brown hybrids were also associated with the diet containing this rapeseed meal.

2. A similar diet containing rapeseed meal (200 g/kg) prepared from the new Canadian variety Tower did not depress egg production when compared with the soyabean meal diet. Compared with the diet containing the British meal, that containing Tower meal caused fewer deaths from liver haemorrhage and it caused enlarged thyroid glands, but to a much smaller degree. However, it did cause the production of as many tainted eggs as did the diet containing the British meal.