Studies on the Metabolizable Energy of Rapeseed Meal for Growing Chickens and Laying Hens

Abstract

STUDIES on the metabolizable energy content of rapeseed meal are limited. Sibbald and Slinger (1963), using chicks, reported a value of 1,670 kcal. of metabolizable energy per kilogram (dry matter basis) for one sample of solvent-processed rapeseed meal which analysed 43.1% protein (N×6.25). On the other hand, Sell (1966), using hens, obtained a value of 2,290 kcal. of metabolizable energy per kilogram for one sample of solvent-processed rapeseed meal which analysed 38.3% protein. It has been well established (Astwood et al., 1949b; and Carroll, 1949) that rapeseed contains a glucoside which on hydrolysis by the enzyme, myrosinase, yields a goitrogen, (–)-5-vinyl-2-oxazolidinethione. The effects of this goitrogen on the thyroid activity of chicks have been studied by Clandinin et al. (1966). It would appear that early effects of feeding this goitrogen to chicks include suppression of iodine uptake by the thyroid glands and reduced secretion of thyroxine from the glands.…