Factors Affecting the Metabolizable Energy Value of Rapeseed Meal

LODHI et al. (1969a) showed that the ability of the chick to utilize the energy in rapeseed meal is limited. Factors known to contribute to its low metabolizable energy content when compared to soybean meal are its lower protein content, higher fiber content and the lower availability of its carbohydrate (Lodhi et al., 1969b). Other factors which may contribute to the low metabolizable energy content of rapeseed meal are the absorbability of its protein and the presence in rapeseed meal of thioglucosides, one of which on hydrolysis by the enzyme myrosinase yields goitrin ([—]-5-vinyl-2-oxazolidinethione), the others volatile isothiocyanates (Astwood et al., 1949a, b; Carroll, 1949). The effect of hypothyroidism on rate of absorption of specific nutrients and on the secretion of digestive enzymes has been studied. Althausen and Stockholm (1938) found that, in rats, injection of thyroxine increased the rate of absorption of glucose and galactose while thyroidectomy decreased…