Toxicity of rapeseed meal and its use as a protein supplement in the diet of two hybrid strains of caged laying hens

Abstract An experiment is described in which extracted Algerian rapeseed meal was included at levels of 4, 8, 12, 16 and 20% in the diet of two hybrid strains of caged laying hens. The rapeseed meal was thyrotoxic and this effect, when assessed by thyroid weight per kg of body weight, was more marked for the light‐weight hybrid than for the medium‐weight hybrid birds. The light‐weight hybrids exhibited a high mortality when fed rapeseed meal at a level of 8 % or above in the diet but inclusion of rapeseed meal did not cause increased mortality in the medium‐weight hybrids. The medium‐weight hybrids gave satisfactory egg production when fed up to 16% of dietary rapeseed meal; food conversion efficiency was best with 8% of dietary rapeseed meal, and metabolisable energy conversion (Meal/kg eggs) and the efficiency of utilisation of protein were, satisfactory at all levels of rapeseed meal inclusion. The rapeseed meal used had a standard metabolisable energy content of 1820 kcal/kg at a dry matter content of 89 %.