The effects of rapeseed meal fed during the growing and/or laying periods on mortality and egg production in chickens.
White Leghorn pullets of two strains were fed soybean or rapeseed meal during either or both the growing period and laying period in two separate experiments. Rapeseed meal may be fed to growing pullets at levels up to 17% of the diet without adversely affecting the subsequent rate of egg production or egg size. Birds fed laying diets containing 19% of rapeseed meal produced a greater egg mass per hen-day and gained more weight during the laying period when the growing diet contained rapeseed meal instead of soybean meal. Birds shifted at sexual maturity from soybean to rapeseed meal as dietary protein supplement undergo metabolic adjustment which retards the attainment of maximum rate of production and induces cannibalism. Both rate of production and egg size were lower when rapeseed meal constituted 19% of the laying diet in replacement of soybean meal as protein supplement. Mortality, exclusive of that resulting from cannibalism, was 4.1% and 4.6% respectively in the two experiments. Death from liver haemorrhage occurred only in birds of one strain which were fed rapeseed meal during the laying period and principally in birds which had been fed rapeseed meal during the growing period as well.