The Effect of a Residue from the Decolourisation of Pyrethrum Extract on Yolk Colour

Abstract

EXTRACTION of dried pyrethrum flowerheads with light petroleum solvent yields a dark viscous oleoresin which contains approximately 30% of the insecticidal constituents, “pyrethrins.” The production of decolourised and dewaxed concentrate from this crude extract results in the separation of a very dark residue which is rich in carotenoids. The problem of pale egg yolks associated with modern intensive poultry keeping methods is well known and many natural and synthetic carotenoids have been investigated for their suitability as additives to poultry feeds for increasing egg yolk pigmentation. Pyrethrum residue (henceforth termed “residue”) is produced in substantial quantities and the experiment reported here shows the effect on egg pigmentation of adding it at different concentrations to the diet of laying hens. The effect of the residue on the growth rate of young hens is also described.Pyrethrum residue is a very viscous liquid having a carotenoid content of between 1 and 1½% …