Effect of Tannic Acid on Egg Production and Egg Yolk Mottling

Abstract

THE incidence of egg yolk mottling has become somewhat of a problem in commercial flocks, and in most cases the cause can not be found. At the present time the recognized causes of this phenomenon are limited primarily to the presence in the diet of Nicarbazin, (Polin and Porter, 1956 and Baker et al., 1957), gossypol, (Heywang et al., 1955) and certain worming compounds, (Fry and Wilson, 1965). A brief report by McNally and Brant (1958) implicated tannic acid derivatives as possible causes of egg yolk mottling but details of their experimental work are lacking. The toxicity of dietary tannins and tannic acid per se for chicks was demonstrated by Chang and Fuller (1964), Vohra et al. (1966) and Fuller et al. (1967). During the course of studies at this laboratory, it was observed that tannic acid, added to the diet of laying hens at levels of two percent, caused . . .