The Nature of Egg Yolk Discoloration Produced by Cottonseed Meal

Effect of Increased Protein Level in the Hen Diet on the Transfer of Gossypol-Cephalin to the Egg

“…This was confirmed by Lorenz (1939) and by Swenson, Fieger and Upp (1942). The latter workers speculated as to the nature of the olive green to choclate-colored compounds produced in the yolks of these eggs on storage, but the nature of these pigments is still unsettled.…”

Gossypol, a Pigment of Cottonseed.

“…The extraction (25) and isolation of gossypol from the seed kernels of the cotton plant were accomplished by Withers and Carruth (226) in 1915; since that time their basic procedure has generally been used. Refinements in the method have been described by Withers and Carruth (225), Carruth (45), Clark (49), and Campbell, Morris, and Adams (43), the last workers having been aided by suggestions made by Halverson (103). The procedure consists in extracting ground cottonseed kernels with low-boiling petroleum ether to remove the bulk of the oil, followed by extracting with diethyl ether (peroxide-free) to remove the gossypol along with the residual oil.…”

Tolerance Levels of Free Gossypol in Layer Diets as Influenced by Iron: Gossypol Ratios

“…Schaible et al (1934) indicated that one to two percent ferrous sulfate protected against egg discoloration in rations containing as high as 40 percent cottonseed meal. Swensen et al (1942) concluded that the addition of 0.5 percent ferric salts to diets containing 30 percent cottonseed meal prevented the absorption of gossypol by hens and the formation of olive yolks in the stored eggs. Card (1952) stated that 0.5 percent ferric chloride or ferrous sulfate mixed with cottonseed meal would prevent the absorption of gossypol but without this precaution no more than 5 percent cottonseed meal could be fed to laying hens if yolk discoloration was to be avoided.…”