The effect of feeding di-(2-ethylhexyl) phthalate and related compounds on lipids in the laying hen.

Di-(2-ethylhexyl) phthalate (DEHP) and three structurally related side-chain analogs were fed to laying hens to determine relationships of structure to effects on lipid metabolism. Hubbard broiler breeder hens were fed either a standard laying mash control diet or the control diet containing DEHP, 2-ethylhexanol (2-EH), 2-ethylhexanal (2-EHALD), or 2-ethylhexanoic acid (2-EHA). Experimental treatments lowered feed consumption, body weight, and egg production. The DEHP and side-chain analog diets lowered plasma total lipids. DEHP, 2% 2-EH, and 1% 2-EHA diets lowered plasma free cholesterol. Liver weights were not significantly changed, but liver fat was reduced. Lipid classes were measured by quantitative thin layer chromatography densitometry. The decreases observed in plasma lipids occurred primarily in the triglyceride fraction. Liver lipid decreases occurred mainly in triglyceride and free fatty acid classes. Hen egg yolk percent fat, lipid classes, and free and total cholesterol were unaffected by any DEHP or side-chain analog diets. Plasma and liver hypolipidemic effects were observed with all of the oxidation state structural analogs of DEHP's side chain, but 2% 2-EH was the most effective treatment. These results suggest that the active portion of DEHP may be the metabolite, 2-EH, formed in vivo by hydrolysis of DEHP's ester bond.