Effect of dietary tung oil on the growth and lipid metabolism of laying hens

The influence of dietary tung oil, containing a high level of alpha-eleostearic acid (cis-9, trans-1 1. trans-1 3-octadecatrienoic acid. EA) on growth, egg production, and lipid and fatty acid compositions in tissues and egg yolks of laying hens was studied in White Leghorn hens. Forty-week-old hens were divided into three groups of eight birds each and fed diets containing 0, 0.5, or 1.0% tung oil for 6 wk. The average body weight, feed consumption. rate of egg production. and weights of eggs and yolks were not affected. The weight of adipose tissue was remarkably small in hens fed tung oil, whereas the yolk lipid content did not change. Triglyceride level in heart and adipose tissue decreased in hens fed tung oil, and the level of linolenic acid (C-18:3) in all tissues was decreased. alpha-EA was not almost deposited in the tissues and egg yolk of hens fed tung oil. but conjugated linoleic acid (CLA) was detected in all tissues and egg yolks. The level of CLA in the tissues was significantly higher with increased dietary tung oil. The order of CLA level in tissue lipids was adipose tissue> liver> heart>breast muscle. Especially, the level of CLA in the lipids of adipose tissue and egg yolks of hens fed 1.0%, tung oil was 2.0%) of the total fatty acid. These results supposed that dietary tung oil affected the lipid metabolism of laying hens and could modify the lipid and fatty acid composition in tissues and eggs.