Elevation of serum cholesterol and increased fatty streaking in egg yolk: Lard fed castrated miniature pigs

Abstract

The effects of feeding an experimental diet containing 16.25% (w/w) dry powdered egg yolk and 30.8% total fat (20% from lard) were compared with an isocaloric amount of control (stock) diet in castrated (N = 11 each) and sham-operated (N = 8 each) male miniature pigs of Hormel origin. Piglets were castrated at 2 weeks of age. The experimental diet was fed from 9 weeks of age and serum lipids (cholesterol and triglycerides) and plasma testosterone were determined at 5-week intervals up to 52 weeks of age. At 52 weeks of age, the animals were sacrificed and the aortas evaluated for fatty streaking after Sudan IV staining. Castration was accompanied by significantly ( P <= 0.02) elevated serum cholesterol (castrated 84 ± 4 mgm/dl vs. sham, 67 ± 5 mgm/dl; mean ± SEM) within 5 weeks after feeding the stock diet and throughout the duration of the expriment. Except for the initial cholesterol concentration (castrated, 118 mgm/dl vs. sham, 88 mgm/dl), both castrated and sham-operated animals on egg yolk had significantly higher ( P <= 0.05) serum cholesterol than their littermate controls. At 52 weeks of age, the serum cholesterol of sham-operated and castrated animals on experimental diet were 152 ± 29 and 292 ± 41 mgm/dl as compared with 68 ± 5 and 96 ± 4 mgm/dl for their littermates on stock diet respectively. No correlation was found between the concentrations of plasma testosterone and serum cholesterol. Consistent with the elevation of serum cholesterol, the castrated animals on egg yolk diet had significantly greater area of the aorta covered with fatty streaking than did the sham-operated group. These data show that castration and feeding of egg yolk: lard diet resulted in hypercholesterolemia and increased fatty streaking.