Comparative yolk cholesterol content in four Spanish breeds of hens, an F2 cross, and a White Leghorn population.

Yolk cholesterol content (milligrams per gram of yolk and milligrams per egg) was studied in eggs of four Spanish breeds of hens (Castellana, Buff Prat, Vasca, and Villafranquina), an F2 from a cross between Castellana and Buff Prat (C x BP-F2), and a White Leghorn population. Birds were tested at 30 wk of age. There were differences among breeds (P < .001), cholesterol concentration being significantly lower in the C x BP-F2 (13.14 +/- .26 mg/g yolk) than in the other breeds. Villafranquina and Buff Prat showed significantly lower cholesterol (14.54 +/- .26 and 14.56 +/- .26 mg/g yolk, respectively) than the White Leghorn (16.30 +/- .26 mg/g yolk). Eggs from the Vasca breed contained significantly more cholesterol (19.09 +/- .26 mg/g yolk) than did eggs laid by the other breeds, whereas no differences were found between Leghorn and Castellana. A negative heterosis percentage of -13% was found in the C x BP-F2 when compared with the parental breed means. The reduction in cholesterol concentration per egg observed in the C x BP-F2 (220.49 mg per egg) was not related to breed differences in egg weight or to the proportion of yolk per egg. Eggs from the Vasca breed, with the lightest yolk and smallest yolk: albumen ratio (P < .05), contained the highest amount of cholesterol (304.29 mg per egg). Eggs from the White Leghorn containing the second highest amount of cholesterol (275.63 mg per egg). Thus, the variation in cholesterol content per egg was not attributable to differences in the proportion of yolk.