Egg cholesterol content is correlated with serum low density lipoprotein

Chen, X. Liu, Y. Du, and Z. Geng, Anhui Agricultural University, Hefei, China.

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Cholesterol content in egg yolk could influence embryo development. To screen proper index for cholesterol selection, at 42 wks of age, 331 female Wenchang chickens, a Chinese indigenous breed with complete pedigree records, within 24 sire families were selected as experimental group. Eggs were collected within 4 continuous days from each female bird for egg quality and yolk cholesterol content measurement. Blood was collected from brachial vein of male and female birds for serum lipid content determination. Cholesterol content was compared among female individuals and sire families by using SAS one-way ANOVA. Cholesterol content was further analyzed for its normal distribution by using univariate analysis and data from 2 tails of cholesterol content was analyzed by independent t-test. Partial correlation was conducted between cholesterol content and egg quality, serum lipid content by using Proc GLM. Statements of significance were based on P < 0.05. The egg weight was 45.16 g, shape was 0.80, shell strength was 2.97 kg/cm2, shell thickness was 0.330 mm, yolk weight was 15.32 g, egg-white height was 3.26 mm, Haugh unit was 57.52 and cholesterol content was 45.25 mmol/L. No significant difference was observed in egg quality within the same individual bird. However, egg weight, egg shape, eggshell strength, eggshell thickness, yolk weight, egg-white height and yolk color were all distributed in a great range and significantly differed among female chickens. In sire families, egg weight was 44.81g, shape was 0.82, shell strength was 3.07 kg/cm2, shell thickness was 0.337 mm, yolk weight was 15.52 g, egg-white height was 3.36 mm, Haugh unit was 58.86 and cholesterol content was 45.16 mmol/L. Egg weight, eggshell strength, eggshell thickness, yolk weight, egg-white height and cholesterol content were differed significantly among sire families. Among females, high or low content of cholesterol did not affect egg quality. However, higher cholesterol content in sire families was associated with lower yolk weight (P < 0.001), eggshell thickness (P< 0.001) and higher egg-white height (P<0.001). Serum total cholesterol and HDL exhibited no difference among females and males. Increase or decrease of yolk cholesterol did not significantly affect serum lipid content in females, however, greater yolk cholesterol associated with higher serum glucose (P = 0.001), and lower LDL level (P = 0.002). The heritability of cholesterol might be low in female individuals but higher in sire families. Therefore, egg cholesterol content could be directly selected first by sire families. Serum LDL might be used as a potential index for cholesterol selection.