GENETIC-VARIATION OF EGG-YOLK CHOLESTEROL CONTENT

In the article a survey of papers of forty three various authors together with our own results concerning the genetic and partly also environmental influence on variation of yolk cholesterol content in poultry is presented. There are given also results of experimental breeding for lower yolk cholesterol content which where successfully only in few experiments. The coefficient of heritability h(2) estimated by various authors and methods varied between 0.11 to 0.28. Between egg production and yolk cholesterol content there was generally estimated a negative correlation. Correlations between yolk cholesterol content and egg weight and also weight off egg components were very weak and inconsistent. Results of some authors suggested a possibility to utilize the heterosis in breeding for lower yolk cholesterol content. The decrease of yolk cholesterol content by selection was in most experiments linked with decrease of hatchability but we found also the opposite situation in our experiments. Considerable variation of yolk cholesterol content found by various authors is caused also by different laboratory methods used. Concerning the laboratory method of yolk cholesterol estimation in selection studies we recommend the enzymatic colorimetric methods because it is very quickly and relative cheap.