Lipids and Proteins in Eggs and Blood Serum from two Strains of Hens

Abstract

In 2 White Leghorn strains, blood and eggs from 52 wk old hens were investigated. The 1 strain was selected for a high number of eggs (strains EN), and the other strain was selected for a high egg wt (strain EW). The egg yolk and albumin were examined for protein content. The total lipid and phospholipid, as well as the cholesterol content of the yolk were determined. In the blood, Hb and hematocrit were determined. In blood serum the content of protein and protein fractions as well as content of total lipid and phospholipid, cholesterol and triglyceride were also determined. Correlations were calculated between data from the analysis of blood/blood serum and eggs, and the production traits: rate of lay, egg wt, bbody wt, age at 1st egg. The specialized selection during 2 generations resulted in the strains differing in the following important parameters. In blood from hens of the EW-strain the levels of hematocrit and Hb were significantly higher than in blood from hens of the EN-strain. In blood serum, hens from the 2 strains did not differ regarding the components investigated, but for .beta.-globulin which was significantly higher for the hens belonging to the strain EW. In yolk from hens of strain EW the content of protein, total lipid and cholesterol were, when expressed in g/100 yolk, significantly higher than in yolk from hens of strain EN. When expressed as g/egg the differences were even higher. Hens from strain EN showed a higher laying capacity of about 13% more eggs laid until the age of 40 wk than hens from strain EW, but due to larger eggs and a higher concentration in yolk, hens from strain EW deposit nearly the same amount of lipid and lipid fractions per day as the hens from strain EN.