THE RELATION OF THE CHOLESTEROL LEVEL AND TOTAL LIPIDS IN BLOOD-PLASMA TO HATCHABILITY, LAYING AND EGG WEIGHT IN THE HENS OF LAYING STRAIN

The level of cholesterol and of total lipids was determined in the blo od plasma (Tab. I) in 84 hens of three lines originating from two bree ding rearings during their pedigree hatching. The values detected were compared with the proportion of hatched chickens and the number and w eight of laid eggs to determine potential dependences. The investigati ons included 20 hens of the maternal line Rhode Island White (RIW-1) a t the age of 54 weeks, 32 hens Bar Plymouth Rock (BPR) at the age of 5 1 weeks and 32 hens of the maternal line Rhode Island White (RIW-2) at the age of 56 weeks. The higher level of cholesterol and total lipids in blood plasma of the hens of the RIW-1 line (4.84 +/- 0.94 and 20.8 2 +/- 3.67 mmol/l) and BPR (5.77 +/- 1.85 and 20.00 +/- 7.39 mmol/l) a gainst hens of the RIW-2 line (3.26 +/- 0.78 and 15.06 +/- 4.11) is pr econditioned by a little time elapsed from feeding and blood collectio n. Higher hatchability by 6.8 to 13.2 % and 1.1 to 15.2 was recorded i n hens with low level of cholesterol (Tab. II) and total lipids (Tab. III) than in hens with a high level. The number of laid eggs was highe r in two groups of hens with low level of cholesterol (by 3.08 and 2.4 2 pieces) and total lipids (by 3.49 and 2.21 pieces), this was higher by 5.62 and 3.50 pieces in the third line. The egg weight was identica l in both groups in three lines and the difference reached ultimately 0.64 g. The values of correlation coefficient between the cholesterol level and hatchability (Tab. IV) were practically zero in both RIW lin es (r2 = 0.02 and 0.01) and low in the BPR line (r2 = 0.14). Higher va lues are determining the relationship between the total lipids level a nd hatchability in the BPR and RIW-2 (r2 = 0.32 and 0.25), zero values were recorded in the RIW-1 line (r2 = 0.07). A low positive dependenc e of hatchability can be recorded on the level of total lipids contain ed in blood plasma. The dependence, however, will be rising with falli ng level of cholesterol or of total lipids comprised in yolk (e. g. du e to selection performed), whereby this will result in the fall in hat chability below the required level. A potential selection, concentrate d oh the reduction of the lipid level m the egg yolk can be applied ma inly in paternal lines, the resulting effect in hybrids will not be hi gh.