EN
An outbreak of the egg drop syndrom (EDS’76) in laying hens of a meat type (Astra B) and in a flock of market laying hens (Astra S) was described and lesions in eggs caused by the disease are described. In the stra S hens the symptoms of the EDS’76 appeared first in brids agging 43 weeks and after 3 and 7 weeks the iisease appeared in birds aging 39 and 36 weeks, respecti- /ely. During four weeks egg production dropped from 73.9, 75.9 and 68.5% to 38.4, 31.9 and 28.6%. Egg pro- iuction was not restored by the end of 60—62 weeks. Jowever, in a herd of reproductive hens (Astra B) course if EDS’76 was less intense. The first symptoms of the iisease appeared both in bird aging 39 and 34 weeks and ifter 7 days in egg laying hens aging 32 weeks. After i weeks egg production droped from 68, 70 and 73% to 14.3, 57.7 and 64%, respectively, and after 6—7 weeks egg production reached a normal level. From 6 to 8% of eggs torn sick hens was excluded from hatching and a hat- :hing index was lowered by about 5—10%. Pathological esions caused by the EDS’76 in eggs laid by the two ypes of hens were similar. Apart from a qualitative :hanges of egg shell (decolorization, thin shell, lack of hell) a significant dilution and egg white dulness were ibserved, white deposits were formed on egg white, pH lecreased, and quantitative and qualitative changes in [lubulin fractions were noted.