Transfer of Dietary Tylosin into the Eggs and Its Residue in the Liver of Laying Hen

概要

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Tylosin was fed to laying hens for 7 days at the dietary levels of 0, 20, 500, 1, 000, 2, 000, 4, 000 and 8, 000ppm, and thereafter, tylosin-free diet was fed to all of the hens for another 7 days. Even at the extremely high level of 8, 000ppm, dietary tylosin had little influence on feed intake, egg production and other performance of the hens during the experimental period.Tylosin was not detected in either the egg yolk or egg white at the dietary level less than 500ppm. At the higher dietary level than 1, 000ppm, content of tylosin in the whole egg increased curvilinearly with the increase in dietary level of tylosin. After the withdrawal of dietary tylosin, its content in the egg white and in the liver decreased rapidly and no tylosin was detecded after 3 days in the egg white and 7 days in the liver, while that in the egg yolk decreased gradually and disappeared after 7 days.Biological half life of tylosin in the whole egg was estimated to be 1.3 days, which was significantly longer than 0.6 days, the biological half lives in the egg white and in the livers of both growing chicks and laying hens.
日本家禽学会の論文