Studies on the Egg Dipping of Tylosin by the Pressure Differential Method

Preventive effects of dipping with tylosin against egg transmission of avian mycoplasmosis and the antibiotic levels in eggs and chicks after dipping were studied by the pressure differential method.The results were as follows:1. There were significant differences in weight gain of eggs after dipping between the ages of embryonated eggs, applied reduced pressures or individual farms, but not between the duration of dipping or antibiotic concentration applied. The antibiotic levels in egg increased with the duration of egg storage and antibiotic concentration.2. Anti-mycoplasmal effect of tylosin at 2, 500ppm in the experimentally inoculated eggs was apparently noted. The effect was not influenced by the age of embryonated eggs, applied reduced pressure and duration under atmospheric pressure. However, Mycoplasma gallisepticum was isolated in one of the 15 eggs which had been treated with tylosin at 156.8 to 1, 250ppm.3. Though hatchability at 2, 500ppm tylosin was not affected at all by a negative pressure over than 300mmHg and did not hatch lower 30mmHg.4. Tylosin appeared in albumin in a few minutes and in yolk 2 days after dipping. It remained in 3-day-old chicks from dipped eggs. However, the 4-day-old chicks were infected by the inoculation of Mycoplasma gallisepticum.From these results, it is considered that dipping with tylosin by the pressure differential method was very effective for the prevention of egg etansmission of avian respiratory mycoplasmosis. However, the effect may be variable according to the eggs used.