EVALUATION OF ANTIBIOTIC TREATMENT OF MYCOPLASMA GALLISEPTICUM INFECTION BY THE USE OF CHICKENS AND TURKEYS FROM INFECTED EMBRYOSA

Prophylactic application of an antibiotic to chicks and poults during the first few days of life as an aid in the control and prevention of chronic respiratory disease, offers several advantages over treatment of older birds. The probability exists that mycoplasma are present in smaller numbers in young chicks or poults than in older birds and may be more easily eliminated. Further, the mycoplasma, not being encapsulated by tissue, as in more advanced infections, might be more readily accessible to the antibiotic. Prophylactic disease treatment is usually more beneficial and less expensive than therapeusis. This report describes a system of injecting embryonating chicken or turkey eggs with Mycoplasma gallisepticum and the use of the hatched chicks and poults for comparing tylosintreated birds with untreated control birds. This system may also be used to demonstrate the stress of Newcastle disease (ND) and infectious bronchitis (IB) vaccination. Mycoplasma innoculation of embryonating eggs produces a uniform infeotion in day-old birds; therefore, experimental evaluations can be made wiith few birds compared to the large numbers required for similar evaluations under field conditions.