CUTANEOUS VACCINE FOR FOWL POX 241 



chart. Those of 1927 were unsuitable because the use of a connmercial vac- 

 cine had caused a pronounced decrease in productiort during this early 

 period. The control curve shows a nnarked decrease in production beginning 

 on October 9. This was due to a natural outbreak of the infection which 

 occurred at that time. A curve for house 3 is not shown on the graph be- 

 caus^e the birds in this pen were of a late hatch and had not come into pro- 

 duction at the time this study was ma,de. 



Interpretation. — The birds in house 1 were producing 5 per cent on 

 September 10, the day they were housed. They were vaccinated on Septem- 

 ber 12. On Septemlber 22 the gradual increase in percentage of early egg pro- 

 duction was sllightly retarded, wavering somewhat until October 7 when it 

 a,gain began to increase. The birds in house 2 were housed on September 17 

 and vaccinated on September 20. In this case the curve wavered between 

 Septemlber 29 and October 11. The effect of the vaccination on the early egg 

 production was similar for the two houses. 



This slight retardation in the increase of early egg production cor- 

 responds to the decrease in egg production following vaccination in pullets 

 more advanced in production, whicli was shown in our previous report (3). 

 It began on the eightli day after vaccination and had reached its lowest 

 point on the twenty-first day after vaccination. This slight effect on the 

 increase in early egg production should not be considered of any great im- 

 portance. Any preventive treatment given to the domestic fowl will have a 

 similar effect. The benefits derived from this method of vaccination war- 

 rant its use. The results of this experiment indicate that it is safe to vac- 

 cinate birds cutaneously against fowl pox as they are transferred from the 

 range to laying houses, even though they are in the early stages of egg pro- 

 duction at the time. 



The birds used in the above experiments were in good physical condition 

 and free of any infectious, dietary, or marked parasitic disturbance. It is 

 possible that if their health had been otherwise there might have been some 

 adverse effect following the vaccination. All the investigators who have 

 worked with this vaccine mention its danger when administered to unhealthy 

 flocks. 



The Effect of Cutaneous Vaccination on Body Weight and Temperature 



The following experiments were designed to determine what change, if 

 any, would take place in Ijody weight and temperature of birds of various 

 ages following cutaneous vaccination. The results would indicate at what 

 age it is safe to vaccinate a flock in this manner. Our previous work had 

 been carried out on birds of approximately five and six months of age or 

 older. It is undesira,ble to vaecinate after birds are well into egg produc- 

 tion because Of the marked decrease that follows. It was demonstrated in 

 the previous experiment that early production was not affected to any great 

 degree, but the results ma^y not always be favorable, especially if the vac- 

 cine is administered improperly or carelessly by one who has not had pre- 

 vious experience in using it. Therefore, it seems desirable to vaccinate on 

 range where the birds are not subjected to the crowded conditions of the 

 laying houses, where the chance of contact infection following vaccination 

 is greatly lessened, and the contamination of the houses with the virulent 

 vaccina,tion material is avoided. 



