F"ehniary, 1929] agricultural experiments 1938 19 



SKIN VACCINATION FOR FOWL POX 



The presence of chicken pox each fall in commercial flocks in old and 

 settled poultry communities has come to be expected. In fact, diseased 

 birds have often been introduced in flocks to cause an early infection so 

 that the disease would run its course while the birds were still on the range. 

 Believing that a more definite method of immunization is necessary, E. M. 

 Gildow has experimented with skin vaccinations for chicken pox in poultry 

 with a non-attenuated virus. The object was to determine the ef^ciency of 

 the immunity produced, its effect on egg production and mortality, the 

 fluration of the immunity, and to investigate any factors which might 

 develo]"). 



To find the best age at which poultry could be safely vaccinated and the 

 most satisfactory number of follicles to infect, the birds were separated into 

 four groups, one at 2^2 months, the second at 3^/2, the third at 4^4, and the 

 fourth lot at 55^ months. Each lot was separated further into four groups 

 of five birds each, and three, six, nine or twelve follicles were infected with 

 the virus. It was found that the smaller the number of follicles infected, 

 the greater was the gain in weight shown by the pullets. The lot with three 

 follicles infected gained a total of S lbs. ; six follicles, 6 lbs. 9 oz. ; nine 

 follicles, 5 lbs. 9 oz. ; and with twelve follicles infected, the gain was but 

 3 lbs. 14 oz. There was little difference in the weight gain between the 

 groups of birds vaccinated at the four different ages. 



Eleven months after vaccination, nine of the pullets taken from the orig- 

 inal lots were inoculated by rubbing virus in the comb, after it had been 

 scarified. Every three weeks thereafter data were taken to determine 

 definitely the time of development of lesions. No evidence of fowl pox 

 developed in the jniUets previously vaccinated ; in fact, they continued to 

 gain weight, and four of the five pullets began laying. However, the con- 

 trol pullets showed fowl pox lesions. From this test one would conclude 

 that birds vaccinated between 214 and 5^4 months of age, with at least 

 three follicles infected, retain the immimity developed for at least eleven 

 months. 



To check up on the possible transmission of the disease to normally 

 healthy birds, three cockerels were placed with the pullets for five months. 

 No evidence of fowl pox lesions developed. In later tests two of them 

 proved susceptible and the third immune. These data suggest that vac- 

 cinated birds may be placed with clean susceptible stock four months after 

 vaccination without danger of spreading the disease. 



Five commercial flocks were vaccinated, and it was found that a slight 

 disturbance occurred in the amount of feed consumption within three 

 weeks after vaccination. The birds, as a rule, recovered their appetites 

 within a week. There was no apparent correlation between food consump- 

 tion and egg production. The egg production in all cases remained the 

 same or showed a normal increase. (Pnrnell Fund.) 



