18 MASS. EXPERIMENT STATION BULLETIN 311 



some planning in order to make vaccine and birds to be vaccinated come out even. 

 Poultrymen should not indulge in the practice of borrowing infectious laryn- 

 gotracheitis exudates from each other, for such practice will result in the spread 

 of diseases other than infectious laryngotracheitis, and may lead to the ruination 

 of the poultry industry in Massachusetts. 



Vaccination 



If the birds are housed they should be driven into a corner and held there by 

 crates standing on end, or some other fence. On the range it is usually most 

 convenient to fasten the required number of birds for a day's work in the roosting 

 houses the night before. In the case of laying hens, some poultrymen with good 

 lighting facilities prefer to have the vaccinating done at night, because then it is 

 only necessary to lift the birds from the roosts with little disturbance and loss 

 in production as a result of handling. 



A vaccinating crew ordinarily consists of three men: one to catch the birds, one 

 to hold the birds, and one to do the vaccinating. The first man should remain 

 with the birds, the other two should go beyond the range of dust and where the 

 light is good. The prepared vaccine should be on a table, box, or barrel nearby. 

 Also some cotton should be twisted on the ends of some applicators or sticks about 

 the size of matches or larger. 



The first man catches a bird and hands it to the second man who grasps it 

 by the legs with one hand and the wings with the other, and holds it head down 

 and back to the third man, ready for vaccination as shown in Figure 1. The 

 third man grasps the upper or dorsal fold of the cloaca with the thumb and 

 forefinger, and opens the cloaca. On the upper or dorsal side of the cloaca a 

 pink groove will be seen leading into a little fold or slit. With the other hand, 

 he picks up an applicator, dips the cotton into the vaccine, and rubs it into 

 this groove, going clear into the fold or slit as shown in Figure 2. This groove is 

 the bursal groove, the fold is the bursal fold, and the slit is the opening into the 

 bursa of Fabricius. All of these parts must be recognized and distinguished in 

 order to vaccinate properly. As soon as the vaccine has been rubbed into the 

 bursal groove, the bursal fold, or the bursa of Fabricius, the vaccination is com- 

 plete and the bird should be placed where it cannot rejoin the unvaccinated 

 group. 



It should be pointed out that the bursa of Fabricius is usually absent in laying 

 hens and breeding cocks. In these birds it is replaced by a bursal fold. In 

 pullets and cockerels which have been killed and opened to expose the abdominal 

 cavity, the bursa of Fabricius appears as a bulb-like organ dorsal to the cloaca. 

 The mucous membrane of the bursa is soft like that of the larynx and trachea. 

 In vaccinating pullets and cockerels the vaccine should be swabbed into the 

 bursa of Fabricius in order to secure a lasting immunity. 



The success of the vaccination depends upon the number of takes. Four 

 days after vaccination the birds should be examined for takes. In checking up 

 on the number of takes, the same procedure can be followed as in vaccinating 

 the birds. The person reading the takes should have a supply of swabs handy 

 and revaccinate any birds in which takes aid not occur with exudate from birds 

 which show good takes. A take has occurred in those birds in which the mucous 

 membrane of the cloaca is moist, inflamed, or covered with pseudomembrane. 

 In pullets and cockerels the opening into the bursa of Fabricius will often be 



