Blood is collected from chickens for two purposes:
1. To obtain serum which will be tested for Newcastle disease virus antibodies, no anticoagulant is required and the blood is allowed to clot. The levels of antibody detected in individual birds and flocks give an indication of the response to a vaccination. It also indicates whether birds have been challenged by field strains of Newcastle disease virus.
2. To obtain red blood cells, the blood is collected into anticoagulant. The cells are washed and used to test for the presence of virus in the haemagglutination test. They are also used in the haemagglutination inhibition test for the presence of antibodies.
It is important that those who bleed chickens use a quick and effective technique. This will develop with practice and by applying the following advice.
Handle the chickens gently.
Collect the blood samples quickly.
Take care not to damage the vein. Damaged veins will result in haematomas being formed.
Minimize the loss of blood. This minimizes trauma to the chickens and stress to their owners. The owners are then more likely to cooperate by supplying chickens for the collection of blood samples in the future.
Wing vein bleeding
1. Ask an assistant to hold the chicken horizontally on its back. The assistant uses one hand to hold the legs and places the other hand under the back to support the chicken.
2. Pull a wing of the chicken out towards you.
3. Note the wing vein, clearly visible running between the biceps and the triceps muscles. The wing vein forms a V (bifurcates). Note the tendon of the pronator muscle that runs across the V.
4. Pluck away any small feathers that obscure the vein.
5. Disinfect the area around the bleeding site by swabbing with 70 percent alcohol.
6. Insert the needle under the tendon. Direct the needle into the wing vein in the direction of the flow of blood. Do not insert the needle too deeply. Keep clear of the ulnar nerve.
7. Once the tip of the needle is in the vein, gently pull the plunger of the syringe. Blood will flow into the syringe. If blood does not flow, release the plunger and make a very slight adjustment to reposition the end of the needle.
8. Be patient and use a gentle suction to withdraw the blood. Chicken veins collapse readily.
9. If a haematoma forms, try bleeding from the other wing.
10. After removing the needle, apply pressure to the vein for a few seconds to discourage further bleeding.
11. Ideally the needle should be removed into a needle disposal container and the cap place on the end of the syringe to prevent leakage of the serum. However in many places these containers are not available and the cap will be placed over the needle.
TAKE CARE! Do this very carefully to avoid a needle stick injury.
12. Pull the plunger back approximately 1 cm and place the syringe at an angle with the needle end up in a rack facilitate clotting.
Figure 10: Chicken wing vein bleeding (1)
Figure 10: Chicken wing vein bleeding (2)
Bleeding a chicken alone
The staff at the John Francis Virology Laboratory use the following method for bleeding chickens without an assistant. The method is a modification of the procedure described above and is written for a right-handed person. Left-handed people soon make their own modifications once they start bleeding chickens alone.
1. Sit on a chair. Turn the chicken on its back and place it on your thighs.
2. Arrange the chicken with its head away from you and place the right wing securely between your thighs.
3. Use your left elbow to secure the legs by holding them down onto your left thigh.
4. Place your left forearm across the chicken and use your left hand to spread out the left wing of the chicken.
5. Use your right hand to bleed the chicken as described above.
Figure 11: Bleeding a chicken alone, positioning the chicken (1)
Figure 12: Bleeding a chicken alone, positioning the chicken (2)
Figure 13: Bleeding a chicken alone, taking the blood sample