Injections are preferred in many places to treat chicken diseases, especially duck diseases. What are the pros and cons?

Injections are preferred in many places to treat chicken diseases, especially duck diseases. What are the pros and cons? To carry out biological safety treatment. I think injection is very stressful, except for severe venereal diseases. It is better to mix the material with drinking water-- injection is a measure taken only when the disease is serious in the population or when it is necessary to use injection to get the effect. -agree with my friends upstairs-- but duck disease dies so quickly. That's true, but in practice, many maintainers, whether they are seriously ill or not, People who like injections-- prevention first-- have gained a lot of recognition in pig farms. -drinking water in large groups Severe (no more than 10%) injection.