Personally, I wouldn't want to be involved with a livelihood that depended on killing living beings; although we do realize that we can't totally get away from it. That's probably the reason why Steve and I failed as farmers, because we saw that it was impossible to produce food, even organic food, without killing living beings. So by understanding the cycle of birth and death as it is, the unsatisfactoriness of supporting this body, we tried to find a livelihood that would maximize the benefits of our human life, rather than just earning money to survive. Because we understand that we are involved in killing living beings, we take responsibility for that, and we think, "Ok, if we have to survive, if other beings are dying for us, out of compassion for ourselves and all beings what can we do with our lives to maximize the benefits of this human life?
So you may find that your intention is to provide food, and some people do have to provide food. However, we have choices with our life, don't we? Just like Steve and I had the choice between being organic farmers, herb farmers, and many other livelihoods; we became Dhamma teachers. We didn't plan this. We just knew we had to find something more satisfying, because we had developed a feeling of Samvega. Samvega is a Pali word that means "a sense of urgency". When we had a deep insight into human existence and the suffering involved, then a great compassion arose in us to do more with our lives, rather than just providing food and shelter, and the other requisites, that support the body and the bodies of others.
So we encourage people to choose livelihoods that are not directly connected with killing living beings in order to survive. Also, we encourage towards livelihoods that help life in some way, especially on a mental level. There are a lot of psychologists and psychotherapists who do retreats with us. People in helping professions: nurses, doctors, physiotherapists, etc. Also, people in many helping professions that try to help around the world. Even if they are just doing computer work, they feel ok about it because they are particularly connected with a livelihood that is being of some benefit to others.
So try to maximize your precious human life when you consider your choice of livelihood. Even if you are "just doing book work", it depends on where you're doing it and what your intention is. The assistants here do often have to do mundane jobs, but if they didn't do these jobs you wouldn't have an opportunity to do this retreat. So they are directly connected with helping get the Dhamma to others, and they are certainly not getting any wonderful financial rewards from it. However, the reward that they get is the making of very good Kamma, and the development of the mind.