Chicken And Watering System Are Ducks And Chickens In My Garden Useful?

Are ducks and chickens in my garden useful? - chicken and watering system

Save OK, I have to deal, and some money, because my son thinks he wants to be an architect ... And I have all the lawns and planted fruit trees in season, nuts and various fruits and some kale, spinach, onions, herbs, five wineries and a mango and passion fruit vines ... and maintain a system of water harvesting and solar panels installed to collect solar energy and sell them to the place of local and buy energy from them that I need. I also very isolated, all my walls and ceiling, my double glazing, boarded windows, installed interfere with my effectiveness, I closed the draft stoppers and windows and doors locked. I installed a solar heated swimming pool on my roof for extra insulation.

I thought that some chickens and ducks in the garden would be useful. Can be avoided that in the city? What do you think? Can you kill em and eat em?