The management and ethics of pest control, best practice, methods etc. For example, rats are the main problem around the stables, they spread disease, eat into any feed sacks they can get to and freak the horses out.
Poison is not favoured though due to the high risk of secondary poisoning should a bird of prey eat the rat afterwards. A terrier is one option, or a patient night with an air rifle.
Rats are not the only pests that need controlling of course, and the definition of pest varies depending upon what you do. A fox is a pest to a poultry farmer, but not necessarily a problem to an arable farmer.
What methods do you use, and on what pests? Are there any constraints making it more difficult to manage pests? How can pest management be made more effective?