You will be billed every quarter for all the gas, electricity and oil you have used in the business.
Until you have been trading for a few months you will not know exactly how much energy the poultry enterprise will use. Your energy consumption will be affected by the size of your property and the number of buildings you plan to have. Depending on the nature of your poultry unit, it is likely that you will use a considerable amount of energy - bear in mind that an intensive unit will have lights on in the sheds for a large proportion of the day, and there will also be the cost of running equipment such as incubators. It is possible that your energy supplier may be able to give you some guidance on likely consumption and if you're taking over an existing poultry farm then the vendor should be able to give you a good idea of the energy costs to expect. You can adjust the figures once you have been in business for a few months.
It's worth shopping around the different energy companies to get the best deal for your business, particularly if you're going to be a heavy energy user. You might also want to consider renewable energy solutions like solar PV or small-scale wind. Although these usually require a considerable initial investment, you may find that they will reduce your energy expenditure in the longer term.