New standards covering the welfare of chickens raised for meat came into effect on Thursday.
The previous code concentrated soley on chickens that are fully housed, but the new code also includes chickens that have access to the outdoors.
The chair of the National Animal Welfare Advisory Committee says farmers will now have to take the environmental conditions for chickens into account when deciding on numbers.
John Hellstrom says they will still be required to stay within minimum standards for stocking density, but now also have to consider litter quality, lighting, air quality and temperature when deciding how to house their birds.
