COMMERCIAL BROILERS
Fast-Growing Broiler Chickens
The parent birds (breeder birds – see section at the end) used to produce meat chickens have their eggs removed and placed in an incubator. In the incubator, the eggs are kept under optimum atmosphere conditions and highly regulated temperatures. At 21 days, the chicks are ready to hatch, using their egg tooth to break out of their shell (in a natural situation, the mother would help with this). Chicks are precocial, meaning that immediately after hatching they are relatively mature and can walk around. A chick classified as a ‘day-old chick’ is up to 72 hours old
(this is when the yolk sac in the egg runs out).
Eggs, broiler chickens and other poultry products are important sources of animal protien throughout the world.
COMMERCIAL BROILERS
Meat broilers are usually slaughtered at approximately 35 to 49 days of age, well before they become sexually reproductive at 5 to 6 months of age. However, the bird’s parents, often called “broiler-breeders”, must live to maturity and beyond so they can be used for breeding. As a consequence, they have additional welfare concerns.
Meat broilers have been artificially selected for an extremely high feeding motivation, but are not usually feed-restricted, as this would delay the time taken for them to reach slaughter-weight. Broiler-breeders have the same highly increased feeding motivation, but must be feed-restricted to prevent them becoming overweight with all its concomitant life-threatening problems. An experiment on broilers’ food intake found that 20% of birds allowed to eat as much as they wanted either died or had to be killed because of severe illness between 11 and 20 weeks of age – either they became so lame they could not stand, or they developed cardiovascular problems.
Broiler breeders fed on commercial rations eat only a quarter to a half as much as they would with free access to food. They are highly motivated to eat at all times, presumably leading to chronic frustration of feeding.