So last year world production of broiler chicken meat was 85 million tons of chicken meat. That's a lot of chicken. In developing countries, such as China and India, the demand for poultry products is increasing. So broiler chicken production is likely to continue to rise for the forseeable future. Almost 18 million broiler chicks are placed on UK farms every week. That is a lot of chickens being produced in the UK. The broiler chick starts off as a 42 gram bird when it's first hatches. And in just six weeks, by the time it goes to slaughter, it can reach a weight of about 3,000 grams or three kilos. That means that the bird has increased it's body weight 70 times in the six short weeks before it goes for slaughter. If we compare that to the growth of a, a, a beef a calf for example, when a beef calf is first born it weighs 40 kilograms. If it grew at the same rate as a broiler chicken making its growth body weight increase by 70 times in 6 weeks then it would reach 2800 kg of beef in just 6 weeks' time. So as you can probably guess, the broiler chicken is the fastest growing animal on the planet. So meat chickens are very efficient at converting their food that they eat into muscle mass, which is the chicken meat that we eat. And the reason this has happened is because over the past 60 years or so, breeding companies have been selecting for high food conversion ratios. And also inadvertently they've been selecting for the chickens to be rather inactive. And the combination of these two things means that the broiler chicken deposit a lot of muscle mass in a very short period of time. Broiler chicks are handled in a very similar manner to the layer chicks that we were talking about earlier. They're artificially incubated as eggs, they hatch, they're transferred under warm conditions to the rearing farm. Where they're provided with supplementary heat for the first two weeks or so until they can self-regulate their own body temperature. But, the similarities really end there. So, we're going to focus on boiler production systems now. But, I'm only going to talk about conventional rearing, because the other forms of rearing such as free range and organic only make up less than 5% of broiler production in the UK. In some broiler rearing some places rear broilers in cages, but that's comparatively rare in Europe. In European systems, we tend to rear birds in deep litter. So it's this kind of wood shavings material or something similar that the birds can sit on and be fairly comfortable on. A typical The other shed might hold anywhere between 25 and 50,000 broiler chickens in a, in a football field style shed. Big open spans, with lots of feeders and drinkers down so the birds help themselves to food and water during the whole course of the day. The lights would typically be on for about 18 hours, by European rules they have to have six hours of darkness. And the space allowance will be anything between 33 and 42 kilograms of chicken per square meter of floor space. What that refers to, is the terminal stocking density that the birds will be at just before they're taken away for slaughter. So at a stocking density of up to 33 kilograms per square meter, the producer has to meet basic EU requirements of meat chicken production. However EU regulations requires that the producer meets increasingly stricter requirements for keeping birds at stocking densities of between 33 and 39 kilograms per square meter, or between 39 and 42 kilograms per square meter. Of course, other poultry standards can stipulate lower stocking amnesties than these for indoor reared birds. Some indoor reared broilers may also be housed with things to enrich the environment. So, for example, they might be provided with natural daylight from window,s or bails of hay or straw, or bails of wood shavings to peck at. And they can also sit on these, of course. They might also have perches, and they can have whole grains scattered into the litter or vegetables to peck at. Furthermore, free range chicken production will have additional requirements, such as a minimum rearing age of eight weeks, and access to range for at least half of their lifetime. A free range production scheme, such as Freedom Foods, will have additional requirements. Such as stocking density of no more than 27.5 kilograms per square meter, and a range area of at least one square meter per bird. So, what sort of welfare problems do broiler chickens suffer from? Well most problems stem from their rapid growth rate. So for example one of the major concerns over rapidly growing meat chickens, is their inability to walk normally after about two to three weeks of age. And this is possibly due to one or more of the following factors. So one of these issues is just plain body confirmation. If you look at a broiler, they're depositing a lot of breast muscle mass and this will cause their body shape to alter compared to a non-selected chicken. Making the dynamics of walking just different for them compared to a bird th, that is slimmer. There's also the issue of skelito mechanics. The increased rate that a rapidly growing chicken has to support on undeveloped legs, may cause altering of the bone shape. And while this may not necessarily cause the bird discomfort, it may alter their walking style. And then finally, there's a possibility the birds are suffering from painful pathologies. So, some forms of leg weakness are caused by infection, or conditions that are likely to be painful. Which can make the bird walk poorly, as it tends not to bear so much weight on the sore limbs. Conditions such as femoral hedinacrosis or synovitis are likely to be painful. Towards the latter stages of their production, broilers can experience heat stress. Which they exhibit by panting and holding their wings away from their body in an attempt to cool themselves. This is caused by their high metabolic rate, which generates a lot of heat. And, the birds then struggle to dissipate this extra heat, particularly as the floor is becoming more crowded with other growing chickens. This can be reduced by thinning the flock out, and taking some of the chickens away earlier than others for slaughter, which then allows the remaining birds to spread out. It can also be diminished by slowing their growth rate. In addition, broiler chickens can be exposed to pathogens, just like their laying hen counterparts can, and the risk can be greater with free range systems. So next what I want to talk to you about is the parents of broiler chickens, and should we be considering their welfare when we think about the progeny, the actual production animal. The parent stock of broilers, are known as broiler breeders. Their dilemma arises when they still have the growth potential of their progeny. But if we allow them to grow at the same rapid rate, eating ad libitum from the time that they hatch, then they would become obese, and they would probably produce poor quality eggs. And a lot of them wouldn't reach sexual maturity because they would die prematurely. So, in order to prevent this and ensure we rear robust, healthy adult breeder chickens, the amount of food that they eat during their rearing phase is limited to a small ration of food, which they feed on once a day. Now in some countries, they do something called skip a day feeding. And they get a bigger portion of food, but only every second day. And restricting them in this way, means that for the females at least, at six weeks of age, they should only reach a target weight of a little less than 700 grams. And remember we said earlier, that a six week broiler chicken could get to as much as 3,000 grams. And then by the time they reach adulthood at about 20 weeks of age, they'll weigh a little under 2,200 grams or 2.2 kilos. The benefits of restricting boiler breeders in this way, is that they grow up to be robust, healthy and active birds. But the drawbacks are that the birds may show signs of chronic hunger. For example, by expressing high levels of foraging activity, by showing escape behavior from their home pens. And by physiological indicators of stress, such as increased levels of corticosterone and AGRP.
