RED DEER – Farmers might be tempted to pack as many broiler chickens into a barn as possible to try and generate higher profits.
While that might be possible, said University of Alberta poultry researcher Martin Zuidhof, ethically and physically there is a limit to what should be grown in a small space.
Higher density barns tend to have lower fixed costs and tend to be more profitable because more chicken is produced, Zuidhof told a research seminar in Red Deer.
“The bird environment is more important than stocking density, but never forget the bird environment is also affected by stocking density,” he said.
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Canadian industry broiler codes of practice recommend maximum stocking densities of up to 38 to 42 kilograms per sq. metre. That is the equivalent of 17 to 23 birds per sq. metre.
Stocking density studies conducted in the United Kingdom, Germany, Pakistan and the United States have compared stocking rates and impacts on animal health, barn environment, feed intake and carcass quality.
The high density barns generally have more wet litter and ammonia that may lead to quality issues but not necessarily carcass contamination. However, animal health is affected. The higher the density, the easier it is for birds to transmit disease.
“If we want to sell chicken to consumers who are not interested in having antibiotics used in the production system, then we probably need to rethink our production systems,” Zuidhof said.
Research from the U.K. and the University of Alberta found similar results in feed intake and conversion, but there seems to be a limit on what the birds can achieve. When there are more birds in a barn, feed intake is lower, resulting in lower body weight, but overall feed conversion and mortality are not usually affected.
Zuidhof said researchers are not sure what the production limits are until problems appear. That makes it hard to make recommendations.
Animal welfare research from Great Britain 15 years ago showed that in higher stocked barns, the birds displayed more fearfulness, more breast blisters, more ammonia burns on foot pads and hocks and more skeletal problems because they could not walk around comfortably.
It also found broilers raised at higher stocking densities had reduced antibody production and increased incidence of aschites, where birds drop dead suddenly.
There was also a negative effect on carcass quality with more scratches, lesions, cellulitis and breast blisters, especially in females.
Zuidhof participated in a stocking trial at the University of Alberta to calculate the economics of various levels of high stocking densities and final meat yield.
The total cost of production was lower but the value of the birds with no injuries is hard to determine. Also, it is difficult to know if consumers would pay more for chickens raised in a barn with more space.
Consumers seem to want cheap food, and a higher stocking rate is one way for farmers to remain profitable said Zuidhof.
Caring for chickens
The code of Canadian practice for broilers recommends the following:
- Chickens raised in floor pens should be able to stand normally, turn around and spread their wings without difficulty
- Broilers and roasters should be provided with enough space to eat and drink without restriction
- The recommended weight per unit of floor space is 31 kg/m2
- However, variations in stocking density up to 38 kg/m2 are acceptable if justified by adequate husbandry programs, feeding and watering equipment, ventilation systems, lighting programs and litter materials
