How aisle width in cage-free systems impacts hen welfare

Cage-free specialists discuss the need for space in aisle ways that often gets over looked in planning

Allowing birds enough space to express natural behaviors and peacefully coexist is essential to avoiding aggression. | Photo: Courtesy Salmet

“When you are planning your cage-free operation you must understand the importance of aisle width and how it will affect your flock,” said Bill Snow, Big Dutchman’s cage-free specialist during the webinar "Learning the fundamentals for cage-free egg success," which was sponsored by BASF and Big Dutchman and hosted by WATT Global Media. Aisle width effects lighting, ventilation, litter, flock movement and management which will directly affect the welfare of the birds.

“Aisle space is nothing and it can often times be over looked in the planning stages,” Snow said. He refers to it as nothing because of the availability of room it offers the birds. “Workers are more likely to spend more time in the houses because they can move around and monitor things easier,” he said.

In each system that producers consider they should find out how tall it is, how wide it is, the location of the nest, how many hens it will accommodate, where the lights will be located and what kind of ventilation system will be used.  “All of these should be carefully thought out when deciding what aisle width should be,” said Snow. The bigger the aisle is the better it is for management to step back and analyze the system and how birds are responding to it, without forcing as much stress on the birds.

Jasper Heerkens, PhD, poultry specialist with Jansen Poultry Equipment agreed with Snow during the same Webinar. “Use the room to sit or stand still in the house and observe the overall picture every other day so that birds are used to you being in the house,” he said. Make sure that your staff is properly trained to read bird behaviors, he added.

While every bird has daily necessities, facilities to meet those requirements should be found in the house, Heerkens explained. This means there are different functional areas of the house, but they all serve a specific purpose.

How much space is really needed

15 percent of the space that a hen is given is too little to have in the aisle ways, Snow explained. Birds gather in the aisle ways for numerous reasons. Space under the systems is still available space, however, birds will come to the aisles. Overseas they allow for more room but currently 15 percent is the required U.S. allotment per bird.

This number may be affected by how much employees are in and out of the houses moving the birds. “I’m not one to tell you that 15 percent is just not enough, you (producers) may just have to manage those houses better,” Snow said.

Traditional cage houses had three-foot aisles. “If you have that amount of space you’re going to wish you had more,” said Snow.

“I know it costs more to have that extra space, but in the long run it should be worth it,” Snow said. More space per bird does not mean there are fewer birds in the house, it all depends on how big your system is. To have the optimum house for the birds, producers should design the dimensions of the house around the aviary system they’re using.

Lighting in wider aisles

“Lighting should be as uniform as possible,” Snow said. The wider the aisle the more opportunity there is for light to reach each tier. If there are darker areas of the house then you are creating a choice for the birds; while choice is good, you don’t want too many birds to choose one area of the system and create congestion.

“Congestion may lead to problems with ventilation, mislaid eggs and litter quality,” said Snow.

Heerkens agreed that good light improves performance, behavior and welfare. “Lighting regulates biorhythms, physiological processes (e.g. sexual maturation), stimulates feed intake and laying behavior,” Heerkens said.

However, Heerkens noted that it might be of value to have different light conditions in different functional areas. Those lighting options should be controlled by management and may vary on the time of day. “Nesting areas should be darker,” he said.

For birds to have a smooth transition from rearing to production, housing management should use the same feeding and lighting schedule that was used in the last week of rearing, Heerkens suggested. Even the same feeders and drinkers may be beneficial.

Some producers are trying different colors of lights and natural light. Natural light is harder to manage in terms of uniformity and may not be the best option, Snow noted.

Wider aisles allow for better ventilation

Proper aisle width allows for a more uniform temperature, optimal flock spacing, improved air quality and flow, better bird movement and a more ideal litter quality. “You can have the perfect ventilation system set up for you but if you don’t have the proper aisle width it will not be as effective,” Snow said.

The floor space that is between the system rows is always going to be a little more crowded than underneath the system itself. With a wider aisle, birds have more room to separate and allow air to move through the litter. You are not only ventilating the house for the birds, but you are drying your litter quicker. “You want birds engaged in the litter,” said Snow. Greater aisle space creates more room for dust bathing and foraging.

Add substrates and scatter feed to use to your advantage. “40 percent of the birds’ daytime activity is spent on foraging,” said Heerkens. The hens using the litter this much will only help dry it out.

Litter quality control in wide aisle system

“Litter and ventilation really work hand -n-hand,” Snow said. More space results in a dryer litter. The more hens that are packed in the given space of an aisle, the harder it is to control the quality of litter, Snow explained. The better the litter is, the more the birds will use it.

“Wet or excessive litter in your house is a risk for health problems for your personnel as well as your animals,” Heerkens said. Litter should be no deeper than 2-3 inches, he added. Excessive litter may create a greater risk for floor eggs; an attractive nest will help eliminate this issue.

If litter is a bit wet producers, should add stir fans and move through the house themselves to get the birds to circulate more. Dry litter is important so that birds have something to do to occupy their time, as Heerkens previously suggested. By doing this, producers are reducing the risk of feather picking and cannibalism.

Navigation in such systems

“Cage-rearing (of pullets) is definitely unsuitable for preparing hens for cage-free systems during production,” Heerkens said. Aviary housing is more complex housing than what pullets raised in cages would be accustomed to. Birds need to learn to go up high to look for water and feed as soon as possible, not only to fill their nutritional requirements but also to strengthen their physiques and to learn navigation systems and what jumps to take. This will ultimately lead to less injuries later, Heerkens explained.

Rearing systems can be relatively simplistic if you can provide a training system that’s realistic to the expectations the birds will need to meet in their production houses. 

Dimming of the lights at the end of the day in the house may teach the birds to go up high, he added.

Management should watch birds closely to make sure they are properly using the system, Heerkens noted. Place yourself in the shoes of the bird to figure out what works.

“Flock movement is what we are after,” said Snow. This results in less competition, more activity and fewer mislaid eggs while still directly improving the welfare of the hen.