Aviary systems allow for freedom of movement of layers and pullets through a three-dimensional environment which can allow for expression of the bird’s natural behaviors. Laying hens can and will fly short distances, but they aren’t graceful fliers. Michael J. Toscano, PhD, group leader, center for proper housing: poultry and rabbits, University of Bern, said that commercial poultry lack the muscle fiber type and weight to wing surface ratio to be good flyers. In addition to not flying particularly well, hens aren’t gymnasts either and sometimes have trouble “sticking the landing.”
Crash landings by hens can lead to keel bone fractures. Toscano, speaking at the Egg industry Center’s 2021 Virtual Egg industry Issues Forum, said that in hens housed in aviaries without ramps, as much as 80% of the birds could have had keel bone factures by 50 weeks of age.
Ramps provide a means of hens moving up in an aviary system without having to fly. Toscano reported on research into whether adding ramps to aviaries, both in rearing and in lay, reduced keel bone fracture incidence. In order to effectively use ramps, birds need the leg strength to move up and down on the ramps. Toscano also said that pullets and layers need to have the cognitive development to prepare for inclines and declines on the ramps and make adjustments to both the speed and force with which they climb or descend the ramp. He also said that on the way down a ramp, many birds hop off the edge of the ramp mid-way, so they need to be able to pick a landing spot and stick the landing.
In studies conducted at the university, pullets were housed in aviaries with or without ramps. The pullets were introduced to the ramps at two weeks of age. When the birds were moved to the layer house, the pullets were split into houses with or without ramps. This resulted in the following experimental groups: control birds never housed with ramps, birds always housed with ramps, birds housed with ramps as pullets but not as hens, and birds housed without ramps as pullets but with ramps as hens.
In the pullet house, ramps initially lead to more birds spending time on the top tier of the aviary, but the difference in distribution of the birds was not statistically different by the end of rearing. Overall, pullets made more transitions from one tier to another throughout the rearing period in the aviaries with ramps. More than 80% of transitions from one tier to another made by the pullets through 14 weeks of age in the aviaries with ramps were done using the ramps.
Hens housed with ramps in the laying house had significantly fewer keel bone fractures than did the control birds. There was not a significant difference in the severity of keel bone fractures between birds housed with ramps in rear and lay and birds that only had ramps during lay. Toscano said that he was surprised by this result and will be investigating this further.
Toscano said that ongoing research is looking into ways to encourage ramp usage as well as to design ramps that are simple to install and easy to clean and operate. They have tested the use of LED lighting along the ramp, positioning a robotic hen on the ramp and pecking beak to try and encourage hens to use ramps more frequently. He said that preliminary data shows that lights help to increase ramp use.