By Karen Dallimore
Studying hen preferences
By Karen Dallimore
The public wants to know that birds are being well kept and the poultry industry wants the same, but what does the bird want?
That’s what Dr. Alexandra Harlander wants to know. She is leading a series of poultry behavioural studies at the University of Guelph’s Arkell Poultry Research Center where the birds are having their say.
Poultry producers are under public pressure to provide the best possible environment for chickens, and single- or multi-tier aviary systems may provide commercial options. In these systems, birds can walk and flap and fly – performing species-specific behaviour – but they also seem to have increased risk of bone fractures, particularly keel bone fractures, with 80 percent of birds sustaining injuries while navigating the cages.
Until now, there has been no science behind the locomotor skills of the birds on the ground or in the air, nor has there been any study of the laying hens’ preference for flying or walking. Are pullets and hens of different strains better able to adapt to different heights, angles and arrangements of perches and tiers? Are some genetic lines better able to adapt to alternative housing systems?
Harlander and her research students are investigating the set up of aviary systems, including perches, nest boxes, feeders, drinkers and litter, and the behaviour of birds in them with the intention of providing recommendations for these aviary systems in commercial settings.
One of three current projects involves testing the optimum ramp incline that hens can master across ages and strains. A steeper ramp means less room used but are the hens more likely to fly up and risk injury? Chantal LeBlanc, a Master’s student at the University of Guelph, is testing ramp inclines of 20, 50 and 70 degrees leading to two different platform heights similar to those found in commercial aviaries. “Nobody has tested that before,” said LeBlanc. She is also comparing two different surface materials on the ramp – sandpaper versus more commonly used wire mesh.
Starting at just one week old the birds have been tested weekly through 8 weeks of age, bi-weekly from 8 weeks to 20 weeks old, then will be tested further at 25 and 30 weeks of age. LeBlanc places birds from the same home pen — the hen’s friends — in a ‘social attraction’ cage at the top of the ramp, as well as offering food rewards (the birds love raisins) to entice them up the ramp. The hen is first placed on the platform so she sees the reward, then she is released at the bottom of the ramp and allowed to climb. LeBlanc is measuring their behaviour – how do they go up the ramps? Will she fly? Will she walk? At what point do they change from walking up to flying up?
At the bottom of the ramp is a force plate that measures how much they anticipate the climb by the ground-reaction force exerted on the plate – the hypothesis is that the greater the ramp incline, the greater the ground reaction force: it’s more effort.
In another research study, Master’s student Stephanie LeBlanc is looking at how typical production diseases affect the balancing ability of laying hens. Does physical impairment have any impact on the incidence of falls and subsequent keel bone fractures in aviary systems?
LeBlanc tested birds on a motorized moving perch system that sways back and forth. The birds were 69 weeks old and had some typical damage such as footpad dermatitis, poor wing feather coverage or keel bone fractures. This study is looking at how that damage affected their balancing ability on the moving perch. The research is very realistic, using birds that industry actually deals with every day.
The birds were also subjected to different treatments – rubber chickens, for example, were placed on each side of a bird to allow 15 cm of perch: how does this affect her ability to balance? There can be other birds next to a bird on the perch when she’s trying to take off or land – how does this impact the bird’s balance? “She isn’t able to flap,” said LeBlanc, which could increase the probability of injury. She also put a cotton mask on some birds to mimic low lighting conditions to see how that impacted the birds, adding to much-needed baseline research data for aviary systems.
In another section of the poultry research centre in Arkell, Master’s candidate Madison Kozak is using time loggers to compare the day-to-day behaviour of four different common industry breeds – two Lohman, brown & white, Dekalb white and Hyline white hens in aviaries. “No one has ever made a time budget for a chicken,” said Kozak. How much time do they spend on the ground? How much time do they spend on a platform or perch?
Her research is also going back to the basics to look at the locomotor patterns of the chickens, trying to see how they navigate the aviary systems, trying to distinguish between what we think they want and what they choose. “It’s very basic but necessary,” said Kozak.
Aviaries are becoming increasingly popular, said Kozak, as an option that allows birds to fly, move, run and jump. Aviary systems are supposed to improve hen welfare but a lot of birds are having a hard time navigating them. She has designed an experimental aviary system with a ramp and a ladder, two platforms and a higher perch with two different thicknesses with a spring on it so when they step on it, it’s more like a branch. The wooden features in the pens mimic those made of steel in commercial aviaries. In the industry there will be a higher stocking density.
“We’re getting a time budget,” explained Kozak, who will be measuring the time spent on each behaviour for two hours per day using non-intrusive data loggers attached to the hen’s back. Some birds are fitted with a real data logger; some just have dummy data loggers of the same weight to see if having the apparatus attached to their backs affects their behaviour. The data loggers measure the height of where the bird is in the aviary and an accelerometer is used to measure the speed of the bird and the distance they’ve gone in any direction. Kozak will calibrate this data with videos to evaluate the accuracy of the data logger information for use in further research. “There’s a ton of data that will be easier to analyze with the data logger than with videos,” said Kozak.
How much time to they spend in the ground or in the air? Do they actually use all of the areas of the cage? Maybe they only need one platform? Do they prefer the ramp or the ladder or do they care? Do they prefer to walk or fly, up and down?
She is already seeing that the ladders used by the white birds have a lot of feces on them, which indicates a lot of use compared to the brown birds. Maybe certain breeds are better suited for aviaries?
Kozak also placed brooder boxes in the aviaries for the first eight weeks to simulate the darkness the young birds would experience when hiding in the feathers of a hen. Is it possible these birds will be better adjusted hens later, expressing less feather pecking than those reared without the darkness? Brooder boxes are easy and cheap to construct.
All three studies will combine to help define the right aviary design, one that prevents injuries, and provide suggestions for how birds could be raised for the aviary systems. “We can’t think like a bird,” said Kozak, but we will soon know more about what a bird thinks. Results are expected starting this fall.
Leading this research is Dr. Alexandra Harlander, an assistant professor in Animal Science at the University of Guelph, who has recently been gifted $500,000 by Burnbrae Farms, Canada’s largest egg producer, to establish a professorship in the Department of Animal and Poultry Science. Harlander received her veterinary degree in Vienna, continuing her poultry research at the University of Hohanheim in Germany and the University of Bern in Switzerland before choosing to come to Canada, lured by the positive research atmosphere here. She currently advises five research projects involving the welfare and behaviour of poultry. “I’m very grateful to all my students,” said Harlander. “It’s hard to convince students that chickens are exciting…they are great and they are funny. You can train chickens – they’re very clever. I’d like to raise the excitement level just a bit.”