Scientists Find That Exposing Chicken Eggs to Light Reduces Anxious Behaviors

Raising chickens is an activity enjoyed by farmers and hobbyists alike. But of course, regardless of capacity, raising livestock comes with plenty of challenges. Even if you’ve done everything right — you’ve laid down two inches of dry nesting material, you’ve collected the eggs in the morning so that they don’t break, you’ve provided adequate nesting space — there are still a number of things that can go wrong once the eggs hatch.

Many chicken farmers have found that chickens can become fearful of their handlers and can often hurt themselves in the process. This behavior can be especially dangerous to the chicken as well as financially harmful if the farmer is raising the chickens for profit.

But researchers at the University of California, Davis may have found a solution to prevent flighty birds. Gregory Archer and Joy Mench, animal scientists at the university, published a study in Applied Animal Behaviour Science that suggests incubating the eggs under light for at least 12 hours every day could help reduce the chicks’ distress once they’ve hatched.

With a 1,006-egg sample, the researchers divided the eggs into testing groups that would receive a different amount of light per day. Some eggs were incubated in complete darkness, while others were exposed to 12 full hours of sunlight. The remainder were incubated to various degrees.

At three to six weeks of age, the chicks were divided randomly for observation. A group of 120 chicks from the sample was placed into a box with a human “predator” in sight. Those who incubated the longest only made 179 distress calls, while those that incubated in darkness made a 211 distress calls — all within just three minute’s time.

Archer said that the chickens that were exposed to more light were also more willing to socialize with handlers.

They “would sit in the closest part of the box to me and just chill out,” he said.

This experiment could significantly improve the welfare of chickens at large corporate farms. There, farmers often struggle with distressed chickens that become anxious, peck at each other, and pull out their feathers. Oftentimes by the time the chickens are ready for slaughter, they are in too poor of shape to be processed.

These corporate farms often incubate eggs in warm, dark, places, however, so making the switch to lighter, brighter incubation rooms could help improve the industry overall.

The direct connection between light incubation and decrease in anxiety among chickens is still being evaluated.

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