Lilong Chai’s research looks to a cage-free future for poultry farming

In conventional caging, birds' eggs automatically go to an egg collection and transportation system. In cage-free systems, however, hens often opt to lay their eggs directly on the floor instead of in nesting areas. Some farmers report up to 10% of eggs can be laid on the floor, which-in a colony producing a million eggs in a day-means 100,000 of them must be collected manually.

It's not a tenable situation.

Chai aims to reduce the number of floor eggs, as well as the amount of time eggs spend on the floor, which can affect their value.

"Birds lay eggs everywhere," said Chai, noting this increases costs to producers because it leads to higher rates of contamination with harmful bacteria. In addition, floor eggs are not considered table eggs for direct sale and have a higher chance of getting broken and eaten by the hens.

"If the egg is not tracked and the issue not addressed in a timely manner, an egg could be buried by the birds in thick litter," Chai said. "If the farm staff cannot find an egg in a couple of days, you never know if it is found like three weeks later and maybe is not healthy to eat. The farmer cannot tell if that is fresh from today or from a month ago."

Additional studies by Chai's lab investigates ways to detect floor eggs using computer vision and machine learning, which combined can be used to develop a robotic egg-retrieval system. The technology also can monitor laying hens' behavior to try to determine why hens lay eggs in certain locations.

"Is it light intensity or light quality?" Chai said. "Environmental factors can affect mislaid floor eggs. If we can identify the reasons, we can suggest farmers to improve the management. For example, the birds like to lay eggs beneath the aviary system because that place has a low light intensity; we can increase the light intensity beneath the aviary system. Some Iowa farmers reduced floor eggs by 50% to 60% using this method."

Quality of the litter is another contributing factor.

"If the litter is too deep and soft, especially close to the corner of the house, we may suggest farmers manually adjust litter depths as that could be a natural spot for the bird to nest," Chai said.

If farmers can keep eggs from collecting on the floor, it could help avoid ingraining laying habits among the hens.

"Because mislaying is a learned behavior," Chai said. "If they see eggs on some spots, they may think that's maybe a nest spot."

Conversely, Chai's students have found that some hens refuse to lay eggs on the floor, waiting patiently for available space in nesting boxes.

"We can track those birds and use that for future breeding birds," Chai said. "Offspring from these birds may not lay eggs on the floor."

Chai's work also helps determine the optimal size and design of cage-free systems.

"Theoretically a larger space is better, but we don't want producers to invest too much on that," Chai said. "So that is our research project currently. We still don't know which space is best in terms of production efficiency, mislaying reduction, and cost."

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