Advice on dealing with welfare issues in multilayer systems


Tiered laying hen systems are growing in popularity, allowing more birds to be kept in a given shed footprint. However, it is important to understand the additional welfare considerations associated with using these configurations.

Vicky Sandilands, Senior Behavioral and Wellbeing Scientist at Scotland’s Rural College, led a research project comparing tiered and platform systems and also looking at the value enrichments could offer.

These are his key findings, which will be unveiled in full at the British Pig & Poultry Fair on May 10 and 11.

See also: Expert tips to cut vet and poultry medicine costs

What are the main differences?

Tiered systems are expensive to install. However, one advantage for producers is that they can fit more birds in a tiered system compared to a platform system, but with the same shed footprint.

“Some farmers were adamant that they weren’t going to use multiple tiers as it was bad for the birds, but others said it was good for them when moving through space as they would do so naturally if they climbed trees to roost,” says Dr Sandilands.

Dr. Sandilands’ research did not show a significant difference between the two systems in terms of mortality, although it was slightly higher in the flat-deck system (7.5% in flat-deck, compared to 4.8% in multi-tier at 70 weeks of age) in 42 herds, visited between 69 and 90 weeks of age.

“A higher mortality rate and lower average egg production, due to fewer birds in the flat deck system, makes a significant financial difference in favor of the tiered system.”

She found a margin of £10.32 per bird on feed up to 70 weeks in a flat deck system versus £10.92 in a tiered system.

However, keel damage was much higher in the tiered system; keel deflection was found to be 48% versus 28%.

“We know this is more likely to happen where the birds have the ability to move around a lot – such as in multi-level systems, where the birds have to descend to a crowded floor,” says Dr Sandilands.

Average percentage of flocks with keel fractures and deviations

Keel fractures

Number of birds in the sample group

flat bridge






Keel deviations

Number of birds in the sample group







While descending, they try to land on occupied ground with other birds and furniture – which can be a source of injury when the keel dips or twists.

The percentage of flocks with a keel fracture is almost double in a multi-tier system (7.4%) compared to a flat deck system (3.2%).

This is a real wellness issue, says Dr. Sandilands. “The problem is you can’t see it.”

So how to reduce it? “One of the recommendations is to provide ramps, so birds can descend between levels – they can also help stop birds falling if they are knocked down.”

How enrichments can help

Dr. Sandilands has also looked into the effectiveness of various means of enriching the environment for birds. “Enrichment is an important consideration in bird welfare, with benefits such as reduced feather pecking.

“Some accreditation programs also require enrichment per 1,000 birds. We were curious about the enrichments that on-farm and organic producers had to put in place, were they really good?”

She examined four different enrichments, provided at the rate of one enrichment per 1000 hens. In each colony of 4,000 hens, there were at least four enrichments of two different types, to comply with regulations.

The enrichments were: bales of alfalfa hay, pecking blocks, scattered fodder and rope. “Rope is a commonly used enrichment because it is cheap. We mainly wanted to use enrichments that were already in use on the farm because we felt it was more important to evaluate them than to try something new. »

Key Wellness Outcomes

  • The design of the scratching mat makes no difference in the behavior of the hens
  • Strings do not generate much interest, but they are the least expensive and therefore may be worth offering with another enrichment.
  • Multi-tier systems have the greatest risk of keel fracture and deflection compared to flat-deck systems

Birds were observed within 1m of the enrichment – this was classified as showing interest, while those farther away were not.

The study showed that there is a lot of interest in dispersing food. “The food was dispersed twice a day at the rate of 1 g per bird. We saw a spike in interest in the area where the food was scattered as well as continued interest in the area after the food ran out.

“Some regulations do not classify dispersed feed as enrichment because it is not continuously available – so we had to get permission for the farms to use it in the study,” she adds.

While there was a steady interest in peck blocks and balls, there was less interest in ropes. They’re commonly used because they’re cheap, but they might as well not be there; there was no difference comparing the 1m circle around the ropes with the area outside the circle.

“Maybe it’s because the birds don’t find the ropes interesting or because they’re only 30cm long looped on a rail – they’re not very big compared to a ball or a block to peck,” she says.

© Matt Cartney

Dr Sandilands also calculated the cost of enriching a flock of 16,000 hens housed for 80 weeks. Including replacing enrichments if necessary, balls cost £2,000, peck blocks £6,500 and pellet feed £3,000, but ropes cost £6.54.

So, financially, ropes are an attractive option. “If you need to provide two different types of enrichment for 1,000 hens, ropes are cheap so could be combined with another enrichment. You might not want to spend almost £9,000 when you can spend 2 £000.

“That’s one of the realities – you have to balance it with what’s practical. If your accreditation stipulates two enrichments, perhaps consider offering ropes as one and pecking blocks or balls as a second.

Are scratch mats worth it?

Welfare legislation requires producers to provide bedding, allowing for pecking and scratching in enriched layer cages. As a result, cage manufacturers offer a variety of scratching mats in different sizes, shapes, and materials.

The idea behind scratching mats is to encourage pecking and scratching behavior, as in the wild chickens would spend a lot of time looking for food.

“I wanted to find out if it actually made a difference to the hens in terms of the time they spent there and the proportion of time they spent showing foraging-type behaviors,” says Dr Sandilands.

In a commercial setting, producers distribute a small amount of feed on the mats to encourage foraging, but since the mats are not very large, only two or three hens can fit on them at a time.

“The stream is quickly exhausted, the original interest is lost and they may seek to peck at something else – like others, leading to feather pecking.”

Despite the different sizes and designs of scratching mats, there didn’t seem to be an optimal one and overall usage was low.

However, Dr Sandilands acknowledged that commercial hens are not used to people standing and watching them, which may have affected their behavior and trial results. “For the scratching mats to be effective, I think food needs to be fed to them frequently.”

Expected physical performance and financial margins on food



Egg production per bird up to 70 weeks (housed hens)



Cumulative mortality at 70 weeks (%)



Average second-grade eggs at 70 weeks (%)



Average feed consumption (g/bird/day)



Margin per bird on feed up to 70 weeks (£)



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