The move to cage-free egg production has spawned a new generation of aviary systems available for hen housing. The question now is how well the new systems perform when balancing egg production and profitability with bird welfare.
Researchers at Michigan State University (MSU) led by Kathryn Baugh, graduate student in the MSU Department of Animal Science, sought answers to that question by comparing production data from two styles of cage-free hen housing.
“We evaluated whether aviary configuration impacted egg production, location of where eggs are laid, mortality and hen well-being,” Baugh explained.
“Overall, hen productivity and bodyweight were comparable between systems,” she said. But they did see elevated mortality rates and a higher incidence of floor eggs in one system compared to the other.
Baugh discussed her research at the 2024 Poultry Science Association annual meeting.
Test parameters
“Our study evaluated differences in experimental measures between two styles of cage-free systems: Big Dutchman’s NATURA 60 (N60) and NATURA STEP (STEP) systems,” Baugh said.
“The N60s provide nests on the top tier and a floor litter area on one side that is accessible from the bottom tier. The STEP aviaries have nests on the middle tier and bilateral floor litter areas that are accessible from all tiers.”
The research team conducted their study at the MSU Poultry Teaching and Research Center from June 2023 to April 2024. A total of 3,697 Hy-Line Brown pullets were moved into the facility at 16 weeks of age (WOA).
“We had three rooms per system divided into four sections each for the N60,” Baugh explained. “The stocking density was 144 birds per section with 576 hens per room. For the STEP, due to some differences in resource provision, the stocking density was 164 birds per section for 556 hens per room. Birds were provided > 929 cm2 of floor space per bird.”
The researchers manually collected eggs, noted their location (nest, tiers, floor) and counted them daily from 22 to 43 WOA and at 49 WOA.
They also recorded mortalities daily from 18 to 53 WOA. At 17, 19, 27, 32, 36 and 44 WOA, the research team evaluated 5% of the hens using the Welfare Quality® Assessment Protocol, which evaluates animal welfare according to animal-based measures, such as injuries and behavior.
Production age, floor eggs and mortality
“We hypothesized that there would be differences in production, floor eggs, mortality and welfare measures between the birds housed in different system types,” Baugh said.
The N60 hens came into production a little faster at 20 to 21 WOA compared to STEP hens. The N60 hens then fell off production a little earlier at 49 WOA than those in the STEP aviary.
“Floor eggs were significantly increased (8.35%) in N60 across all time points,” Baugh said. “By the last collection at 49 WOA, floor eggs were 10.4% of total eggs.”
There were no detectable differences in mortality in the birds from 15 to 35 WOA. But from 36 to 53 WOA, N60 birds had a higher mortality rate (3.7%) than STEP (1.4%).
“Importantly, while there was a significant difference in mortality rates, the mortality rates were still under 5%, which is acceptable for these systems,” she added.
Bodyweight, keel and feather damage
“There were no significant differences in bodyweight between the two system types,” Baugh said. “This really speaks to the consistency of genetics, nutrition and management.”
Keel damage and feather damage worsened over time in both systems. By 44 WOA, 25.6% of N60 hens and 18.65% of STEP hens had substantial keel damage.
“Keel bone damage is a big issue in aviary systems, so it was not surprising to see that the majority of hens in the study ended up with some form of damage,” Baugh said. “Tip fractures were also very commonly recorded, with 95% of hens affected by 44 weeks of age.”
Hen productivity good
“Overall, hen productivity was comparable between systems,” Baugh said. “The hens clearly got enough of what resources they needed to perform well.
“However, floor eggs in the N60 were a really big issue,” she continued. “This is something that warrants more investigation to figure out if it was a nest height and access issue or something else going on.
“The hens in the N60 also had significantly higher mortality toward the end of the study. In addition, we had a large feather-pecking problem in this block.”
Keel scores, fractures and feather coverage occurred over time with both systems. Baugh suggested further analysis is needed to see if there were any kind of system-wide differences in the keel scores, fractures and feather coverage. She noted that they were still analyzing the Welfare Quality measures.
