Verandas and egg shell examination could help farmers improve the health of free range layers, according to new research by poultry experts from Bristol University.

The research, which was funded by supermarket Morrisons, examined health challenges facing free range laying hens.

The study found health improvements could be made by using verandas or winter gardens, which would reduce stocking density inside the shed and offer birds shelter during the cold and wet winter months.

Another perceived benefit of the glass structures was that they would give birds access to clean air, sunlight and exercise without exposing them to predators, wild birds and infections, which are often present in ranges.

The early scrutiny and examination of eggshells is also believed to improve bird welfare.

“Early treatment of birds laying eggs which show tell tale signs of distress on the shell, such as white specks, lumps or ridging, may help avoid long-term ill health and poor productivity,” the report said.

Other improvements cited in the report, titled Managing Health Risks In Free-range Laying Hens, included adjustments to the time at which pullets are introduced to the laying farm.

For example, postponing the transportation of pullets straight after vaccinations could help to establish stronger disease immunity and put birds under less stress, said Claire Weeks from the University of Bristol, who led the research.

“What we found was there is astonishingly little scientific or published evidence-based information on the health of free range hens,” said Dr Weeks.

“This is all the more surprising given the substantial shift to this production method in Britain in recent years, which is associated with a greater risk of exposure to pathogens and parasites.”

Results from the report are due to be shared with egg farmers who are part of Morrisons’ producer group network.

The Morrisons Farming Programme is investing £1million in applied research over the next four years to help build a sustainable farming industry.

The latest report builds on the supermarket’s previously commissioned work in poultry welfare, including encouraging hens to range better and how the use of enrichment in broiler chicken sheds can positively impact on bird well-being.