The results of a major study on the advantages and disadvantages of different types of laying hen housing were presented at the Midwest Poultry Conference in Minneapolis in March. People were eagerly awaiting these findings because many egg producers are concerned on how they are going to comply with California’s new rules on space for laying hens. The rules require that a laying hen can fully stretch her wings.  

Dr. Temple Grandin

Dr. Temple Grandin
(photo: Rosalie Winard)

Dr. Joy Mench, Univ. of California-Davis, was one of the leaders of the study conducted by the Coalition for Sustainable Egg Supply. McDonald’s Corp. and many other stakeholders participated in this research.

Mench explained that this was the first US study to compare three different types of hen housing in actual commercial houses. The systems that were evaluated were: 1) conventional battery cages, 2) colony housing, and 3) aviary cage free. In a colony system, the hens are still in cages but they provide amenities that enhance hen welfare. A hen in a colony house can stand at full posture, has a secluded nest box, perches and a pad to scratch on. To keep conditions constant, all three systems were stocked with Lohman white hens.

There are trade-offs, and advantages and disadvantages of each system. The aviary system had the highest ammonia, dust levels, dirty egg shells and death losses. Egg shell cleanliness, death losses and air quality were similar in both conventional cages and colony housing. The aviary system was the best on condition of the hen’s bones and prevention of
loss of feathers. (To see a chart which compares and contrasts the three systems, you can visit

Mench predicted the market for shell eggs will probably move to cage-free. Many people forget that half of all eggs are used for liquid eggs that are ingredients in baked goods and other products. She predicts that liquid egg producers may slowly move to colony housing.

Mench also explained that the study compared the three systems with the same white hens. The use of different genetics may affect the performance of a housing system. People are constantly innovating. A walk through the trade show clearly showed that equipment companies are inventing new designs.

The problems in the present aviary system can probably be fixed. The higher percentages of dirty egg shells is due to hens laying eggs on the floor. Equipment innovators will find a way to stop floor eggs, improve air quality and reduce death losses.

Avian flu from Migrating Birds

The recent outbreak of avian influenza (AI) in turkeys and other poultry was likely due to manure droppings from migrating birds. David Soarez and Erica Spackman from USDA/ARS in Athens, Ga., presented the results of a study on bird susceptibility to AI. Wild mallard ducks easily became infected, but they get a very slight illness. In other words, they are well adapted to AI.

Turkeys require a high dose of the virus to get infected, but a high percentage of birds die when they get sick. Keeping AI out of poultry houses is going to get more and more difficult.

A map in the March 16 Feedstuffs showed that the major migration routes for wild birds move over major broiler and laying hen areas in Arkansas, Iowa and Minnesota. The migratory routes extend up into Canada and may enable the virus to pass in from Asia. Dale Lauer with the Minnesota Board of Health told attendees at the poultry conference that three out of four of the migration flyways are now infected. The virus will continue to spread in the flyways.

I fear that disease problems in intensive animal agriculture may continue. Paul Sundberg told a recent National Pork Industry Forum that he did not know where PEDv (Porcine Epidemic Diarrhea virus) came from. He said, “This is a production disease outside the scope of USDA.” Maybe to stop some of these diseases, we need to start breeding animals for optimum production instead of maximum production.

Some producers say we have to feed a hungry world, but dead piglets and turkeys feed nobody. There is a point where drastic biosecurity procedures such as filters and baking trucks may stop working. We may need to breed more hardy animals, and look at all parts of an integrated system.