Should Eggs Be a Seasonal Ingredient?
Unless you’ve been living under a rock, you’ve probably noticed people care more and more about eating healthier, and fostering food systems that are ethical and sustainable. With the rise in popularity of farmers markets and local CSAs, it’s easy to recognize and adopt the benefits of eating foods when they’re “in season.” It’s more sustainable on a lot of levels: more natural and beneficial farming practices, a smaller carbon footprint, and the food just tastes better when it’s fresh off the local farm.
But should that mindset apply to the eggs we eat? Should eggs be seasonal? Are any of us even aware that egg laying has a season? Because it does.
If you have a few chickens in the back yard, or you’re new to poultry farming and have noticed a sharp decline in your flock’s laying production as it’s gotten colder, you’re not alone. Many poultry farmers in the Pacific Northwest struggle with chicken egg production in the winter months as the amount of natural daylight hours decreases. As a result of this decrease and the need to meet the demands of production, the use of artificial light in hen houses or confinement cages is common. I’m doubtful many (if any) consumers are aware of this, but exposure to this artificial light and the “forced” aspect of production is harmful to the birds on many levels, and if good husbandry and the well being of birds is a priority on your farm, it’s usage should be carefully considered.
Here’s the scientific nuts and bolts of it: the chicken egg laying cycle is directly affected by a hormonal response to light and as a result, farmers will see a drop in the production of eggs as the days shorten and the hens are exposed to increasingly long hours of darkness. To combat this, many farmers will use artificial illumination in their hen houses to stimulate production and egg-laying behavior.
When it gets dark at 4:30pm, these chickens can be “encouraged” to lay longer into the night when an artificial light is introduced into the hen house.
According to a study by Lingbin Liu, concentrations of the hormones required for egg production were found to be increased in birds exposed to artificial light, and egg laying rates increased along with egg size. We know that artificial light works to produce more eggs, especially over the winter months, but is it really all that harmful to the bird and ultimately the egg that consumers then eat? Studies show that it is indeed harmful to both.
Hens typically begin laying when the amount of daylight hours reaches 14 hours a day during early spring with maximum egg laying when day length reaches 16 hours per day. On a typical fall day in mid-November, a Pacific Northwest farmer can expect only roughly 9 hours of daylight, with that amount decreasing through the winter to about 8.5 hours, accounting for a severe decrease and sometimes complete dearth of egg production. While studies have shown that the implementation of artificial light works to “trick” the laying hen’s endocrine system into keeping the egg production engine running, there is evidence to show that there is a reason why chickens naturally need to rest during the winter and that the interruption of this natural cycle is harmful to the birds on several levels.
One such concern is the increased risk of vent prolapse. The vent is the muscular tube that the egg passes through as it exits the hen. When the vent muscles become weak from overuse, the vent pops out but does not return to its proper position. Vent prolapse can lead to infection and death. Another unfortunate but very real possibility is the increase of pecking and cannibalistic behavior that can occur with vent prolapse. Other birds in the flock can become fixated on pecking at a prolapsed vent leading to increased injury and even disembowelment of the unfortunate hen.
Another health problem observed in birds that do not get the benefit of natural circadian rhythm is the increased risk of ovarian cancer. According to another study, the more eggs they lay, the higher the risk of cancer. Cancer will of course lead to reduced life span and overall fewer eggs produced for the farmer and the consumer.
An additional health issue is a severe infection called egg yolk peritonitis. This occurs when a “mistake” is made by the bird’s reproductive system and the egg exits the ovary but misses the lip of the infundibulum and enters the hens’ abdomen instead. This causes an infection in the abdomen and leads to death. Without the rest from egg laying that comes with shorter winter days the chance that this mistake of the reproductive system will occur rises.
While all of the previously mentioned issues directly affect the laying hens lack of much needed rest, this forced laying cycle can also directly affect the egg that we eat and subsequently the health of those that consume eggs from these hens. In a study completed by H. Paczoska-Eliasiewicz in 1998, it was found that there was an “increase of histamine production and concentration in chicken oviduct parts during the egg-laying cycle”. This histamine is passed through the shell and into the egg eaten by the consumer. According to a recent article in Medical News Today, increased histamine levels in the body can lead to “diarrhea, headaches, bloating, abdominal pain, nausea, flushing of the head and chest, congestion, dizziness, heart palpitations, low blood pressure, bronchospasms, and even shock”. (Huizen, 2021, p2).
Secondary molt in the cold winter months should also be a concern. Birds lose their feathers and regrow them over a period of several weeks, typically in early fall just as the daylight hours begin to shorten. With the use of artificial light, the molting cycle can be interrupted, and if the artificial light system fails, even for a short period of time, this can cause a secondary molt to occur. If this happens in the cold of winter, the risk of death due to exposure rises.
If the goal of the farm and the food system is production above all other concerns, the question of artificial light use in poultry houses may be moot. But if the goal is healthy animals that produce healthy food that lead to healthier humans, studies show that artificial light should not be used. The “rest period” for birds has a purpose and when that period of rest is removed, we compromise the health of the bird and the product sold to consumers.
It’s hard to improve on nature - the natural cycle of rest for birds protects their health, longevity, and is perfectly designed so that chicks hatch in spring and develop and mature during the warmer summer months. The quality of the egg produced and the quality of the life of the hen all depends on an unforced cycled of egg laying and the discontinuation of the use of artificial light in hen houses.
So do we lay off chicken egg consumption during the winter months? An argument could be made about us humans sucking it up and doing without instead of constantly demanding what we want, when we want it. There are some amazing plant-based egg alternatives being introduced into the market which might afford us the opportunity to have our cake and eat it, too.
At the end of the day—however early that might be—if we truly care about the welfare of our food makers and the quality of the food we’re consuming, it’s a conversation worth having.
Resources for this blog post:
Liu, L., Li, D., Gilbert, E. R., Xiao, Q., Zhao, X., Wang, Y., Yin, H., & Zhu, Q. (2015). Effect of Monochromatic Light on Expression of Estrogen Receptor (ER) and Progesterone Receptor (PR) in Ovarian Follicles of Chicken. PLoS ONE, 10(12), 1–14. https://doi.org/10.1371/journal.pone.0144102
Ockert, Katie. (2019). Decreasing Daylight and Its Effect on Laying Hens. Michigan State University Extension, 14(1-3). https://www.canr.msu.edu/news/decreasing-daylight-and-its-effect-on-laying-hens
Adekokum, S, Olojede, O. (2018) Optimizing Gastrointestinal Integrity in Poultry: The Role of Nutrients and Feed Additives. Frontiers in Veterinary Science 5, 1-2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6366008/
Lesley, C. (2021, April 20). Keeping Chickens Laying During the Winter: The beginner's guide. Chickens And More. Retrieved November 24, 2021, from https://www.chickensandmore.com/keeping-chickens-laying-during-winter/.
Paczoska-Eliasiewicz, H., Rzasa, J., & Mika, M. (1998). Changes of Histamine Concentration in Chicken Oviduct During the Egg-Laying Cycle. Journal of Veterinary Medicine Series A, 45(2), 69. https://doi.org/10.1111/j.1439-0442.1998.tb00802.x
