What causes "stress" in hens and what effect does it have on them?
There are many causes of "stress" in hens. We humans are used to discussing stress in terms of our mental health and although that certainly applies to our hens as well, there are also physiological causes of stress that may not be so obvious.
The following are examples of causes of mental stress in hens
Pecking order changes due to new birds or having to say goodbye to pen mates
Predator attack from foxes, rodents or hawks
Changes in environment, for example when housed or hen boarding
Changes in routine
During veterinary procedures e.g. medicating
The following are examples of causes of physiological stress in hens
Coming into lay for the first time at around 16-18 weeks
Peak lay, at around 27-30 weeks of age
Heat stress during hot weather
Sudden cold snaps of weather during the winter
Periods of illness
After veterinary treatments and procedures
Becoming broody
Being bullied
Moulting
Diagram illustrating the types of stress that can affect hens.
What effect does stress have on the body?
Stress causes chemicals in your hens body to stimulate the release more of the hormone corticosterone (like cortisol in humans). There is normally a low level of this hormone inside hens that is responsible for controlling energy intake, storage and mobilization.
During a short episode of stress, like when a bird spies a predator, corticosterone release helps the bird survive by "turning up" the immune system and muscle activity ready to fight or flight and "turning down" distractions like egg production. This is a helpful defence response.
Prolonged periods of stress can cause detrimental changes and is unhelpful. Their immune systems are most detrimentally affected leaving them susceptible to infection by viruses, bacteria, protozoa and worms that might try to take advantage of an "open door" resulting from poor immunity. Other organs that can be negatively affected by stress include the heart, reproductive system, gut, liver and spleen. A typical sign in hens is rapid deterioration in egg shell quality.
How can you manage stress in hens?
There are two ways to address stress levels in your hens.
1. Give hens stress-lowering phytogenics such as quality Passionflower and Chamomile extracts.
Passionflower: Studies have shown that extracts of passionflower can have anti-inflammatory effects in animals. There is also plenty of evidence that gamma-aminobutyric acid (GABA), an amino acid, acts on the brain to provide anti-anxiety effects.
Chamomile: Extracts have been shown to produce safe calming effects on the numerous body systems, including the central nervous system, skin, and gastrointestinal tract. These effects are brought about by its active ingredients of polysaccharides, phenolic compounds, terpenes and aromatic compounds.
2. Support the organs affected by stress - the immune system and the gastrointestinal tract.
Provide products that boost the immune system or provide anti-inflammatory and anti-oxidant effects.
Offer products that support the gut health such as quality organic acids, prebiotics and poultry probiotics.
How can you prevent stress in hens?
Excellent housing, husbandry and planning is the key to stress prevention in hens. Avoid stress where possible, and plan enact reduction and support strategies when inevitable stress is predicted.
References
Rostagno MH. Effects of heat stress on the gut health of poultry. J Anim Sci. 2020 Apr 1;98(4):skaa090. doi: 10.1093/jas/skaa090. PMID: 32206781; PMCID: PMC7323259.
Bokelmann, Jean M. Medicinal Herbs in Primary Care : an Evidence-Guided Reference for Healthcare Providers. Philadelphia, PA: Elsevier, 2022. Print.
