The Importance of Calcium for Laying Hens
by Alexa Lehr | The Pioneer Chicks | September 12, 2023
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The homestead flock needs to have a balanced and nutritious diet in order to stay healthy and productive. One of the most important dietary elements in a laying hen’s diet is calcium. Calcium is not just used for making eggshells and keeping bones healthy. You may be surprised at all the other functions it plays in the health of a hen! Knowing the importance of calcium for laying hens will help you raise a healthy, productive homestead flock! Let’s go over the role of this essential dietary element and how you can ensure your flock is getting the calcium they need during all seasons on the homestead.
Why is Calcium Important for Hens?
As you may already know, an eggshell is composed of mostly calcium. Which means, a hen needs a source of calcium in her diet in order to form strong eggshells. However, calcium is not just needed for making eggshells, it also has a variety of other important functions. Here are just a few important roles calcium plays in a laying hen’s body:
- helps with blood clotting– important for when birds get injured
- helps maintain a healthy nervous system
- important for controlling muscle spasms- especially the ones that occur when a hen is laying an egg
- activate enzymes in the digestive system
- essential for bone growth
- essential for proper eggshell formation
- important for breeding hens to lay strong eggs for hatching
- helps the body maintain a proper pH level
- helps control the heartrate of a laying hen
- promotes hormone production for proper reproductive functions
- is needed for the absorption of phosphorus
As you can see, calcium is important for reproductive health. But it also plays a role in nervous system health, digestive health, and proper growth.
Do Chicks Need Calcium to Grow?
One function of calcium that often gets misconstrued is the vital role it plays on growth. Calcium is needed for proper bone development, which is important for growing chicks.
It can get confusing when you read that chicks should not be fed laying hen rations due to the high calcium levels. You would think that since they are growing, they would need a lot of calcium, right?
Actually, the amount of calcium needed for proper growth is less than the amount of calcium needed for the everyday production of an eggshell. Protein is another essential factor in chick growth. Growing chicks need more protein than laying hens. That’s why chick starter feed is high in protein and lower in calcium.
Chicks do not need supplemental calcium, but laying hens do. Let’s find out why!
How is Calcium Digested?
Learning how a hen uses calcium is key to understanding why hens rely so much on supplemental calcium in their diet. Laying hen feed is already higher in calcium than any other chicken feed. So why would they need even more supplemental calcium?
Here’s how it works:
- Storage– Calcium absorbed from the diet is stored in the medullary cavity of the hen’s bones.
- Availability– This storage method allows the calcium to be immediately used for eggshells then replenished by the diet.
- Use– For the creation of an eggshell, calcium is released into the blood stream.
- Function– This triggers the kidneys to stop excreting extra calcium. Instead, they conserve calcium for replacing the calcium released into the blood stream.
- Replacement– Calcium is then drawn from foods in the diet to help replace the used calcium.
- Repeat– Then the ovaries release estrogen which sends a signal to the body to start making more medullary bone to store more calcium.
This constant cycle of calcium use, absorption, conservation, and bone development is what makes calcium so important in a laying hen’s diet.
When a hen starts laying, her need for calcium increases by four times the normal amount for daily survival! That’s because an eggshell is composed of 90% calcium. That calcium is drawn from the bones (medullary bone) which then triggers a need for new bone growth. Bone growth and development also requires calcium. When a hen is building both eggshells and bones, she is going to need supplemental calcium in her diet!
To make things more complicated, calcium cannot work by itself. It must be accompanied by phosphorus and vitamin D in the diet in order to be metabolized.
Calcium & Phosphorus
Phosphorus and calcium have an intimate yet fragile relationship with each other. Phosphorus binds to calcium. An imbalance in one ultimately causes an imbalance in the other. Both are needed in order for each other to be metabolized by a chicken’s body.
Since phosphorus is essential to the absorption of calcium, it also has similar roles as calcium. It helps with bone development, but it also plays an important role in the digestion of carbohydrates and fats. Phosphorus is also needed for balancing the pH levels in the body.
As for sources of phosphorus in a hen’s diet, grains are naturally high in phosphorus. Unfortunately, very little of plant-based phosphorus is available for absorption. Organ meats, muscle meats, and fish provide phosphorus that is readily available for digestion.
Calcium & Vitamin D
Vitamin D is essential for the usage of both calcium and phosphorus. It must be present in the diet in order for both calcium and phosphorus to be metabolized.
Vitamin D helps regulate the excretion of calcium for making eggshells. It is the controlling factor in whether more calcium is absorbed into the blood stream (sourced from the bones) or whether calcium absorption is decreased to help resupply the bones. Vitamin D monitors this intricate balance by regulating the plasma calcium in the blood.
Vitamin D is a fat-soluble vitamin, which means it can be stored in fat within the hen’s body. Once vitamin D is absorbed from the diet via the intestines, it is then transported to the liver where it is stored. When it’s needed to help with the metabolism of calcium and phosphorus, the kidneys trigger vitamin D secretion.
How to Give Chickens Calcium
A hen’s calcium needs vary depending on age, diet, rate of lay, environmental factors, and overall health. Grains are naturally low in calcium, so feed manufacturers have to add a source of calcium to the feed mixes. Laying hen feed contains a base amount of calcium. However, since calcium needs vary depending on the bird, free-choice supplemental calcium must also be provided.
You can provide a free-choice calcium supplement in a supplement dispenser that is separate from your flock’s daily feed. I like to use stainless-steel rabbit feeders as calcium supplement dispensers. The hens then consume the supplement particles as needed and I refill the dispenser whenever it gets low.
Supplemental calcium allows each hen to meet her individual calcium needs. Here are some factors that cause calcium needs to vary.
Calcium Need Factors:
- Age: Older hens need more calcium since their medullary bones are more depleted.
- Diet: Diets that are diluted (excess snacks or treats) will cause a hen to eat more supplemental calcium.
- Good Layers: Hens that lay regularly will need more calcium than poor layers.
- Season– High production seasons, like spring and summer, will cause a hen to need more calcium since she is laying more regularly.
- Weather: Warm weather can be an inhibitor to calcium absorption, thus increasing calcium needs.
- Disease: Kidney and liver diseases can cause poor absorption of calcium, phosphorus, and vitamin D.
- Health: Poor digestive health will cause an increased need in calcium.
Some of these factors we can prevent, such as maintaining a healthy flock and feeding them a well rounded diet. Other factors cannot be controlled, such as natural aging and rate of lay. That’s why providing free-choice supplemental calcium is so important.
It is interesting to note studies done on ground-raised hens. They show that hens who are raised on the ground or in a pasture-like setting eat less supplemental calcium. The theory is that they are able to reuse calcium and phosphorus through coprophagy, or eating their own poop. I’m not sure if this true, but I do know that free-range hens can find their own sources of supplemental calcium while out foraging.
Calcium Supplement Tip: Size Matters
The particle size of supplemental calcium is important. Supplemental calcium needs to be provided in fairly large particle sizes. This ensures that it stays in the digestive track for a longer period of time. The longer it’s in the digestive track, the more completely it can be absorbed. However, the particles still need to be small enough for the hens to be able to swallow them.
If you buy crushed oyster shells, you will notice that the pieces are larger than say grit or pieces of grain. These size pieces allow for a trickle of supplemental calcium to be absorbed in the digestive system and added to the diet.
Calcium Supplement Tip: Phosphorus and Vitamin D
Calcium can’t be utilized without phosphorus. Neither calcium nor phosphorus can be absorbed without vitamin D. It would make since than that these two elements need to be supplemented as well. Grains do contain phosphorus. However, most of that phosphorus is unavailable for digestion.
Most laying hen feeds have the correct amount of phosphorus and vitamin D added to compliment any supplemental calcium that is consumed. Free-ranging or giving your flock healthy treats can also help supplement some phosphorus and vitamins into the diet.
For a complete list of supplemental calcium sources, download this free printable! It contains daily supplements you can provide for your hens. It also has a list of phosphorus and vitamin D sources!
Calcium Deficiencies & Excesses
When talking about supplemental calcium, it would only be right that we discuss calcium deficiencies and excess calcium.
A deficiency usually occurs when a hen does not consume enough supplemental calcium to meet her needs. Some of the factors we discussed that cause varying calcium needs can also be a cause of a calcium deficiency. Signs of a calcium deficiency include:
- thin shelled eggs
- abnormal skeletal development- more apparent in growing chicks
- rickets- which is actually a deficiency in vitamin D
- osteoporosis- when too much calcium is removed from the bones
- feather loss
- egg eating- as hens try to add more calcium to their diet
A deficiency in calcium, and likewise in phosphorus, can cause hens to stop laying. It also decreases their immunity to disease and parasites. Healthy hens should not have a problem with calcium deficiencies. Especially if they have access to a quality free-choice calcium supplement.
Excess calcium can occur when a hen consumes too much supplemental calcium. She may not use the extra calcium she consumes. Signs of excess calcium include:
- hypercalcemia- causes damage to the heart and other organs, is toxic to the liver, and causes the kidneys to calcify (gout)
- rough eggshells- may appear as small bumps on the shell
The kidneys are in charge of removing excess calcium and phosphorus. This usually is done through the excretion of feces. In general, a deficiency in calcium is more common than an excess of calcium in the diet.
Summer Calcium Needs for Hens
A change in calcium needs often occurs during the summer. Not only are the hens laying regularly, but warm weather can also inhibit calcium absorption.
When a hen gets hot she pants as a method of cooling down. Panting increases the respiratory rate. This in turn removes carbon dioxide from the blood stream. A decrease in carbon dioxide causes the body’s pH levels to increase. Increased pH levels reduces the amount of calcium in the blood since the calcium is used to balance the pH levels.
For a more in-depth study on how calcium, pH, and vinegar relate, check out How Vinegar Affects Chickens. Electrolytes are a beneficial supplement to add to your flock’s diet during the summer. They help keep hens from becoming deficient in calcium by balancing out electrolyte and pH levels in the body.
During the summer hens also tend to eat less feed. This means they are consuming less calcium. Check out What to Feed Chickens During the Summer to find ways to help your flock get the proper nutrition they need during the summer.
Calcium: The Essential Supplement
Calcium is an essential part of a laying hen’s diet. Hopefully you now have a better understanding of why calcium is so important for the homestead flock. Calcium helps with proper eggshell development. However, it is also essential for overall health and body functions. Ensuring your hens have access to supplemental calcium all year round will keep them healthy and productive! A free-choice calcium supplement should be supplied alongside your flock’s daily feed.
Crushed oyster shells are the best free-choice calcium supplement for laying hens.
Being knowledgeable about the health and well-being of your flock is an important step in becoming a modern pioneer. For more tips on living a modern pioneer lifestyle and caring for a flock of homestead chickens, make sure you join our modern pioneer community! We would love to have you along as we journey towards self-sufficiency together!
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