Seashells are a great source of calcium for laying hens, but can they also aid digestion? What are the key problems caused by a lack of grit? What do we mean by digestibility and how can farmers best use seashells to enhance feed use efficiency in poultry?
Feed costs are the biggest single item within a producer’s overall costs, and there is a wide variation in feed to egg conversion ratio (FCR) efficiency between individual hens. Improving feed efficiency can help to significantly reduce the costs of poultry production and the environmental impact of poultry production.
In addition to improved production and economic performance, increased digestive efficiency also improves environmental performance – in terms of increased eggs and meat per kg CO2 emitted. This is becoming increasingly important as more and more producers are looking to become carbon neutral.
What do we mean by digestibility?
When discussing animal diets, efficiency and performance, the terms solubility and digestibility may easily be mixed or misunderstood. Solubility is the degree to which the food breaks down to smaller particles, for example, how much protein breaks down into amino acids. Digestibility is the amount that is absorbed by an animal and therefore affects the availability of nutrients for growth, reproduction etc.
Hens lack teeth and so their digestive system must be able to process un-masticated food. A bird’s stomach has two chambers: the proventriculus, where gastric juices are produced to digest food before entering the stomach, and the gizzard, where food is stored, soaked, and mechanically ground. Thus, hens swallow stones or grit, which are stored in the gizzard, to aid the grinding process. It has been known for a long time that grit can improve the digestive performance of chickens.
Crushed up seashells are often used as grit. However, there are two types of grit:
- Soluble grit – includes shell grit, crushed seas shells. They offer slow-release calcium.
- Insoluble grit – includes tiny rocks and pebbles to aid digestion.
This is where solubility is important. Larger limestone particles have a lower in vitro solubility and are retained in the gizzard for a longer time1, this results in more calcium being available for the laying hen2.
Grit helps to improve digestibility, and feed efficiency, a Lack of grit can result in as much as 20% greater feed consumption3. Poultry fed grit have gizzards that are as much as 50% larger than those not fed grit. This results in a more powerful masticating muscle and, consequently, better digestion4.
Digestive problems due to a lack of grit
Feeding grit to chickens can help prevent a range of health problems.
- One of the most common digestive problems in laying hens is an impacted crop, caused by blockages. This can be caused by tough stems of woody grass or other things that get stuck such as bailing twine that cannot pass from the crop down into the proventriculus.
- A pendulous crop is also when the crop gets blocked, but the weight of the food stretches the chicken’s crop so that it hangs down lower than it should (and often swings ‘like a pendulum’ as the bird moves around5. Preventing an impacted crop is much easier than treatments, thus adequate insoluble grit must be provided to birds to help digest feed and grass6.
Seashell grit is also a vital source of calcium for laying hens. Calcium and phosphate deficiencies can lead to abnormal skeletal development, chickens that are unwilling to stand due to weak bones, or rickets in the growing chick, and osteoporosis in older birds.
How can farmers best use seashells to enhance feed use efficiency in poultry?
For optimum use of seashells as a grit producers need to consider the following factors:
- Are the birds kept indoors or free-range?
- Particle size;
- Method of feeding e.g., on top of the feed or separately;
- Time of feeding, day, or night.
Free-range hens will find and peck at tiny rocks, pebbles, and large grains of sand. These are insoluble shell grit for poultry and aid digestion by assisting the grinding of food in the gizzard. However, free-range chickens are not always kept on land containing the right sort of grit, so it’s always a good idea to provide a chicken grit feeder just in case. Indoor chickens cannot find their grit, so they will need it to be fed to them.
The finer the grit, the faster it is absorbed. However, we want the hen to still access and digest the shell grit after she’s retired for the evening to the chicken coop. So, it pays to ensure that grit particles are not too small.
Grit is often needed at different times to other feeds, so grit is best fed in a separate hopper, so birds can take what they need when they need it. By doing this you know what the hens are eating which helps with making sure you have enough grit available throughout the year.
Overall growing birds, as well as adult birds, are partial to insoluble grit, particularly if you are feeding whole grains. Chickens also need slow-release sources of calcium, such as Morgan Agro’s seashells. Therefore, stick to a balanced diet supplemented with seashells.
Where to buy Seashells?
Morgan Agro provides the highest quality seashells from the Caspian Sea. Our Seashells are a healthy and effective alternative to limestone, oyster shells and crushed eggshells as a calcium source and can help improve hens’ digestion and the economic performance of laying hens. If you are a feed manufacturer, supplier or poultry farmer interested in what our product can do to improve laying hen performance and nutrition then please contact us for samples or more details.
- Zhang and Coon, “The Relationship of Calcium Intake, Source, Size, Solubility In Vitro and In Vivo, and Gizzard Limestone Retention in Laying Hens.”
- Morgan Agro, “The in Vitro Solubility of Morgan Agro Sea Shells in Relation with the Egg Shell Quality of Laying Hens.”
- APPPA, “Comprehensive Guide to Feeding Grit to Pasture-Raised Chickens, Turkeys, and Poultry.”
- Daniels, “Pendulous Crop.”
- The Chicken Vet, “THE ADVICE HUB IMPACTED CROP.”
- Digestive system image saved from: https://courses.lumenlearning.com/bccc-bio101/chapter/digestive-systems/