Mary Allen
With a 55 gram hen’s egg, the shell weighs around five grams. But what happens if the shell is of poor quality?
All bird eggs have a shell that encloses the contents. Because the hen’s egg is an important foodstuff for humans, demands are repeatedly made for an optimal structure of the shell and corresponding quality. The most important component of the eggshell is calcium in the form of calcium carbonate, which determines the thickness of the shell and the shape of the egg. The individual eggshell weighs about 5 to 6 grams and contains about 2 grams of pure calcium, although these values only apply to a normal laying hen with a bodyweight of 1.5 to 2 kilograms, while the data for various bantam breeds differ significantly.
The chicken absorbs the calcium with its food, and the calcium is first built into the skeleton. Only later does the hen remove the calcium for egg production. However, this metabolic system only works if the animal is optimally supplied with calcium, otherwise, more calcium is taken from the skeleton during laying than is built in again. Therefore, in the case of a calcium deficiency, the laying performance is first reduced and then the laying activity is stopped completely so that the skeleton of the chicken does not lose its stability.
Crushed Mussel Shells Provide Enough Calcium in the Chicken Feed
As an intermediate phase of incomplete calcium absorption, the eggs become thin-skinned and brittle. If this occurs in a laying hen farm, it is important to check the supply of calcium in the feed and especially the composition and amount of the feed components that contain calcium. The feed of laying hens must contain around four percent calcium. This value should be increased to 4.5 percent at the end of the laying period, with the most important source of calcium being the supply of minerals in the form of crushed mussel shells. The main component of the same is calcium carbonate, with the size of the crushed mussel shells being between one and two millimeters. That depends on the size of the chickens.
Adding organic acids to drinking water promotes the absorption of calcium. Ascorbic acid, also known as vitamin C, is particularly suitable for this purpose. In addition, ground limestone can also be used, but this is already in the finished feed. Any supplemental calcium should be offered in the late afternoon when the eggshell formation is at its peak. If this requirement is observed, it can be assumed that the shell will form evenly.
It should be noted that the content of chlorine ions in the feed does not exceed 0.4 percent, as otherwise, the chlorine with the calcium leads to an insoluble compound of both elements so that the calcium is no longer available for shell formation. This prohibits the feeding of salty household leftovers because then only eggs with a thin shell or even shellless eggs would be laid. As soon as too much chlorine is ingested with the feed and drinking water, an attempt can be made to improve the feed composition by adding sodium bicarbonate instead of table salt to make it more palatable for the animals.
An important component of the feed is phosphorus, but its amount in the total feed must not exceed 0.4 percent. Otherwise, calcium absorption will be reduced. Vitamin D plays an important role in calcium metabolism and it must be ensured that the required amount is provided with the feeding. Therefore, appropriate additives are mixed into the finished feed by the feed manufacturers, so that around 3000 to 4000 international units per kilogram are available. This amount is sufficient for normal circumstances.
The Chicken Processes about Two Grams of Calcium in the Shell for Each Egg Laid
Scientific studies have shown that adding calcidiol, the first metabolite of vitamin D formed in the body can improve calcium absorption in laying hens. However, problems can be caused by certain mycotoxins, primarily zearalenone, which bind the vitamin D in the feed so that it is no longer available for calcium metabolism.
The animal’s organism processes around two grams of calcium per egg in the shell – larger eggs, therefore, have a thinner shell compared to normal-sized eggs. This only applies to the commercially available eggs from commercial chicken farming.