The Calcium Carbonate Content of White to Brown Eggshells Essay

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The concepts of eggshell qualityA good quality eggshell should contain, on average, 2.

2 grams of calcium in the form of calcium carbonate. Approximately 95% of a dry eggshell is calcium carbonate and has a typical mass of 5. 5 grams, although these values can differ depending on sources. The remaining mass is composed largely of phosphorus and magnesium, and trace amounts of sodium, potassium, zinc, manganese, iron, and copper.

If the calcium from the shell is removed, the organic matrix material is left behind.

This organic material has calcium binding properties and its organization during shell formation influences the strength of the shell. The organic material must be deposited so that the size and organization of the crystalline components (calcium carbonate mostly) are ideal, thus leading to a strong shell. The majority of the true shell is composed of long columns of calcium carbonate. There are other zones that are involved in the self-organization giving the eggshell its strength properties.

Thus, hell thickness is the main factor but not the only factor that determines strength. Presently, dietary manipulation is the primary means of trying to correct eggshell quality problems.

However, the shell to organic membrane relationship is also critical to good shell quality and should be considered. 2. 2 Structure of an eggshellFig. 1: Structure of the egg shellThe small amount of organic matter mostly consists of matrix proteins (mixture of proteins and polysaccharides rich in sulphated molecules) and shell pigment.

The matrix proteins are critically important in determining the egg shell structure and serves as oundation for the deposition of calcium carbonate. There are about 8000 microscopic pores on the shell. The outer surface of the shell tself consists of a mucous coating (cuticle) which is deposited on the egg Just prior to the lay. This proteinous covering helps to protect the interior content of the egg from bacterial penetration through the shell.

2. 3 How calcium influences shell quality? Both excess and deficiency of calcium will negatively affect the shell quality.

An egg contains almost 2 grams of calcium; hence, an average of 4 grams of calcium intake per day is required by a layer to maintain a ood shell quality, since only 50 – 60% of dietary calcium is actually used in shell formation. Calcium requirement of a laying hen is 4 – 6 times that of a non-laying hen.

The egg enters the shell-gland region of the oviduct (the uterus) 19 hours prior to oviposition, and the shell does not store calcium ions to attach on protein matrix. During the last 1 5 hours of shell formation, calcium movement across the shell gland reaches a rate of 100-150 mg/hr.

This process draws calcium from two sources: diet and bone. Normal blood calcium level is about 20 – 30 mg/dl with a normal layer ation of 3. 56% calcium or higher, while layers on a 2% calcium diet, 30- 40% of the a high level of calcium to store it on body.

Intestinal absorption of calcium in the diet is about 40% when the shell gland is inactive, but reaches 72% when active. This time closely coincides with late afternoon or the dark hours for the layer. Having higher calcium levels in the gut during this time is important to ensure calcium is being taken from the diet and not bone.

Large particle sizes of calcium sources allow calcium to be metered throughout this time. In growers, most importantly, high alcium levels during the growth period will interfere with the proper development of the parathyroid gland by increasing gut pH, which will decrease absorption.

The damage to the parathyroid would be permanent and would affect the bird’s laying cycle afterwards. 2. 4 Differences in white and brown eggshellsThe color of the eggs is nothing more than a result of a different breed; and the quality, nutritional value, and taste are identical between white and brown eggs, though two notable differences are size and price.

Brown eggs are usually larger and slightly more expensive. The reason for the price increase is because brown eggs come from larger hens, which need to be fed more food daily.

With a larger intake of calcium each day, one might expect the produced egg to have higher calcium carbonate content. However, large sized eggs will usually break more easily than small ones. The main reason for this is that the hen is genetically capable of placing only a finite amount of calcium in the shell. As the hen ages and the eggs get bigger a similar amount of calcium has to be spread over a larger surface.

Therefore, controlling the rate of egg weight change can nfluence eggshell quality as the hen ages.

A brown eggshell has increased tendency to break, when compared to white, is often attributed to this thinning out of calcium during deposition. 2. 5 Eggshell quality and economicsPoor egg shell quality is a huge hidden cost to the egg producer. Estimates are that more than 10% of eggs produced in the hen house are uncollectible or break before intended use. The first 2-5 percent is lost simply due to form which may be shell less, cracked or broken to the extent that they are not suitable for collection.

Another 3-8 percent is lost during collection, moving through he belts, cleaning, packing and transportation to the end user. Because the first 2-5% loss is due to uncollectible eggs, most egg producers often estimate their egg loss due to poor shell quality at only this percentage, which is most likely an underestimation. Even a 5 percent loss could be as much as about 2. 7 million/year for 100 thousand layer house. The economic losses for the breeders will be even more due to reduced hatchability and chick livability. Therefore, every effort must be directed towards improving shell quality and reducing egg breakage.

METHO . 1 DesignThe major component of eggshells s calcium carbonate (CaC03). The analysis of quality of the eggshells will be done volumetrically by using a characteristic reaction of carbonate compounds, namely their reaction with hydrochloric acid. Calcium carbonate (limestone) is very insoluble in pure water but will readily dissolve in acid according to the reaction:2HCl(aq) + titrate the calcium carbonate because it is very slow when the reaction is close to the endpoint.

Hence, a procedure, called a back titration must be carried out.

This is achieved by adding an excess of hydrochloric acid to dissolve all of the calcium arbonate and then titrating the remaining H30+ with sodium hydroxide solution to determine the amount of acid which has not reacted with the calcium carbonate. The difference between amounts of the acid (HCI) initially added and the amount left over after the reaction is equal to the amount used by the calcium carbonate. The reaction used to determine the leftover acid is:HCl(aq) + NaOH(aq) ”+ H20 (l) + NaCl(aq)Aim: to determine the mass percent of calcium carbonate (CaC03) in different types of the eggshells (white and brown).

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