Egg shell full of value

By Vision Reporter

Added 31st August 2010 03:00 AM

MANY poultry farmers in Uganda consider egg shells as waste and usually throw them away. What these farmers don’t realise is that egg shells can be processed to provide minerals that can be used in chicken feed.

The Farm Expert

MANY poultry farmers in Uganda consider egg shells as waste and usually throw them away. What these farmers don’t realise is that egg shells can be processed to provide minerals that can be used in chicken feed.

Egg shells are rich in calcium, which is important in the growth of chicken. It is necessary in the strengthening of bones and the formation of egg shells.

Layers need a lot of minerals for their bones and for egg shell formation. In a layer chicken, an egg matures and is released from the ovaries without the hard outer shell. This is acquired at a later stage.

A lot of nutrients are required in the process of shell formation. Sometimes these nutrients are not sufficiently available in the chicken feeds but are readily available in egg shells.

So farmers can utilise the egg shells by grinding them and mixing them with chicken feeds.

A convenient source of egg shells in urban areas are the road side vendors who make egg omelette rolled in a chapattis (rolex) .

These rolex dealers, mainly the youth, use several trays of eggs everyday, and have problems disposing off shells. All a farmer needs to do is provide them a container where they can keep the shells to be collected later.

Other sources are restaurants and institutions like schools and the confectionary industry where eggs are consumed in large quantities.

The fear that feeding crushed egg shells to chicken will encourage them to start eating their eggs, or that the egg shells can transmit disease are unfounded.
Poultry feed should provide a source of energy that is rich in carbohydrates, fats, proteins and minerals.

The size of an egg is largely determined by the nutrients in the chicken feed.

Edward Kakonge is a
retired professor of biochemistry and animal nutritionist formerly at Makerere University

How an egg is formed
Anyone raising chickens for eggs should have knowledge of the female avian reproductive system so that he or she can understand any problems that may occur and how to correct them.

The female reproductive system of a chicken is divided into two separate parts: the ovary and the oviduct.

The ovary

It is a cluster of developing yolks or ova and is located midway between the neck and the tail of the bird, attached to the back. The ovary is fully formed by the time a chick is hatched. It contains tens of thousands of potential eggs (i.e. ova) which theoretically could be laid.

Most of these, however, never develop to the point of ovulation. So the maximum possible egg production of a hen is determined at the time it is hatched.

The female chicken’s reproductive system is sensitive to light exposure to light, especially the number of hours of light in a day. The release of the next ova typically occurs 30-75 minutes after the previous egg has been laid. If the egg was laid too late in the day the next ovulation will wait till the next day, and the hen will have a day when it does not lay.

The oviduct

It is the second major part of the female chicken’s reproductive system. The oviduct is a long convoluted tube which is divided into five major sections —the infundibulum or funnel, magnum, isthmus, shell gland, and vagina.

The infundibulum engulfs the ovum released from the ovary. The released ovum stays in place and the muscular infundibulum moves to surround it. The ovum or yolk remains in the infundibulum for 15-18 minutes. Fertilisation also takes place there.

The next part of the oviduct is the magnum. The ovum remains here for three hours during which time the thick white or albumen is added.

The third section is the isthmus. The developing egg remains here for 75 minutes. The isthmus (a narrow band of tissue connecting two larger parts of an anatomical structure) is slightly constricted. It is where the inner and outer shell membranes are added.

The fourth part of the oviduct is the shell gland or uterus. The ‘egg’ remains here for 20 plus hours. The shell, largely made up of calcium carbonate, is placed on the egg here.

The hen mobilises 47% of her body calcium from her bones to make the egg shell, with the diet providing the remainder (53%) of the calcium.
The last part is the vagina. It is made of muscle which helps push the egg out of the hen’s body. The bloom or cuticle is also added to the egg in the vagina prior to oviposition (the laying of the fully formed egg).

Online sources

Send your questions to

Egg shell full of value

Related Articles

More From The Author

Related articles