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Considering the Egg Shell

By Russ Gillie

Egg shell is made up of the cuticle, a calcium carbonate layer and two shell membranes. About 10 000 pores on the shell surface allow air, but inhibit moisture and water passing through. The cuticle is the most external layer and is the first line of defence against water and to a certain extent any micro organisms that may come into contact with it. Washing or damaging the cuticle can facilitate a bacterial invasion. The shell itself is approximately 11% of the weight of the eggs and consists of 98% calcium. The other 2% being magnesium, potassium, nitrogen, amino acids, and acids, with traces of iron and sulphur. A total 17 amino acids are present, all within the cuticle and in very small percentages. Although at present the shell is considered a waste product, research is underway to process and use it as supplements for human consumption, calcium replacement being the most obvious use but other uses are possible. Easily digestible and almost supplying all the components in the right proportions for our birds to produce their own eggs, egg shell should not be a “maybe” in their diet. It is a necessity!! So don’t even consider the egg shell, just DO IT!!

Egg shell is made up of the cuticle, a calcium carbonate layer and two shell membranes. About 10 000 pores on the shell surface allow air, but inhibit moisture and water passing through. The cuticle is the most external layer and is the first line of defence against water and to a certain extent any micro organisms that may come into contact with it. Washing or damaging the cuticle can facilitate a bacterial invasion. The shell itself is approximately 11% of the weight of the eggs and consists of 98% calcium. The other 2% being magnesium, potassium, nitrogen, amino acids, and acids, with traces of iron and sulphur.
A total 17 amino acids are present, all within the cuticle and in very small percentages.
Although at present the shell is considered a waste product, research is underway to process and use it as supplements for human consumption, calcium replacement being the most obvious use but other uses are possible.
Easily digestible and almost supplying all the components in the right proportions for our birds to produce their own eggs, egg shell should not be a “maybe” in their diet. It is a necessity!!
So don’t even consider the egg shell, just DO IT!!

When I first started trying to breed Gouldians, way back in 1980, I did not have much success, until a good friend, Arthur Dare, told me that I could forget about breeding them without egg shells. Obviously there are many other factors that can affect breeding these birds, for example cleanliness, water, soft food, light, seed mix, sprouted seed, housing, nest boxes and nesting material, to name some. All of the above are controllable, but one major factor beyond our control is the weather.

About 5 years ago I started feeding calcium powder in the soft food, enabling me to withdraw the egg shells which were very labour intensive in their preparation. A huge problem developed with egg binding, but it was not caused by the bird being unable to expel an egg, rather it was that the bird was trying to pass an egg that had little or no shell. When I took my problem to the Society, no-one was sure how much calcium powder was needed to replace the calcium derived from the egg shells, but it was obvious that lack of calcium was at the root. Extra calcium was then added to the soft food and no improvement was noted. The calcium powder was increased yet again but the problem then became so bad that hens started dying with egg sacs stuck in the oviduct; anyone can imagine the muscular activity involved in moving a normal egg down the duct and laying it, but if there is no shell the sac just contracts, reforms in its old shape and does not move anywhere. The energy expended, the stress, and the build up of faeces behind the blockage not only can, but does kill hens. I know! It happened to me.

When my problem was at its worst, Dave Dennison, together with two of his senior bird nutritionists, coincidently held a talk at Le Grange Bird Park in Boksburg, and I took the opportunity to bring up my predicament. After explaining the circumstances, I learnt that without potassium and to a lesser extent, magnesium and phosphorous, the calcium cannot be processed into an egg shell. Too much of one nullifies the others and the result is the same as not enough calcium : ergo, no egg shell.

At this stage all calcium powder was withdrawn and egg shell was introduced. At the same time I started feeding a product called Plume Plus twice a week. Plume Plus contains a mixture of five different oils with added vitamin E, making it an aid to feather condition, fertility and laying. This whole situation was en expensive experiment not only in the loss of five hens, but the set back to the breeding season cost an estimated 30 – 40 fertile eggs. Within two weeks the season was back on track and the school fees had been paid. Lesson learnt!

My egg shells are first skinned, then dried before storing them in a plastic container until needed. I am lucky to have a small garden restaurant collect their egg shells for me and when they arrive home they are soaked in cold water for about an hour. Hot water tends to cook the membrane making it brittle, whilst the cold softens it, making it easier to extract.

I have found out over time that the fresher the egg, the easier the membrane comes out; also the half that has the air pocket is easier than the other half. There must be some reason for going to all this trouble, and that is a bacterium called salmonella. The bacteria can occur under the membrane of the chicken egg and by removing this protection, the bacteria is exposed to the air where its life is significantly reduced. The other reason pertains to the source of the shells, where they may have been exposed to all sorts of other bacteria, viruses and fungi, so it makes sense that the cleaner they are, the safer they are. Salmonella itself is a major cause of food poisoning in humans and we know what the effect is, but in a small bird, it kills. Egg shells are not the only source of the bacteria. Rats and mice are a major cause of salmonella and must be eradicated at the first signs of their presence.

Symptoms in nests include dead chicks on pipping, smelly wet nest, red coloured dehydrated nestlings, babies dying up to 5 days old. In juveniles watch out for watery eyes, nasal discharge, smelly pasted vents and conjunctivitis to name some. Baytril is a good treatment against salmonella, but the cause of the problem must be eliminated. Treatment should be continued for 10 days and the housing and utensils must be disinfected.

Just in case any of the nasties have survived, the egg shells are popped in the microwave for five minutes on high before feeding them to the birds. Some say that the microwaves do not reach all parts of the shells allowing some of the bugs to survive, but believe me, when I say that after their five minutes they are too hot to touch. Personally I cannot see anything living through that. Others bake them in an oven at 180 degrees for 30 minutes, whether skinned or not (a personal decision), whilst I have heard of one person who feeds the shells absolutely fresh saying that the birds actually drink the residue of white. Another treatment is to boil them, dry the shells and feed them in a crushed state. I feed the shells in large pieces as smaller ones just fall through the bars in the bottom of the cages. I have tried feeding them in finger feeders, finely crushed, but the resultant wastage as the birds scratched around, made all the preparation time seem squandered.

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