Avian Nutrition: Calcium

[Snowbird]

Calcium is the most prevalent mineral in a pigeon’s body and is required in the diet in a greater amount than any other mineral. The chick needs calcium for skeletal mineralization and the egg laying hen has a higher demand for egg formation. From a nutritional viewpoint calcium is the most challenging mineral, because the requirement is extremely variable, depending on the bird’s physiological state, and because many foods are likely to be deficient in calcium. Feral pigeons, for example, have periods of very low calcium consumption and periods where calcium may be 5% to 8% of the diet—and higher in chicks. Calcium is one of the most metabolically active minerals and its metabolism is tightly regulated.

Absorption: Dietary calcium is absorbed from the duodenum and the jejunum (beginning of the small intestines). The efficiency of absorption is controlled by the levels of the parathyroid hormone vitamin D3. When dietary levels of calcium are low, most calcium is absorbed by active transport. Without getting into the how active transport works, a low-calcium diet requires D3, but calcium rich diet uses diffusion-based pathways that are Vitamin D-independent.

Calcium is absorbed in the ionic form (it has a positive charge) and inorganic forms such as calcium carbonate, limestone, oyster shell and phosphates are readily solubilized in the acidic environment of the gizzard and the stomach. Liquid forms are more soluble and thus more readily absorbed as are powdered solid forms (hawks and falcons need an especially acidic stomach environment to make the calcium in large bones bio-available and pigeons need time with large grit in the gizzard). Free fatty acids may form insoluble soaps with calcium, inhibiting its absorption. Phytic acid exists in some plants and seeds and these compounds can complex calcium and also complex calcium from other foods consumed at the time and renders them poorly digestible (1 mol of phytic acid can complex up to 6 mol of calcium to form insoluble phytates).

Metabolism: Calcium constitutes more than a third of the total mineral content of an adult bird. The skeleton contains about 98% of a birds calcium, most of which is in the form of a chemical called hydroxyapatite. Bones not only serve a structural role but provide a pool of calcium, phosphate and other compounds. Though the hydroxyapatite form provides structural rigidity in bones it is also readily solubilized to provide minerals elsewhere in the body. Contrary to popular belief, the proportion of the body weight that is the skeleton is similar in birds and mammals. The required lightness of birds is achieved through design solutions not a loss in bone mass (teeth are not needed if you have a crop and a gizzard; a keel replaces a full rib cage, etc.). Across avian species, the proportion of body weight that is comprised of bone increases with size.

In the hen, 25% of the calcium in the blood is free ionic Ca (+2), and the balance is bound to proteins (albumin), or complexed with citrate, phosphate, or sulfate. The low levels of calcium in the plasma of non laying birds are precisely regulated, because of their important role in intracellular communication, macro molecular interactions and blood clotting. This regulation is accomplished by the Vitamin D endocrine system.

Information on skeletal development and egg development (Medullary bone; shell gland; embryo metabolism) may be forthcoming if there is an interest.

Calcium Requirements: The maintenance levels for birds are not precisely known, but granivores such as pigeons usually are not deficient since phosphorous levels of seeds are also low (not to mention supplementation). Note: high calcium increases the need for phosphorous, iron and manganese.

Calcium requirements for growth are very high—turkey poults require 12% dietary calcium for the first six months and the maintenance requirement at six months drops to 0.55%. Altricial birds, like pigeons (born blind, naked and helpless), have skeletal growth rate considerably higher than other kinds of birds (precocial) but the experimental work has not yet been done to establish the precise requirement, but pigeons must eat more than seeds to meet the demands for growth. Supplementation in feral pigeons is done with mollusk shells (documented 35 kinds of mollusks consumed by feral pigeons), egg shells, bone fragments, dirt—always see them pecking selectively at dirt.

Egg Laying: Small birds have a higher calcium demand than large birds—perhaps pigeons are somewhere in the middle of this reckoning. I don’t know precise pigeon requirements, but continuous daily egg production in poultry, ducks, quail and pheasants requires between 2.25% to 3.25% calcium in grain based diets. An altricial bird like a pigeon will be less (Budgies can lay large clutches with normal shells with as little as 0.8% calcium in the diet). There is no physiological need to have hens sit on fake eggs—there is no calcium deficiency concern with a continuous egg laying pigeon hen with decent nutrition. Growth of the chicks is another matter (see above).

Deficiency: A calcium deficiency may occur due to low calcium or to excess dietary phosphorous (Calcium to phosphorous ratio is OK between 1.4:1 and 4:1). Insufficient Vitamin D3 may cause a secondary calcium deficiency by impairing calcium absorption and bone formation. Increasing the calcium in a secondary deficiency does not solve the problem but supplementing D3 will (drop of cod liver oil rubbed into the seed, flax seed, etc.).

Deficiency will lead to bone mobilization, malformed bones, weakened, porous bones, skeletal abnormalities in chicks, an osteoporosis-like condition in laying hens, decreased egg shell thickness, fewer eggs,

Toxicity: When dietary levels of calcium are in excess, absorption is minimal and the excess is excreted in the feces. Prolonged dietary excesses can lead to hypercalcemia, rickets, gout and nephrosis (kidney problems).

Secondary problems occur with excessive calcium when the digestibility of other nutrients is compromised including phosphorus, magnesium, manganese, and zinc.

[Trees Gray]

Snowbird,

Thank you for this very informative information about calcium.

I guess the best way for our pigeons to consume calcium, is giving it to them in its most natural state, therefore insuring that the other minerals will be there in proportion to allow maximum absorption, like kale, spinach, and other vegies, pick cake, etc. Also, vitamin C helps absorption of calcium. Fatty diets also decreases absorption of calcium. I would still use liquid calcium gluconate if I needed to help a severly depleted hen, for emergencies. I feel sorry for the feral pigeons that have to resort to eating scraps from the McDonalds and fried chicken stands.

Was there a study done that proved that hens could lay egg after egg without losing their calcium reserves when given a nutritious diet? I may believe it, but I'm still not taking the dummies away from my hens not for physiological reasons, but for their psychi. It is such a major head trip when they are sitting on eggs, that is their life's work and they are so intent and serious when they are sitting on their eggs.

Treesa

[Snowbird]

Don't have the breakdown of nutrients for all the vegetables we feed our birds, but I would agree that there is a better chance to balance the mineral content in the diet with nature sources, and since the requirements differ with species and the composition differs with plant species--I give the birds a variety so they have tools to strike the balance.

Yes the liquid would be the most bioavailable along with a powdered grit in solution.

As long as the soil is not decalcified by acid rain, which limits the calcium in any plants grown on such soil, or all the snails are wiped out, the ferals outside of the inner city are in good shape for calcium. It would be interesting to ask a pigeon what she gets from McDonalds and fried chicken stands. Generally it's just a lack of calories.

There is no study about pigeons that I know of on calcium requirements of egg laying hens. There is tons on chickens since cash is king. Pigeons have a lower requirement for calcium because they are altricial and don't need a big egg, but a higher requirement than chickens because they are smaller (the smaller the bird the higher the calcium requirement).

The psychology is definitely another real issue and I'm speaking only to the phsysiological. A short explanation which could be developed further:
'The number of eggs that could be synthesized by utilizing all the calcium in the entire skeleton is about five for Zebra Finch and ten for chickens. When fed adequate levels of dietary calcium, these birds are capable of laying continuously for many weeks with little or no loss of skeletal mass." This is from Comparative Avian Nutrition by Kirk Klasing (Chair at UC Davis Avian Sciences Dept.). And my Zsa Zsa, who just had her sixth clutch this season agrees, though she looks for calcium for a couple of days around egg laying.

[TerriB]

Interesting information, especially the interaction of calcium with the different minerals. Since I started offering several different pickstones and mineral powders, the grit container doesn't get much activity.

[Trees Gray]

I've noticed my hens will hit the pick cakes more then the males, yet they all consume the grit as well as all the greens provided them.

I think inactive hens also have a loss of calcium, due to lack of excercise. The supportive muscle tissue around bones is important also to maintaining normal calcium levels. Muscle has to be excercised or it turns to fat!
I'm not joking about this either.

Treesa

[Snowbird]

More and more I see studies that say exercise is among, if not the most important element of a healthy life. That's an advantage for a feral pigeons and a disadvantage for humans and their home birds--we have to make an effort to get regular exercise--our bodies evolved to do work and use or lose it is no bull****.

An addendum to the value of vegetables--not only are they likely to be balanced better in terms of interbiochemical activity, but they have so many unknown benefits. Recently birdy showed me that article that three day old brocolli sprouts have 50 times more of a cancer fighting compound, and recently that study came out about how cilantro is far more powerful against paratyphoid then standard antibiotics, and before that it was shown that the Allicin in fresh garlic has a broad spectrum of activity against bacteria, virus, and protozoa. No resistance can be built up so it is an absolutely safe to use. My assumption is that other notable benefits will be discovered in the green world.

[Trees Gray]

..."recently that study came out about how cilantro is far more powerful against paratyphoid then standard antibiotics" ...

There are 4 advantages to using natural/homeopathic method for healing. 1.You don't have to get a prescription to get it as you can get it in your local health food store. 2. There are no side effects3. You can't overdose 4. When using more then one remedy, no worry about one counteracting the other.

I use garlic as a daily remedy for all rehabbing birds. It has great results with only one side effect...the smell!! the aroma...LOL

I have also recently been informed about a natural remedy for Pox.

Treesa

Good info! I agree with everything you've said Treesa...from the all natural means to the wooden eggs....I figure it's the least I can do for them since they can't have babies. It is part of their well -being...to be able to mate, make a nest-brood, etc.and from what I've read, it helps prevent egg-binding.

I am inclined to think that's maybe why my birds became ill...lack of exercise. Having them in for about a year, they did lose a lot of breast muscle. I also found out that some of my seed was bad (brand new out of the bag) so this probably led to it as well.

I have about three more weeks of antibiotics for my pigeons and my pet starling and just finished my meds for the Chlamydia Psittacosis. This was an ordeal...let me tell you.

[Trees Gray]

Hi Donna,

Glad you are on the mend.

I'm glad you resolved the health issues in your coop.

I'm also inclined to think not only do pigeons need excercise for healthy bones and general health, but also not-overfeeding is another big issue.
I have had to cut back, so there is just a llittle tiny bit of seed left after each meal. These are issues we all face with domestic and "pet" pigeons.

Pigeons were born to fly, and lack of excercise is defenitely not a problem for the feral pigeons, lack of food nutrtitious is one major issue for a lot of them.

Treesa

[NumberNine]

Brought back to the top.

It is a shame that those who are responsible for pigeons.com do not create a folder with all the must-read, rare information that could benefit the welfare of our birds.

[Pigeonpal2002]

Hi Numbernine,

I decided to stick this thread as you were right, it contains a lot of very informative information concerning calcium

[Trees Gray]

Originally Posted by NumberNine

Brought back to the top.

It is a shame that those who are responsible for pigeons.com do not create a folder with all the must-read, rare information that could benefit the welfare of our birds.

This rare information is already listed as part of the "Prevention and Nutrition" thread, under food, grit & calcium- in the daily forum under resources.

http://www.pigeons.biz/forums/showthread.php?t=5760