Мнения, препоръки, оценки за снимка
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Мнения и оценки за снимка
| Дата / Оценка | ИМЕ / Мнение, препоръка | |
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| 2014-09-23 13:58:54 (оценка 6) |
Dr. Velev / Борис Велев
Calcium is the most prevalent mineral in a racing pigeonsbody 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 pigeons 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 andpigeons 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 pigeon. 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 in Racing Pigeons Part 2
Calcium Requirements: The maintenance levels for birds are not precisely known, but granivores such as pigeonsusually 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.
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| 2014-05-19 21:57:10 (оценка 6) |
Plamena Iankova / Пламена Янкова
Много добре сте се справили, браво!
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| 2014-05-19 20:49:52 (оценка 6) |
pegeon / Рафаил Янакиев
Супер е , ваша ли е докторе? И аз съм замислил нещо подобно на село , само че ще има орпингтон и брама - и декоративни фазани ! Купили сме материал само работници трябва . В края на лятото ще снимам резултатите. Поздрави и успех!
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| 2014-05-19 12:43:02 (оценка 6) |
Dr. Velev / Борис Велев
Колеги разгледайте снимките на фермата.
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