Calcium bioavailability
1995; Elsevier BV; Linguagem: Inglês
10.1016/b978-012056250-3/50032-9
Autores Tópico(s)Ruminant Nutrition and Digestive Physiology
ResumoCalcium is one of the most abundant elements in the body and is often the major cation in the diet. Ninety-nine percent of the body's calcium is located in the skeleton. The remaining 1% is extremely important in cellular metabolism, blood clotting, enzyme activation, and neuromuscular action. Animal weight gain, bone breaking strength, tibia ash, and various parameters of calcium metabolism have been used by many researchers as useful indicators to measure available calcium in the diet. Yoshida and Hoshii fed combinations of calcium and phosphorus to broiler chicks and found that toe ash correlated well with tibia hardness. Radioisotopes have been quite useful to determine the availability of calcium from several sources. Several factors have been shown to influence absorption of calcium from the gut. Absorption of calcium in the anterior small intestine is both an active (mediated by vitamin D) and a passive process. Several reports have indicated that particle size is a major determinant of calcium and phosphorus availability in defluorinated phosphates. Calcium availability, as determined by radio-calcium recoveries from pair-fed 25 kg barrows, was 42% in a cereal grain-based diet. Feedstuffs that are considered to have relative calcium bioavailability values, for both nonruminants and ruminants, of 95% or more in comparison to calcium carbonate include aragonite, bone meal, calcium gluconate, dicalcium phosphate, ground eggshell, ground limestone, ground oyster shell, calcium sulfate, nonfat dry milk, and tricalcium phosphate.
Referência(s)