Digestibility of calcium and digestible calcium from inorganic sources evaluated in swine by two methods

SUMMARY The objective of the study was to determine the digestible calcium from different sources by direct and indirect methods. Thirty castrated male pigs were used, distributed in randomized blocks, in six treatments: 1- Calcitic limestone; 2-Dicalcium phosphate powder 18%; 3- Dicalcium phosphate powder 20%; 4- Dicalcium microgranulated phosphate 18%; 5- Monodicalcium microgranulated phosphate 20%; 6- Monodicalcium microgranulated phosphate 21%, with six replicates and one animal per experimental unit. A basal diet was formulated to meet the nutritional requirements of the animals, except for calcium (0.06%) and the evaluated sources replaced the basal diet in order to provide 0.45% of total Ca. At the same time, two stool collection methods were evaluated: total collection and fecal indicator. The animals were housed in metabolism cages for 12 days to collect feces and urine to determine the calcium values used to estimate digestibility coefficients and digestible calcium. The total collection method and the faecal indicator method did not affect the true digestibility coefficient of calcium. The calcium digestibility of the microgranulated dicalcium phosphate 21% (MM21) was superior in comparison with the other calcium sources evaluated by the indirect method in the present study. The average values of true digestibility of the calcium sources, in percentage, were: calcitic limestone: 82.47; dicalcium phosphate powder 18%: 80.87; dicalcium phosphate powder 20%: 85.65; dicalcium microgranulated phosphate 18%: 81.65; monodicalcium microgranulated phosphate 20%: 84.15; and monodicalcium microgranulated phosphate 21%: 88.35. The two methodologies can be used to determine the digestibility of calcium. RESUMO Objetivou-se determinar o cálcio digestível de diferentes fontes pelos métodos direto e indireto. Foram utilizados 36 suínos machos castrados, distribuídos em blocos casualizados em seis tratamentos, sendo: 1- calcário calcítico, 2- fosfato bicálcico pó 18%, 3- fosfato bicálcico pó 20 %, 4- fosfato bicálcico microgranulado 18%, 5- fosfato monobicálcico microgranulado 20% e 6- fosfato monobicálcico microgranulado 21 %, com seis repetições e um animal por unidade experimental. Uma ração basal foi formulada para atender as exigências nutricionais dos animais, exceto para cálcio (0,06%) e as fontes avaliadas substituíram a ração basal de modo a fornecer 0,45% de Ca total. Foram avaliados ao mesmo tempo dois métodos de coleta de fezes: coleta total e indica