Calcium and phosphorus fractional excretion in Nellore before and during pregnancy

• Autor(a) principal: Borges, Alexandre Secorun
• Data de Publicação: 2000
• Outros Autores: Barros, Breno Peloso de, Alves, Ana Liz Garcia, Ciarline, Paulo César, Bicudo, Pedro Luiz, Kohayagawa, Aguemi
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Pesquisa Agropecuária Brasileira (Online)
• Texto Completo: https://seer.sct.embrapa.br/index.php/pab/article/view/5862
• topic: bovines; mineral metabolism; urine; blood; biochemistry; nutritional status; bovinos; metabolismo de minerais; urina; sangue; bioquímica; estado nutricional

The assessment of calcium and phosphorus nutrition is difficult when using serum concentrations of these elements, because they remain within normal ranges despite a wide variation in Ca and P contents in different diets due to the high efficiency of body homeostasis process. Significant alterations are observed in chronic deficiencies when economic losses have a relevant importance. The use of fractional excretion of Ca and P allow quantitative evaluation without need of timed urine volumetric determinations. Fractional excretion ratios for Ca and P were determined using eight consecutive 45-day urine and serum sample collections performed on 22 heifers before (two samplings) and during pregnancy (six samplings). The values presented by fractional excretion of Ca and P ranged from 1.06% to 3.72% and 1.09% to 2.70%, respectively. There was a tendency to diminishing fractional excretion median values of Ca when comparing before pregnancy with values observed during pregnancy. This experiment showed that there is wide variation in Ca and P fractional excretion in different animals at the same moment and this results in difficulties to access nutritional status of these elements in cattle raised on pasture using this method.