Resumen

MIRANDA LOPEZ, Silvio; GONZALEZ, Decio; ROJAS, Nidia  y  VILLALOBOS, Gloria. Blood Levels of Calcium, Phosphorus, and Magnesium in Crossbred Heifers (Taurus-Indicus) Strategically Fed During Peripuberty Period. Rev. Cient. (Maracaibo) [online]. 2006, vol.16, n.3, pp.264-272. ISSN 0798-2259.

With the objective of examining serum concentrations of calcium, phosphorus and magnesium during the peripuberal period in grazing heifers feeding two supplemental strategies (balanced commercial food and Gliricidia sepium), An experiment was carried out with 24 dual purpose crossbred heifers, distributed in 3 randomized groups (8 animals each): T1: gramineous grazing (CGP); T2: CGP + commercial balanced food and T3: CGP + nutritional supplement that contained flour of leaves of Gliricidia sepium (GS). Serum samples were taken, 2 weeks before and 2 weeks after the puberty to determine the concentration of calcium, phosphorus and magnesium. The data was analyzed by an analysis of variance of the statistical analysis system (SAS) using the procedure GLM. The serum concentrations of P and Mg observed in the weeks 2 (6.27 and 2.53 mg/dL, respectively), 3 (6.41 and 2.55 mg/dL, respectively), 4 (6.31 and 2.60 mg/dL, respectively) and 5 (6.39 and 2.49 mg/dL, respectively) were higher (P < 0.01) to those shown in the weeks 1 (5.07 and 1.30 mg/dL, respectively). Particularly the serum Ca during the weeks 3 (11.60 mg/dL), 4 (11.43 mg/dL) and 5 (11.72 mg/dL) it was superior (P < 0.01) that the weeks 1 (9.68 mg/dL) and 2 (10.80 mg/dL). Heifers of T2 and T3, showed higher serum concentrations of Ca, P and Mg presented (P < 0.01) compared to those observed in T1. In attention to the results of the present investigation, the serum levels of Ca, P and Mg, were increased one week before the puberty, being this levels maintained until the last week of the peripuberal period. The commercial balanced food and the nutritious supplement with GS, were effective in increasing the serum concentrations of Ca, P and Mg.

Palabras clave : Heifers; puberty; minerals; calcium; magnesium; phosphorus.