Abstract

RABELO, L.S. et al. Body composition and macrominerals nutritional requirements for growing Guzera and Holstein heifers. Arq. Bras. Med. Vet. Zootec. [online]. 2007, vol.59, n.2, pp. 395-405. ISSN 0102-0935.  http://dx.doi.org/10.1590/S0102-09352007000200021.

Twenty-two heifers, 11 Holstein and 11 Guzera, with initial live weight (LW) of 189kg were used in this study. Six animals of each breed were slaughtered (treatment R), and two groups of five animals of each breed were fed ad libitum diet of Tifton 85 (Cynodon spp.) hay, ground corn, soybean meal and mixture minerals, for a daily gain of 1kg. The animals were slaughtered after reaching weight gain of 100kg. All tissues were weighted and representative samples were taken from the ninth to eleventh rib, and analyzed for body contents of Ca, P, Mg, Na and K. The body composition and the mineral requirements for a 1kg LW daily weight gain were determined. Decreases in the concentration of macrominerals in the empty body weight and in carcass weight gain were related to LW increased. No differences among breeds for macrominerals were observed. The Ca, P, Mg, Na and K dietary requirements for animals of 200kg of LW were 11.57; 5.97; 0.36; 1.30 and 0.86g/day, respectively.

Keywords : cattle; calcium; magnesium; phosphorus; potassium; sodium.