Abstract 346

Echevarria,-M; Garcia,-M; Meini,-G; Stosic,-D; McDowell,-L

IVITA, Univ. Nacional Mayor de San Marcos, Lima, Peru.

Nutrition-Reports-International. 1985, 32: 2, 463-468; 11 ref.

Aqueous solutions of copper, cobalt and zinc were given to 32 Nellore heifers grazing tropical grasses, Hyparrhenia rufa and Paspalum conjugatum, during 7 months at the Tropical Research Station in Pucallpa, Peru. A 2 X 2 X 2 factorial experiment was used with the following treatments: control; Cu; Co; Zn; Cu and Co; Cu and Zn; and Cu, Co and Zn. Daily doses were as follows: Cu, 45 mg; Co, 7.2 mg; Zn, 225 mg. All heifers received 4.5 g phosphorus daily to correct this deficiency found in previous research. Liveweight gains were 200, 213, 151, 188, 149, 181, 117 and 166 g daily for Cu, Co, Zn, Cu-Co, Cu-Zn, Co-Zn, Cu-Co-Zn and control groups, respectively. Significant differences (P <0.1) were found, with economic benefits resulting from providing Cu and Co as supplements. Zn supplementation did not improve liveweight gains.