Suplementación parenteral con cobre y zinc en vacunos machos mestizos Brahman en los Llanos Occidentales de Venezuela

Durante 129 dias, 60 vacunos mestizos Brahman con peso vivo (PV) de 201,6 ± 2,65 kg ubicados en los llanos occidentales de Venezuela fueron asignados a cuatro tratamientos: 1) suplementacion mineral oral (SMO), 2) SMO con cobre inyectado (50 mg Cu/100 kg PV, cada 73 d), 3) SMO con zinc inyectado (57,35 mg Zn/100 kg PV, a los 0, 28, 73 y 101 d) y 4) SMO con cobre y zinc inyectado para evaluar PV, ganancia diaria de peso (GDP), medidas corporales (MC) y quimica sanguinea (QS). Los animales se manejaron a pastoreo con suplementacion proteica (23,2% PC y 1,74 Mcal/kg MS de energia metabolizable). Cada 28 d se midio el cambio de PV y se tomaron muestras de forraje y sangre para analisis quimico de hemoglobina, hematocrito, Cu y Zn. El perimetro toracico y altura a la cruz se midieron al principio y final del experimento. Los datos fueron analizados realizando un ANAVAR bajo un diseno complemente aleatorizado con arreglo factorial 2x2. No se observaron diferencias entre tratamientos (P>0,05) para PV y GDP con promedio general para GDP de 363,0 ± 11,9 g/d, mostrando interaccion (P 0,05). Bajo las condiciones de este experimento, la suplementacion parenteral con Cu y Zn no mejoro el comportamiento productivo ni la quimica sanguinea de los animales. ABSTRACT During 129 days, 60 crossbred Brahman steers with body weight (BW) of 201.6 ± 2.65 kg located in the western plains of Venezuela were assigned to four treatments: 1) oral mineral supplementation (OMS), 2) OMS with injected Cu (50 mg Cu/100 kg BW, every 73 d), 3) OMS with injected Zn (57.35 mg Zn/100 kg BW, every 28 d), and 4) OMS with injected Cu and Zn, to evaluate BW, average daily gain (ADG), body measurements (BM), and blood chemistry (BC). The animals were kept on pasture with protein supplementation (23.2% CP and 1.74 Mcal/kg DM metabolizable energy). BW changes were measured every 28 d, and forage and blood samples were taken for chemical analysis of hemoglobin, hematocrit, Cu, and Zn. Heart girth and wither height were measured at the beginning and end of the experiment. Data were analyzed by ANOVA in a complete randomized design using a 2x2 factorial arrangement. No differences were found among treatments (P>0.05) for BW and ADG with overall average ADG of 363.0 ± 11.9 g/d, showing (P 0.05). Under the conditions of this experiment, Cu and Zn parenteral supplementation had no effect on animal performance and blood chemistry.