Composição Corporal e Exigências Nutricionais de Magnésio, Potássio e Sódio de Cordeiros Santa Inês em Crescimento dos 15 kg aos 25 kg de Peso Vivo

This study was carried out to determine body composition and magnesium, potassium and sodium requirements for weight gain of Santa Ines lambs (hairy coat breed). Eighteen animals were used with average 15 kg initial LW. At the beginning of the experiment, six animals were slaughtered for the determination of the amount of each mineral retained in the body, and serving as reference animals in the comparative slaughter technique. The remaining 12 animals were divided in two groups: six were ad libitum fed and six animals were restricting fed at maintenance plus 20%. The animals from the ad libitum and restrict feeding groups started in the experimental period by pairs and they both were slaughtered when the animals from the ad libitum group reached 25 kg LW. The estimates of magnesium, potassium and sodium body composition were obtained through the prediction equations obtained by the logarithm regression of the amount of each present minerals in the empty body in function of the empty body weight (EBW). The net requirements for weight gain were obtained through the derivation of these prediction equations. The estimates of body composition per kg EBW for the animals from 15 to 25 kg were: 0.591 and 0,578 g for Mg: 2.914 and 2.776 g for K 1.830 and 1.637 g for Na; and the net requirements for kg weight gain were: 0.515 and 0.503 g for Mg: 2.408 and 2.294 g for K; 1.315 and 1.177 g for Na, respectively.