The objective of this trial was to determine the body composition and nutritional requirements of macrominerals for Morada Nova sheep. Thirty lambs averaging 15 kg of initial body weight (BW) and 70 days of age were used in this study. Six lambs (reference-animals) were slaughtered with 15 kg of BW to determine the initial body composition using the comparative slaughter methodology; six other lambs were slaughtered with 20 kg of BW (intermediary slaughter) and the remaining 18 lambs were distributed to six groups of three animals (one lamb for each treatment) and received diets with the following forage(F):concentrate(C) ratio: 1) 40F:60C; 2) 55F:45C; and 3) 70F:30C. Animals from each group were slaughtered when the lamb that had been fed the diet with the highest concentrate level reached 25 kg of BW. Body composition varied from 14.33 to 12.42 g of Ca, 8.12 to 7.15 g of P, 0.47 to 0.46 g of Mg, 1.60 to 1.40 g of Na, and 2.30 to 2.23 g of K per kg of empty body weight. Net gain requirements ranged from 13.54 to 11.74 mg of Ca, 7.96 to 7.02 mg of P, 0.57 to 0.55 mg of Mg, 1.54 to 1.35 mg of Na, and 2.75 to 2.68 mg of K per g of gained BW. Daily macromineral requirements for lambs from 15 to 25 kg of BW gaining 100 g/day varied from 2.76 to 4.74 g Ca, 1.91 to 3.15 g of P, 0.60 to 0.93 g of Mg, 0.60 to 0.76 g of Na, and 1.51 to 1.79 g of K.
calcium; magnesium; phosphorus; potassium; requirements; sodium
