Performance of confined and grazing lambs fed diets with different mineral-concentrate supplements

For confined animals, performance is improved when their diet is supplemented with a mineral mixture and protein energy. This study evaluated the effect of dietary supplementation on feedlot sheep on native pasture. Two experiments were conducted in sequence, with the animals constrained in one and animals confined to pasture in the other. The experiments were conducted with 32 Santa Ines lambs, with average initial weights of 16.8 and 19.9 kg for the constrained and pasture studies, respectively. In both experiments, the animals were offered the following supplements: Supplement 1 = 200 g of the concentrate without mineral mixture; Supplement 2 = 200 g of the concentrate with mineral mixture + Mn + Zn; Supplement 3 = 300 g of the concentrate with mineral mixture + Mn + Zn; and Supplement 4: 300 g of the concentrate with mineral mixture + Zn without Mn. The intake of the mineral mixture resulted in a higher average intake of crude protein in feedlot lambs and neutral detergent fiber in pasture lambs than the other diets, regardless of the presence of manganese and thus provided more consistent weight gain among the animals. The mineral mixture supplementation increased the average daily intake of Zn and Mn. The animals on the diets containing 300 g day(-1) supplementation with the concentrated mineral mixture also had more weight gain and better feed conversion than those on the other diets, most likely because of the greater responsiveness to supplementation in these animals.