The aim of this study was to determine the net requirements of calcium (Ca), phosphorus (P), magnesium (Mg) and sulfur (S) for gain of high or low residual feed intake (RFI) Dorper lambs confined in full sun or shade. Sixty-four intact male Dorper lambs with an average initial body weight (BW) of 17.8 ± 2.43 kg and an average age of 70 ± 10 days were confined for 40 days to separate them into two groups (high or low RFI). Thereafter, a group of 4 animals (2 high RFI and 2 low RFI) were slaughtered to estimate initial empty body weight (EBW) and body composition of animals slaughtered at the end of the experiment. The 60 remaining lambs were distributed in a randomized block design, with a 2 × 2×3 factorial scheme, with two feedlot environments (full sun or shade, 30 animals in each), two groups of feed efficiency (high RFI or low RFI, 30 animals in each) and different levels of concentrate (30, 45 and 60 %), with 5 repetitions in each interactive treatment. The animals from each feedlot environment and from each RFI were distributed in three dietary treatments with different levels of concentrate to have different body compositions necessary to determine their macromineral requirements. The animals were confined for 60 days until slaughter. Neither RFI nor feedlot environment affected the net macromineral requirements for gain of Dorper lambs (P > 0.05). There was a decrease in net Ca, P and S requirements as fasting BW (FBW) increased from 20 to 40 kg (P < 0.05). However, the net requirements of these macrominerals for gain increased as average daily gain (ADG) increased from 100 to 300 g/day (P < 0.05). In contrast, the net Mg requirement for gain increased as both FBW and ADG increased (P < 0.05). The results showed that there was no significant effect of RFI and shade environment on the net requirements of macrominerals for weight gain of Dorper lambs. Possible differences could be in the dietary level or in the maintenance level. Therefore, further studies are needed to assess the effect of RFI and shade environment on the mineral requirements of lambs.

这项研究的目的是确定钙（Ca），磷（P），镁（Mg）和硫（S）的净需求量，以获取高或低残留饲料摄入量（RFI）多珀羔羊在全日照或全日照下的生长。阴影。将平均初始体重（BW）为17.8±2.43公斤，平均年龄为70±10天的六十四只完整的雄性杜泊小羊限制在40天之内，以将其分为两组（高或低RFI）。此后，宰杀了一组4只动物（2只高RFI和2只RFI低），以估计实验结束时被宰杀的动物的初始空体重（EBW）和身体组成。剩下的60只羔羊采用2×2×3因子分解方案进行随机区组设计，有两个饲养场环境（全日照或阴凉，每只30只动物），两组饲料效率（高RFI或低RFI，每只30只动物）和不同浓度的浓缩物（30％，45％和60％），每次互动治疗均重复5次。来自每种饲养场环境和来自每个RFI的动物在三种饮食处理中分配不同的浓缩物水平，以具有确定其宏观矿物质需求所必需的不同身体成分。将动物禁闭60天直至屠杀。RFI和饲养场环境均未影响获得杜泊羔羊肉的净矿物质净需求（P> 0.05）。由于禁食体重（FBW）从20 kg增加到40 kg，净Ca，P和S需求减少（P <0.05）。然而，随着日平均增重（ADG）从100克/天增加至300克/天，这些大型矿物质对增重的净需求增加（P <0.05）。相比之下，随着FBW和ADG的增加，增加的净Mg需求也增加（P <0.05）。结果表明，RFI和遮荫环境对大矿物质增加Dorper羔羊体重的净需求没有显着影响。可能的差异可能在饮食水平或维持水平上。因此，需要进一步的研究来评估RFI和阴凉环境对羔羊矿物质需求的影响。