Abstract The aim of this study was to evaluate the relationship between residual intake and body weight gain (RIG) and the performance, ingestive behavior, and characteristics of longissimus muscle of crossbred ½ Dorper × ½ Santa Ines lambs. Nineteen non-castrated male lambs, with a mean age of 4 months and a body weight (BW) of 23.04 ± 3.16 kg, were individually fed ad libitum in a feedlot for 90 days. The ration was composed of 640 g/kg Cynodon hay and 360 g/kg concentrate feed; it contained 158.6 g/kg crude protein and 2.12 Mcal/kg metabolizable energy on a dry matter (DM) basis. At the end of the trial, lambs were classified as efficient (n = 7), intermediate (n = 6), or inefficient (n = 6) for RIG based on ± 50 % of the standard deviation for this trait. The lowest and highest values for dry matter intake relative to BW (DMIBW) were verified in the efficient and inefficient groups, respectively (3.13 vs. 3.43 % BW/day). The feed conversion ratio (FCR) decreased by 15.94 % (8.47 to 7.12 kg DM/kg gain) from the inefficient to the efficient group. The time spent feeding, in rumination, and in idleness, as well as the intake rate (IR), were similar among RIG groups, but the rumination rate (RR) was lower in the efficient group (1.61 g DM/min) compared with the intermediate and inefficient groups (1.82 g DM/min on average). Average particle size (APS) and chemical composition of the orts were not influenced by RIG and were similar among the efficiency groups. Backfat thickness, as measured by ultrasound (BFTUS) at the start and end of the trial, and backfat thickness and loin eye area, as measured directly from the longissimus muscle (BFTLE and LEA, respectively) after slaughter, were similar among RIG groups. Improving the efficiency for RIG leads to better feed utilization, without affecting the characteristics of longissimus muscle in lambs.

中文翻译：

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Dorper × Santa Inês 羔羊最长肌性能、摄食行为和特征的残留摄入量和体重增加

摘要 本研究的目的是评估剩余摄入量和体重增加 (RIG) 与杂交 ½ Dorper × ½ Santa Ines 羔羊的性能、摄食行为和最长肌特征之间的关系。19 只未阉割的公羊羔，平均年龄为 4 个月，体重 (BW) 为 23.04 ± 3.16 公斤，在饲养场中单独自由采食 90 天。日粮由 640 g/kg 狗牙根干草和 360 g/kg 精饲料组成；按干物质 (DM) 计算，它含有 158.6 g/kg 粗蛋白和 2.12 Mcal/kg 代谢能。在试验结束时，根据该性状的 ± 50% 的标准偏差，将羔羊的 RIG 分类为有效 (n = 7)、中等 (n = 6) 或低效 (n = 6)。干物质摄入量相对于 BW (DMIBW) 的最低和最高值分别在高效组和低效组中得到验证（3.13 与 3.43 % BW/天）。从低效组到高效组，饲料转化率 (FCR) 降低了 15.94%（8.47 至 7.12 kg DM/kg 增重）。RIG 组的进食、反刍和闲置时间以及摄入率 (IR) 相似，但高效组的反刍率 (RR) (1.61 g DM/min) 低于中间组和低效组（平均 1.82 g DM/min）。ort 的平均粒径 (APS) 和化学成分不受 RIG 的影响，并且在效率组之间相似。背膘厚度，在试验开始和结束时通过超声波 (BFTUS) 测量，以及背膘厚度和腰眼面积，在屠宰后直接从最长肌（分别为 BFTLE 和 LEA）测量，在 RIG 组之间相似。提高 RIG 的效率可以提高饲料利用率，同时不会影响羔羊最长肌的特性。