This study aimed to evaluate the digestibility of starch, ruminal protozoa count and blood parameters of sheep with high or low residual feed intake (RFI) fed different levels of concentrate in the diet. Sixty male Dorper lambs with a mean initial body weight of 17.8 kg ± 2.43 were confined for 40 days for the determination of RFI, receiving a complete diet in a 70:30 forage: concentrate ratio, on a dry matter basis. RFI was estimated considering the differences in observed and predicted values of dry matter intake, based on average daily gain and metabolic body weight. Sixteen animals with the highest values of RFI (high RFI) and 15 animals with the lowest values of RFI (low RFI) were selected. The experimental design was a randomized block design (2 × 3), with two groups of animals (high and low RFI) and 3 treatments with diets containing different levels of concentrate (30, 45 and 60 %). The lambs remained under this confinement regime for 60 days. The different levels of concentrate promoted differences (P < 0.05) between hemoglobin and hematocrit counts. There was an interaction between RFI and diet for hemoglobin and hematocrit counts (P < 0.05). Animals with high RFI presented larger volume of urine excreted in relation to animals with low RFI (P = 0.006), with mean values of 1.59 l/day and 1.09 L/day, respectively. Diets containing 30 % concentrate resulted in lower starch intake (P < 0.0001) and lower digestibility of starch in the total digestive tract (P < 0.0001). Animals with low RFI had lower counts of protozoa in the ruminal fluid (P = 0.04). Diets containing 60 % concentrate in their composition provided lower counts of total protozoa (P = 0.0003) in the ruminal fluid. This diet also promoted a smaller population of protozoa of the genus Dasytricha (P = 0.04) for high RFI animals. Blood parameters and utilization of starch in the total digestive tract are not affected, while ruminal fauna is affected by RFI in lambs.

这项研究旨在评估饲喂不同浓度饲料的高或低残留饲料摄入量（RFI）的绵羊的淀粉消化率，瘤胃原生动物数量和血液参数。将六十只平均初始体重为17.8 kg±2.43的雄性Dorper羔羊禁食40天，以测定RFI，以干物质为基础，以70:30的草料：浓缩物比例接受完全饮食。根据平均日增重和代谢体重，考虑到干物质摄入量的观察值与预测值之间的差异，对RF​​I进行估算。选择了具有最高RFI值（高RFI）的16只动物和具有最低RFI值（低RFI）的15只动物。实验设计是随机区组设计（2×3），包括两组动物（高和低RFI），以及3种采用不同浓度精矿（30％，45％和60％）的饮食进行的处理。羔羊在这种监禁制度下呆了60天。不同浓度的浓缩物会促进血红蛋白和血细胞比容计数之间的差异（P <0.05）。RFI和饮食之间存在血红蛋白和血细胞比容计数之间的相互作用（P <0.05）。RFI高的动物相对RFI低的动物表现出更大的尿液排泄量（P = 0.006），平均值分别为1.59 L /天和1.09 L /天。日粮中含有30％的精矿会降低淀粉的摄入量（P <0.0001），并降低淀粉在整个消化道中的消化率（P <0.0001）。RFI低的动物的瘤胃液中原生动物的数量较少（P = 0.04）。日粮中浓度为60％的浓缩液在瘤胃液中提供的原虫总数较少（P = 0.0003）。这种饮食还促进了原生动物的种群减少高RFI动物的Dasytricha（P = 0.04）。血液参数和整个消化道中淀粉的利用不受影响，而瘤胃动物则受羔羊RFI的影响。