Evaluation of olive leaf extract as a growth promoter on the performance, blood biochemical parameters, and caecal microflora of broiler chickens

ABSTRACT The objective of the study was to examine the effects of an alcoholic liquid olive leaf extract (OLE) obtained from fresh leaves on the growth performance, carcass weight, caecal microflora, and some plasma variables, such as triglycerides, total cholesterol, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol in broiler chickens. A total of 375 one-day-old male broilers (Ross 308) were randomly divided into five treatments with five replicate pens (15 birds each) per treatment. The birds were fed either a basal diet with no supplement (control), with 75 (OLE75), 150 (OLE150), 300 (OLE300), and 600 (OLE600) mg kg−1 oleuropein, provided by 0.66, 1.33, 2.65, and 5.32 g kg−1 of the OLE. The dietary supplementation of OLE linearly increased daily body weight gain (BWG), feed intake (FI), and carcass weight and improved feed conversion ratio (FCR). Although the OLE600 broilers had the highest daily FI among the treatments, there were significant increases in their BWG and improvements in FCR compared with the control, OLE75, and OLE150 birds. The carcass weights of OLE150, OLE300, and OLE600 birds were higher than those of the control group. The OLE600 diet increased the dressing percentage compared with the OLE75, OLE150, and OLE300 diets. The abdominal fat weight and the plasma HDL concentration of the control broilers were lower than those of all OLE birds. All doses of OLE supplementation decreased the caecal E. coli content. A growth-promoting effect is obtained from the dietary supplementation of 600 mg kg−1 oleuropein due to its beneficial effect on growth performance and caecal microflora populations of broilers.

摘要 本研究旨在探究以新鲜橄榄叶为原料制备的酒精性液体橄榄叶提取物（Olive Leaf Extract, OLE）对肉鸡生长性能、屠宰体重、盲肠微生物区系，以及甘油三酯、总胆固醇、高密度脂蛋白（HDL）、低密度脂蛋白（LDL）胆固醇等血浆指标的影响。共计375只1日龄雄性罗斯308（Ross 308）肉鸡，随机分为5个处理组，每组设置5个重复栏舍，每栏饲养15只肉鸡。试验日粮分别为基础日粮（对照组，无添加）、添加75（OLE75）、150（OLE150）、300（OLE300）及600（OLE600）mg·kg⁻¹橄榄苦苷的日粮，对应添加的橄榄叶提取物剂量分别为0.66、1.33、2.65及5.32 g·kg⁻¹。日粮添加OLE可线性提升肉鸡的日均体增重（Body Weight Gain, BWG）、日均采食量（Feed Intake, FI）及屠宰体重，并改善饲料转化率（Feed Conversion Ratio, FCR）。尽管OLE600组肉鸡的日均采食量在各组中最高，但与对照组、OLE75组及OLE150组相比，其体增重显著提升，饲料转化率得到有效改善。OLE150、OLE300及OLE600组肉鸡的屠宰体重均高于对照组。OLE600组日粮的屠宰率高于OLE75、OLE150及OLE300组日粮。对照组肉鸡的腹脂重量及血浆高密度脂蛋白浓度均低于所有OLE添加组。所有剂量的OLE添加均降低了盲肠大肠杆菌（Escherichia coli, E. coli）含量。日粮添加600 mg·kg⁻¹橄榄苦苷可发挥促生长作用，因其对肉鸡生长性能及盲肠微生物区系种群具有有益影响。