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叶片提取得到的酒精性液体橄榄叶提取物（Olive Leaf Extract, OLE）对肉鸡生长性能、屠体重量、盲肠微生物群（caecal microflora）以及部分血浆指标的影响，具体包括甘油三酯（triglycerides）、总胆固醇（total cholesterol）、高密度脂蛋白（high-density lipoprotein, HDL）与低密度脂蛋白（low-density lipoprotein, LDL）胆固醇。本试验共纳入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，每栏饲养15只肉鸡。试验肉鸡分别饲喂以下日粮：无添加的基础日粮（对照组），以及添加75（OLE75）、150（OLE150）、300（OLE300）、600（OLE600）mg·kg⁻¹橄榄苦苷（oleuropein）的日粮，对应橄榄叶提取物添加量分别为0.66、1.33、2.65与5.32 g·kg⁻¹。日粮添加橄榄叶提取物可线性提升肉鸡的日均体增重（daily body weight gain, BWG）、采食量（feed intake, FI）与屠体重量，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处理组中最高，但相较于对照组、OLE75组与OLE150组，其日均体增重显著提升，饲料转化率显著改善。OLE150、OLE300及OLE600组肉鸡的屠体重量均高于对照组。相较于OLE75、OLE150与OLE300组日粮，OLE600组日粮可提升肉鸡屠宰率。对照组肉鸡的腹脂重量与血浆HDL浓度均低于所有橄榄叶提取物添加组。各剂量的橄榄叶提取物添加均降低了肉鸡盲肠大肠杆菌（E. coli）含量。日粮添加600 mg·kg⁻¹橄榄苦苷可发挥促生长作用，这得益于其对肉鸡生长性能与盲肠微生物菌群的有益调控效果。