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.

ABSTRACT The objective of this study was to determine the effects of raw bee propolis and water or ethanol extract of propolis on growth performance, some blood parameters, and immunoglobulins in 15-20-week-old Ross-308 broiler breeders. The birds in the control were fed a diet without propolis, whereas the birds in the treatment groups were fed diets with raw propolis (RP), water (WEP), and ethanol (EEP) extract of propolis at the level of 1200, 400, and 400 ppm, respectively. Raw propolis and propolis extracts did not affect body weight gain, feed intake, feed conversion ratio, and some blood parameters, such as aspartate aminotransferase, alanine aminotransferase, total antioxidant status, triglyceride, and phosphorus. Birds fed EEP and those in control group had a lower IgA value compared with birds fed RP. Birds fed RP had higher IgM level than those of the other groups, and birds fed EEP had lower IgM level than those of control and RP-fed group. The IgY value of breeders fed EEP was higher than those of the other treatment birds, whereas that of WEP-fed birds was higher than those of control and RP treatment. The antibody levels of Anti-Newcastle disease virus and anti-infectious bursal disease virus were higher in EEP and RP-fed groups than those in the control and WEP-fed groups. The WEP decreased total oxidant status value compared with the control and RP treatments, whereas EEP and WEP increased plasma total protein and calcium contents compared with the control. The EEP increased plasma albumin content compared with RP. The addition of propolis extracts, especially WEP and EEP, to diet improves immunity and antioxidant activity, as well as enhances Ca absorption of broiler breeders.