Effect of olive leaves on ascites incidence, hematological parameters and growth performance in broilers reared under standard and cold temperature conditions

The effects of dietary olive leaves supplementation on ascites indices, hematological parameters, and broiler performance were separately assessed under standard (based on Arian strain management guide) and cold temperature conditions (induced ascites) with same experimental diets. For the standard temperature conditions, 400 day-old male broilers were divided into four experimental groups: control group, and three groups with olive leaf supplementation at 5, 10, or 15 g/kg diet (oleuropein content, 72.63 mg/g). The experiments were performed in four replicates of 25 birds per pen. The same grouping with another 400 birds was used for the cold temperature conditions. Growth performance, physiological and biochemical parameters, and ascites indices (right ventricle [RV] and total ventricle [TV] weight and RV/TV) were evaluated. Under both temperature conditions, growth parameters were similar among all groups. Ascites-related mortality, systolic blood pressure, packed cell volume, alanine aminotransferase, erythrocyte osmotic fragility, red blood cell count, and triiodothryronine level decreased linearly with increasing olive leaf supplementation under both conditions (P<0.05). Lactate dehydrogenase and alkaline phosphatase activities showed the same, although non-linear trend (P<0.05), and thyroxine levels showed a linear increasing trend (P<0.001) under both conditions. Increasing olive leaf supplementation was associated with a linear decrease in RV/TV under the standard temperature condition and a linear decrease in RV, TV, and RV/TV under cold stress (P<0.001). It concluded that dietary olive leaf supplementation at a dose of 10 g/kg has an anti-hypertensive effect and decreases ascites incidence without impairing broiler performance under standard and cold ambient temperatures.