Comparison of Different Levels of Thyme and Rosemary Ether Extracts on Growth Performance and Carcass Characteristics of Broiler Chickens

Abstract

An experiment was conducted to compare the effects of different levels of thyme and rosemary ether extract on growth performance and carcass characteristics of broiler chickens. 336 male sexy chicks were used in a randomized complete design with 7 treatments and 4 replications cages (12 birds per cage). The experimental diets consisted of: 1: Control treatment: Basal diet based on corn-soybean meal without supplementation with medicinal plants, 2: base ration + 0.25% of rosemary ether extract, 3: base ration + 0.5% of rosemary ether extract, 4: base diet + 0.75% Rosemary ether extract, 5: base diet + 0.25% Thyme ether extract, 6: base diet + 0.5% Thyme ether extract and 7: base diet + 0.75% Thyme ether extract. Results showed that tratments 4, 6 and 7 (which contained 0.75% Rosemary ether extract, 50% extract of Thyme extract and 0.75% Thyme ether extract) average body weight and daily gain increased. At the end of the experiment, there was no significant difference between the treatments in feed intake. The best feed conversion coefficient in treatment was 0.75% of thyme extract and the other treatments also had less feed conversion than control treatment. Characteristics of carcasses were not significantly affected by experimental treatments. The level of 0.75% of rosemary ether extract showed better performance than the other two levels and its yield was similar to 0.75% of thyme ether extract. Supplementation of dietary of broiler chicks with Thyme extract at the level of 0.50% and 0.75% was the same results.