Use of Essential Oils In Broiler Nutrition as Growth Promoters

Abstract

Four experiments were conducted to evaluate the response of broiler chicks to diets containing various levels of essential oils (ES) extracted from different medicinal plants including Black cumin (BC O); Lemon grass (LG O); Spearmint (SP O) and Halfa bar (HB O)as natural feed additives. Experimental parameters covered growth performance ; slaughter and carcass values, serum metabolite, enzyme activities , and electrolytes and economical appraisal. The experimental design used wsa the complete randomized design (CRD) . A total of 140, five day-old , 71gm initial weight , un sexed Ross-308 broiler chicks were used in each experiment . Chicks were divided into five groups of 28 birds in each and randomly assigned to 5 treatment diets . each treatment has 4 replicates . The first group A , fed on the basal diet Negative control diet; (NC) with no antibiotic or essential oils, the second group B were fed basal diet with antibiotic ( Neomycin 16mg /kg) as positive control diets (PC) ,the other groups of chicks C, D and E were fed basal diet with one of tested essential oils in each experiment – levels of 50, 100, 150 mg/kg respectively . The basal diet was formulated to meet the nutrients requirements of broiler according to NRC, (1994). Experimental diets were fed for 6 weeks. The results showed that addition of all essential oils tested at different levels improved significantly ( p< 0.05) the body weight gain, feed intake and feed conversion ratio values compared with NC, while no differences were observed between essential oils groups and PC group. The mortality rate was not influenced significantly by the dietary treatments. The results indicated that there were no significant differences among all treatment groups in the percentages of carcass dressing, giblets, commercial cuts and their percent of separable tissue; meat chemical composition and subjective meat quality parameters of broiler chicks. The results of serum metabolites showed that addition of the essential oils at different levels were reduced significantly (p< 0.05) the cholesterol and urea values, while treatment effect on total protein was not significant, the treatment effect on electrolytes and enzyme activities was not significant in Ca, P and AST, where it is higher in ALP in NC and Pc groups compared to groups fed on essential oils. Economically appraised values were profitability ratio ( 1.13) of group D and E ( 100 and 150 mg/kg Bc 0) were the highest of tested groups. Profitability (1.14) of group E ( 150mg/kg Sp 0) was the highest in the tested groups. Profitability ( 1.13) of group E ( 150 mg/kg LG O) was the highest in the tested groups . Profitability ( 1.14) of group D( 100 mg/kg HB O) was the highest of the tested group. This study showed that herbal extracts ( essential oils ) , when added in the broiler diets as growth promoter have a similar effect as that with antibiotic without any adverse effects.