Four essential oils (oregano, thyme, peppermint and garlic) were in vitro evaluated for their antimicrobial activity against some pathogenic microorganism with concentrations of 10, 20, 50, 75, and 150 μg/ml. The laboratory results showed that oregano and garlic essential oils were found to be more effective against all tested pathogenic microorganism. Consequently, the oregano essential oil and garlic powder were chosen as feed additives on diets of quail birds. A total number of 480 Japanese quail chicks, 10 day old, were randomly selected, weighed and divided into eight experimental groups each of 60 birds (3 replicates each of 20 birds). The first group was fed on basal grower diet (considered as control). The second group was fed on diet supplemented with 1.0 g oxytetracycline /kg diet. Birds of the 3rd, 4th and 5th groups were fed on diets supplemented with oregano essential oil at levels of 50, 100 and 150 mg/kg combined with 0.5g oxytetracycline /kg diet, respectively, while birds of the 6th, 7th and 8th groups were fed on diets supplemented with garlic powder at levels of 0.1, 0.2 and 0.3 g/kg combined with 0.5 g/kg oxytetracycline, respectively. The obtained results showed that chicks fed on the diet supplemented with 150 mg/kg oregano combined with 0.5 g/kg oxytetracycline significantly improved body weight, body weight gain, feed conversion, carcass weight and economic efficiency. Moreover, it had the lowest intestine pathogenic populations content and mortality percentage followed by those fed on the diet supplemented with 0.2 g/kg garlic powder combined with 0.5 g/kg oxytetracycline. |
