Abstract
Although, it is common practice to add antibiotics to poultry diets to improve chicken health and productivity, it is generally accepted that the use of dietary antibiotics may potentially affect human health due to emergence in food animals of zoonotic microorganisms that are resistant to antibiotics. This health threat has urged European countries to ban recently certain feed additives including antibiotics and anticoccidal substances. As a result, use of alternatives to these feed additives is currently being encouraged. The purpose of this study was to investigate the potential use of ground oregano plants in feeding of broiler chickens. For this study, two experiments were carried out. In the first experiment, the effects of diet supplementation with ground oregano on growth performance and oxidative stability of breast and thigh muscle tissue of broiler chickens were investigated. In the second experiment, the effect of diet supplementation with ground oregano on performance of b ...
Although, it is common practice to add antibiotics to poultry diets to improve chicken health and productivity, it is generally accepted that the use of dietary antibiotics may potentially affect human health due to emergence in food animals of zoonotic microorganisms that are resistant to antibiotics. This health threat has urged European countries to ban recently certain feed additives including antibiotics and anticoccidal substances. As a result, use of alternatives to these feed additives is currently being encouraged. The purpose of this study was to investigate the potential use of ground oregano plants in feeding of broiler chickens. For this study, two experiments were carried out. In the first experiment, the effects of diet supplementation with ground oregano on growth performance and oxidative stability of breast and thigh muscle tissue of broiler chickens were investigated. In the second experiment, the effect of diet supplementation with ground oregano on performance of broiler chickens challenged with oocysts of Eimeria tenella was examined. In the first experiment, a total of 6.300 day-old Cobb-500 chicks randomly allocated into 7 equal groups with three subgroups of 150 males and 150 females each, were used. One of the groups was given a basal diet containing 30 mg α-tocopheryl acetate/kg feed and served as control. The remaining six groups, were administered diets based on the same basal diet supplemented further with oregano at 5.0 g/kg (OR5 group), or oregano at 10.0 g/kg (OR10 group), or oregano at 5.0 g/kg plus a-tocopheryl acetate at 170 mg/kg (OR5-TOC group), or oregano at 10.0 g/kg plus a-tocopheryl acetate at 170 mg/kg (OR10-TOC group), or a-tocopheryl acetate at 170 mg/kg (TOC group), or flavomycin at 4 mg/kg plus lasalocid at 75 mg/kg (FLA-LAS group). During the feeding trial that lasted 42 days, body weight and feed intake were weekly recorded, and feed conversion ratios were calculated. Oocyst counts in excreta were also investigated weekly whereas mortality was recorded daily. At the end of the experiment, samples of breast and thigh muscle tissues from each group were collected and analyzed for their protein, fat, moisture, ash and α-tocopherol content. To evaluate the oxidative stability of the muscle tissues, part of the collected samples was submitted to iron-induced lipid oxidation by incubation with ferrous sulfate and ascorbic acid for 270 min, whereas another part to lipid oxidation by refrigerated storage at 4 oC for 9 days. Lipid oxidation was assessed by monitoring malondialdehyde formation through use of a derivative spectrophotometric assay. The results from this experiment showed that ground oregano could serve as an alternative to antibiotic growth promoters. At the age of 42 days, the OR5, OR5-TOC and FLA-LAS groups presented body weight values that were significantly better (P<0.05) than the Control group. The OR10, OR10-TOC and TOC groups presented body weight values that did not differ from the other groups, although they were numerically lower than the OR5, OR5-TOC and FLA-LAS groups, and numerically higher than the Control group. Incorporation of ground oregano at the levels of 5 g/kg or 10 g/kg in the diets did not influence (P>0.05) total feed consumption. However, its use at 5 g/kg diet had a significant (P<0.05) effect on feed conversion ratio. Thus, at the age of 42 days, the OR5, OR5-TOC and FLA-LAS groups presented feed conversion ratio values that were significantly better (P<0.05) than the Control group, whereas the OR10, OR10-TOC and TOC groups presented values that were not different from all other groups. Incorporation of ground oregano at 5 g/kg or 10 g/kg diet had no effect (P>0.05) on chickens mortality, or on protein, crude fat, moisture and ash content of breast or thigh tissues. However, it significantly (P>0.05) influenced oocyst counts in the excreta of broilers, as OR5, OR5-TOC, OR10 and OR10-TOC groups presented oocyst counts lower (P<0.05) than the Control and the TOC groups but significantly higher (P<0.05) than the FLA-LAS group.
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