飼糧中添加牛至精油對肉雞生長性能、屠體性狀、血液生化值及肉品質之影響

牛至精油（oregano essential oil, OEO）為天然植物所萃取之產物，其成分中富含香芹酚（carvacrol）及百里酚（thymol）等活性物質，使其具有對微生物抗菌及抗氧化之能力，本研究之目的旨在探討飼糧中添加牛至精油對肉雞生長性能、屠體性狀、血液生化值及肉品質之影響。試驗採用336隻一日齡科寶（Cobb）肉雞，隨機分配於七個處理組，各處理組進行四欄重複，兩欄公雞兩欄母雞。七個處理組分別為：C組（基礎飼糧）、A組（飼糧中添加100 mg/kg之次級植物化合物）、B組（飼糧中添加150 mg/kg之百里香精油）、O2組（飼糧中添加200 mg/kg之OEO）、O3組（飼糧中添加300 mg/kg之OEO）、O4組（飼糧中添加400 mg/kg之OEO）及O5組（飼糧中添加500 mg/kg之OEO）。飼養過程中，飼糧及飲水皆採任食。於肉雞21日及35日齡進行犧牲採樣，各處理組逢機選擇8隻雞進行犧牲並分析生長性能、屠體性狀及血液生化值，並將肉品質樣品冷凍保存於負20̊ C冷凍櫃以利後續分析。結果顯示，於生長性能方面，餵飼OEO之處理組，其體增重及飼料轉換率皆顯著優於控制組（P < 0.05），採食量方面，於肉雞後期及全期皆無顯著差異。於屠體性狀部分，飼糧中添加OEO之處理組，其胸肉百分率顯著高於控制組及其他精油處理組（P < 0.05），腿肉百分率方面則無顯著差異。在臟器百分率方面，各處理組之間則無顯著差異。血液生化值方面，C組與OEO處理組之間並無顯著差異存在。在肉品質方面，0至48小時之滲水失重，與控制組相比，餵飼500 mg/kg OEO之處理組顯著較低（P < 0.05），而在肌纖維密度方面，餵飼OEO之處理組具有較高的數值；而酸鹼值、色澤、蒸煮失重、截切值、脂質過氧化程度、肌纖維數量、肌原纖維斷裂指數及感官品評方面，OEO之處理組與控制組間皆無顯著差異（P > 0.05）。綜合上述，飼糧中添加牛至精油有助於改善肉雞之生長性能、提升其屠體胸肉比率。對肉品質而言，則可提高胸肉肌纖維密度，並降低胸肉滲水失重之比率，顯示牛至精油的添加不僅可改善肉雞生長性能，亦有助於肉品質之提升。

關鍵字

肉雞；屠體性狀；生長性能；肉品質；牛至精油

並列摘要

Oregano essential oil (OEO) is a production which extracted by natural plant, and is rich in active ingredients such as carvacrol and thymol, making it resistant to microorganisms and reveal antioxidant capacity. The purpose of this study was to investigate the effect of dietary supplementation with oregano essential oil on growth performances, carcass characteristics, blood biochemistry and meat quality in broilers. Three hundred and thirty-two day-old Cobb broilers were randomly divided into seven treatments with 2 replicate pens per treatment group. The seven treatment groups were: C (basal diet), A (diet with 100 mg/kg Activo), B (diet with 150 mg/kg thyme essential oil), O2 (diet with 200 mg/kg OEO), O3 (diet with 300 mg/kg OEO), O4 (diet with 400 mg/kg OEO) and O5 (diet with 500 mg/kg OEO). The experiment lasted for 35 days, during experiment feed and water were provided ad libitum. Eight birds were randomly selected from each treatment and were sacrificed on day 21 and 35 for sample collection and analysis. The item including growth performance, carcass characteristics and blood biochemistry were analyzed. The meat quality samples were stored at -20 ̊C for further analysis. The results showed that all OEO groups (O2, O3, O4 and O5) increased average daily gain and feed conversion ratio compared to C group on 21 and 35 days. Feed intake was not significantly different among treatments. For carcass characteristics, the breast muscle percentage of OEO groups were higher than other groups (C, A and B). However, all treatments had no effect on leg muscle percentage and relative organ weights ratio. For blood biochemistry, there was no significant different between C group and O group. For meat quality, purge loss of O5 groups was decreased than other groups on 0-24 hour and 0-48 hour. Muscle fiber density of OEO groups were higher than other groups (C, A and B). There were no significant differences in pH value, meat color, cooked loss, shear value, muscle fiber number (MFN), thiobarbituric acid reactive substamces (TBARs), myofibril fragmentation index (MFI) and sensory evaluation among treatments. In conclusion, dietary supplementation with OEO could improve growth performance, increase the percentage of breast muscle and muscle fiber density, and decrease the percentage of purge loss, indicating that OEO may be a potential alternative to growth promoters.