飼糧中添加味精菌體蛋白對肥育其肉豬生長性能、血液生化值、屠體性狀及肉品質之影響

菌體蛋白（bacterial protein, BP）是利用細菌生產之單細胞蛋白質（single cell protein, SCP），其特點為產量高、生產週期短且不受季節限制。味精（monosodium glutamate, MSG）於製造過程中剩餘之發酵母液經分離乾燥後所得之副產物為味精菌體蛋白。本報告旨在探討，飼糧內添加味精菌體蛋白對肥育肉豬生長性能、血液生化質、屠體性狀及肉品質之影響。本試驗採用24頭平均體重80 ± 2.8 kg之LYD三品種雜交肉豬（Landrace × Yorkshire × Duroc），閹公豬及肉女豬各12頭，依體重逢機分配至3個處理組：基礎飼糧（Con）、A組及B組（分別添加1.5%及3%之味精蛋白處理組）。每欄飼養同性別肉豬4頭，每處理組2欄。試驗期間飼糧及飲水皆採任食，肉豬每2週進行個別秤重並紀錄平均日採食量、平均日增重及飼料轉換率。當肉豬平均體重達120公斤後結束生長試驗，每處理組隨機選取2頭肉豬送往屠宰場測定屠體性狀及肉品質。實驗結果顯示，肉豬飼糧中添加味精菌體蛋白對平均日採食量、平均日增重及飼料轉換率無顯著影響。血液生化值方面，血中丙胺酸轉胺酶（alanine aminotransferase, ALT）濃度隨味精菌體蛋白增加而下降，B組之ALT顯著低於Con組，A組之三酸甘油脂（triglyceride, TG）顯著高於Con組（P < 0.05），其他皆無顯著差異。屠體性狀方面，各組於屠宰率、瘦肉率、背脂厚度及屠體評級皆無顯著差異，B組有顯著較高之里肌肉pH1，A組腰眼面積顯著低於Con及B組（P < 0.05）。於肉品質方面，A組里肌肉之粗脂肪顯著高於Con及B組（P < 0.05）；色澤、pH值、肉色、大理石紋、緊實度、蒸煮失重及感官品評各組間皆無顯著差異，對於里肌肉之肌纖維數目也無顯著影響。綜合上述，於飼糧中添加味精菌體蛋白，對肥育期肉豬生長性能、血液性狀及屠體性狀不會造成負面影響，並能改善肉豬屠體pH值而促進豬肉品質。因此，味精菌體蛋白能夠取代肥育期肉豬飼糧內大豆粕作為蛋白質來源，達到降低生產成本及改善豬肉品質之結果。

關鍵字

菌體蛋白；屠體性狀；生長性能；肉品質；肉豬

並列摘要

Advantages of bacteria for single cell protein (SCP) production are a rapid growth rate, a high protein content and the ability to grow on hydrocarbons. MSG (monosodium glutamate) bacterial protein is the organic residue of microbial fermentation during the production of MSG. The present study was conducted to evaluate the effects of dietary MSG bacterial protein on growth performance, blood biochemistry, carcass traits and meat quality in finishing pigs. Twenty four Duroc × Landrance × Yorkshire finishing pigs (initial BW of 80 ± 2.8 kg) of equal barrows and gilts were randomly allocated into 3 dietary treatments with 2 replications per treatment, and 4 pigs per pen. The 3 dietary treatments were: CON (basal diet), group A (1.5% MSG bacterial protein) and B (3% MSG bacterial protein). Feed and water were provided ad libitum. Pigs were weighed individually and feed consumption was recorded every two weeks during the period of growth trial. Two pigs from each pens were randomly selected at the end of growth trial for analysis of carcass traits and meat quality. The results showed that there were no significant difference among treatments in growth performance. For blood biochemistry, group B has significantly lower alanine aminotransferase (ALT) than CON (P < 0.05). Group A has significantly higher than CON in triglyceride (TG) (P < 0.05). The results of carcass traits showed there were no significant difference among treatments in dressing percentage, lean meat percentage, back fat thickness and carcass evaluation but had significantly highest pH1 value of loin in group B (P < 0.05). For meat quality, crude fat was significantly higher in Group A than group B and CON (P < 0.05). However, there were no significant difference among treatments in L*a*b* value, pH value, color, marbling score, firmness, cooking loss, sensory evaluation and muscle fiber number in longissimus muscles. In summary, dietary supplementation of MSG bacterial protein has no impairment to the growth performance and carcass traits of finishing pigs, and showed better meat quality due to higher pH value of loin. Therefore, MSG bacterial protein has the potential to replace soybean meal as a protein source and improving meat quality.