Application of soybean hulls fermented by Aureobasidium pullulans SH-218 in broiler diet

Abstract

大豆殼為生產大豆油之加工副產物，普遍應用於反芻動物飼糧中，因其半纖維素含量達15 %，於家禽飼糧中鮮少使用，因此做為飼料原料之營養價值不高。A. pullulans為具有生產半纖維素酶之類酵母真菌，能降解植物細胞壁之半纖維素成分。因此本試驗之目的為探討以A. pullulans SH-218發酵大豆殼作為肉雞飼料添加物之效果。體外試驗結果顯示以A. pullulans SH-218接種大豆殼於30℃、pH 6.0、水分40 %，培養12天後可得最佳半纖維素酶生產條件 (甘露聚醣酶：110 Unit/g DM；木聚醣酶：39 Unit/g DM)。同時，發酵產物之寡醣含量提升且其水解液具有降低pH值及大腸桿菌數之效果。動物試驗以400隻白肉雞隨機分成四個處理組，分別為空白組、添加商業化甘露聚醣酶之正對照組、與添加0.5及1.0 ％發酵大豆殼之處理組。結果顯示，添加1.0 %發酵大豆殼處理組肉雞體增重與正對照組相似 (2008及1991 g) 且高於空白組 (1861 g) (P<0.1)。添加0.5 ％發酵大豆殼處理組之盲腸相對重量較其空白組為輕 (P<0.05)，又添加1.0 %發酵大豆殼免疫器官脾臟之相對重量較空白組為重 (P<0.05)。添加發酵大豆殼處理組雞隻盲腸內容物乳酸菌菌數(11.2 及12.0 Log CFU/g) 顯著高於空白組 (9.7 Log CFU/g) (P<0.05)，並以添加1.0 %之處理組之迴腸大腸桿菌群數顯著低於空白組 (P<0.05)，而梭狀芽孢桿菌則顯著低於正對照組 (P<0.05)，且可顯著增加迴腸絨毛高度 (P<0.05) 及提升半纖維素利用率 (P<0.05)，而添加1.0 %發酵大豆殼相較於空白組亦可降低排泄物及盲腸中氨態氮含量 (減少12 及15 %) (P<0.05)。此外，添加1 %發酵大豆殼具有降低血液中三酸甘油酯含量與刺激雞隻血液PBMC合成NO之效果 (P<0.05)。最後，由經濟效益評估結果顯示，添加1.0 %發酵大豆殼可降低整體飼養成本且對於雞隻生長並無影響。綜上所述，大豆殼以A. pullulans SH-218發酵可產生甘露聚醣酶與益生物質而降低腸道之有害菌數，進而改善生長，並降低氨態氮之排出、改善血液性狀及調節免疫能力。

Soybean hulls are by-product during the soybean oil production. Since the high hemicellulose content in soybean hulls, they are thought of as a roughage feed in ruminant, instead of in poultry diets. A. pullulans, a yeast-like fungus, has the potential to degrade the plant cell wall, since it is proficient in hemicellulase production, such as xylanase and mannanase. Therefore, the aim of this study is to explore the effects of soybean hulls fermented by A. pullulans in broiler diet. In the in vitro experiment, the optimum condition of soybean hulls fermentation, and the prebiotic effect of fermentation product was evaluated. The results showed the optimal condition for soybean hulls fermentation was at 30℃, pH 6.0, and with the moisture content of soybean hulls was at 40 % for 12 days. The amount of oligosaccharides in fermented soybean hulls was increased by the fermentation, and it had the ability to reduce the pH value and coliform count. In the in vivo trial, four hundred 1-day-old broilers were allocated randomly into 4 dietary treatments including the basal diet, and basal diet containing commercial enzyme, 0.5 % or 1.0 % fermented soybean hulls (FSBH) with 4 replicates per treatment for 5 weeks. Feed and water were supplied ad libitum with floor feeding. The results showed that the birds fed with 1.0 % FSBH were significantly better than the control group in weight gain, whereas there was no significant difference existed in the feed consumption and feed conversion rate among the treatments. 0.5 % treatment had lower relative weight but higher content of total volatile fatty in cecum, comparing with the other treatments. Fermented soybean hulls treatments had significantly higher lactic acid bacteria count in cecum (0.5 %: 12.0 Log CFU/g; 1.0 %: 11.2 Log CFU/g), comparing with control (9.7 Log CFU/g). Moreover, 1.0 % treatment had significantly lower coliform and Clostridium perfringens count than control and commercial enzyme treatment in ileum. 1.0 % FBSH also could incease villus height and promote the nutrient apparent ability of hemicellulose. Meanwhile, feed containing fermented soybean hulls could reduce the content of ammonia nitrogen in cecum and feces and reduce the content of triglyceride in serum. Moreover, it was cost-effective for 1.0 % FSBH supplementation in broiler diets. In conclusion, this study cleared that fermented soybean hulls could produce mannanase and prebiotic which was contributed to reducing pathogen. Hence, feed adding fermented soybean hulls could improve growth performance, reduce excreta ammonia nitrogen, improve serum parameters and immunomodulatory.