論文宣讀

壞死性腸炎(necrotic enteritis, NE)是發生在家禽中常見的腸道疾病，通常與產氣莢膜梭菌(Clostridium perfringens, CP)在腸道中過度增殖有關。NE可分為急性臨床型及亞臨床型，相較於高死亡率的急性臨床型，患亞臨床型的家禽較無明顯症狀且鮮少死亡發生，但腸黏膜受損嚴重影響營養的消化與吸收，使生長性狀表現下降，造成家禽業龐大的經濟損失。抗生素作為生長促進劑(antibiotic growth promoters, AGPs)而產生抗藥性疑慮日漸劇增，已被多國禁用。為了取代抗生素，產學界積極研究各類飼料添加劑作為替代品，其中包含益生菌與後生元。後生元的定義為能為宿主提供健康益處的無生命微生物或其片段產物。與益生菌相比，後生元更不容易引起菌血症，儲存的條件也相對容易。乳酸乳球菌(Lactococcus lactis, LL)後生元現已被研究出能夠促進傷口癒合、維持腸道菌群平衡等，但尚未有研究將其作為家禽飼糧添加劑。因此本篇研究目的為探討LL後生元是否能改善肉雞的壞死性腸炎，並與商業益生菌(OPTIMAX)混合成複方一同比較。試驗肉雞品系為Ross 308白肉雞，處理組共分為5組：無攻菌的negative control (CON)、有攻菌的positive control (CON+CP)、飼糧中含LHK(Heat- killed Lactococcus lactis)、OPTIMAX、或LHK +OPTIMAX。試驗為期35天，在第18、20天灌食2 x 10⁸ cfu/ml的CP；每週秤量體重、採食量，以計算飼料轉換率；第21、28天採翼靜脈血分析發炎相關指標；於第28天採腸道樣本並收集腸道內容物，記錄病變評分、觀察腸道形態，後續再以 Western blot或qRT-PCR分析樣本。結果顯示:全期(Day 0-35) CON+CP與CON相比，體增重有下降的趨勢，但未達顯著差異，OPTIMAX及LHK+OPTIMAX組之體重則有顯著高於CON+CP組。腸道形態結果中，LHK、OPTIMAX及LHK+OPTIMAX組皆優於CON+CP組。第28天腸道切片觀察白血球浸潤情形，LHK、OPTIMAX、LHK+OPTIMAX顯著優於CON+CP組，且LHK組在空腸表現最佳。第28天血液白血球(WBC)數量，LHK、OPTIMAX及LHK+OPTIMAX組皆顯著低於CON+CP組。第28天血漿IL-1β含量，LHK、OPTIMAX及LHK+OPTIMAX組皆顯著低於CON+CP組。迴腸IL-6蛋白表現量，LHK及OPTIMAX組顯著低於CON+CP組。腸道緊密連接蛋白分析，LHK組空腸的Occludin及Zonula occludens-1 (ZO-1)表現量顯著高於CON+CP組。抗菌蛋白分析，LHK組空腸與迴腸之Mucin 2及Cathelicidin 3基因表現量顯著高於CON+CP組，且迴腸AvBD-8 (avian β-defensin 8)基因表現量也顯著高於CON+CP組。綜上所述，LL後生元及與益生菌複方皆可改善NE帶來的負面影響，雖在生長性狀表現不如益生菌處理佳，但LL後生元對於抗發炎、腸道屏障及先天免疫有更顯著的改善效果。

關鍵字：壞死性腸炎、白肉雞、後生元複方、益生菌、抗發炎

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