國產苜蓿、盤固草半乾青貯添加綜合乳酸菌、糖蜜與丙酸銨對於半乾青貯品質以及泌乳羊生產表現之影響

Abstract

本研究目的在探討綜合乳酸菌、糖蜜與丙酸銨對於國產牧草半乾青貯發酵與表層發霉之效果並評估此模式下調製出來的半乾青貯對於泌乳羊生產表現之影響。本試驗分成兩個階段，第一個階段接續陳等(2019)之盤固草半乾青貯研究，探討盤固草半乾青貯在綜合乳酸菌（Lactobacillus plantarum, L. buchneri, Pediococcus acidilactici）與表層3%丙酸銨的處理之下，10週與42週開封性狀之差異；與接續劉(2018)之研究，探討苜蓿半乾青貯草捆在不同處理下之差異：(1) 對照組（未處理草捆）；(2) 處理組：內部綜合乳酸菌（L. plantarum, L. buchneri, P. acidilactici; 1 × 106 in fresh grass）、3%糖蜜與外部3%丙酸銨。第二階段分別以體內以及體外試驗的方式評估半乾青貯的營價值，在動物試驗當中一共使用四頭泌乳中期的阿爾拜因泌乳羊個別飼養於代謝籠中，採交叉試驗設計的方式分成兩組進行試驗，一組餵飼以半乾青貯為主之飼糧，另外一組餵飼以乾草為主之飼糧（精芻比50：50），並調整精料中玉米跟大豆粕的比例，使兩組在等能量、等蛋白質的狀況下進行試驗。 在盤固草半乾青貯的試驗當中，42週與10週開封之草捆在發霉的比例、表層霉斑的數量與pH值上均無顯著差異，而42週相較於10週則有較高的乳酸與乙酸含量（P < 0.05），顯示在綜合乳酸菌與表層3%丙酸銨的共同處理下，能夠使盤固草半乾青貯在正常的保存環境下，穩定的存放42週。在苜蓿半乾青貯的試驗當中，處理組相較於對照組具有較低的中洗纖維、水溶性碳水化合物含量與pH值（P < 0.05）並且有較高的乳酸含量與瘤胃中有效可降解乾物質（P < 0.01），顯示綜合乳酸菌與糖蜜的添加能夠促進苜蓿半乾青貯的發酵狀態並改善其可消化營養組成性狀，然而pH值改變的幅度並不是很大（對照組：5.54；處理組：5.34），可能與本研究苜蓿半乾青貯乾物質比例較高有關（Dry matter：63.86%），在表層霉斑的數量上，處理組相較於對照組有較低的趨勢（P = 0.07），而在黴菌毒素的檢測當中，兩個組別均有發現玉米烯酮毒素超標的現象；在動物試驗當中，半乾青貯飼糧組與乾草飼糧組在乾物質採食量、有機物質採食量、泌乳量、乳脂、乳蛋白與乳糖上均無顯著差異，而半乾青貯飼糧組相較於乾草飼糧組則是有較高的乾物質消化率、有機物質消化率、非纖維碳水化合物消化率與採食量，並且有較低的乳中尿素氮含量（P < 0.05），在成本的計算上，半乾青貯飼糧（每公斤乾物質8.083元）則低於乾草飼糧（每公斤乾物質10.243元）。 綜合上述試驗結果，綜合乳酸菌與3%丙酸銨的添加，能夠使盤固草半乾青貯穩定的保存42週；而綜合乳酸菌、3%糖蜜與3%丙酸銨的添加，則是能夠促進苜蓿半乾青貯的發酵狀態與改善其可消化營養組成性狀，並且對於表層霉斑的抑制也有部分效果，然而在pH值變動的幅度上則較不明顯；若以本試驗所調製出之半乾青貯作為泌乳羊之芻料來源，能夠使泌乳羊維持與乾草飼養下相等的乾物質採食與泌乳表現，並且能夠提供夠多的非纖維碳水化合物給予泌乳羊，同時使酪農戶之飼料成本降低五分之一。

The aim of this study was to evaluate the effect of mixed lactic acid bacteria (LAB), molasses, and ammonium propionate (AP) on domestic haylage fermentation, surface spoilage and lactating goat performance. This study was divided into two parts. The first part followed Chen et al. (2019) and Liu (2018), continued on studying the difference between pangolagrass haylage with the addition of mixed LAB (Lactobacillus plantarum, L. buchneri, Pediococcus acidilactici) and 3% AP after 10 weeks’ and 42 weeks’ ensiling, and examining the the difference between alfalfa haylage under different treatments: (1) control group (deionized water) (2) treatment group (3.33 × 105 cfu/g of L. plantarum, 3.33 × 105 cfu/g of L. buchneri, 3.33 × 105 cfu/g of P. acidilactici, 3% molasses, and 3% ammonium propionate). In the second part of this study, we used in vivo, in vitro and in situ methods respectively to evaluate the feeding value of haylage produced in the first part of the present study. In feeding experiment, a crossover experimental design using 4 mid-lactation Alpine goats in metabolic cages was set up to compare the feeding value of haylage based diet to hay based diet (concentrate : forage = 50 : 50). The crude protein and metabolizable energy of two groups were equalized by adjusting the proportion of corn and soybean meal in the concentrate. There was no statistically significant difference on surface spoiled rate, spoilage spot, and pH value between pangolagrass haylage after 10 and 42 weeks’ ensiling, whereas pangolagrass haylage after 42 weeks’ ensiling had higher lactic acid and acetic acid content than pangolagrass haylage after 10 weeks’ ensiling (P<0.05). In alfalfa haylage experiment, treatment group had lower pH value, neutral detergent fiber, and water soluble carbohydrate contents (P<0.05) and higher lactic acid content and effective DM degradability than control group (P<0.01). However, the changes of pH value were limited (treatment group: 5.34; control group: 5.54). This may be attributed to high DM content before ensiling (DM: 63.68%). Treatment group had a tendency of decreased surface spoilage spot than control group (P = 0.07). Nevertheless, both of them were found to contain zearalenone exceeding the advisory levels set up by European commission. In lactating goat feeding experiment, DM intake, organic matter intake, milk yield, milk fat, milk protein, and lactose did not differ between two different diets. However, dairy goats fed haylage diet had higher DM, OM, and non-fiber carbohydrate digestibilities and intake and lower milk urea nitrogen than hay diet (P<0.05). In addition, the cost of haylage diet (8.083 NT$/kg DM) was lower than hay diet (10.243 NT$/kg DM). In conclusion, pangolagrass haylage treated with mixed LAB and 3% AP could keep quality stable under 42 weeks’ storage in normal condition, and adding mixed LAB, 3% molasses, and 3% AP on alfalfa haylage could improve fermentation quality and digestive indices and inhibit surface spoiled condition. However, the changes of pH value were limited. Using alfalfa and pangolagrass haylage to replace all the hay could maintain the same DM intake, production performance, and provide more non-fiber carbohydrate for lactating goats, and meanwhile reduce feed cost up to 20%.