纤维素酶处理荞麦秸秆对其纤维结构和滩羊肉品质的影响

本试验旨在研究荞麦秸秆经不同酶活纤维素酶处理对其发酵前后纤维结构、营养成分、微生物数量以及滩羊肉品质的影响。本试验分为两部分，第1部分为酶处理试验，第2部分为饲养试验。酶处理试验共设计3个组，分别为对照组（未经酶处理的荞麦秸秆），试验I组（纤维素酶I处理的荞麦秸秆），试验Ⅱ组（纤维素酶Ⅱ处理的荞麦秸秆），每组3个重复。荞麦秸秆在发酵罐中密封贮存30 d后取样，然后测定其处理前后纤维结构、营养成分和微生物数量。饲养试验选择体重相近、健康状况良好的3月龄宁夏滩羊24只，采用完全随机分组设计分为3组，每组8只。日粮精粗比为30∶70，对照组饲喂基础日粮+未经处理的荞麦秸秆，试验I组饲喂基础日粮+纤维素酶I处理的荞麦秸秆，试验Ⅱ组饲喂基础日粮+纤维素酶Ⅱ处理的荞麦秸秆。预饲期15 d，正饲期60 d。正饲期结束后，每组选择5只体重接近的羊只禁食24 h后屠宰，测定羊肉理化指标和营养成分。结果表明：1） 未经酶处理的荞麦秸秆细胞壁结构完整，经纤维素酶处理的荞麦秸秆细胞壁结构存在不同程度的破坏；2） 试验I组和试验Ⅱ组中荞麦秸秆的酸性洗涤纤维分别显著降低18.71%和13.78%，中性洗涤纤维分别显著降低19.75%和17.81%（P<0.05）；3） 试验I组和试验Ⅱ组荞麦秸秆中的乳酸菌数量显著增加（P<0.05），霉菌数量显著降低（P<0.05）；4）纤维素酶Ⅱ处理荞麦秸秆能够显著提高肌肉熟肉率（P<0.05），纤维素酶I和纤维素酶Ⅱ处理荞麦秸秆后使得羊肉剪切力分别显著降低9.31%和11.84%（P<0.05）；5）试验I组和试验Ⅱ组的羊肉粗蛋白质含量分别为14.22%和14.23%，显著高于对照组（P<0.05）。综上所述，纤维素酶处理荞麦秸秆可以有效破坏秸秆细胞壁结构，改善秸秆营养成分，提高秸秆饲料品质和肉品质。在本试验日粮条件下，纤维素酶I处理荞麦秸秆的饲喂效果较优。

Effects of cellulase treatment of buckwheat straw on fiber structure and meat quality of Tan sheep

The aim of this study was to determine the effects of cellulase treatment on the fiber structure and nutrient composition of buckwheat straw， the quantity of microbes in fermented buckwheat straw， and the mutton quality of Tan sheep fed with the treated straw. This experiment was divided into two parts； the first part consisted of enzyme treatments， and the second part was a feeding test. The enzyme treatment experiment had three groups： the control group （unprocessed buckwheat straw）， trial group Ⅰ （cellulase Ⅰ treatment of buckwheat straw）， and trial group Ⅱ （cellulase Ⅱ treatment of buckwheat straw）. Each group had three replicates. Buckwheat straw with enzymes was sealed and stored in a fermenting tank for 30 days and then sampled. The fiber structure， nutrient composition， and microorganism abundance in buckwheat straw before and after the enzyme treatments were analyzed. In the feeding experiment， 24 healthy 3-month-old Ningxia Tan sheep with similar body weight were randomly assigned to three groups （eight sheep/group）.The ratio of basal diet to forage was 30∶70. The control group was fed basal diet+unprocessed buckwheat straw， trial group Ⅰ was fed basal diet+buckwheat straw treated with cellulose Ⅰ， and trial group Ⅱ was fed basal diet+buckwheat straw treated with cellulose Ⅱ. The preparation period was 15 d， and the formal experimental period was 60 d. At the end of the formal experimental period， five Tan sheep with approximately equal body weight were selected from each group and slaughtered after fasting for 24 hours. Then， the physicochemical indexes and nutrient contents of the mutton were determined. The main results were as follows： 1） The cell wall fibrous structure of untreated buckwheat straw remained intact， while that of buckwheat straw treated with cellulase was disrupted to different degrees； 2） The acid detergent fiber content of buckwheat straw in trial group Ⅰ and trial group Ⅱ was reduced by 18.71% and 13.78%， respectively， compared with that in the control group （P<0.05）， and the neutral detergent fiber content of buckwheat straw in trial group Ⅰ and trial group Ⅱ was reduced by 19.75% and 17.81%， respectively， compared with that in the control group （P<0.05）； 3） The contents of lactic acid bacteria were higher in the cellulase-treated groups than in the control （P<0.05）， and the contents of molds were lower in the cellulase-treated groups than in the control （P<0.05）； 4） Compared with mutton from sheep in the control group， mutton from sheep in trial group Ⅱ showed a significantly improved muscle cooked meat rate （P<0.05）， and that from sheep in trial groups Ⅰ and Ⅱ showed a reduction in shear force by 9.31% and 11.84%， respectively （P<0.05）； 5） The crude protein content of mutton from sheep in trial group Ⅰ and trial group Ⅱ was increased by 14.22% and 14.23%， respectively， compared with mutton from sheep in the control group （P<0.05）. In summary， these results show that cellulase treatment can effectively degrade the fiber structure and improve the nutrient status of buckwheat straw， thereby enhancing its feed quality. Ultimately， this leads to better meat quality. Under these experimental conditions， treatment with cellulase Ⅰ provided the best improvement in the feed quality of buckwheat straw.