胡麻饼代替豆粕对绵羊瘤胃代谢的影响

Effects of Replacement of Soybean Meal by Oil Cake of Flax Seed on Rumen Metabolism in Lambs

本文通过研究绵羊瘤胃发酵、消化酶活性及瘤胃上皮组织中挥发性脂肪酸(VFA)吸收相关基因表达量,探讨胡麻饼代替豆粕对绵羊瘤胃代谢的影响。试验选取5月龄、体重为(26.0±1.0)kg的杜泊×小尾寒羊杂交F1代公羔24只,随机分为4组[对照(CK)、Ⅰ、Ⅱ和Ⅲ组],每组6只羊,分别饲喂胡麻饼代替豆粕的饲粮,胡麻饼添加比例分别为0、6%、12%和18%。试验结束后,屠宰并取样,采集瘤胃液和瘤胃组织,研究瘤胃液发酵参数、消化酶活性及瘤胃上皮组织VFA吸收相关基因的表达。预试期10 d,正试期60 d。结果表明:1)Ⅰ和Ⅱ组的平均日增重(ADG)与CK组无显著差异(P>0.05),但显著高于Ⅲ组(P<0.05);Ⅱ组的料重比(F/G)显著低于CK组(P<0.05)。2)与CK组相比,Ⅱ和Ⅲ组的羟甲基纤维素酶、β-葡萄糖苷酶和蛋白酶的活性显著提高(P<0.05),Ⅲ组木聚糖酶和果胶酶活性显著提高(P<0.05)。3)与CK组相比,胡麻饼代替豆粕对绵羊瘤胃液p H、丙酸和乳酸浓度、乙丙比无显著影响(P>0.05),但Ⅱ组乙酸、丁酸和总挥发性脂肪酸(TVFA)的浓度显著提高(P<0.05);Ⅰ、Ⅱ和Ⅲ组氨态氮(NH3-N)浓度均显著降低(P<0.05),微生物蛋白(MCP)浓度显著提高(P<0.05);4)与CK组相比,Ⅱ组单羧酸转运蛋白1(MCT1)和单羧酸转运蛋白4(MCT4)的mRNA相对表达量显著提高(P<0.05),腺瘤下调蛋白(DRA)的mRNA相对表达量显著降低(P<0.05);Ⅲ组Na+/H+交换蛋白(NHE3)的mRNA相对表达量显著提高(P<0.05),MCT1、MCT4和DRA的mRNA相对表达量显著降低(P<0.05);胡麻饼代替豆粕对阴离子交换蛋白2(AE2)的mRNA表达量无显著影响(P>0.05)。综上,绵羊饲粮中一定比例的胡麻饼代替豆粕能够改善瘤胃代谢状况,在本试验条件下,饲粮中胡麻饼替代豆粕的适宜添加比例为12%。

The objective of this study was to investigate the effects of replacement of soybean meal by oil cake of flax seed on rumen metabolism by detecting rumen fermentation, digestive enzyme activities and expression of genes related to volatile fatty acid （VFA） absorption in rumen epithelial tissue in lambs. A total of 24 five-month-old Dorper×Small Tail Han sheep ram lambs with body weight of （26.0±1.0） kg were randomly selected, equally assigned into 4 groups [CK （control）, Ⅰ, Ⅱ and Ⅲ groups] with 6 sheep in each group, and fed diets replaced soybean meal by oil cake of flax seed （the adding proportion of oil cake of flax seed were 0, 6%, 12% and 18%, respectively）. At end of the experiment, all lambs were slaughtered, and the rumen fluid and rumen tissue samples were collected. The pre-test lasted for 10 d, and the formal test lasted for 60 d. The results showed as follows： 1） the average daily gain of groups Ⅰ and Ⅱ was not significantly different from that of CK group （ P 〉0.05）, but significantly higher than that of group Ⅲ （ P 〈0.05）. The feed to gain ratio of Ⅱ group was significantly lower than that of CK group （ P 〈0.05）. 2） Compared with CK group, the activities of carboxymethyl cellulose, β-glucosidase and protease of groups Ⅱ and Ⅲ were significantly increased （ P 〈0.05）, and the activities of xylanase and pectase of group Ⅲ were increased significantly （ P 〈 0.05 ）. 3） Compared with CK group, no significant effects were observed on rumen pH, propionic acid and lactic acid concentrations, and acetic acid/propionic acid ratio when soybean meal were replaced by oil cake of flax seed （ P 〉0.05）; however, acetic acid, butyric acid and total VFA concentrations of levels Ⅱ group were significantly increased （ P 〈0.05）; ammonia nitrogen （NH 3-N） concentration level was significantly decreased （ P 〈 0.05 ）, and microbial protein （MCP） yield was significantly increased （ P 〈0.05）. 4） Compared with CK group, the mono-carboxylate transporters 1 （ MCT1 ） and mono-carboxylate transporters 4 （ MCT4 ） mRNA relative expression levels of Ⅱ group were significantly increased （ P 〈0.05） and the adenoma （ DRA ） mRNA relative expression level was significantly decreased （ P 〈0.05）; additionally, the Na ＋/H ＋ exchange （ NHE3 ） mRNA relative expression level of group Ⅲ was significantly increased （ P 〈0.05）, but the MCT1 , MCT4 and DRA mRNA relative expression levels were significantly decreased （ P 〈0.05）; no significant difference was found in the anion exchanger 2 （ AE2 ） mRNA relative expression level among groups （ P 〉0.05）. In conclusion, replacing soybean meal by oil cake of flax seed in a certain proportion in lamb diets could effectively improve metabolism and development of rumen. Moreover, the optimal proportion of oil cake of flax seed is 12% under the condition of this experiment.