发酵工艺在饲料行业中的应用日益成熟,研究发现,通过发酵处理能有效改善非常规饲料原料中的营养成分,降低或消除非常规原料中抗营养因子的含量.这将有利于缓解部分常规饲料原料短缺或价格昂贵的现状,提高畜牧生产效益.本文就发酵工艺对饲料营养成分及饲料中抗营养因子的影响进行介绍,旨在为发酵工艺在饲料工业上的应用提供参考.

[目的]将粉碎的饲料桑按15％比例与玉米秸秆共同发酵后制成混合发酵饲料,分析发酵产物的营养成分,评价饲喂混合发酵饲料对羔羊采食量、生长性能、营养物质表观消化率等指标的影响.[方法]选取健康的3月龄断奶肉羊100只,随机分为试验Ⅰ组、Ⅱ组、Ⅲ组、Ⅳ组和对照组,每组20只,各组试验羊初始体重差异不显著(P>0.05).对照组饲喂基础饲粮,试验Ⅰ组、Ⅱ组、Ⅲ组、Ⅳ组在基础日粮中分别添加15％混合发酵饲料(含15％饲料桑)、15％发酵玉米秸秆、15％饲料桑、15％玉米秸秆.试验期45 d.[结果]混合发酵饲料与发酵玉米秸秆和饲料桑相比,DM、Ash、EE含量差异不显著(P>0.05),氨基酸总量、CP含量差异显著(P<0.05);混合发酵饲料与饲料桑相比,CF含量差异显著(P<0.05);混合发酵饲料与发酵玉米秸秆和饲料桑相比,NDF含量差异显著(P<0.05);混合发酵饲料与发酵玉米秸秆相比,ADF含量差异显著(P<0.05).试验Ⅰ组与试验Ⅱ组、Ⅲ组、Ⅳ组及对照组相比,采食量显著增加(P<0.05);试验Ⅰ组的只均增重、平均日增重、粗饲料采食量及饲料转化率均显著高于其余各组(P<0.05);各组的DM、EE表观消化率差异不显著(P>0.05);试验Ⅰ组的NDF、ADF、Ca、P表观消化率与其余各组相比差异均显著(P<0.05).[结论]由15％饲料桑与玉米秸秆制成的混合发酵饲料,营养价值较发酵玉米秸秆和饲料桑有所提高;与饲喂基础日粮相比,在基础日粮中添加15％的混合发酵饲料,可以提高肉羊的采食量和饲料转化率.

Bacillus subtilis is an aerobic positive bacteria which is used as a probiotic for both human and ani-mal. It can be induced to differentiate into the spore by unfavorable condition of circumstances. Because of the special structure and physiological characteristics of Bacillus subtilis spore, researchers found that the spore was the ideal vector of enzymes and antigens, and had been used the coat protein as a carrier, adsorption or cova-lent methods to display foreign proteins on the surface of the spore. Now, some enzymes, antigens and other functional proteins have successes to be displayed on the spore. The paper introduced the structure of Bacillus subtilis spore, the technology of spore surface display and its application.

The study aimed to construct a Tibetan pig IGF-1 mature peptide gene's eukaryotic expression vector,and to obtain the IGF-1 mature protein with biological activities expressed by Pichia pastoris expression system.A pair of primers was designed based on the IGF-1 gene sequence from GenBank,and the IGF-1 mature peptide sequence was amplified with the pMD19-T-IGF-1 as a template.Then the IGF-1 mature peptide sequence was cloned into pPIC9K to construct a pPIC9K-IGF-1 plasmid,which was transformed into Pichia pastoris GS115 by electrotransformation.Finally the multi-copy colonies were acquired after the transformed cells were confirmed with both PCR and MM/MDplate screening methods and screened by G418 resistance gradient.The target proteins were induced by methanol and detected by method of Tricine-Tris-SDS-PAGE and Dot Blot.Analysis of Tricine-Tris-SDS-PAGE and Dot Blot showed that the recombinant IGF-1 mature peptide protein was successfully expressed,of which the molecular weight was about 13 ku,The analysis of CCK8 showed that the recombinant protein IGF-1 could promote porcine lymphocyte proliferation.The results showed that the eukaryotic expression plasmid pPIC9k-IGF-1 was constructed successfully and expressed efficiently in pichia GS115,and the recombinant IGF-1 mature peptide protein possesses the biologic activities in promoting porcine lymphocyte proliferation.

试验选用10株芽孢杆菌,对其产淀粉酶的能力进行了测定,测定方法分初选(染色法)和复选(3,5-二硝基水杨酸显色法)两步。结果表明,其中9株菌具有产淀粉酶能力,以编号为Pab03、Pab02的两株枯草芽孢杆菌的产酶活性最高,在未优化发酵条件的前提下,酶活力分别达到31.331和21.521U,作为新型的消化酶饲料添加剂显示出广阔的应用前景。

[Objective] The research on the screening of Bacillus strain with the ability in high-yielding amylase was conducted.[Method] The capacity of 10 Bacillus strains producing amylase was primarily tested with the staining method and finally determined with the chromogenic method of 3,5-dinitro-salicylic acid for the screening of the Bacillus strain with the ability in high-yielding amylase. [Results] 9 Bacillus strains had the capacity of amylase production,among which,two Bacillus subtilis strains: Pab03 and Pab02 showed the highest activity and the diameters of the chromatin circle of colony were 2.284 and 1.961,respectively.Under the premise of no fermentation as the optimal treatment,their enzyme activities were(31.331±0.985) and(21.521±1.390),respectively.As new type of digestive enzymes,they had a wide prospect in the application of feed additives.The strain coagulans Bacillus PSAF1and Bacillus subtilis PJK01 had the lowest ability in amylase-producing,which was(0.366±0.022) and(0.704±0.089),respectively.[Conclusion] Two Bacillus subtilis strains:Pab03 and Pab02 with the ability in high-yielding amylase-producing were successfully screened out.

[Objective] The research aimed to study the effects of high enzyme activity-producing Bacillus subtilis agent on the milk yield and milk component of dairy cow.[Method] Selecting 24 cattles of Holstein with the similar physiological status such as variety,birth order,body weight,milk yield and lactation period,under the accordant situations of feed formula,management and environmental conditions,different dosages of high enzyme activity-producing B.subtilis micro-ecological agent were added into the basic diet in test groups.The cattles in control group were fed normally.The milk yield and components in each group in different periods were calculated.[Result] The milk yield in test groups and control group increased to different extent.Compared with control group,the milk yield in test group C and D increased by 26.34% and 20.53% respectively.During the experimental period,the milk yield in different groups B had significant difference.In the third test stage,that in test group C alsohad extremely significant difference with control group(P0.01)and that in test group C and in test group B had the significant difference(P0.05).In the fourth test stage,that in test group C also had extremely significant difference with control group (P0.01),that in test group C and in test group B also had extremely significant difference(P0.01).With different increased quantity of milk yield in different group,the content of milk fat and milk protein had different changes.In control group,milk fat decreased by 3.16% and milk protein increased by 1.41%.In test group C,milk fat decreased by 3.21% and milk protein increased by 1.40%,being at the same level with control group.In test group D,milk fat increased by 0.68% and milk protein increased by 2.04% with higher increased percentage than control group.[Conclusion] High enzyme activity-producing B.subtilis agent could increase the milk yield of dairy cow.When the adding dosage was different,the increased milk yield was different.It could not only increase the milk yield,but it could also decrease the percentage point of milk fat ratio and increase the content of milk protein.

试验选用10株芽孢杆菌,根据其分泌胞外纤维素酶的活力对菌株进行了初选和复选,初选均采用平板培养、染色法;复选采用分光光度计比色法测定芽孢杆菌发酵培养液酶活力。筛选出胞外酶活性较高且连续发酵酶活力相对稳定的枯草芽孢杆菌菌株,菌株编号为Pab02,其单位生物量纤维素酶活力为1582.854U。并进一步对其发酵培养基的初始pH、发酵温度及时间进行了优化,结果显示该菌株在pH值7.5、温度37℃、时间48h条件下单位生物量酶液酶活达到2200.925U,是优化前酶活的1.39倍。

枯草芽孢杆菌为大多数动物肠道中的过路菌群,被世界各国列为允许在畜禽体内使用的益生素生产菌种.其作为饲料添加剂的作用主要有以下几方面:其一,枯草芽孢杆菌以其内生孢子进入动物消化道内虽然不能增殖,但能迅速生长发育并分泌活性很强的胞外酶-蛋白酶、脂肪酶、淀粉酶、糖苷酶等多种酶类,同时还产生降解植物饲料中非淀粉多糖的酶-果胶酶、纤维素酶、葡聚糖酶,这些活性酶直接作用动物消化道的"酶池",降解饲料中相应的营养成分,提高饲料中营养成分的消化,从而提高蛋白质和能量的利用率,降低料肉比.