调质对饲料营养价值影响的研究进展

调质是饲料加工过程中的重要工段,饲料调质效果直接影响饲料产品加工质量,进而影响畜禽对营养物质的消化吸收及生长性能。调质温度、蒸汽类型等是影响调质效果的主要因素,但调质过程中原料特性及结构变化同样对调质效果有较大程度影响。了解调质过程中饲料原料成分结构的变化对提高颗粒饲料加工质量及畜禽生长性能具有十分重要的意义;控制好调质参数将提高饲料配方中热敏性饲料原料的保留率,为热敏性抗生素替代产品在日粮中的应用提供技术支撑。本文综述了饲料调质过程中淀粉及蛋白质的变化对颗粒饲料加工质量的影响,以期为调质过程中的自动化控制提供思路。     

膜联蛋白A8在小鼠早期妊娠子宫中表达研究

膜联蛋白A8(Annexin A8,ANXA8)是一种磷脂结合蛋白,与炎症反应、癌症的发生以及血管生成有密切联系。本实验旨在利用实时荧光定量PCR、原位杂交与免疫组织化学的方法研究ANXA8 mRNA与蛋白在小鼠早期妊娠和人工蜕膜子宫中的表达。原位杂交结果表明:ANXA8 mRNA在小鼠早期妊娠第1～4天子宫腔上皮和腺上皮有微弱表达,ANXA8 mRNA在妊娠第5、6天的初级蜕膜区与第7、8天的次级蜕膜区表达,并随妊娠进行逐渐增强;人工蜕膜化模型中ANXA8 mRNA表达在蜕膜区。实时荧光定量PCR证明:ANXA8 mRNA的表达量在早期妊娠模型中的第7、8天显著提高,人工蜕膜侧子宫与对照侧相比也显著提高。免疫组织化学结果表明:ANXA8蛋白与ANXA8 mRNA表达规律相似。体外分离培养小鼠子宫基质细胞,并诱导蜕膜化,实时荧光定量PCR结果表明ANXA8随着基质细胞的蜕膜化表达升高。以上体内和体外实验表明,ANXA8在小鼠子宫中的表达具有着床相关特异性,ANXA8参与小鼠子宫蜕膜化过程。     

SLC24A5基因影响脊椎动物色素沉积的研究进展

黑色素广泛分布于细菌、真菌、植物和动物体内并扮演了重要的作用。人类浅色皮肤的色素沉积是由于黑色素细胞内黑色素小体数量、大小和密度的减少造成的,而黑色素小体变化也导致斑马鱼由灰色突变为金色,这个金色突变位点编码一个推定的阳离子交换体SLC24A5基因,该基因位于黑色素小体或其前体的细胞膜上。人类和斑马鱼在这个基因的序列及功能上有很高的同源性。该基因的多态性主要出现在非洲和东亚人身上。而等位基因固定在欧洲人的身上,这与局部杂和性大量减少和较浅的皮肤色素沉积有关,表明SLC24A5基因在人类色素沉积方面起关键作用。作者总结了SLC24A5基因与黑色素的研究进展,并简要介绍了乌骨绵羊的发现及其分子特征。     

Characterization of virulence properties of Listeria monocytogenes serotype 4b strains of different origins

In this study, the virulence heterogeneity of Listeria monocytogenes serotype 4b strains of different origins was analysed on different levels. On one hand, the survival of L. monocytogenes strains in synthetic gastric fluid was studied. On the other hand, the pathogenic potential of strains with different inlB expression levels was analysed in an A/J mouse model for gastrointestinal listeriosis. Differences in survival capacity in gastric fluid and in in vivo virulence potential were observed between the tested strains. No clear correlation between the origin and the obtained data could be made. However, these results confirm the existence of heterogeneity in virulence potential of L. monocytogenes serotype 4b strains.     

苷元型大豆异黄酮对母羊氧化应激、乳中免疫球蛋白和羔羊生长的影响

本试验旨在研究日粮中添加不同水平的苷元型大豆异黄酮对妊娠后期及泌乳期母羊氧化应激、乳中免疫球蛋白和羔羊生长的影响。试验选用33只年龄、体重、胎次相近的妊娠100 d的崇明白山羊,随机分为3组,对照组饲喂基础日粮(C0组,11只),试验组分别在基础日粮中添加20 mg/kg(T1组,9只)和30 mg/kg(T2组,13只)苷元型大豆异黄酮。结果表明:T1和T2组母羊的窝产羔数、初生窝重、断奶窝重和窝日增重显著高于C0组(P0.05);分娩当日,T2组母羊血清中过氧化氢(H_2O_2)含量显著低于C0和T1组(P0.05);与T1和T2组相比,C0组血清中总超氧化物歧化酶(T-SOD)活性最高(P0.05),总抗氧化能力(T-AOC)最低(P0.05),3组间丙二醛(MDA)无显著差异(P0.05);在泌乳21 d,T2组母羊血清中H_2O_2含量显著低于C0和T1组(P0.05);与C0和T2组相比,T1组血清中T-SOD活性最高(P0.05),3组的T-AOC和MDA无显著差异(P0.05);T1和T2组初乳中免疫球蛋白A(Ig A)含量显著高于C0组(P0.05)。结果提示,在妊娠后期及泌乳期母羊饲粮中添加苷元型大豆异黄酮可有效减缓母羊的氧化损伤,提高初乳中免疫球蛋白含量,促进羔羊生长发育,且添加量以30 mg/kg效果更显著。     

The impact of direct‐fed microbials and enzymes on the health and performance of dairy cows with emphasis on colostrum quality and serum immunoglobulin concentrations in calves

Thirty‐six cows were blocked by calving date and randomly assigned to one of three treatments. Cows were on treatments 3 weeks prepartum through 8 weeks post‐partum. Treatments were as follows: (i) no direct‐fed microbial (DFM) or cellulase and amylase enzymes (C), (ii) 45.4 g/day of DFM (D) or (iii) 45.4 g/day of DFM and 18.2 g/day of enzyme (DE). Total mixed ration fed and refused were measured daily to determine dry matter intake (DMI). Blood samples were taken three times weekly and analysed for β‐hydroxybutyrate, glucose and non‐esterified fatty acids. Body weight (BW) was measured weekly. Colostrum was weighed and analysed for IgA and IgG concentration. Calves were fed 4 L of colostrum within 2 hr of birth. Calf blood samples were taken at 0 and 24 hr for analysis of IgA and IgG concentrations and apparent efficiency of absorption. Milk yield was measured daily and samples collected weekly. Initial BW was different among treatments with D being lesser than C or DE treatments. Body weight, weight gain, efficiency of gain, DMI and blood parameters were unaffected. Treatment did not affect colostrum yield. Ash percentage of colostrum tended to increase with D and DE, while IgA and total solids yield decreased with D. Colostrum fat yield was decreased in D and DE. Treatments did not impact BW, serum IgA and IgG concentrations or apparent efficiency of absorption of calves. Post‐partum BW, DMI, blood parameters, milk production and composition were unaffected by treatment. However, cows on D gained more BW and tended to have greater efficiency of gain compared to those on DE, but were similar to C. Somatic cell scores were greatest for D. Results indicate that DFM and enzyme supplementation did not improve health and performance of dairy cattle during the pre‐ and post‐partum periods under conditions of this study.