杀菌剂对沙打旺种子萌发和幼苗生长的短期影响

病害是导致沙打旺(Astragalus adsurgens)草地产量下降的主要原因之一。本研究用杀菌剂对沙打旺种子进行预处理,在培养皿和盆栽两种培养条件下模拟沙打旺种子在自然环境中受到不同病原真菌侵染后的萌发和生长状况,探讨杀菌剂预处理的作用和效果。结果表明,人工接种病原菌后,经杀菌剂处理的种子,其发芽率,植株的株高、根长和干重较无菌水处理种子显著提高(P0.05),而发病率、死亡率和平均病情指数则相应地显著降低(P0.05)。不同杀菌剂的防治效果有所不同,在多菌灵、代森锰锌和甲基托布津3种杀菌剂中,代森锰锌预处理防治效果最好。     

无机磷溶解菌RW8的筛选、鉴定及对白三叶促生效果研究

从白三叶根际分离筛选9株溶磷微生物,并对挑选菌株进行形态、细胞以及种属鉴定,并分析其对白三叶的促生效果。通过分析溶磷圈与溶磷菌落直径的大小与比值获得溶磷量与持续溶磷能力较强的RW8菌株。通过形态与扫描电镜观察发现RW8是具有鞭毛的短杆菌,其菌落形态表面光滑,不透明;将RW8 16S rDNA序列比对NCBI数据库发现其与阴沟肠杆菌属(Enterobacter sp.)的同源性高达99.5%,Biolog鉴定其与阴沟肠杆菌(Enterobacter cloacae ss dissolvens)的相似性为0.610。RW8溶磷量达424.85 μg/mL,溶磷能力可能与RW8的产酸性能(12.30 μg/mL)密切相关。RW8对白三叶根系与幼苗的生物产量的分配有显著影响,接种RW8后能抑制白三叶根系伸长,根系鲜重与干重有下降趋势,但差异不显著;而幼苗的生物产量(干重与鲜重)均显著高于对照(P<0.05),并且该现象与植物生长激素IAA无关,其具体的作用机制还有待于进一步研究。     

黄土区封育和放牧草地物种多样性和地上生物量对氮素添加的响应

氮素添加对草地生态系统地上生物量具有普遍促进作用,但对解释引起物种多样性丧失的机制仍存在较大争议。本研究以黄土高原半干旱区长期封育和连续放牧草地为对象,通过设置不同氮素添加水平来探索两种典型的草地管理方式下群落地上生物量、物种多样性、群落组分结构对氮素添加的响应及其异同以及物种多样性与地上生物量的关系,并研究这些响应的潜在生态学机制。结果显示,1)氮素添加显著提高长期封育草地地上生物量的同时降低了物种多样性;放牧草地群落地上生物量、物种多样性对氮素添加的响应与封育草地相同,但其响应程度均小于封育施肥草地;2)草地群落物种多样性随地表凋落物生物量增加而降低,随植被透光率增加而升高; 3)封育施肥草地Shannon-Wiener多样性指数与地上生物量存在显著线性负相关关系,而放牧施肥草地的物种多样性与地上生物量不存在显著的相关关系。以上结果表明放牧能够减缓施肥对物种多样性的负效应,在轻微降低物种多样性的前提下显著提高群落地上生物量,是一种合理的草地管理方式。     

鸭疫里默氏菌的分离鉴定

本研究经过菌落形态、染色形态、生化实验以及PCR实验,从来自湖北4个鸭场的81份病料中,分离到11株鸭疫里默氏茵。以5.0×10~8CFU/mL剂量感染健康昆明鼠和健康樱桃谷鸭,鼠和鸭分别在感染后7 h和12 h出现症状,直到感染后1周,实验动物均死亡,而对照组则未出现任何症状,表明该菌株为有毒力菌株,药物敏感实验结果显示部分细菌对某些药物已经产生耐药性。     

猪低蛋白日粮研究进展

低蛋白日粮具有节省成本,低氮污染等经济的和环境的优势。利用猪的理想蛋白模式,采用可消化氨基酸和净能体系等技术配制玉米和豆粕为主要原料的猪日粮时,通过补充合成氨基酸,降低日粮蛋白水平(2%～4%)能使氮的排出量显著减少,且不影响猪的生长性能。     

不同免疫方式对鸡新城疫疫苗免疫效果的影响

为探索鸡新城疫疫苗的最佳免疫方式,通过3组不同的试验对14日龄雏鸡进行新城疫疫苗接种,采用间接酶联免疫吸附试验方法检测不同时间段鸡血清中的抗体水平,并利用SPSS16.0软件对各组数据进行方差分析。结果显示:肌肉注射新城疫疫苗7~21天时鸡血清NDV特异性HI效价与滴鼻试验组相比有较大的差异(P≤0.05),30天后两者差异变小(P≥0.05)。肌注组的抗体水平始终大于滴鼻组,肌注与滴鼻叠加免疫组的抗体水平一直大于肌注组,且90天后两者数值差异显著,肌注与滴鼻叠加免疫后效果最好且持续时间最长。     

修剪频率和留茬高度对草地早熟禾与多年生黑麦草混播草坪质量的影响

研究了不同修剪频率（1次/周、1次/2周、1次/3周3个处理水平）和留茬高度3、5、7、9cm处理组合对草地早熟禾与多年生黑麦草混播草坪质量的影响。结果表明：随修剪频率降低、留茬高度的增加草坪草密度减小,叶片宽度增加,质地变劣,叶片颜色加深,生长速度先增大后减小,地上植物量和地下植物量均呈先增大后减小的趋势。草坪综合质量评价显示,H5F1处理草坪综合质量最优,H5F2处理次之,H3F2处理最差,12种处理草坪的综合质量从优到劣依次为：H5F1〉H5F2〉H7F2〉H7F3〉H7F1〉H5F3〉H9F1〉H9F2〉H9F3〉H3F3〉H3F1〉H3F2。     

Effect of dietary supplementation of chitosan and galacto-mannan-oligosaccharide on serum parameters and the insulin-like growth factor-I mRNA expression in early-weaned piglets

The study was to determine effects of dietary supplementation of chitosan (COS) and galacto-mannan-oligosaccharids (GMOS) on some serum biochemical indices, serum growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels, and hepatic and long gissimus muscle IGF-I mRNA expression in early-weaned piglets. Twenty six Duroc × Landrace × Yorkshire piglets at the age of 15 days were used. The piglets had access to creep feed during the suckling. Six piglets were sacrificed for sampling at the beginning of the study. The other 20 piglets were individually housed in metabolic cages and randomly allotted to four corn and soybean meal-based diets including the control group, the antibiotic group with 110 mg lincomycin/kg diet, the COS group containing 0.025% COS, and the GMOS group with 0.20% GMOS, respectively, in a 2-week feeding experiment. Blood urea nitrogen (BUN) level was reduced whereas serum total protein concentration was increased (P < 0.05) in responses to the COS and GMOS supplementation. Dietary supplementation of COS and GMOS also increased (P < 0.05) the serum GH and IGF-I levels along with enhanced hepatic and the muscle IGF-I mRNA abundance. Dietary supplementation of oligosaccharides such as COS and GMOS may improve growth and feed conversion efficiency by increasing plasma GH and IGF-I levels, in the early-weaned piglets.     

益力素及其它抗生素与酶制剂配伍对异育银鲫生产性能的影响

试验选300尾异育银鲫夏花(均重5g左右),随机分为5组,分别饲喂相同的基础日粮、并分别添加益力素、黄霉素、维吉尼亚霉素及益力素+复合酶、益力素+植酸酶日粮,饲养56d,结果表明:3种不同抗生素中以益力素添加组试验鱼增重率较好;在配伍添加组中以益力素与复合酶配伍组增重率最好,且差异显著(P<0.05),比添加益力素组提高了9%,其饲料系数下降了10%,但各组间饲料利用率差异不显著(P>0.05)。     

Effect of simulated transport stress on the rat small intestine: A morphological and gene expression study

The present study investigated the effects of simulated transport stress on morphology and gene expression in the small intestine of laboratory rats. Sprague Dawley rats were subjected to 35 °C and 0.1×g on a constant temperature shaker for physiological, biochemical, morphological and microarray analysis before and after treatment. The treatment induced obvious stress responses with significant decreases in body weight (P < 0.01), increases in rectal temperature, serum corticosterone (CORT), serum glucose (GLU), creatine kinase (CK) and lactate dehydrogenase (LDH) levels (P < 0.01), as well as expression of Hsp27/70/90 mRNA (P < 0.05; P < 0.01). The rat jejunum was severely damaged and apoptotic after mimicking transport stress, which may mainly be related to cell death, oxidation reduction and hormone imbalance determined by microarray analysis. The bioinformatics analysis from the present study would provide insight into the potential mechanisms underlying transport stress-induced injury in the rat small intestine.