1~14日龄北京鸭维生素D3和25-羟维生素D3需要量的研究

试验采用单因子完全随机试验设计,研究了不同的维生素D3水平(0、400、800、1200、1600、2000、3000 IU/kg)及25-羟维生素D3(25-OH-D3)水平(0、10、20、30、40、50、75μg/kg)对1~14日龄北京鸭生产性能的影响,进而探讨1~14日龄北京鸭维生素D3及25-OH-D3需要量.选取1040只体重基本一致、健康的1日龄雄性北京鸭,随机分为13个处理,每处理8个重复,每重复10只鸭.结果表明,维生素D形式对1~14日龄北京鸭平均日增重、日采食量、料重比和死亡率均无显著影响(P>0.05),维生素D水平对1~14日龄北京鸭平均日增重、日采食量、料重比均有显著的影响(P<0.05),但维生素D缺乏组试验鸭无明显缺乏症.以平均日增重为评价指标,依据二次曲线模型和折线模型估测1~14日龄北京鸭维生素D3和25-OH-D3的需要量分别为1849.8 IU/kg(P=0.0206)和38.1μg/kg(P=0.0294).     

Evaluating the efficacy of an attenuated Streptococcus equi ssp. zooepidemicus vaccine produced by multi-gene deletion in pathogenicity island SeseCisland_4

Streptococcus equi ssp. zooepidemicus(SEZ) is a pathogen associated with a wild range of animal species. Frequent outbreaks have occurred in recent years in pigs, horses, goats and dogs which is liable to infect humans. There is a lack of efficient vaccines against this disease and the occurrence of antibiotic resistance may render drug therapies ineffective. In this study, gene deletion mutant(ΔSEZ) in pathogenicity islands SeseCisland_4 was constructed. The mutant ΔSEZ had a 52-fold decrease in 50% lethal dose(LD_(50)) and had less capacity to adhere epithelial cells. Importantly, immunization of mice with attenuated vaccine ΔSEZ at the dose of 10~2 colony-forming units(CFU) mL~(–1) elicited a significant humoral antibody response, with an antibody titer of 1:12 800. Therefore, 10~2 CFU mL~(–1) might be used as the appropriate immune dose for the attenuated vaccine ΔSEZ, which provided mice with efficient protection against virulent SEZ. In addition, the hyperimmune sera against 10~2 CFU m L–1 attenuated vaccine ΔSEZ could confer significant protection against virulent SEZ infection in the passive immunization experiment and exhibited efficient bactericidal activity in the whole blood assay. Meanwhile, no viable bacteria was detected in blood when mice were immunized with ΔSEZ at the dose of 10~2 CFU mL~(–1) via hypodermic injection. Thereafter, the mutant ΔSEZ at the dose of 10~2 CFU mL~(–1) could confer significant protection in mice and had less negative effects on host, which could be an effective attenuated vaccine candidate for the prevention of SEZ.     

The effects of soil moisture and salinity as functions of groundwater depth on wheat growth and yield in coastal saline soils

In the coastal saline soils, moisture and salinity are the functions of groundwater depth affecting crop growth and yield. Accordingly, the objectives of this study were to: 1) investigate the combined effects of moisture and salinity stresses on wheat growth as affected by groundwater depth, and 2) find the optimal groundwater depth for wheat growth in coastal saline soils. The groundwater depths (0.7, 1.1, 1.5, 1.9, 2.3, and 2.7 m during 2013–2014 (Y1) and 0.6, 1.0, 1.4, 1.8, 2.2, and 2.6 m during 2014–2015 (Y2)) of the field experiment were maintained by soil columns. There was a positive correlation between soil moisture and salinity. Water logging with high salinity (groundwater depth at 0.7 m in Y1 and 0.6 m in Y2) showed a greater decline towards wheat growth than that of slight drought with medium (2.3 m in Y1) or low salinity (2.7 m in Y1, 2.2 and 2.6 m in Y2). The booting stage was the most sensitive stage of wheat crop under moisture and salinity stresses. Data showed the most optimal rate of photosynthesis, grain yield, and flour quality were obtained under the groundwater depth (ditch depth) of 1.9 m (standard soil moisture with medium salinity) and 2.3 m (slight drought with medium salinity) in Y1 and 1.8 m (standard soil moisture with medium salinity) and 2.2 m (slight drought with low salinity) in Y2. The corresponding optimal soil relative moisture content and conductivity with the 1:5 distilled water/soil dilution, in the depth of 0–20 cm and 20–40 cm in coastal saline soils, were equal to 58.67–63.07% and 65.51–72.66% in Y1, 63.09–66.70% and 69.75–74.72% in Y2; 0.86–1.01 dS m^–1 and 0.63–0.77 dS m^–1 in Y1, 0.57–0.93 dS m^–1 and 0.40–0.63 dS m^–1 in Y2, respectively.     

几种农药对桑椹小粒性菌核病的防治效果试验

桑椹菌核病是果用桑树的重要病害,为高效、安全控制该病对桑果生产的危害,进行了大田农药防治筛选试验。结果表明,70%甲基托布津可湿性粉剂500倍液、50%多菌灵-硫磺粉剂500倍液和1 000倍液对桑椹小粒性菌核病具有较好的防治效果,且对桑叶和桑椹无明显药害;70%甲基托布津粉剂1 000倍液、25%吡唑醚菌酯乳油1 500倍和3 000倍液以及40%嘧霉胺粉剂1 000倍液也有一定的防治效果。     

Diet is a main source of vitamin D in Finnish pet rabbits (Oryctolagus cuniculus)

During the winter time in Finland, sunlight is inadequate for vitamin D synthesis. Many pet rabbits live as house rabbits with limited outdoor access even during summer and may therefore be dependent on dietary sources of vitamin D. The aims of this study were to report the serum 25‐hydroxyvitamin D concentrations in Finnish pet rabbits and to identify factors that influence vitamin D status. Serum 25‐hydroxyvitamin D concentrations from 140 pet rabbits were determined using a vitamin D enzyme immunoassay (EIA) kit. Eleven rabbits were excluded from the statistical analysis because of unclear dietary data. The remaining 129 rabbits were divided into groups depending on outdoor access during summer (no access n = 26, periodic n = 57, regular n = 46) as well as daily diet: little or no hay and commercial rabbit food ≤1/2 dl (n = 12); a lot of hay and no commercial food daily (n = 23); a lot of hay and commercial food <1 dl (n = 59); a lot of hay and commercial food ≥1 dl (n = 35). The range of serum 25‐hydroxyvitamin D concentration was from 4.5 to 67.5 ng/ml with a mean of 26.1 ng/ml. Statistical general linear model adjusted for weight, age and season indicated that diet was associated with vitamin D concentrations (p = 0.001), but outdoor access during summer was not (p = 0.41). Mean 25‐hydroxyvitamin D concentration was significantly higher in the rabbits receiving a lot of hay and commercial food ≥1 dl (33.9 ± 13.2 ng/ml) than in rabbits in other diet groups (24.0 ± 8.5 ng/ml, 21.7 ± 8.1 ng/ml, and 22.2 ± 18.0 ng/ml, respectively). This investigation showed wide variation in 25‐hydroxyvitamin D concentrations among Finnish pet rabbits. Diet remains a main source since outdoor access seems to be too limited to provide adequate vitamin D synthesis for most of them, and the use of vitamin D supplements is rare.     

乳牛口服大量β-胡萝卜素对维生素D3及钙磷代谢的影响

６头健康成年荷斯坦乳牛被随机均分为２组。试验组牛第１周每头口服β－胡萝卜素２３．０ｇ,以后每周每头口服１１．５ｇ,对照组不做任何处理。试验期共８周。结果表明,试验组乳牛血清钙及无机磷水平呈下降趋势;血清维生素Ｄ３活性代谢产物２５－ＯＨ－Ｄ３和１,２５－（ＯＨ）２－Ｄ３均呈现明显下降;至第５周末,血液β－胡萝卜素水平最高,２５－ＯＨ－Ｄ３水平下降非常明显。据此认为,乳牛对β－胡萝卜素的吸收存在一阈值,大剂量的β－胡萝卜素进入机体,可能直接干扰维生素Ｄ３的羟化,使其活性代谢产物呈下降趋势,但由于吸收阈值的存在,其对维生素Ｄ３和骨骼钙磷代谢的干扰作用可得到一定程度的减缓。     

匙吻鲟大规格鱼种培育技术研究

2011年4月～6月,从湖北引进平均全长8mm,平均体重0．006g的匙吻鲟（Polyodon spathuk）水花50000尾,进行了大规格鱼种培育技术研究。苗种培育前期主要采用枝角类作为生物饵料,当鱼苗全长达到50mm时开始进行人工微颗粒配合饲料驯化,经一周左右驯化,鱼苗均可摄食微颗粒配合饲料。经过48d培育,鱼苗平均全长为186mm,平均体重为25．635g,存活率达57．8％,取得了较好的培育效果。     

25%阿米西达悬浮剂防治辣椒疫病田间药效试验

25％阿米西达悬浮剂对辣椒疫病具有较好的控制效果,第3次药后第10天其相对防效最高可达82．50％,且对辣椒安全无药害,可大面积推广应用。     

草地螟中肠肉碱-脂酰肉碱转位酶基因(LstiSLC25)的克隆及表达

利用甜菜夜蛾(Spodoptera exigua)围食膜多克隆抗体免疫筛选草螟(Loxostege sticticalis)中肠cDNA表达文库,得到编码肉碱-脂酰肉碱转位酶(LstiSLC25)基因的全长cDNA克隆.该cDNA克隆全长1 474 bp(GenBank登录号EU924506),开放阅读框长897 bp,编码299个氨基酸,预测分子量和等电点分别为32.1 kD和9.46.序列含有3个典型的溶质运转重复结构,具有溶质运载蛋白家族的典型特征.将该基因与pET30载体重组后,经IPTG诱导,蛋白在大肠杆菌(Escherichia coli获得了表达.     

玉米新品种鄂玉25生育特性及栽培技术

玉米新品种鄂玉25具有高产、稳产、优质、广适、抗病、抗倒等特性,已通过湖北省及国家农作物品种审定委员会审定,在湖北省二高山组品种区域试验、多点示范和武陵山区国家玉米品种生产试验(4省、市)中,增产极显著.在二高山、中、低山都适应种植,都比当地主推品种增产8%～20%.