Effects of dietary starches and the protein to energy ratio on growth and feed efficiency of juvenile cobia,Rachycentron canadum

Optimization of the protein to energy ratio in juvenile cobia (Rachycentron canadum) would allow the production of diets that maximize growth without the addition of excess energy that may increase costs or even be detrimental to the health of the fish. During a 6‐week growth trial, juvenile cobia (5.6 ± 0.5 g fish^?1 initial weight) were fed five isonitrogenous and isolipidic diets containing various protein to energy ratios using starch as the energy source. At the end of the trial, some fish were analysed for body composition characteristics while the rest were used to examine the excretion of dietary starch in the feces. Survival and growth were not significantly affected, but feed efficiency (ranging from 0.64 to 0.94) and daily consumption (ranging from 45.3 to 64.1 g kg^?1 of body weight d^?1) were affected. No reduction in consumption due to excess energy was noted. Analysis of the fecal carbohydrate data showed a linear relationship between dietary inclusion and excretion of carbohydrates with no sign of reaching saturation. Results of this study suggest that cobia can utilize dietary carbohydrates up to at least 340 g kg^?1 of dry diet with an optimal protein to energy ratio of approximately 34 mg protein kJ^?1metabolizable energy.     

浅谈档案信息化管理——以河北宣化钢铁公司为例

综述档案信息化的内涵、优势和搞好档案工作的重要性及意义。介绍宣化钢铁公司档案信息化管理的具体实施办法及在档案信息化管理工作中遇到的各种问题及解决办法。     

不同模拟降水量下草地早熟禾根系形态与解剖结构的动态变化

以草地早熟禾为研究对象,采用人工控水模拟降水量的方法,比较对照组(浇水量为小雨组的60%),小雨组(24 h内的降水量小于10 mm)、中雨组(24 h内降水量为10~25 mm)、大雨组(24 h内降水量为25~50 mm)根系形态与解剖结构的差异,以探究不同模拟降水量对草地早熟禾根系发育的影响机制。结果表明,总体上处理组与对照组相比差异较为显著。在试验进程中,中雨组水分条件下草地早熟禾根系生长全程均良好。在根系构型方面,根长、根表面积、根总体积、根平均直径与根分叉数均显著增加,比根长与根干重密度较为稳定,各项根系构型数据均显示草地早熟禾在中雨组的水分处理下生长状况优于其他处理。在根系解剖方面,到生长第50 天时,对照组继续受干旱的影响,根系结构受损,中柱和导管直径显著变小,占根系直径比例减小;小雨组出现轻微干旱情况;中雨组根系解剖结构正常;大雨组出现水淹情况。以上结果表明,中雨组为最适合草地早熟禾生长的水分条件。     

不同温度对甜菜种子吸胀过程中线粒体CCO和MDH活性的影响

吸胀温度显著地影响甜菜种子的萌发速率。吸胀温度为３０℃和２０℃时,５０％萌发所需要的时间分别为３６ｈ和５６ｈ;在７℃中吸胀１２０ｈ,仍未见萌发。在种子吸胀过程中,粗线粒体蛋白的含量,细胞色素Ｃ氧化酶和苹果酸脱氢酶的活性增加,且它们在３０℃和２０℃中的活性较高,在７℃下较低。     

Transmission of virulent footrot between sheep and goats

OBJECTIVE: To determine the infectivity of ovine and caprine strains of Dichelobacter nodosus for both sheep and goats. DESIGN: Pen experiments in which 20 sheep and 19 goats were challenged directly with the two strains, and transmission experiments on pasture, using donors infected by experimental challenge. RESULTS: Sheep and goat strains of D nodosus infected both animal species in experimental challenges. Animals so infected transmitted footrot to both sheep and goats on pasture plots. A significantly smaller proportion of goats than sheep was infected when challenged with either strain. The interval between exposure and development of footrot in goats was longer than in sheep when recipient animals were exposed to infected donors on pasture. The disease was less invasive in goats than in sheep. CONCLUSIONS: With the strains of D nodosus used there was no evidence of host specificity. Direct transmission of footrot can occur between sheep and goats in the same environment. There is a need to include goats in ovine footrot eradication programs and vice versa.     

小麦抗赤霉病鉴定及其抗病基因的检测

小麦赤霉病是由镰刀菌和禾谷镰孢菌引起的小麦真菌病害,严重影响小麦的产量与品质。为了筛选适合黄淮麦区利用的抗病品种资源,于2017-2018年度利用单花滴注对107份黄淮麦区小麦资源进行田间赤霉病抗性鉴定;同时利用与 Fhb1、 Fhb2、 Fhb4和 Fhb5共4个与抗赤霉病相关QTL紧密连锁的8个分子标记对供试小麦材料进行了检测。经鉴定,扬富麦101表现为抗赤霉病(R),宁麦13、宁麦资119、扬麦16等12个品种表现为中抗赤霉病(MR);分子标记检测发现,这些抗赤霉病品种携带1个或多个抗赤霉病QTL位点,其中 Fhb1基因及其基因组合效应最为明显, Fhb1可以作为主要抗性基因应用于小麦赤霉病抗性育种。     

土壤肥力对烤烟不同部位中性香气成分含量的影响

以烤烟(Nicotiana tabacum L.)品种中烟100为材料,通过田间试验研究了土壤肥力对烤烟不同部位中性香气成分含量的影响,并对不同肥力条件下烤烟各部位烟叶进行单料烟感官评吸鉴定。结果表明,类胡萝卜素类降解产物总量在中部叶(腰叶、上二棚)及顶叶以高肥力条件下较高;茄酮含量在除顶叶外均以低肥力条件下较高,顶叶以高肥力条件下含量较高;非酶棕色化反应产物总量在烟株的大部分位置高、中肥力处理间没有显著差异;芳香族氨基酸类降解产物总量在除底脚叶外的其他部位均以高肥力处理最高,中肥力处理次之,低肥力处理最低;新植二烯含量在下部叶以中肥力条件下最高,其他部位以高肥力条件下最高;在烟株的中部高、中肥条件下烟叶的除新植二烯外香气物质总量无显著差异,在顶叶高肥力条件下香气物质总量显著高于中肥力。评吸结果以中肥力条件下腰叶得分最高。综合认为,中肥力土壤有利于生产出优质烟叶。     

甘肃省生态环境建设与水资源合理配置研究

地处西北内陆的半干旱与干旱气候区的甘肃省，降水资源少且分布不均，水资源的配置必须在保证生态环境建设必要用水和社会经济合理用水的同时，大力节约并逐步压缩农田灌溉用水。外流河流域的降水首先为当地的植被耗用，剩余的才形成可供开发的地表径流和地下水；水资源配置的顺序是：当地植被耗水，当地社会经济用水，最后形成干支流出境的径流供中下游地区使用。内陆河流域首先满足居民生活用水和生态用水，再满足工业用水，最后供给农业；同时，内陆河流域用水量的最高开发利用率应不超过70％，并确保生态环境的耗水不低于水资源总量的50％。     

施氮水平对大豆氮素积累与产量影响的研究

以绥农14为材料,利用砂培和15N标记的方法研究了施氮水平对大豆氮素积累及产量的影响。结果表明:随着施氮水平的提高,大豆全株氮素积累量及叶柄、荚皮、籽粒中氮素积累量呈现先增加后下降的趋势;高氮水平增加了叶片和茎中氮素积累量,N150较N0处理叶片的氮素积累量增加了3倍,而茎增加了5倍,但减少了根中氮素积累,降低了大豆全株和籽粒中根瘤固氮量及其所占比例,降低了肥料氮和根瘤氮的收获指数,其中根中氮素积累N150较N50处理降低了60.3%,全株根瘤氮和籽粒中根瘤氮N150较N0分别降低了74.9%、85.7%,肥料氮的收获指数N150较N50降低19.8%,根瘤氮的收获指数N150较N0降低25.5%。随着施氮水平的增加,大豆产量也呈现先增加后下降的趋势,施氮水平的增加促进了大豆植株株高、结荚高度和始荚节位的显著增加,但对节数没有明显影响,N150和N0比较株高增加了55.2%,结荚高度增加了199.7%,始荚节位增加了142.9%。