Growth, survival and fillet composition of paddlefish, Polyodon spathula (Walbaum) fed commercial trout or catfish feeds

Paddlefish are gaining increasing acceptance as an aquaculture species worldwide. Commercial trout feeds, containing high protein and lipid levels, are currently used in intensive culture; however, nutritional requirements of paddlefish are not currently known. A study was conducted examining the effects on growth, survival and fillet composition of juvenile paddlefish when fed commercial feeds differing in protein and lipid levels. Paddlefish larvae were first stocked in 14.0 m³ round tanks and fed trout starter feeds for 43 days until trained to accept a 1.6 mm pellet. Paddlefish juveniles of mean weight (±SE) 20±0.27 g were randomly stocked into six0.02 ha ponds at 12 500 ha^?1 and fed floating commercial trout or catfish (lower protein and lipid) feeds, twice daily (08:00 and 15:30 hours) for 92–97 days. At harvest, there were no significant differences in final weight, percent survival, specific growth rate , relative growth and feed conversion ratio between treatments, which averaged 223.6 g, 96.2%, 2.5% day^?1, 10.2 and 1.98 respectively. Surface feeding activity index was significantly higher in ponds supplied with catfish feed than in ponds supplied with trout feeds. Relative pellet buoyancy was not a factor in feeding activity. Fulton's condition factor averaged0.238, was not significantly different, and was similar to a reported value for extensively cultured paddlefish (zooplanktivore). There was no significant difference in liver somatic index between treatments, which averaged 1.91%. Percent protein and moisture of fillets averaged 14.9% and 80.9%, respectively, and were not significantly different between treatments. However, lipid content of fillets was significantly higher in paddlefish fed the trout feed (4.45%), compared with paddlefish fed the catfish feed (2.42%). Fillet lipid content for both treatments was higher than reported values for extensively cultured paddlefish. Percent abdominal fat was significantly higher (0.82%) in paddlefish fed the trout feed compared with paddlefish fed the catfish feed (0.52%). Results from this study indicate that paddlefish can be fed a commercial catfish feed labeled to contain 32% protein and 4.5% lipid without adverse effects on growth, survival and fillet composition, lowering production costs.     

Growth and mortality of sibling triploid and diploid Sydney rock oysters, Saccostrea glomerata (Gould), in the Camden Haven River

Growth and mortality of sibling triploid and diploid Sydney rock oysters, grown at two tidal heights, three stocking densities and three different sites on the Camden Haven River estuary, were compared. Triploids grew faster than diploids. The majority of the growth rate difference occurred after the oysters reached 2 years of age. By 3.2 years, triploids were 49% heavier than diploids. Oysters grown intertidally were larger than those grown subtidally. Oysters stocked at the lightest density of 2 L per basket grew to a significantly larger size than baskets stocked at 3 or 4 L. Growth rates were significantly different at the three sites. Growth was reduced the further the oysters were from the mouth of the estuary. There was no significant difference in mortality between ploidy level, but there were differences between tidal heights, stocking densities and sites. Intertidal oysters suffered higher mortality than subtidal. Oysters stocked at the highest density had a significantly higher mortality than the lowest density; neither of these was significantly different from the medium density. The site closest to the mouth of the estuary had significantly lower mortality than the middle and upper estuary sites.     

运输应激状态猪血液皮质醇含量与肉质性状之间的关联性分析

试验旨在研究商品猪血液中皮质醇含量与宰后的胴体性状和肉质表观指标之间的相关性并探讨其内在联系。在具有秋季典型气温时间（2012年8月20日）,选取120头商品猪,猪只运输时间约为2h,运输到屠宰场后休息1．5h后屠宰,取血液样品测定皮质醇含量,取背最长肌测定肉质指标,并测定猪只的胴体重和背膘厚。根据测定得到的皮质醇浓度,将猪只分成三个组,低皮质醇组（〈120ng／mL）、中皮质醇组（120～130ng／mL）和高皮质醇组（〉130ng／mL）,比较三组之间肉质和胴体指标之间的差异。结果表明,在肉质指标方面,除中皮质醇组猪只的24h的电导率有升高的趋势（P=0．08）外,其余均无显著差异;在胴体性状方面,高皮质醇组胴体重极显著高于（P〈0．01）低皮质醇组,高皮质醇组背膘厚显著高于（P〈0．05）低皮质醇组,与中浓度皮质醇组差异均不显著。猪只血液中皮质醇含量与胴体重和背膘厚度都存在着极显著的正相关,相关系数分别为0．349和0．274。各肉质指标之间也存在相关性,其中PH与电导率为极显著的负相关,pH与肉色的L值呈极显著的负相关,45min时测定的肉色L值与滴水损失相关系数为0．234,猪只胴体重和背膘厚度呈极显著的正相关关系,相关系数为0．596。结果提示,无法通过猪只血浆皮质醇浓度的高低来评估宰后猪肉品质,但一定程度内较高的皮质醇浓度会有利于个体增重和背部脂肪的沉积。     

反射光谱法估计小麦叶片表皮蜡质含量的初步研究

为了探讨利用冠层反射光谱技术估计小麦叶片表皮蜡质含量的可行性,以小麦高叶片表皮蜡质含量材料2912与低叶片表皮蜡质含量品种普冰201和晋麦47及其杂交构建的F2:3株系为材料,通过氯仿提取称重法测定了小麦抽穗期的旗叶表皮蜡质含量,并采用FieldSpec 3测定了冠层反射光谱,分析小麦冠层反射光谱与叶片表皮蜡质含量之间的关系。结果表明,三个亲本以及株系间蜡质含量差异显著。高蜡质材料的可见光波段反射率整体高于低蜡质材料,短波长波段光谱反射率与叶片表皮蜡质含量相关性较高。以550和675nm波长的反射光谱为基础的单波/差值指数[R550/(R550-R675)]能较好地反映小麦叶片蜡质含量,两F2:3群体拟合模型的r2值分别为0.761和0.679,回归方程分别为y=0.07x-0.575和y=0.088x-1.481。     

直接药敏试验在肉鸡生产中的临床应用意义

以信阳市和谐动物医院在2012²013年间接诊的112个细菌病例为研究对象,选取18种常见的抗菌素药敏片,运用纸片扩散法来分析直接药敏试验在临床上的应用效果。结果表明:从112个细菌病例中选出92个病例做研究,36个病例可筛选出3种以上的高敏药物,28个病例可筛选出2种以上的高敏药物,39个病例只能筛选出1种高敏药物,16个病例只能筛选出中敏药物,4个病例对常规的18种药物全部耐药。     

贵州省甘蓝型油菜主推品种的SSR遗传多样性分析(英文)

[目的]从分子水平上了解贵州省甘蓝型油菜主推品种的遗传多样性。[方法]利用国家油菜区域试验DNA指纹鉴定使用的40对SSR引物对贵州省9个甘蓝型油菜主推品种进行多态性检测,并进行聚类分析。[结果]试验共扩增出条带191个,其中多态性条带143个,多态性比率为75%。经聚类分析,9个油菜品种被分为A、B 2簇,其中A簇包含7个品种,B簇为贵州省油料研究所选育的2个品种。A簇在相似系数0.643 4处又分为A1和A2 2个亚簇,A1亚簇为贵州省油菜研究所选育的3个品种,A2亚簇为贵州省油料研究所选育4个品种。[结论]同一单位选育出的品种都有更为接近的遗传背景;在该研究所用品种中,贵州省油料研究所选育的品种遗传基础相对较广,但黔油17与黔油29的遗传相似性系数达0.87,遗传基础较为相近。     

黑珍珠莲雾在福建沿海的反季节生产技术

介绍了莲雾的开花习性,并总结了进行反季节栽培管理的技术要点,主要包括花期调控、控梢、催花、催花后管理、病虫害防治、采收等方面内容.     

集对分析法在大兴安岭用材林土壤养分评价中的应用

对大兴安岭兴安落叶松用材林进行不同强度的采伐改造,采用集对分析法,对不同强度采伐后的土壤养分进行综合评价,对比采伐改造后土壤养分.结果表明：大兴安岭地区,兴安落叶松用材林中,采伐强度为19％时,土壤养分最优,低强度和高强度的采伐对土壤养分有负面影响,且采伐强度越高,土壤综合养分越差.     

含蜡原油管道含蜡量计算及加剂油头跟踪方法

针对高含蜡原油因结蜡导致管道堵塞和停输再启动困难的问题,基于运行参数分析,通过长输管道水力摩阻计算公式变换及SPS模型拟合,计算得到了管道内以结蜡为主的不可流出物的含量,并利用加剂油头到达末站引起过滤器堵塞及油头凝点变低的现象,得到了管道内实际不可流出物的体积,与模型计算结果对比表明：计算含蜡量与实际含蜡量相吻合,模型基本满足要求。由于乍得加剂高凝油与非加剂高凝油的黏度差别较大,提出了一种根据各阀室站场间压力差变化来跟踪加剂油头的方法,用于判断加剂油头到达的大概位置,为高凝高含蜡原油管道加剂时间及加剂量的确定提供参考。     

不同温度下单相含蜡原油的蜡沉积规律

针对石油工业中的蜡沉积问题,利用冷指实验装置研究了单相含蜡原油体系冷却液温度、油流温度和同一温差不同温度区间对蜡沉积规律的影响,得到了单相含蜡原油蜡沉积规律的宏观特性,并利用高温气相色谱（HTGC）装置分析沉积物组分的宏观变化。在相同油温条件下,随着冷却液温度的升高,蜡沉积速率减小而沉积物中高碳数组分比例增大;在相同冷却液温度条件下,随着油温从凝点附近增大至析蜡点以上,蜡沉积量先减小后增加最后再减小,沉积物中高碳数组分比例增大;在同一温差条件下,随着温度区间温度的升高,蜡沉积量的变化有波动但油温在析蜡点附近沉积量达到最大值,沉积物中高碳数组分比例一直增大。针对实际管流,环境温度基本恒定,通过升高入口油温减少沉积的发生,因此,在含蜡原油管输中,入口油温的选取对整个管输过程中蜡沉积的形成以及形成后的清理很重要。根据实验结果,入口油温不是越高越好,应保证入口油温低于析蜡点且整个管输过程中高于凝点5℃左右。（图6,参12）