充分发挥磷肥后效作用是实现玉米节本增效的重要举措

通过吉林省中等肥力黑土玉米磷肥13年田间与盆钵定位试验及室内大量化验分析得出磷肥当季虽具有较明显的增产效果,但其利用率(9.8%)并不高.四个量级磷肥(45、90、135和180kg/hm2)利用率最高的时期均在施后第二年(14.9%～38.8%)和第三年(12.3%～30.5%),到第四年虽能被玉米吸收利用一部分(9.1%～18.6%),但其增产效果已不显著.残留在土壤中的磷肥前两年利用率之和可达到27.4%～68.5%.产量与效益结果表明,磷肥在施用后的第二年和第三年,即磷肥前两年后效的年均增产(1003～1443 kg/hm2)增收(802～1154元/hm2)效果最高.     

长吻鮠精巢及精子结构的研究

目的研究不同投喂频率(2次/d、3次/d)和水平(即每日投喂量占试验鱼体重的比例,2%、4%、6%、8%、10%)对长吻鮠幼鱼消化酶和肝胰脏脂肪代谢酶活性的影响,为长吻鮠的人工养殖提供更健康的养殖模式。方法采用SPSS 17.0软件进行双因素方差分析后采用Duncan多重比较检验,显著水平为0.05。结果(1)当每日投喂频率为3次、投喂水平为6%时,长吻鮠幼鱼消化酶中的肠道蛋白酶、肠道淀粉酶和胰蛋白酶的活性最高,显著高于每日投喂频率为2次、投喂水平为10%的试验组以及每日投喂频率为3次、投喂水平为2%和10%的试验组(P<0.05)。(2)当每日喂频率为3次、投喂水平为6%时,肝胰脏脂肪代谢酶中的肉毒碱脂酰转移酶(CACT)、乙酰辅酶A羧化酶(ACC)、脂蛋白酯酶(LPL)和肝脂酶(HL)的活性最高,显著高于每日投喂频率为2次、投喂水平为2%的试验组以及每日投喂频率为3次、投喂水平为8%和10%的试验组(P<0.05)。结论最适宜投喂频率和水平分别是3次/d和6%,更适合长吻鮠幼鱼的健康养殖。     

荒漠草原区饲草组合对苏尼特羔羊的饲喂效果

为合理利用荒漠草原区饲草资源,本研究分别以华北驼绒藜（Ceratoides arborescens）和紫花苜蓿(Medicago sativa)为主要饲草,配合谷草（Setavia italica）、冰草(Agropyron cristatum)饲喂苏尼特羔羊,根据组合效应原理科学组合为6组：100%驼绒藜、50%驼绒藜+50%谷草、50%驼绒藜+50%冰草、100%苜蓿、50%苜蓿+50%谷草和50%苜蓿+50%冰草。结果表明,100%苜蓿饲喂的羔羊增重、屠宰率和净肉率都明显高于其它处理,饲喂效果最好。不同组合饲喂效果为：50%驼绒藜+50%谷草＞100%驼绒藜、50%驼绒藜+50%冰草;100%苜蓿＞50%苜蓿+50%谷草、50%苜蓿+50%冰草。     

浅议园林景观工程造价控制

针对园林景观工程造价难以控制的现状以及园林景观工程造价控制存在的问题,分析了影响园林景观工程造价的因素,分别对决策阶段、设计阶段、招标阶段、施工阶段以及竣工养护阶段提出了园林景现工程全过程造价控制的相应对策。     

草地贪夜蛾对小麦的为害风险:取食为害性及解毒酶活性变化初探

为了探究草地贪夜蛾对小麦的为害风险,我们以取食玉米作为对照,开展研究取食小麦对草地贪夜蛾的存活率、取食选择性、生长量和3种解毒酶及乙酰胆碱酯酶的影响。结果表明:草地贪夜蛾初孵幼虫在小麦上的存活率与玉米并无显著差异,高达90%以上。用小麦连续饲喂3龄幼虫7 d,日均体重增加迅速,与取食玉米无显著差异(P0.05)。2龄幼虫取食选择率为小麦玉米,3龄和4龄幼虫的取食选择率为玉米小麦,但均无显著差异。值得注意的是,小麦饲喂48 h后草地贪夜蛾谷胱甘肽S-转移酶活性和多功能氧化酶含量表现为显著诱导上升,而羧酸酯酶和乙酰胆碱酯酶的活性无显著变化。本试验结果初步表明草地贪夜蛾存在为害小麦的风险,应加强草地贪夜蛾在麦田发生情况的监测,同时应重视草地贪夜蛾取食不同寄主对药剂敏感性机制的研究。     

Exploiting a readily available but hard to digest resource: A review of exudativorous mammals identified thus far and how they cope in captivity

Gum is a widely available carbohydrate, composed mainly of non‐digestible structural carbohydrates. No mammalian enzymes can digest gum; therefore, a mammal ingesting gum must rely on microbial fermentation to access the energy it possesses. Gums are relatively nutrient poor. Despite this, some mammals have evolved to exploit this food resource. We aim to review the literature for all mammal species which have been recorded to ingest gum, whether quantified or not, and discuss this in the context of their evolutionary adaptations. We also investigated the recommended captive diets for these species to look at whether gum is recommended. We conducted a literature search on ISI Web of Knowledge to tabulate all mammal species observed ingesting gum and classified them as obligate, facultative or opportunistic feeders. We encountered 94 mammal species that eat gum in the wild (27 obligate feeders, 34 facultative feeders and 33 opportunistic feeders). Obligate feeders have entirely evolved to exploit this resource but were found to not be given gum in captivity, which may explain why they are failing to thrive, as opposed to facultative feeders, which have fewer issues. Gum may be necessary for the health of obligate feeders in captivity. Future research should focus on the physiological effects that gum ingestion poses on different digestive systems.     

Exposure to blue LED light before the onset of darkness under a long‐day photoperiod alters melatonin secretion,feeding behaviour and growth in female dairy calves

The effect of blue LED on melatonin secretion, feeding behaviour and growth was addressed in Holstein female dairy calves. In Exp.1, six animals (8 weeks old, 97 ± 4.1 kg BW) were exposed to yellow or blue LED for 2 hr before darkness over 7 days under a long‐day photoperiod (LDPP). In Exp. 2, six animals (8 weeks old, 88.5 ± 4.8 kg BW) were exposed to blue light from a white LED all daytime or a yellow LED for 2 hr before the darkness of LDPP (blue light cut) over 3 weeks. In Exp. 1, blue light mildly suppressed melatonin secretion during the 2‐hr treatment but did not affect the timing of the nightly melatonin rise. However, the rise in nighty melatonin levels was higher with yellow than blue LED. In Exp. 2, white LED completely suppressed melatonin secretion during the 2‐hr treatment, but plasma melatonin concentrations were similar during the darkness. Grass hay intake, rumination time, frequency of water intake and body weight gain were higher in animals exposed to the yellow rather than the white LED. Overall results indicate that exposure to blue light from white LEDs under an LDPP suppresses melatonin secretion and might negatively impact the development of female dairy calves.     

鸡蛋自动上料装置机构分析与试验

为了优化鸡蛋加工生产线吸盘自动上料装置的结构参数,并确定样机安装中关键零部件同步位置,对该装置的核心部分——吸盘摆臂组合机构进行了结构分析和运动仿真。结果表明:由曲柄摇杆、齿轮和同步带串联组合的吸盘摆臂组合机构自由度为1、曲柄整周转动、摇杆往复摆动60°、摆臂往复摆动180°;同步带角度补偿可以保证在摆臂180°摆动中,吸盘组件始终处于水平状态,保证鸡蛋水平搬运;摆臂末端运动参数(位移、速度、加速度)变化曲线显示,当摇杆摆动到2个极位146°和206°附近时,摆臂存在一段水平速度为零的垂直上下运动,分别对应曲柄84°~108°和252°~312°,以确保吸蛋和放蛋时吸盘垂直运动;为了保证该装置同步协调运动,样机安装时必须使曲柄在96°时,摇杆处在146°、摆臂处在174°位置。样机试验表明:理论分析和仿真结果与样机实测值一致性较好。     

7种林木植物对华北大黑鳃金龟取食和繁殖的影响

为明确华北大黑鳃金龟Holotrichia oblita(Faldermann)的嗜食植物,优化其室内人工饲养技术及为诱虫植物提供候选材料,以花生叶片为对照,研究了7种林木植物叶片对华北大黑鳃金龟取食和繁殖的影响。结果表明,华北大黑鳃金龟对8种植物日均取食量由高到低依次为金叶女贞、刺槐、核桃、榆树、花生、柳树、香椿、毛白杨,其中金叶女贞、香椿和毛白杨与花生间有极显著差异,金叶女贞与刺槐、核桃、榆树间无显著差异;单雌产卵量由高到低依次为金叶女贞、柳树、核桃、香椿、花生、榆树、毛白杨、刺槐,其中金叶女贞、柳树、核桃、刺槐与花生间有极显著差异,而金叶女贞与柳树间无显著差异。研究表明,饲养华北大黑鳃金龟成虫适宜饲料植物为金叶女贞,日均取食量最高为4.70 g,产卵期最长为56.00 d,单雌产卵量最多为58.88个,其次为核桃和柳树。     

高蛋白料精等量替代鱼粉饲喂肥育猪对比试验

应用高蛋白料精等量替代鱼粉饲喂肥育猪 ,其结果在 42d试验期内高蛋白料精组头均增重 19.0 6kg ,比鱼粉组多增重 2 .12kg ,增重率提高 12 .5 2 %,头均多增收益 2 1.2 1元 ,差异显著 (P <0 .0 5 )。