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61.
62.
用体外产气法测定了桂牧1号象草不同月份、不同高度的产气量及添加聚乙二醇(PEG)对产气量的影响。结果显示:(1)桂牧1号象草各月份的干物质含量比较为:11月〉10月〉9月〉4月。其中,1.0m左右及1.0m以上的象草的干物质含量明显较高(P〈0.01)。(2)在体外产气法实验中添加PEG能显著增加样品12h和24h的产气量(P〈0.01),证明象草中所含有的抗营养因子对黑山羊瘤胃微生物活动有一定的制约作用。(3)9、11月份象草的最佳刈割高度应为1.5m左右,4、10月份象草的最佳刈割高度应为1.0m左右。(4)4月、9月份的象草,添加PEG后产气量提高率较高。利用此时期的象草喂食黑山羊时,适当做PEG处理可以提高象草的饲用价值。 相似文献
63.
Md. Touhidul Islam Baoli Qiu 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(4):320-325
Abstract Three eggplant (Solanum melongena L.) varieties – ‘Dafeng’, ‘Beisite’, and ‘Baiyu’ – were used in this experiment to discover the least susceptible variety among them to sweetpotato whitefly (Bemisia tabaci) infestation. The investigations were carried out after completing one generation of whitefly based on two points of view. Initially, host preference and suitability of whitefly was investigated based on adult feeding, oviposition, and developmental time. Therefore, it was investigated based on growth responses of eggplant. The average developmental time was shortest for the cohort reared in ‘Dafeng’ (21.3 days), while the longest period (23.2 days) was recorded in ‘Baiyu’. In comparison with the control, less significant changes in the six growth parameters, viz. plant height (12.6%), leaf area (12.7%), dry matter (8.2%), absolute growth rate (26.0%), relative growth rate (25.0%), and net assimilation rate (22.2%) were found in ‘Baiyu’ infested by B. tabaci. Adult attraction and oviposition were reduced while developmental time was increased in ‘Baiyu’ compared with the other two varieties. In addition, the reduction percentages of all the six plant-growth parameters of ‘Baiyu’ were comparatively less than other two varieties to whitefly stress. Our research is focused on a shorter development time; higher feeding, oviposition, and the reduction percentage of plant growth indicate that a plant is a suitable host. In view of this, the present findings indicate that ‘Baiyu’ is less susceptible than the other two varieties, ‘Dafeng’ and ‘Beisite’, for whitefly infestation. 相似文献
64.
投喂频率对尼罗系吉富罗非鱼幼鱼胃排空、生长性能和体组成的影响 总被引:2,自引:3,他引:2
通过胃排空试验与养殖试验研究了不同投喂频率对尼罗系吉富罗非鱼幼鱼的胃排空、生长性能以及体组成的影响.在试验开始时,观测尼罗系吉富罗非鱼幼鱼的胃内饲料排空情况,胃排空试验结果表明,胃排空率的最佳描述为平方根函数,胃内饲料在饱食投喂后15 h左右完全排空,达到投喂前水平,80%胃排空为9h,也就是投喂后大约9h恢复食欲.360尾试验鱼(初始体质量3.72 g)以不同的投喂频率(1d4次、1d3次、1d2次、2d4次、2d3次、2d2次)分组,每组设立3个平行组,随机养殖于18个网箱中,每箱养殖20尾鱼,按饱食量投饲膨化饲料.养殖期为6周.尼罗系吉富罗非鱼幼鱼在投喂频率为1d4次、1d3次和1d2次时特定生长率和饲料效率显著高于投喂频率为2d4次、2d3次和2d2次时(P<0.05);投喂频率为1d2次、2d4次、2d3次和2d2次时其摄食量显著低于1d4次和1d3次时(P<0.05).随着投喂频率降低,鱼体水分含量逐步上升,脂肪和蛋白质含量逐步下降,其中1d4次、1d3次组鱼与2d2次组鱼有显著性差异(P<0.05).各投喂频率组间的肝体指数无显著性差异(P>0.05).3.7~48.0 g尼罗系吉富罗非鱼幼鱼的适宜投喂频率为1d2次,较2d2次、2d3次和2d4次时明显提高了生长速度和饲料效率,较1d3次、1d4次摄食量显著降低.2种试验结果较为一致. 相似文献
65.
玉米是我国主要农作物之一,其生产效率与生产质量的好坏,直接关系着我国粮食安全。传统的玉米播种方式,不仅生产效率、作业质量和标准化程度均比较低,无法实现高效率全自动大面积玉米播种或者套种的实际需求。在新时期,随着城镇化进程加快,农村劳动力日益短缺,加上社会经济发展与科学技术的进步,为我国玉米移栽机自动化技术开发设计提供了必要的支撑条件。为此,对我国东北地区玉米试验田进行相关研究,就自动化玉米移栽机及其送苗装置技术的研发、设计进行探究,并重点阐述其基本工作原理。 相似文献
66.
The effect of feeding rate on the growth performance of green sturgeon (Acipenser medirostris) fry 下载免费PDF全文
Four one‐week growth trials were conducted on green sturgeon fry to determine the effect of feeding rate on their growth performance at 18 °C when they were fed a salmonid soft moist feeds containing 445–457 g kg?1 of crude protein and 201–207 g kg?1 of lipid. The fry used in Trials I‐IV were 5–8 weeks after their initiation of exogenous feeding. Their average initial body weights were 1.63 ± 0.01, 2.63 ± 0.03, 5.08 ± 0.08 and 7.49 ± 0.05 g, respectively. Six feeding rates used were as follows: 2.5–15.0% body weight per day (% BW day?1) with a 2.5% increment in Trial I; 1.25–7.50% BW day?1 with a 1.25% increment in Trial II; and 2.0–7.0% BW day?1 with a 1.0% increment in Trials III and IV. Four replicates with 50 fry per tank in Trials I‐III and 30 fry per tank in Trial IV were assigned randomly to each feeding rates. The final body weight, specific growth rate, feed efficiency, protein retention, and whole‐body moisture, lipid, and energy contents were significantly (P < 0.05) affected by the feeding rates. The optimum feeding rates determined by the broken‐line model were 7.1, 5.7 and 5.3% BW day?1 for Trials I, II and IV, when the fry were 5, 6 and 8 weeks after their initiation of exogenous feeding, respectively. 相似文献
67.
秦志清 《福建省农科院学报》2014,(12):1167-1173
为确定黑莓鲈仔鱼的饥饿耐受能力及死亡不可逆点(PNR),采用实验生态学方法研究饥饿对黑莓鲈仔鱼摄食、生长与发育的影响。结果表明,在19.5~22.8℃水温条件下:①黑莓鲈仔鱼在6日龄开口摄食,8日龄卵黄囊消失,其混合营养期仅维持2 d 左右,属于易遭受饥饿胁迫鱼类;②仔鱼最高初次摄食率出现在9日龄,初次摄食期仔鱼的 PNR 发生在孵化后第11~12 d,仔鱼具有摄食能力的时间仅4~5 d,且在到达 PNR 后仅1 d 多即全部死亡,其耐受饥饿的能力较差;③在饥饿胁迫条件下的仔鱼对卵黄囊和油球的吸收进程明显慢于正常投喂组仔鱼,且随着饥饿程度的不断加深,仔鱼的生长发育趋于停滞甚至出现负增长;仔鱼在 PNR 期出现胸角,并且表现出一系列明显的由饥饿所导致的形态和行为学特征。 相似文献
68.
转Bt基因棉对棉铃虫抗性的时空动态 总被引:60,自引:20,他引:60
在室内研究了转Bt基因棉对棉铃虫抗性的时空动态及对棉铃虫幼虫取食行为的影响,结果表明,整个棉花生长期,棉花不同器官随着时间的变化其抗性有较大的差异,如7月以后,棉叶对棉铃虫幼虫的抗性明显下降,由6月下旬的100%下降到8月初的62.5%,然后抗性又逐渐回升,但仍为下降的趋势;从空间抗性来看,营养器官的抗性高于繁殖器官,接虫24h后,棉铃虫幼虫在转基因棉繁殖器官上分布数量较多;转基因棉对棉铃虫幼虫取食行为有较大的影响,和常规棉相比,在转基因棉上取食时间减少57.6%,吐丝下垂、爬行和静息的时间分别延长396.1%、22.4%和4.0%。 相似文献
69.
Two experiments were conducted for red sea bream (Pagrus major). In experiment 1, the optimum level of glutamic acid and natural feeding stimulants to enhance feed intake were determined and found that glutamic acid level of 0.5% and fish meat hydrolysate (FMH) were effective. In experiment 2, fish were fed with soy protein concentrate (SPC)‐based diet with synthetic feeding stimulants (Basal diet), the Basal diet with FMH (FMH diet), the FMH diet with glutamic acid (FMHG diet) and with fish meal diet (FM diet) as a control until satiation for 8 weeks. Feed intake of FMHG‐fed fish was significantly higher than others (p < 0.05). Specific growth rate and the feed conversion ratio of FMHG were comparable to those of FM‐fed fish (p > 0.05). Relative visceral fat ratio and crude lipid content of any SPC‐based diet‐fed fish tended to be lower than those of FM diet‐fed fish. There were no significant differences in trypsin and lipase activities hepatopancreas among treatments. SPC can be utilized as a sole protein source in a diet for red sea bream. The lower growth performance in SPC‐based diet‐ fed fish was not due to poor digestive enzyme secretion but could be associated with lipid utilization disorder. 相似文献
70.