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71.
72.
Abstract Floodplain borrow pits created during dike construction for flood protection along regulated lowland rivers are suggested as convenient surrogate habitats for fish communities where natural floodplain features have been lost. Fish community structure and reproduction success in three borrow pits located in the channelised floodplain of the River Dyje, Czech Republic were studied over 3 years. Short-term floods supported the spawning of phytophilic and phyto-lithophilic species; batch spawners capitalised on late summer flood conditions. The highest species richness of 0+ juvenile fishes occurred at sites with extended periods of flooding, at least for 2 months. Flooded vegetation was inhabited mainly by juvenile cyprinids, while 0+ percids were distributed evenly along the littoral zone. Shoreline remained bare even during higher water levels before complete inundation because of the steep banks, and therefore fish were not able to benefit from higher water levels. Borrow pits appear to function as a substitute habitat for fish and their reproduction, but only if they are properly constructed with shallow areas providing appropriate nursing conditions for 0+ fish growth and survival. 相似文献
73.
【目的】探讨卢氏绿壳蛋鸡染色体核型和G带带型。【方法】采用骨髓法制备卢氏绿壳蛋鸡染色体标本片,染色后对其染色体核型和G带进行分析。【结果】卢氏绿壳蛋鸡的体细胞染色体数为2n=78,该鸡种的核型中有10对大染色体和29对微小染色体,且微小染色体基本为端着丝粒染色体。公鸡染色体核型由38对常染色体和1对同配型性染色体ZZ组成,母鸡由38对常染色体和1对异配型性染色体ZW组成。1、2号和Z、W均为中央着丝粒(m)染色体,4号和7号均为亚中央着丝粒(sm)染色体,3、6、8、9、10号均为端着丝粒(t)染色体。前10对大染色体(包括Z、W染色体)的G带共可分为32个区,118条带。【结论】卢氏绿壳蛋鸡的染色体数目为:2n=78,公鸡核型78,ZZ;母鸡核型78,ZW。卢氏绿壳蛋鸡与其他品种鸡的G带存在一定的差异。 相似文献
74.
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为了提高鸡蛋裂纹检测的准确性,建立了声学敲击检测鸡蛋裂纹的装置,采集和分析鸡蛋被敲击后的声音信号。提取了4个特征频率、偏斜度平均值和峰度平均值共6个特征参数,并作为神经网络的输入量,创建了基于MATLAB的结构为6-15-2的3层BP神经网络模型判别鸡蛋裂纹。检测结果显示:对蛋壳受各种程度破坏后的鸡蛋判别精度可达92%以上,对蛋壳完整的鸡蛋判别精度达到96%,对鸡蛋总体的判别精度可达94%。 相似文献
76.
Chukar is a kind of very important wild economical bird species.The research to the eggshell is very useful not only in biology but also in economics.The structure of eggshell of Chukar is the same as the fowl.The structural changes of the inner and outer surfaces,the transverse section of the eggshell,and the outer surface of its membrane during incubation had been observed by scanning electron microscopy (SEM).There was a great change happened for the surface structrue of eggshell and its membrane during incubation.The tortoise-shaped crackles became smaller and longer,and the fibres of the membrane became thinner and shorter.At the same time,the transverse section of eggshell also became thicker. 相似文献
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《The Journal of Applied Poultry Research》2009,18(2):172-184
Phosphorus runoff from the land application of poultry litter has become a concern in watersheds in the Ozark Plateau region, prompting local growers to use alternative litter management practices. One option is the export of excess poultry litter from producers in nutrient-surplus watersheds to users located in areas where nutrient loads are not problematic. In 2006, nearly 100,000 tons of broiler and turkey litter was exported by BMPs Inc., a nonprofit corporation providing litter management services. However, breeder hen litter and pullet litter are rarely exported because there are limited outlets for these lower nutrient value litters. Another poultry industry by-product is eggshell waste from egg-breaking operations, most of which is currently landfilled at a cost of $25/ton. Composting was examined as an alternative method to convert litter and eggshell wastes into a marketable soil amendment, making use of the beneficial soil nutrients available in both; 4 blends and 2 production systems were analyzed. Process results indicated that during composting, the observed temperatures of each of the 4 blends were different, but all followed a similar trend throughout the production cycle. Functional group inventory and diversity analysis indicated that all blends fell within optimal ranges of microbial species, except for the ratio of aerobic to anaerobic bacteria; only blend 4 was within the optimal value for this parameter. Diversity values for each blend fell within the moderate diversity range (3 < d < 6.5). Maturity analysis results indicated that no blends were mature at 11 wk (index <50%) and could not safely be used in horticultural applications but could safely be used in field applications. Break-even analyses indicated that compost could be produced at an average cost (across the 4 blends) of $17.48 to $20.09/ton for systems 1 (small-scale) and 2 (large-scale), respectively. 相似文献
79.
试验采用红(660nm)、绿(560nm)、蓝(480nm)3种发光二极管(处理组)和白炽灯(400~700nm)(对照组),对180羽海兰褐蛋鸡进行人工光照,研究了单色光对蛋重、蛋形指数、蛋长径、短径和蛋壳质量的影响。试验期为19~52周,光强度均为15lx,光照时间为16h。结果表明:在整个试验期,白光组蛋重最高(61.1g),红光组最低(59.2g),二者之间差异显著(P<0.05);38~52周龄,蓝光组蛋长径显著小于其他组,而其短径显著(P<0.05)小于白光组,另外,红光组蛋短径极显著(P<0.01)小于其他组;19~37周龄,绿光组蛋形指数(1.303)显著大于其他组,而38~52周龄,红光组蛋形指数(1.343)极显著(P<0.01)大于其他组;21~45周龄,绿光组蛋壳强度(3.54kg/cm2)极显著(P<0.01)高于白光和蓝光组而绿光组蛋壳厚度(0.368mm)显著(P<0.05)大于其他组;蓝光组蛋壳颜色值(31.6)显著(P<0.05)小于白光组(33.1)。结果提示:蓝光使蛋长、径变短而红光使蛋短径变短,从而使蓝光和红光组蛋重随产蛋周龄而增长的趋势小于白光和绿光组。单色光可影响蛋壳质量,其中绿光组的蛋壳质量最好。 相似文献
80.
对不同深浅羽色甘肃黄鸡的主要产蛋性状作了观测,结果表明:甘肃黄鸡羽色深浅对蛋用性能没有影响;蛋壳颜色勺蛋壳厚度、哈氏单位和母鸡产蛋量有显著的相关关系;甘肃黄鸡今天产蛋较为分散,生产中应适当推迟集蛋时间;蛋壳颜色与鸡群产蛋时间可以作为甘肃黄鸡产蛋量选择的辅助指标。 相似文献