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Martia Ferreira Ana Maseda Jaime Fbregas Ana Otero 《Aquaculture (Amsterdam, Netherlands)》2008,279(1-4):126-130
The effect of semi-continuous culture on the nutritional value of microalgae was tested in the rotifer Brachionus plicatilis in short-term enrichment experiments. Isochrysis aff. galbana clone T-ISO was cultured semi-continuously with renewal rates from 10 to 50% of the volume of the culture per day and used to feed the rotifers. After 24 h, dramatic differences in dry weight and protein, lipid and carbohydrate contents were observed in the rotifers depending on the renewal rate applied to the microalgal culture. Rotifers fed T-ISO cultured with low renewal rates showed low dry weight and organic content, whereas rotifers fed microalgae from nutrient-sufficient, high renewal rate cultures showed higher dry weight and increases up to 60% in protein, 35% in lipid and 100% in carbohydrate contents. Feed conversion rate (FCR) and organic FCR decreased with increasing renewal rates, indicating a more efficient assimilation of the microalgal biomass obtained at high growth rates. The fatty acid profile of rotifers reflected that of T-ISO, with maximum content of polyunsaturated fatty acids (PUFAs), n-3 fatty acids and docosahexaenoic acid (DHA) being found in the rotifers fed microalgae from the renewal rate of 40%. Results demonstrate that the biochemical composition of B. plicatilis is strongly modified through the use of semi-continuous cultures of microalgae in short-term enrichment processes. This technique provides an excellent tool to improve the nutritional value of the live feed used in fish larvae cultures. 相似文献
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The effects of different diets (natural or pellets) on growth, survival, and moulting interval of juvenile spider crabs, weighing
between 0.011–1.56 g and up to 17.6 mm in carapace length, were tested over a period of 90 days. During experiment I, five
diets were tested: (1) frozen shrimp—Paleomonetes sp., (2) fresh mussels—Mytilus sp., (3) white fish fillets—Merlucius merlucius, (4) blue fish fillets—Sardina pilchardus, and (5) commercial crustacean pellets. Spider crabs fed fresh mussels grew larger (0.98 ± 0.69 g) and had higher growth
rates (4.0 ± 0.7 %BWd−1) compared to the other four diets. The crabs fed shrimp pellet and frozen shrimp grew to intermediate sizes and were smaller
than the ones fed fresh mussels, but they were larger than spider crabs fed either blue or white fish fillets (0.46 ± 0.63
and 0.26 ± 0.13 g, respectively) compared to the ones fed white fish fillets (0.12 ± 0.04) and blue fish fillets (0.04 ± 0.02 g).
The spider crabs fed blue fish fillets only lasted until day 60 of the experiment, after this day none of the 20 fed this
diet were left. During experiment II, two diets were tested: (1) white and blue fish fillets and (2) commercial fish pellet.
There were no differences in growth both in weight or carapace length (2.9 ± 1.8 and 2.1 ± 1.5 g in weight, and 18.9 ± 5.0
and 17.7 ± 3.3 mm, respectively) at the end of the experiment. Similarly, there were no differences in growth rates in weight
between the two diets (1.2 ± 0.4 and 0.9 ± 0.3 %BWd−1, respectively) or in carapace length (0.4 ± 0.1 and 0.4 ± 0.2 %BWd−1, respectively). Fresh mussel appears to be a very good diet to culture the early stages of this species, while shrimp pellets
also deliver acceptable results. On the contrary, frozen shrimp, fish fillets either from blue or white species (much higher
lipid content in the blue species), and fish pellets were found to be bad diets for the culture of the early stages of M. brachydactyla. 相似文献
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炔草酯的控草效果和对油菜田间光照、养分、水分及 产量的影响 总被引:1,自引:2,他引:1
为明确15%炔草酯WP在油菜田的应用前景,建立油菜田的杂草管理体系,研究了不同开沟深度、不同时期施用15%炔草酯WP对油菜田杂草的控制作用以及炔草酯与其他药剂混用的效果,同时研究了该药剂对田间光照、养分、水分和油菜产量的影响。结果表明,开深沟有利于药效的发挥。在禾本科杂草处于1~2叶期时进行药剂处理,一般可以获得比较理想的除草效果。炔草酯与草除灵混用对禾本科杂草和双子叶杂草都具有良好的防除效果。施用15%炔草酯WP能显著提高油菜田间的透光率,降低杂草对田间养分和水分的吸收。15%炔草酯WP的施用对油菜株高、千粒重没有显著影响,但对油菜第一分枝高度、单株分枝数、角果数影响较大,能显著提高油菜产量。 相似文献
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氮、磷、钾肥对丹参根系生长及养分含量的影响 总被引:1,自引:0,他引:1
采用田间小区试验方法,研究了氮、磷、钾肥对丹参根系生长及养分含量的影响。结果表明,氮、磷、钾肥能够促进丹参根系对氮、磷、钾的吸收,提高其含量,并且随着施用量的增加而提高,在N,P2O5,K2O的施用量分别为225,180,225 kg/hm2时,根的氮、磷、钾含量达到最高值;当施入N,P2O5和K2O分别为225,120,150 kg/hm2时,丹参根干质量、根长及根条数达到最高值,根的直径最适宜,此后随着磷钾肥施入量增加,根干质量及根长、根条数反而下降,根直径增加。所以氮、磷、钾合理配合施用能够提高丹参根的养分含量、根干质量、根长、根数及根直径。 相似文献
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菜心的土壤钙、镁营养诊断指标及施肥效应研究 总被引:5,自引:0,他引:5
在不同地方,不同钙、镁含量水平的菜园土壤进行菜心钙、镁肥田间试验。根据20个试验点的钙肥试验和15个试验点的镁肥试验结果,分别建立菜心相对产量与土壤交换性钙、镁含量的回归方程。研究结果表明:菜心产量与土壤交换性钙、镁含量分别呈抛物线相关;在质地为中壤土的菜田上种植菜心,土壤交换性钙的适宜含量为4.26 ̄9.60cmolL-1,交换性镁的适宜含量为2.01 ̄2.31cmolL-1;在参试的所有菜田中,施钙肥增产显著的菜田占50%,增产率为0.65 ̄33.8%;施镁肥增产显著的菜田占47%,增产率为-1.6% ̄34.7%。 相似文献
28.
将64只昆明鼠分为4组,分别给以0,25,50,100mgF/L的饮水,每组动物再分为两小组,设一个低营养组,一个高营养组,以比较相同饮水氟于不同营养条件下肝、肾及心肌的损伤情况。结果表明,在给氟90d时,50及100mgF/L组动物的肝脏可见脂肪及水泡变性,肾脏皮质肾小管上皮可见水泡变性,心肌纤维着色不匀,个别纤维可见颗粒变性。相同氟水平下不同营养组间比较,高营养组上述变化明显减轻,表明补充营养可以缓减氟对软组织的损伤。 相似文献
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就如何提高学生高效率地自主学习专业课是高效教育改革创新的重要环节,其成果对于推动学生对于专业知识的掌握具有积极作用。通过对教育思想大讨论中提出的学生自主学习“食品营养学”的重要性进行论述,并对教学中出现的问题进行剖析,提出采用教学制度的改革创新同移动慕课的混合教学的方式,同时结合食品营养学就业导向这种三位一体的方式来提升学生自主学习能力,旨在培养更多的食品营养学方向的人才。 相似文献