Effect of arachidonic acid levels in broodstock diet on larval and egg quality of Japanese flounder Paralichthys olivaceus

This study investigated the effect of dietary arachidonic acid (AA) in broodstock of Japanese flounder on subsequent egg and larval quality. Diets with similar proximate composition and n-3 HUFA level, but with different AA levels (0.1%, 0.6% and 1.2% of diet), were fed to the broodstock from 3 months before and during the spawning season. Spawning was observed from March to May. Total egg production over the spawning season was highest in fish fed the 0.6% AA diet and lowest in fish fed the 1.2% AA diet. All parameters measured as egg quality (percentage of buoyant eggs, hatching rate, larval survival and normality of larvae.) were highest in fish fed the 0.6% AA diet. AA content in eggs proportionally increased with the dietary AA level. EPA content of polar lipids of eggs had a negative correlation with the AA level in diets whereas the DHA content was independent of dietary AA. The results of this study indicate that a supplement of AA at 0.6 g/100 g diet improved the reproductive performance of Japanese flounder, but a higher level of AA (1.2 g/100 g diet) negatively affected both egg and larval quality due to a potential inhibitory effect on EPA bioconversion.     

山地林火烧迹地土壤水分动态变化

在日本冈山县备前市久久井地区的一片森林火烧迹地,设立了三块不同样地进行调查研究,对火烧后由于降雨引起的水分的动态变化进行了实验分析,发现三块样地的水分流失、pH值和阴阳离子变化程度不同。同时参照国内外其他地区的研究结果,寻求减少土壤水分流失的最佳方法,从而选择最适植被恢复方式,为我国大兴安岭地区火烧迹地的植被恢复提供理论依据。     

管道进口空气吸入的临界水深试验研究

制作1∶3比尺的大小水槽模型,试验研究了灌溉管道进口空气吸入的形式及临界水深与管道流速的关系,得出空气吸入的形式及临界水深与水槽内水流的紊动状态有关,且临界水深随流速的增加而增加的结论。相似性分析表明,临界水深在流速较小时大致符合0.2次方准则,而当流速较大时接近流速一致准则。此外,还根据试验结果对日本有关最小水深标准值进行了讨论     

Effects of feeding time,water temperature,feeding frequency and dietary composition on apparent nutrient digestibility in rainbow trout Oncorhynchus mykiss and common carp Cyprinus carpio

A series of experiments was conducted to evaluate the effects of feeding time (daytime vs nighttime feeding), dietary fat content (8 and 20%), feeding frequency (trout 1–3 times/day, carp 2–7 times/day), water temperature (trout 18 and 11°C, carp 25 and 17°C), on the apparent nutrient digestibility in rainbow trout and common carp. The feeding time had little effect on the macronutrient digestibility in both species. In trout, starch digestibility decreased with the decrease of water temperature and with increase of feeding frequency, but in carp, increase of the feeding frequency markedly decreased the macronutrient digestibility and phosphrrus absorption of the high fat diet. Fat digestibility of the beef tallow diet decreased relative to the pollock oil diet in carp, without affecting the phosphorus absorption. Inclusion of raw starch, the digestibility of which was lower than that of gelatinized starch, increased the phosphorus absorption in carp. These results suggest that reduction of water temperature and increase of feeding frequency notably decreased starch digestibility in trout while in carp, the effects of feeding frequency and water temperature on macronutrient digestibility and phosphorus absorption are notable for a high fat diet.     

Effects of photoperiod on offspring production,development and generation time,survival, adult sex ratio and total life span of freshwater cyclopoid copepod,Mesocyclops sp.: comments on individual variations

The experiments were conducted to examine the effects of five photoperiod regimes (24:00; 16:08; 12:12; 08:16 and 00:24 hours) (Light: Dark) on reproductive traits, development and generation time, survival rate, adult sex ratio and total life span of freshwater cyclopoid copepod, Mesocyclops sp.. Daily offspring production of individual female was monitored from the last moulting until death of all females. Mean daily offspring production affected by photoperiod, with the highest output recorded at 08:16, which was significantly higher than 24:00 and 00:24, but not differ from 12:12 and 16:08. No significant differences were obtained in total egg sacs per female among treatments. Photoperiods other than 12:12 significantly prolonged the inter‐clutch times. A trend of accelerated development and generation time was shown with increasing illumination periods. With the exception of female's life span, the survival rates of offspring and females as well as adult sex ratio were not significantly affected by photoperiod. Based on results of this study, it is recommended that Mesocyclops sp. can tolerate and reproduce in a wide range of photoperiod regimes, however, photoperiod of 08:16 being adopted in controlled culture due to its high reproductive performance, fast development and long longevity.     

Effect of water temperature and short-term fasting on macronutrient self-selection by common carp (Cyprinus carpio)

The influence of water temperature (17 and 25 °C) and a period of fasting on the self-selection of macronutrients were examined in common carp held on a 12:12-h light/dark cycle. Eight replicate groups of juvenile carp (ca. 15 g body weight at 17 °C and 25 g at 25 °C) were fed with three test diets [high-protein (HP), high-fat (HF) and high-carbohydrate (HC) diets] by individual self-feeders for 3 weeks, followed by a 2-week period of fasting and then 3 weeks of refeeding. At 17 °C, the carp initially selected the HP and HF diets [HP/HF/HC (%)=38:40:22], whereas at 25 °C, the carp selected the HP diet over the others (55:21:24). After fasting, the carp tended to increase their demand for the HF diet at 17 °C and for the HC diet at 25 °C, but the overall self-selection of the test diets did not differ markedly from that prior to fasting. Carp held at 17 °C had higher relative whole body fat content and plasma triglyceride concentration; the latter decreased markedly during fasting. These results suggest that water temperature influences the macronutrient selection by carp: a relatively high demand for both protein and fat at 17 °C and for protein at 25 °C. Two weeks of fasting, however, did not markedly alter their macronutrient selection.     

Simultaneous application of silver nanoparticles with different crease resistant finishes

Textiles, especially those made of natural fibers, are suitable medium for the growth of microorganisms which causes disease transmission, stink, colorful spots, and reduction in fabric strength. This research focuses on the antimicrobial finishing of cotton fabrics using colloidal solution of silver nanoparticles. Due to the difficulties of adding a new step to the finishing process of cotton textiles, efforts have been made to combine the antimicrobial treatment with the conventional finishing processes. For this purpose two chemical finishes of Fixapret ECO as a crosslinking agent and Cellofix ME as a resin former have been used in anti crease finishing of cotton fabric and their effects were evaluated. The properties of the samples have been investigated by measuring the resistant of samples against bacteria, crease recovery angle, abrasion, and washing fastness. The results showed that treated samples by pad-dry method have the best antibacterial effect with a direct relation between the increase in drying temperature and antibacterial properties. However, the washing and abrasion fastness were not at the acceptable level. Co-application of the colloidal solution of silver nanoparticles with the crease resistant materials improved both fastness properties while at the same time limited the direct contact between the nanoparticles and the bacteria so the antibacterial efficiency was reduced. Subsequently, it was concluded that the antibacterial finishing method should be selected according to the end uses. In addition, antibacterial treatment could be one of the multi-purpose finishes for cotton fabric.