多个条斑紫菜品系采收期内脂肪酸组成、含量的变化分析

为探讨条斑紫菜不同栽培品系、不同采收期脂肪酸组成及含量的变化,本实验对10个栽培品系进行了跟踪测定分析,结果显示:条斑紫菜的脂肪酸组成稳定,与品系、采收期内季节性变化无关,但含量存在明显的差异。各品系的3个采收期的饱和脂肪酸(16∶0为主,包括13∶0、16∶0、18∶0)的相对含量约为20%;不饱和脂肪酸(以EPA为主,包括18∶1 n-9、18∶2 n-6、18∶3 n-3、20∶1 n-9、20∶2 n-7、20∶3 n-7、20∶4 n-6(AA)、20∶5 n-3(EPA))的相对含量为70%左右。在温度最低2月份的采收样品中,总脂肪酸和EPA含量最高,显示低温有利于条斑紫菜脂肪酸尤其是EPA的积累。另外,条斑紫菜富含以EPA为主的不饱和脂肪酸,在整个采收期内,样品中的n-6/n-3比值为4.9～7.7,符合WHO/FAO膳食推荐值。     

不同新型水溶肥料对茶叶的增产效果及经济效益分析

【目的】探讨不同类型新型水溶肥料在云南茶叶生产上的应用效果,筛选出适合云南茶叶生产应用的新型水溶肥料。【方法】选用6种新型水溶肥料对供试品种云抗10号产量、品质、生化成分及经济效益进行研究,筛选出对该品种具有增产作用的新型水溶肥料。【结果】从产量性状与生化成分角度看,以喷施微量元素水溶肥料、含腐植酸水溶肥料、合氨基酸水溶肥料等效果较好,其中以微量元素水溶肥料增产效果最好,增产10．66％;从对茶叶品质影响和经济效益分析角度看,喷施含腐植酸水溶肥料的茶叶品质综合表现较好,较对照增加收入12153．55元／hm2,产投比为30．0：1。【结论】综合产量、品质和经济效益三方面的效果,建议茶叶生产上推荐使用含腐植酸水溶肥料、含氨基酸水溶肥料、微量元素水溶肥料等较好。     

The development and comparison of bio-thermoset plastics from epoxidized plant oils

This study investigates the development of thermoset plastics from plant-based oils (e.g., linseed, soybean, cottonseed, oilseed radish, and peanut oils) using an optimal process of solvent-free epoxidation. The epoxidation of plant oils can be accomplished economically by reacting the double bonds of fatty-acids with hydrogen peroxide. During the solvent-free process catalyzed by the ion-exchange resin, we observed that the influence of several variables was important: the molar ratio of hydrogen peroxide to unsaturation, acetic acid to unsaturation, and temperature. The epoxidation of plant oils was determined from the liquid mixture and the composite matrix by thermal and spectroscopic analyses. Compounds with a higher double-bond (iodine) value showed higher oxirane oxygen percent and selectivity, and a higher hydroxyl value because of a greater possibility of attack by solutions causing side reactions. Lower iodine values indicated fewer epoxy groups and selectivity, and a lower hydroxyl value. Benzyl pyrazinium hexafluoroantimonate (BPH) yielded good thermal curing properties; as little as 1% added to the plastics produced light-weight composites. Epoxidized linseed oil promises the highest modulus and impact resistance due to the largest number of double bonds to contribute more epoxy groups and the large proportion of linolenic acids to produce epoxy groups rapidly.     

Planktonic and Biochemical Composition of Periphyton Grown on Some Biodegradable and Non-Degradable Substrates

ABSTRACT

Ten locally available substrates, five biodegradable and five non-degradable, were evaluated for their potential to harbor periphyton in cement tanks fertilized with poultry manure. The tanks were fertilized regularly and the periphyton was allowed to grow for 70 days. Weekly samples of periphyton and plankton were collected for enumeration and biochemical analyses. Among the substrates, earthen tiles harbored negligible amount of periphyton. The phytoperiphyton genera encountered on the substrate belonged mainly to Chlorophyceae (14 genera), followed by Cyanophyceae (2 genera), Chrysophyceae (1 genus), Bacillariophyceae (1 genus), and Dinophyceae (1 genus). Nauplius, Keratella, Diaptomus, Cyclops, Moina, Chironomus and insect eggs were the zooplankton encountered on substrates. Phytoplankton density was higher on tyre (86,426 cells or colonies/cm²) and palm leaf (85,808 cells or colonies/cm²) and lowest on ceramic tile (21,081 cells or colonies/cm²). Glass plates harbored the highest number of zooplankton species per unit area (1050 cells or colonies/cm²), while arecanut leaf-sheath had the lowest (210 cells or colonies/cm²). All five families of phytoplankton present on the substrates were also present in tank water. While periphyton contained 26 genera, tank water had only 24. Periphytic dry matter, ash, ash-free dry matter, plankton density on substrates and water showed a general increase with respect to time. Polyvinyl chloride (PVC) (0.972 mg/cm²), glass (0.913 mg/cm²), and bamboo (0.897 mg/cm²) had higher periphytic dry matter and ceramic tile (0.262 mg/cm²) the lowest. All the proximate composition parameters of periphyton, except nitrogen free extract (NFE) varied significantly (P < 0.05) between the substrates. The moisture content of periphyton ranged from 85.58% (bamboo) to 95.27% (arecanut leaf-sheath). Crude protein was high in periphyton from bamboo (3.77%) and tyre (3.66%) and low in that from arecanut leaf-sheath (0.99%).     

Effect of Crude Palm Oil Incorporation on Growth,Survival, Feed Efficiency,and Body Composition of Heterobranchus longifilis Fingerlings

An 8-week feeding trial was carried out to determine the effect of increasing dietary palm oil levels on African catfish juvenile growth and nutrient utilization. Six isonitrogenous diets were formulated to contain 0.5% to 15% crude palm oil with dietary lipid levels ranging from 5% to 20%. Growth performance and protein utilization efficiency of African catfish responded in a positive manner to palm oil addition up to 9% (diet 14% lipid). No further improvement in growth was observed with higher levels of palm oil in the diets, and lower survival was observed with inclusion of 15% palm oil (diet 20% lipid). Whole-body lipid content increased when fish were fed with increasing levels of dietary lipid. Under our experimental conditions, the best growth rate and nutrient utilization were observed with the inclusion of 9% crude palm oil in the diets for African catfish.     

Effect of Dietary Inclusion of Ulva fasciata on Red Hybrid Tilapia Growth and Carcass Composition

Five different levels (0, 25, 50, 75, and 100 g kg^?1) of algal (Ulva fasciata) meal were added to red tilapia feeds to examine its effect on growth and carcass biochemical content. Addition of ulva meal significantly improved growth performance, feed utilization, total crude protein content, and percentage of highly unsaturated fatty acids. Fish fed 75 g kg^?1 or 100 g kg^?1 of U. fasciata performed better than others.     

Effects of Brief Summer or Winter Fasting on the Muscle Quality of Cultured Pacific Bluefin Tuna (Thunnus orientalis)

The effects of fasting on the quality of the dorsal and ventral ordinary muscles from cultured Pacific bluefin tuna (Thunnus orientalis) during chilled storage were investigated. Tuna were subjected to fasting for 2 days in the summer or 6 days in the winter prior to harvesting. The breaking strength of the dorsal ordinary muscle sampled in the summer increased until 24 h and then decreased. There were no significant differences in the lipid and glycogen content of the ordinary muscle after 9 h of storage between the controls and either fasting group. The pH of the ordinary muscle subjected to summer and winter fasting was higher than in the controls after 24–48 h of storage. However, the relationship between the pH and glycogen content was unclear. The metmyoglobin content during chilled storage was lower in the ordinary muscles from either fasting group than in the controls. In conclusion, fasting for 6 days in the winter improved the color stability of the ordinary muscle without a decline in its lipid content.     

An Evaluation of the Suitability of Selected Waste Products in Feeds for Three Fish Species

ABSTRACT

Five types of aquatic food industry waste products (carp offal, carp roe, fish frames, trout offal and surimi processing waste) together with fish meal were evaluated for their suitability as potential fish meal replacements, partially or wholly, in diets for three species (rainbow trout, Murray cod and shortfin eel) cultured in Australia, using a number of criteria.

The proximate composition of the ingredients on a dry matter basis including protein content, lipid and ash, varied considerably. The essential amino acid (EAA) contents of the waste products and fish meal decreased in the order: carp roe > fish meal > carp offal > ‘surimi’ processing waste > fish frames > trout offal. The results of cluster analysis of A/E ratios of waste products and fish whole body fell within three clusters. The EAAI of whole body tissue of Murray cod, rainbow trout and Australian shortfin eel however, were closest to fish meal, followed by fish frame waste and/or ‘surimi’ waste. The results on A/E ratios and EAAI did not conform to the raw data on TAA and EAA. Therefore, the study emphasizes the need to have a multi-prong approach to determine the suitability of ingredients for incorporation into fish feeds.     

Effects of dietary carbohydrate/lipid ratios on growth performance,body composition and glucose metabolism of fingerling blunt snout bream Megalobrama amblycephala

This study aimed to investigate the optimum dietary carbohydrate/lipid (CHO/L) ratio for fingerling blunt snout bream Megalobrama amblycephala (average initial weight: 6.61 ± 0.03 g). Six isonitrogenous and isoenergetic diets were formulated to contain various CHO/L ratios ranging from 1.62 to 24.20. Each diet was tested in four replicates for 10 weeks. Specific growth rate (SGR), feed conversion ratio and nitrogen and energy retention all improved significantly (P < 0.05) as dietary CHO/L ratios decreased from 24.20 to 5.64 but showed little difference (P > 0.05) as dietary CHO/L ratios ranged from 2.45 to 5.64. Hepatosomatic index increased significantly (P < 0.05) as dietary CHO/L ratios increased, whereas intraperitoneal fat ratio showed an opposite trend (P < 0.05). Opposite to moisture content, lipid content of whole body and carcass all increased significantly (P < 0.05) as dietary CHO/L ratios decreased. Liver lipid content showed little difference (P > 0.05) among all the treatments, while liver glycogen content increased significantly (P < 0.05) with increasing CHO/L ratios. High dietary carbohydrate enhanced the activities of liver hexokinase, pyruvate kinase and glucose‐6‐phosphate dehydrogenase but did not induce hyperglycaemia. Based on the second‐order polynomial regression analysis of SGR, the optimal dietary carbohydrate and lipid contents for fingerling blunt snout bream were 291.7 and 81.4 g kg⁻¹, respectively, with a corresponding dietary CHO/L ratio of 3.58.     

Effects of dietary 60 g kg−1 dried distiller's grains in least‐cost practical diets on production and gut allochthonous bacterial composition of cage‐cultured fish: comparison among fish species with different natural food habits

Dried distiller's grain (DDG) is considered as an alternative ingredient of dietary feed due to its high contents of protein, fibre and fat. In this study, 60 g kg^‐1 of DDG was used to feed grass carp (Ctenopharyngodon idella), bluntnose black bream (Megalobrama amblycephala), gibel carp (Carassius gibelio) and black carp (Mylopharyngodon piceus) for 8 weeks, and its effect on fish production and gut allochthonous microbiota was investigated for the development of a suitable fish feed high in nutrients and low in cost for polyculture freshwater fish. DDG supplementation resulted in the less weight gain and higher feed conversion ratio of black carp (P < 0.05), but had no significant effects on other fish or parameters. PCR–denaturing gradient gel electrophoresis (DGGE) analysis indicated that all four fish species had some common and unique bacteria in their digestive tracts, and the gut microbiota of bluntnose black and gibel carp fed the control diet and DDG diets were very similar (Cs > 91%); of them, the total counts of intestinal bacteria studied by qPCR increased in grass carp (P < 0.05) and depressed in black carp (P < 0.05) when fed dietary DDG. Thus, we assumed that dietary DDG modulated production and gut microbiota of fish in a host‐specific way.