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31.
The results of a 56‐day experiment on juvenile Murray cod, Maccullochella peelii peelii, an Australian native fish with a high aquaculture potential, of mean weight 14.9 ± 0.04 g, fed with five experimental diets, one a series of 40% protein content and lipid levels of 10, 17 and 24% (P40L10, P40L17 and P40L24), and another of 50% protein and 17 and 24% (P50L17 and P50L24) lipid are presented. The specific growth rate (SGR) (% day?1) of fish maintained on different diets ranged from 1.18 to 1.41, and was not significantly different between dietary treatments, except P40L10 and the rest. However, there was a general tendency for SGR to increase with increasing dietary lipid content at both protein levels. The food conversion ratio (FCR) for the 40% protein series diets were poorer compared with those of the 50% protein diets, and the best FCR of 1.14 was observed with the P50L17 diet. The protein efficiency ratio (PER), however, was better in fish reared on low protein diets. The net protein utilization (NPU) also did not differ significantly (P > 0.05) in relation to dietary treatment. As in the case of PER the highest NPU was observed in Murray cod reared on diet P40L24 and the lowest in fish fed with diet P50L24. The carcass lipid content reflected that of the diets, when significant increases in the lipid content was observed in relation to dietary lipid content at both protein levels. However, body muscle lipid content did not increase with increasing dietary lipid content, and was significantly lower than in the whole body. The fatty acids found in highest concentration amongst the saturates, monoenes and polyunsaturates (PUFAs) were 16 : 0, 18 : 1n‐9 and 22 : 6n‐3, respectively, and each of these accounted for more than 60% of each of the group's total. The muscle fatty acid content was affected by the dietary lipid content; for example the total amount (in μg mg?1 lipid) of monoenes ranged from 72 ± 5.1 (P40L10) to 112 ± 10 (P40L24) and 112 ± 2.8 (P50L17) to 132 ± 11.8 (P50L24) and the n‐6 series fatty acids increased with increasing dietary lipid content, although not always significant. Most notably, 18 : 2n‐6 increased with the dietary lipid level in both series of diets. 相似文献
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Abstract Ocular pathologic findings in eyes of ascorbic acid-deficient juvenile red drum, Sciaenops ocellatus (L.), are described. Abnormalities in the most severely affected eyes included: reduced globe size and lack of normal globe rigidity; vascular congestion and intraocular haemorrhage; lenticular lesions which included disorganization of posterior cortex, vacuolation of posterior subcapsular cortex and posterior migration of lens epithelium; and severe central retinal degeneration. The authors suspect that retinal degeneration was related to phototoxic injury, to which these fish had increased susceptibility as a result of ascorbic acid deficiency. The cause for lenticular lesions was undetermined, but may have been related directly to ascorbic acid deficiency, indirectly to retinal degeneration, or both. 相似文献
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M. C. WARK M. B. SHEPHERD-CLARK H. V. SMITH W. D. COLLINS 《Australian veterinary journal》1982,59(1):6-10
Living attenuated bluetongue Type 20 virus vaccine was tested in 9 to 12 month-old Australian Merino sheep, held in air conditioned, insect-free accommodation. The vaccine appeared avirulent and immunogenic and protected against infection with a second dose of homologous vaccine virus. No enhancement of virulence or significant change in immunogenicity was observed when the vaccine was passaged 3 times through sheep without antibody to bluetongue virus. 相似文献
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Brian COLLINS 《干旱区科学》2021,13(8):858-878
Agriculture needs to produce more food to feed the growing population in the 21st century. It makes the reference crop water requirement (WREQ) a major challenge especially in regions with limited water and high water demand. Iran, with large climatic variability, is experiencing a serious water crisis due to limited water resources and inefficient agriculture. In order to overcome the issue of uneven distribution of weather stations, gridded Climatic Research Unit (CRU) data was applied to analyze the changes in potential evapotranspiration (PET), effective precipitation (EFFPRE) and WREQ. Validation of data using in situ observation showed an acceptable performance of CRU in Iran. Changes in PET, EFFPRE and WREQ were analyzed in two 30-a periods 1957-1986 and 1987-2016. Comparing two periods showed an increase in PET and WREQ in regions extended from the southwest to northeast and a decrease in the southeast, more significant in summer and spring. However, EFFPRE decreased in the southeast, northeast, and northwest, especially in winter and spring. Analysis of annual trends revealed an upward trend in PET (14.32 mm/decade) and WREQ (25.50 mm/decade), but a downward trend in EFFPRE (-11.8 mm/decade) over the second period. Changes in PET, EFFPRE and WREQ in winter have the impact on the annual trend. Among climate variables, WREQ showed a significant correlation (r=0.59) with minimum temperature. The increase in WREQ and decrease in EFFPRE would exacerbate the agricultural water crisis in Iran. With all changes in PET and WREQ, immediate actions are needed to address the challenges in agriculture and adapt to the changing climate. 相似文献
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ABSTRACT For some, Ireland's pursuit of an exogenous‐led development model has proved to be the cornerstone of recent economic success. Others point to recent high‐profile closures and argue that foreign‐owned operations are attracted to Ireland solely because of the advantageous tax breaks and lucrative grants scheme offered by the Irish government. We pay tribute to both arguments by pushing the level of enquiry beyond that of supply and backward linkages to try and gauge the actual performance of affiliates themselves. This brings some interesting facets of the Irish foreign direct investment scene to light. We highlight complexity of process, attainment of broader investment remits, and the emergence of a managerial class as integral to the ability of affiliates to adapt to and exploit organisational change. By examining 10 case studies and making use of media searches and company interviews, we highlight evidence of Ireland's largest technology transnational corporation affiliates showing positive performance advances. With these movements come, what we term, increased nodal significance of Irish operations within the global production network of their corporations. We argue against policy and theories that see these movements as linear and provide evidence of how some Irish operations have leveraged control and gained significant regional and global remits that have resulted in their growing significance, both in the corporation and in the country in which they are based. In the same line we argue that embeddedness in terms of supply linkages does not fit the Irish case and instead employ the term “network anchoring” of affiliates as they increase their nodal weighting through increased mandates. 相似文献
40.
Triblock copolymer syntheses of mesoporous silica with periodic 50 to 300 angstrom pores 总被引:32,自引:0,他引:32
D Zhao J Feng Q Huo N Melosh GH Fredrickson BF Chmelka GD Stucky 《Science (New York, N.Y.)》1998,279(5350):548-552
Use of amphiphilic triblock copolymers to direct the organization of polymerizing silica species has resulted in the preparation of well-ordered hexagonal mesoporous silica structures (SBA-15) with uniform pore sizes up to approximately 300 angstroms. The SBA-15 materials are synthesized in acidic media to produce highly ordered, two-dimensional hexagonal (space group p6mm) silica-block copolymer mesophases. Calcination at 500 degrees C gives porous structures with unusually large interlattice d spacings of 74.5 to 320 angstroms between the (100) planes, pore sizes from 46 to 300 angstroms, pore volume fractions up to 0.85, and silica wall thicknesses of 31 to 64 angstroms. SBA-15 can be readily prepared over a wide range of uniform pore sizes and pore wall thicknesses at low temperature (35 degrees to 80 degrees C), using a variety of poly(alkylene oxide) triblock copolymers and by the addition of cosolvent organic molecules. The block copolymer species can be recovered for reuse by solvent extraction with ethanol or removed by heating at 140 degrees C for 3 hours, in both cases, yielding a product that is thermally stable in boiling water. 相似文献