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排序方式: 共有818条查询结果,搜索用时 31 毫秒
811.
果粮间作生态系统光能分布规律的研究 总被引:1,自引:0,他引:1
对内蒙古巴盟地区果粮间作生态系统的光能分布研究表明:果粮间作生态系统有其特殊的光照分布规律;果粮间作生态系统可更好地利用光能;根据果粮间作生态系统的光照分布规律可以确定合理的栽植方式和合理的树形、树高、冠幅等指标。 相似文献
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Stefanie M. Colombo Zeyu Zhang David F. Wong Zhirun Yuan 《Aquaculture Nutrition》2020,26(4):1353-1368
The objective of this study was to evaluate hydrolysis lignin (H‐lignin), derived from wood biomass, as a multifunctional component of aquafeeds. Atlantic salmon (28.8 ± 1.1 g) were fed diets for 16 weeks, which included two H‐lignin types (HL1 and HL2) at 15, 30 or 50 g/kg (wt/wt) or a control diet (no added H‐lignin). HL1 was extracted with water such that no soluble sugar and oligosaccharides remain, while HL2 contains a higher fraction of water‐soluble sugars and oligosaccharides. Pellet durability and density were measured. After 16 weeks, salmon were measured for weight and length, and whole carcass, hindgut and digesta contents were sampled. Pellet durability increased from the control to 30 g/kg H‐lignin but decreased at 50 g/kg. Salmon fed diets with HL1 at 15 and 30 g/kg showed higher weight gain and lower feed conversion ratio compared with salmon fed the control diet and 50 g/kg HL1. There were no significant differences in whole‐body composition or intestinal morphology. Microbial characterization (16S) revealed lower abundance of Proteobacteria, higher abundance of Mycoplasmataceae and increasing Lactobacillaceae abundance with higher HL1 inclusion. This study demonstrates that HL1 (at 15 and 30 g/kg) shows potential as a functional feed additive for salmon. 相似文献
815.
Tien‐Tien Vicky Lau Suat‐Moi Puah Ching‐Kee Karen Hon Fui‐Fui Ching Jin‐Ai Mary Anne Tan Savithri Devi Ampalam Puthucheary Ping‐Chin Lee Kek‐Heng Chua 《Aquaculture Research》2020,51(10):3972-3982
Aeromonads are ubiquitous in aquatic environments and have been implicated in fish and human infections. In this study, we isolated, studied antimicrobial susceptibility patterns and screened the existence of 15 virulence genes in aeromonads from two famously consumed fish species—seven marine Tiger Grouper (Epinephelus fuscoguttatus) and eight freshwater Marble Goby (Oxyeleotris marmoratus) from the aquaculture hatchery in Sabah, Malaysia. A total of 30 aeromonads (17 A. caviae, 9 A. rivuli, 4 A. dhakensis) were identified using PCR targeting GCAT gene, rpoD‐restriction fragment length polymorphism and multi‐locus phylogenetic analysis. All 30 strains were resistant to amoxicillin and cephalothin and five strains were multidrug‐resistant. Nine virulence genes (lip, ela, eno, fla, aerA, hylA, dam, alt and ser) present in A. dhakensis, suggesting the virulence potential of this species as a fish pathogen. This study offers as a baseline for future studies in monitoring and managing these two fish in aquaculture industry. 相似文献
816.
The formation of social groups has important impacts on fitness for many animal species, with differences in group compositions resulting in a range of fitness outcomes for individuals. Recent interest in mixed‐species grouping, which extends from a large body of literature invested in understanding single‐species grouping, highlights novel complexities of group formation which relate to phenotypic, behavioural and physiological differences that naturally exist between species. Among fishes, mixed‐species shoaling is a common form of social grouping behaviour displayed across a range of marine and freshwater ecosystems. Research explaining mixed‐species shoaling shows some overlap with explanations for single‐species shoaling; however, it also demonstrates that distinct differences between species give rise to unique cost‐benefit trade‐offs which need to be incorporated into conceptual models of mixed‐species shoaling behaviour. Unique predation related trade‐offs may arise from inefficiency of the confusion effect, variation in vigilance between species and unequal species‐preferences shown by predators, whilst unique foraging‐related trade‐offs may arise from diet partitioning, variations in foraging behaviour and differences in competitive abilities between species. We review the literature on fitness outcomes associated with mixed‐species shoaling and present a new theoretical framework to explain the cost‐benefit trade‐offs for individuals within mixed‐species shoals. The framework incorporates both trade‐offs arising from differences between species and those arising from group size, the former having been largely ignored due to a focus on single‐species shoaling. Our framework is designed to inform future research striving to explain mixed‐species shoaling behaviour. 相似文献
817.
J. Jane Y. Y. Chen L. F. Lee A. E. McPherson K. S. Wong M. Radosavljevic T. Kasemsuwan 《Cereal Chemistry》1999,76(5):629-637
Structures and properties of starches isolated from different botanical sources were investigated. Apparent and absolute amylose contents of starches were determined by measuring the iodine affinity of defatted whole starch and of fractionated and purified amylopectin. Branch chain-length distributions of amylopectins were analyzed quantitatively using a high-performance anion-exchange chromatography system equipped with a postcolumn enzyme reactor and a pulsed amperometric detector. Thermal and pasting properties were measured using differential scanning calorimetry and a rapid viscoanalyzer, respectively. Absolute amylose contents of most of the starches studied were lower than their apparent amylose contents. This difference correlated with the number of very long branch chains of amylopectin. Studies of amylopectin structures showed that each starch had a distinct branch chain-length distribution profile. Average degrees of polymerization (dp) of amylopectin branch chain length ranged from 18.8 for waxy rice to 30.7 for high-amylose maize VII. Compared with X-ray A-type starches, B-type starches had longer chains. A shoulder of dp 18–21 (chain length of 6.3–7.4 nm) was found in many starches; the chain length of 6.3–7.4 nm was in the proximity of the length of the amylopectin crystalline region. Starches with short average amylopectin branch chain lengths (e.g., waxy rice and sweet rice starch), with large proportions of short branch chains (dp 11–16) relative to the shoulder of dp 18–21 (e.g., wheat and barley starch), and with high starch phosphate monoester content (e.g., potato starch) displayed low gelatinization temperatures. Amylose contents and amylopectin branch chain-length distributions predominantly affected the pasting properties of starch. 相似文献
818.
Vivian M. F. Lai Mei‐Ching Shen An‐I Yeh Bienvenido O. Juliano Cheng‐yi Lii 《Cereal Chemistry》2001,78(5):596-602
The differences in pasting properties involving gelatinization and retrogradation of rice starches from IR24 and Sinandomeng cultivars during heating‐cooling processes were investigated using a Rapid Visco Analyser (RVA)and a dynamic rheometer. The results were discussed in relation to the molecular structure, actual amylose content (AC), and concentration of the starches. Generally, both starches possessed a comparable AC (≈11 wt%), amylose average chain length (CL), iodine absorption properties, and dynamic rheological parameters on heating to 95°C at 10 wt% and on cooling to 10°C at higher concentrations. In contrast to Sinandomeng, IR24 amylose had a greater proportion of high molecular weight species and number‐average degree of polymerization (DPn). IR24 amylopectin possessed a lower DPn and greater CL, exterior CL (ECL), and interior CL (ICL). Comparing the results of RVA analysis and dynamic rheology, the gelatinization properties and higher retrogradation tendencies of IR24 starch can be related to the structural properties and depend on starch concentration. In addition, the exponent n of starch concentration for storage moduli at 25°C (G′25 ∝ Cn) increased linearly with increasing AC. 相似文献