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排序方式: 共有151条查询结果,搜索用时 15 毫秒
121.
Robson Andrade Rodrigues Cleujosí da Silva Nunes Leticia Emiliani Fantini Rodrigo Yutaka Dichoff Kasai Carlos Antonio Lopes Oliveira Hamilton Hisano Cristiane Meldau de Campos 《Aquaculture International》2018,26(1):1-11
This study evaluated the effect of graded levels of dietary ascorbic acid (AA) (12.47, 20.27, 115.44, 475.50, 737.72, and 850.70 mg kg?1) on growth, hematology, intestinal morphometry, and phagocyte activity of hybrid sorubim Pseudoplatystoma reticulatum × Pseudoplatystoma corruscans. Fish (n = 420, 14.57 ± 2.71 g, 15.11 ± 0.90 cm) were distributed in 30 polyethylene tanks (80 l) (5 replicates per treatment with 14 fish per tank) and fed for 45 days. Dietary treatment did not have a significant effect on growth metrics (P > 0.05). Fish fed 737.72 mg AA kg?1 had a higher villi height (289.80 ± 19.96 μm) (P < 0.05) than fish fed 850.70 mg AA kg?1 (245.4 ± 18.25 μm). Hemoglobin in fish fed 850.70 mg AA kg?1 (5.34 ± 0.96 g dl?1) was higher (P < 0.05) than fish fed 12.47 mg AA kg?1 (3.42 ± 0.55 g dl?1) and 20.27 mg AA kg?1 (3.06 ± 1.26 g dl?1). The erythrocyte number of hybrid sorubim fed 115.40 mg AA kg?1 (1.73 ± 0.27 × 106 μl?1) and 475.50 mg AA kg?1 (1.70 ± 0.28 × 106 μl?1) were higher (P < 0.05) than in those fed diets containing 20.27 mg AA kg?1 (1.11 ± 0.34 × 106 μl?1). There was no significant effect (P > 0.05) of dietary AA on leukocyte and thrombocyte and on phagocyte activity and phagocyte index. Inclusion of AA in feed seems to increase the integrity of the intestinal mucosa and stimulate erythropoiesis in hybrid sorubim catfish. 相似文献
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123.
Yanina A TORRES Carlos A BUSSO Oscar A MONTENEGRO Leticia ITHURRART Hugo D GIORGETT Gustavo RODRíGUEZ Diego BENTIVEGNA Roberto E BREVEDAN Osvaldo A FERNáNDEZ María M MUJICA Sandra S BAIONI José ENTíO María N FIORETTI Guillermo TUCAT 《干旱区科学》2014,(2):195-204
Pappophorum vaginatum is the most abundant C4perennial grass desirable to livestock in rangelands of northeastern Patagonia,Argentina.We hypothesized that(1)defoliation reduce net primary productivity,and root length density and weight in the native species,and(2)root net primary productivity,and root length density and weight,are greater in P.vaginatum than in the other,less desirable,native species(i.e.,Aristida spegazzinii,A.subulata and Sporobolus cryptandrus).Plants of all species were either exposed or not to a severe defoliation twice a year during two growing seasons.Root proliferation was measured using the cylinder method.Cylindrical,iron structures,wrapped up using nylon mesh,were buried diagonally from the periphery to the center on individual plants.These structures,initially filled with soil without any organic residue,were dug up from the soil on 25April 2008,after two successive defoliations in mid-spring 2007.During the second growing season(2008–2009),cylinders were destructively harvested on 4 April 2009,after one or two defoliations in midand/or late-spring,respectively.Roots grown into the cylinders were obtained after washing the soil manually.Defoliation during two successive years did reduce the study variables only after plants of all species were defoliated twice,which supported the first hypothesis.The greater root net primary productivity,root length density and weight in P.vaginatum than in the other native species,in support of the second hypothesis,could help to explain its greater abundance in rangelands of Argentina. 相似文献
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125.
Gérard Cuzon Leticia Arena Jean Goguenheim Emmanuel Goyard & Aquacop 《Aquaculture Research》2004,35(13):1244-1252
Peneid shrimp are commonly reared in clear‐water aquaria or tanks for short‐term studies of 4–6 weeks during controlled experiments, such as nutrition studies to estimate dietary nutrient requirements. Recently, in line with the genetic program at Centre Océanologique du Pacifique (COP), experimental clear‐water facilities were tested for the first time over a longer rearing period. Environmental conditions used to maintain animal growth in clear‐water system using a well‐balanced diet were defined. After 100 days, shrimp growth rates tended to decrease and only by adjusting the diet could shrimp complete their life cycle and reach maturation size of around 40 g. This paper presents information on stocking density, diet quality and husbandry linked to reproduction that must be considered to successfully rear animals from PL's to breeder size in clear water. By following these protocols a minimum amount of breeders can be used to meet production goals. Moreover, by isolating a small group of individuals, genetic diversity can be preserved, thereby allowing specific crosses for selective breeding purposes. Length of trials, amount of feed, composition of feed, growth performances and maturation success are reported and should encourage further studies to optimize rearing conditions in clear‐water rearing. 相似文献
126.
An optimized index for cold tolerance assessment in rice during germination and early seedling stage
Monzón Daisy Leticia Ramirez Cantero Jorge Danielowski Rodrigo da Luz Viviane Kopp Venske Eduardo Mota Monalize Salete da Silva Raissa Martins de Oliveira Victoria Freitas de Oliveira Antonio Costa de Magalhães Júnior Ariano Martins da Maia Luciano Carlos 《Journal of Crop Science and Biotechnology》2023,26(2):243-253
Journal of Crop Science and Biotechnology - Cold tolerance at germination and seedling stage is one of the most seeked traits in Southern Brazilian rice (Oryza sativa L.) cultivars, thus, the... 相似文献
127.
Thaylise Vey Parodi Luciane Tourem Gressler Lenise de Lima Silva Alexssandro Geferson Becker Denise Schmidt Braulio Otomar Caron Berta Maria Heinzmann Bernardo Baldisserotto 《Aquaculture Research》2020,51(6):2515-2524
Plants are sources of secondary metabolites, and some are rich in essential oils (EOs), which possess a bioactive pharmacological importance as sedatives and anaesthetics that have been experimentally demonstrated in fish. In search of products with lower residual effects and optimization of the production based on the local flora, the properties of the EO of Aloysia triphylla (EOAT) have been investigated. The samples of two years were analysed for the percentage variability of the chemical composition and the totality of the major components according to the season. Limonene, citral isomers (α and β), caryophyllene, caryophyllene oxide and spathulenol were the main constituents of the EOAT throughout these two years. In the second year, caryophyllene predominates over its oxide in all seasons; however, in the first year, it occurs only in autumn and winter. Seasonal pools of EOs were made for the biennium obtaining four samples, and silver catfish (Rhamdia quelen) juveniles were subjected to a concentration range of 20–800 μl/L EOAT in order to assess induction and recovery times of anaesthesia. The relationships between percentages of individual components in EOAT and time to induce deep anaesthesia indicate that its activity may be attributed to the association of several of its components. 相似文献
128.
Costantino Vischetti Mario Businelli Mauro Marini Ettore Capri Marco Trevisan Attilio A. M. Del Re Lucia Donnarumma Elisa Conte Giancarlo Imbroglini 《Pest management science》1997,50(3):175-182
Experiments were carried out on three Italian farms to assess the degree of spatial variation of pesticide field concentration during treatment and during dissipation trials. Test pesticides were chloridazon and metamitron (both sugar-beet herbicides) applied as a tank mix. The classical statistical technique and geostatistics were used to summarize and evaluate variable spatial data. The results show that the actual values of pesticide concentration for application rate and initial concentration in all three areas are lower than expected, thus indicating that under field conditions only a part of the pesticide reaches the soil during the distribution. The actual values for both herbicides in all three areas expressed as percentage of expected values ranged from 44·1% to 64·2% for application rate and from 40·5% to 99·5% for initial concentration. The coefficient of variation was similar for both pesticides and ranged from 23·8 to 74·1 for application rate, 24·1 and 58·8 for initial concentration and 11·1 and 110·0 for dissipation half-lives. The high variability in application rate and initial concentration could be ascribed to an uneven herbicide distribution, and in dissipation studies to variation in half-lives for the rate of herbicide loss from soil in different parts of the field. Geostatistic analysis indicated little spatial correlation, probably because the sampling sites were widely spaced on the field. In all cases, the data were not sufficient to estimate the range of influence, probably because of the size of the experimental fields and the sampling strategy. © 1997 SCI. 相似文献
129.
Ariadne Missono Brondi Josiane Souza Pereira Daniel Vitor Xavier Monteiro de Castro Jerusa Simone Garcia Marcello Garcia Trevisan 《Communications in Soil Science and Plant Analysis》2016,47(22):2506-2513
Humic substances are the main responsible for soil conditioning and are one of the major components of the composting product. However, there is still little information about their composition and mechanisms of activity. This study aimed to evaluate quantitatively the humic and fulvic fraction by size-exclusion liquid chromatography and the metal content by atomic absorption spectrometry. The chromatographic method used was efficient for humic and fulvic acids quantitation. Levels of 1.73 ± 0.03 and 1.6 ± 0.5 g kg?1 were found for chicken manure regarding humic and fulvic acids, respectively, and 5.1 ± 0.9 and 1.2 ± 0.1 g kg?1 for peat. The metal contents indicated the need of a mineral enrichment, because only the levels of iron reached the minimum recommended by legislation. It was also observed that evaluated organic fertilizers were in accordance with the specifications established by legislation in relation to carbon and total nitrogen and the pathogen levels. 相似文献
130.