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Diet-induced changes in the polyunsaturated fatty acid (PUFA) content of immune cells influences the immune phenotype that develops following infection. The aim of this study was to examine the effect of manipulating dietary PUFA supply on tissue fatty acids composition and immunity to a mixed infection with an abomasal and an intestinal nematode parasite in calves. Calves (n=24) were allocated into two treatment groups and fed 25 g/day of either fish oil (n-3 group) or a binary mixture of palm/rapeseed oil (normal group) as a supplement in milk replacer. Within each treatment group eight calves were infected with 2000 L3 Ostertagia ostertagi and Cooperia oncophora, three times per week for 8 weeks, the remaining calves were pair-fed uninfected controls. Faecal egg counts (FEC) were carried out twice weekly. At slaughter, the whole gut was removed intact for worm counts and tissue samples were taken for fatty acid analysis. Samples of abomasum, duodenum and mid-gut were also collected for immunohistological analysis. FEC were not significantly influenced by oil supplement but tended to remain higher in the palm/rapeseed oil-fed group (normal infected). The number of intestinal immature worms was significantly (p<0.05) higher in the n-3 group. Mucosal mast cell (MMC) and eosinophil numbers were significantly increased (p<0.05) by infection and were significantly lower (p<0.05) in the intestinal tissue of the fish oil supplemented and infected group (n-3 infected group). These results suggest that feeding an n-3 PUFA-rich supplement (fish oil) can influence cellular mediators of immunity to nematode infection. This is the first report of the establishment of patency and the subsequent development of immunity to a mixed infection with O. ostertagi and C. oncophora in calves undergoing early rumen development. The trend in the FEC, MMC and eosinophil numbers in the n-3 group suggests that decreasing the dietary n-6/n-3 PUFA ratio may be a worthwhile immunonutritional strategy for potentiating the immune response to nematode parasite infection in the calf.  相似文献   
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During refrigeration, lipid oxidation is a major factor contributing to post-mortem deterioration of flesh quality. Polyunsaturated fatty acids (PUFA), especially n -3 PUFA, are present in high concentration in fish tissues, and in oils used in diets, and are readily susceptible to peroxidation. α-Tocopherol (AT) can reduce tissue lipid peroxidation in vivo and post mortem. The effect of increasing the tissue level of AT by dietary supplementation of α-tocopherol acetate (ATA) was therefore investigated. Commercial salmon diets C, M and H, high in lipids, containing 184, 573 and 865 mg ATA kg−1 diet DM (dry matter) were fed to 18 fish per treatment. Dietary AT: PUFA ratios were 2.0, 6.3, and 9.5 mg g−1 for diets C, M and H, respectively. Fish (mean initial live weight 630 g) were slaughtered after 50 and 78 days of feeding. Fillet samples were analysed fresh or after storage at 4 °C for 12 days and –20 °C for 12 months. Lipid oxidation was measured using the thiobarbituric acid test. Colour score, but not carotenoid content, of fillets was significantly higher between 6 and 12 days of fresh storage in fish fed diets M and H compared with those fed diet C. Colour score, carotenoid content and ΑΤ content decreased and the content of lipid oxidation products increased following storage of fillets at –20 °C for up to 12 months, although lipid oxidation was always significantly lower in fish fed diets M and H.  相似文献   
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Near-infrared reflectance (NIR) spectroscopy combined with chemometrics was used to identify and authenticate fishmeal batches made with different fish species. Samples from a commercial fishmeal factory (n = 60) were scanned in the NIR region (1100-2500 nm) in a monochromator instrument in reflectance. Principal component analysis (PCA), dummy partial least-squares regression (DPLS), and linear discriminant analysis (LDA) based on PCA scores were used to identify the origin of fishmeal produced using different fish species. Cross-validation was used as validation method when classification models were developed. DPLS correctly classified 80 and 82% of the fishmeal samples. LDA calibration models correctly classified >80% of fishmeal samples according to fish species The results demonstrated the usefulness of NIR spectra combined with chemometrics as an objective and rapid method for the authentication and identification of fish species used to manufacture the fishmeal.  相似文献   
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1. A study was undertaken to examine the effect of supplementation of diets with fats of different chain length and degree of unsaturation on the performance, carcase characteristics and tissue fatty acid composition of broilers.

2. Three hundred and sixty 19‐day‐old female broilers were fed on diets containing supplemental fat/oil (50 g/kg) in the form of beef tallow (BT) (diet T‐T), soyabean oil (SBO) (diet S‐S), rapeseed oil (RSO) (diet R‐R), marine oil (MO) (diet M‐M) or binary mixtures (0.5:0.5 w/w) of these lipids (diets T‐S, T‐R, T‐M, S‐R, S‐M, and R‐M) to 54 d of age. Food intake, live weight, plucked weight and the lipid concentration and fatty acid composition of abdominal fat pad, liver and breast muscle were measured.

3. Food intake, plucked weight and live weight were greatest for diet T‐T and lowest for diet R‐R. Food conversion ratio was poorest for birds fed on diets containing BT. Lipid concentration in abdominal fat pad was significantly higher in birds fed on diets containing SBO. liver lipid concentration was significantly reduced by diets containing RSO.

4. Abdominal fat pad fatty acid profile was most readily altered by dietary fatty acids. There was a strong correlation between dietary fatty acid composition and tissue fatty acid composition for all fatty acids except C14:0, C20:0, C20: 2n‐6 and C20: 4n‐6. The tissue P/S ratio ranged from 0.40 for diet T‐T to 1.40 for diet S‐S. The n‐6/n‐3 ratio was significantly increased by the inclusion of SBO and decreased by the inclusion of MO.

5. Liver fatty acid profile was least modified by dietary fatty acids. There was an inverse relationship between liver and dietary C20:4n‐6 concentration. Tissue C18:2n‐6 and C20:4n‐6 were highly correlated, suggesting significant interconversion by ?‐6 desaturase in this tissue. The n‐6/n‐3 ratio was significantly increased by inclusion of SBO and significantly decreased by the inclusion of MO.

6. In breast muscle MO‐based diets increased the proportion of n‐3 PUFA at the expense of n‐6 PUFA. The tissue concentrations of C18:ln‐9, C18:2n‐6, C20:ln‐9, C20:5n‐3, C22:5n‐3 and C22:6n‐3 were strongly correlated with dietary fatty acid composition. Muscle and diet P/S and n‐6/n‐3 ratios were highly correlated.  相似文献   

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The aim of this study was to investigate the effects of dietary supplementation of sows with alpha-tocopherol acetate (ATA) and vitamin C on deposition of alpha-tocopherol (AT) in piglet lymphoid organs, such as bone marrow, thymus, and spleen at birth and at weaning, as well as on indicators of immune response in piglets. Sows were given the following treatment diets: control, vitamin C 10 g/day, ATA 500 mg/kg feed, and combined vitamins (ATA 500+Vit-C 10). Supplementation with vitamins started at the beginning of pregnancy and lasted until weaning at 21+/-3 days of age. AT was determined in colostrum, milk, piglet plasma (cord blood) and tissues at birth and on day 21. Immunoglobulins were measured in piglet plasma, milk, and colostrum. Lymphocyte proliferation in response to PHA and ConA was determined in sow and piglet blood. ATA supplementation resulted in a significant increase (P<0.001) in the AT content of colostrum, milk, piglet plasma, liver, thymus, bone marrow, and spleen at weaning. The AT content of colostrum and milk significantly (P<0.001) influenced the AT content of piglet plasma and tissues at weaning (day 21). Total Ig and IgG concentrations in piglet plasma were significantly increased in piglets given the combined vitamin treatment. No effect of AT supplementation was observed on IgG and IgA in colostrum and milk. In sows, vitamin C given alone significantly increased lymphocyte response to ConA and PHA; whereas, in piglets, there was no significant effect of treatments on lymphocyte response to PHA and ConA.  相似文献   
9.
In summer 2001, visitors to a wildlife park in Norfolk, uk, became infected with verocytotoxin-producing Escherichia coli (vtec) O157, which was associated with wild rabbit faeces. The rabbits lived in an adjacent field together with E coli O157-positive cattle. A pilot study was therefore performed to investigate the factors affecting the association between E coli O157-positive cattle and wild rabbits. Samples of faeces were taken from 16 herds of cattle that lived close to populations of wild rabbits. Analysis by culture and pcr showed that seven of the herds were positive for E coli O157. Faeces were collected from individual rabbits at six of these farms during late winter, when there were few rabbits, and during high summer, when there were many. None of the 32 samples collected on two farms in late winter was positive for E coli O157, but eight of 97 samples collected in summer were positive on four of the six farms. pcr analysis for vtec, including non-O157, showed that 20 of the 97 samples were positive.  相似文献   
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In a study aimed at developing a vaccine against the asexual blood stages of Plasmodium falciparum, two T cell epitopes were identified within a nonpolymorphic region of gp190 of Plasmodium falciparum merozoites. The two epitopes, which were revealed by deletion analysis, stimulated human T cell clones. Peptides containing sequences of the epitopes stimulated the cloned T cells and peripheral blood mononuclear cells (PBMC) from malaria-infected individuals. Moreover, the T cell clones responded to 11 different Plasmodium falciparum isolates in culture, showing that the epitopes are recognized in native parasites.  相似文献   
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