17 research outputs found

    Crack initiation life estimations for notched specimens with residual stresses based on local strains

    No full text
    SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

    Dietary fish and evening primrose oil with vitamin E effects on semen variables in cockerels

    No full text
    1. Our aim was to determine the effect of n-3 (2%, wt/wt, fish oil rich diet) and n-6 (2%, wt/wt, evening primrose oil rich diet) fatty acid dietary supplementation and their combination with two concentrations of vitamin E (40 vs 200 mg/kg) on semen variables and on fatty acid and vitamin E profiles of spermatozoa in broiler breeders at 32, 42 and 52 weeks of age. 2. The inclusion of fish oil in the cockerel diets increased the docosahexaenoic acid proportion in the sperm phospholipid fraction, which was almost threefold higher compared to the other two groups irrespective of vitamin E supplementation. 3. In contrast, an increase in the proportion of total n-6 polyunsaturates, mainly 22:4n-6, was observed in the evening primrose oil group compared to the control only when the dietary content of vitamin E was increased to 200 mg/kg. 4. Sperm concentration was decreased in the fish and evening primrose oil groups if vitamin E was 40 mg/kg, but such an effect was prevented in the fish, not the evening primrose oil group, by increasing the vitamin E to 200 mg. 5. The proportion of motile spermatozoa was improved by the increased supplementation of vitamin E in all oil treatments

    The lipid and antioxidant changes in semen of the broiler fowl from 25 to 60 weeks of age

    No full text
    Spermatozoa and seminal plasma from cockerels at the beginning and end of their reproductive periods were examined for their lipid composition and associated antioxidant capacities. The significant reduction in concentration of spermatozoa with age was associated with a large increase in lipid concentrations in spermatozoa and in seminal plasma. This change in lipid concentration was accompanied by increases in the proportions of phospholipid and free cholesterol; in constrast, the proportions of these lipid moieties in seminal plasma were reduced. The major phospholipid fractions in the spermatozoa and seminal plasma were phosphatidyl choline and phosphatidyl ethanolamine. There was a large decrease with age in the proportion of phosphatidyl ethanolamine and a commensurate increase in that of phosphatidyl choline in the spermatozoa and seminal plasma. These major changes in phospholipid content were accompanied by a decrease in the amount of phosphatidyl serine in the spermatozoa and increases in phosphatidyl inositol and cardiolipin in both spermatozoa and seminal plasma. The reductions in the proportions of phosphatidyl ethanolamine were accompanied by considerable reductions in the content of the major polyunsaturated fatty acids 20:4 (n - 6) and 22:4 (n - 6). The changes in lipid composition owing to ageing were associated with a marked reduction within the spermatozoa of the major antioxidant enzyme glutathione peroxidase. The role of these changes in the specific combinations of polyunsaturated lipids and in antioxidant capacity in the reduction in fertility with age are discussed

    The effect of dietary supplementation with docosahexaenoic acid on the phospholipid fatty acid composition of avian spermatozoa

    No full text
    This study represents an attempt at the dietary manipulation of the fatty acid composition of chicken spermatozoa in order to enhance the levels of n-3 polyunsaturates at the expense of the n-6 fatty acids, which normally predominate in the lipids of avian semen. Male chickens were provided with either a control diet supplemented with maize oil or the test diet supplemented with fish oil (Tuna Orbital Oil) from 10 weeks of age. Semen samples were collected from the birds after 30 and 48 weeks of supplementation. The fish oil diet induced a significant but limited increase in the proportion of 22:6n-3 in the spermatozoan phospholipid in parallel with an equivalent decrease in the proportions of 20:4n-6 and 22:4n-6. However, since the maximal level of 22:6n-3 in the phospholipid that was achieved by fish oil feeding was less than 10% (wt/wt of fatty acids), these changes fell far short of representing a switch from the typical avian pattern to that more characteristic of the n-3 enriched mammalian semen. Analysis of the fatty acid compositions of the constituent classes of phospholipid in the spermatozoa indicated that, in both dietary states, the phosphatidylethanolamine fraction contained much greater proportions of n-6 and n-3 C20-22 polyunsaturates than the phosphatidylcholine fraction. The results indicate that the typical fatty acid profile of the spermatozoa of domesticated poultry, characterised by the predominance of C20-22 n-6 polyunsaturates, displays a considerable degree of resistance to manipulation by dietary means and does not adopt the 'mammalian' type of profile following supplementation with n-3 fatty acids

    Lipid and antioxidant composition of chicken semen and its susceptibility to peroxidation

    No full text
    The antioxidant composition of the chicken seminal plasma and spermatozoa and the effect of sperm storage on fatty acid composition of the phospholipid fraction were investigated. Chicken semen displayed ' range of antioxidants including vitamin E, ascorbic acid, glutathione , superoxide dismutase and glutathione peroxidase. Ascorbic acid was almost equally distributed between seminal plasma and spermatozoa. In contrast, reduced glutathione and vitamin E were located mainly in the spermatozoa. The main form of glutathione peroxidase (GSH-Px) was Se-dependent GSH-Px, which was found in both the seminal plasma and the spermatozoa. On the other hand, superoxide dismutase (SOD) was mainly located (67%) in the spermatozoa. Cu,Zn-SOD was found only in seminal plasma but both forms of the enzyme (Cu,Zn-SOD and Mn-SOD) were found in spermatozoa. The toxic effect of H 2O 2 and cumene hydroperoxide on sperm motility was determined. Sperm incubation for 12 hours at 20\ub0C was associated with a significant decrease in the proportion of 22:4n-6 in the phospholipid fraction. The inclusion of Fe 2+ in the incubation medium at 37\ub0C further increased the rate of lipid peroxidation as indicated by the significant decrease in the proportion of 20:4n-6, 22:4n-6, 22:5n-3 and 22:6n-3 in the phospholipid. Free radical-trapping activity of seminal plasma was measured. Possible mechanisms involved in sperm antioxidant protection are discussed

    Fatty acid composition, glutathione peroxidase and superoxide dismutase activity and total antioxidant activity of avian semen

    No full text
    This work demonstrates that spermatozoa from five avian species (chicken, turkey, guinea fowl, duck and goose) are all characterised by high proportions of polyunsaturated fatty acids, from 46 (turkey) to 55% (duck) of total. For each of the species, the most abundant fatty acids were arachidonic (20:4n-6) and docosatetraenoic (22:4n-6) acids, representing between 22 (turkey) and 40% (chicken) of total. Significant activities of the major isozymes of superoxide dismutase and glutathione peroxidase, which protect against the peroxidation associated with high degree of fatty acid unsaturation, were found in spermatozoa from all species. The seminal plasma also had these activities and showed additional mechanisms for protecting spermatozoa from peroxidation. In general terms, these lipid and enzyme proteins were similar between the five avian species and different from those reported for mammalian sperm. Copyright (C) 1998 Elsevier Science Inc
    corecore