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  • 1
    Electronic Resource
    Electronic Resource
    DEVELOPMENTAL ASPECTS AND FACTORS INFLUENCING THE SYNTHESIS AND STATUS OF ASCORBIC ACID IN THE PIG (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Nutrition 24 (2004), S. 79-103 
    Details
    ISSN: 0199-9885
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Ascorbic acid synthesis in the pig occurs at mid-pregnancy, but activity of the enzyme l-gulono-gamma-lactone oxidase (GLO) declines thereafter during gestation and remains low when the pig nurses the sow. During late gestation the ascorbic acid concentration in the fetus increases, but serum and liver ascorbic acid concentration in the sow declines without affecting the dam's liver GLO activity. It is presumed that as gestation progresses an increased amount of maternal ascorbic acid is transferred to the fetus and to the mammary gland. Colostrum and milk are rich sources of the vitamin and supply the nursing pig with ascorbic acid. The available data suggest that high amounts of ascorbic acid appear to suppress liver GLO activity in the pig. Upon weaning, when exogenous vitamin C is generally not provided, liver GLO activity and serum ascorbic acid increases. During the initial periods postweaning, some reports have indicated growth benefits of supplemental vitamin C. Body tissues differ in their concentrations of ascorbic acid, but tissues of high metabolic need generally have greater concentrations. The corpus luteum in the female, the testis in the male, and the adrenal glands in all pigs contain greater concentrations of the vitamin. Knockout genes preventing ascorbic acid synthesis in pigs have demonstrated poor skeletal and collagen formation and poor antioxidant protection. Under periods of stress ascorbic acid declines in the adrenal, but the pig rapidly recovers to its resting state once the stressor agent is removed. Although there are periods when supplemental vitamin C has been shown to promote pig performance (e.g., during high environmental stress and early postweaning), supplemental vitamin C has not been shown to routinely enhance pig performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.nutr.24.012003.132150
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  • 2
    Electronic Resource
    Electronic Resource
    Feeding stimulants in semipurified diets for juvenile lake sturgeon, Acipenser fulvescens Rafinesque (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 27 (1996), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1996.t01-1-00817.x
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of rainbow trout milt collected with a catheter: semen parameters and cryopreservation success (2000)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 31 (2000), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Collection of fish milt by stripping risks the danger of milt contamination by urine. This may seriously influence milt characteristics and quality, including usefulness for cryopreservation. Urine contamination of milt may be avoided by using a catheter for sperm collection. The objectives of this study were to provide basic characteristics of milt collected with a catheter, to test the usefulness of this milt for cryopreservation, and to correlate characteristics of fresh and cryopreserved semen with sperm fertility rates. Milt from 25 rainbow trout Oncorhynchus mykiss (Walbaum) males were used. All samples were cryopreserved using the pellet method within 1 h of collection, using 0.6 m sucrose and 10% dimethyl sulphoxide (DMSO) as an extender. Catheterization resulted in semen of very good motility (〉 90% motile spermatozoa) and high fertilization rates after cryopreservation (mean fertilization rate 81.8 ± 13.3% of control, at a sperm/egg ratio of 2.4 ± 0.3 × 106). Osmolality of seminal plasma and concentrations of sodium, potassium and magnesium ions had low variability, which suggests that they are important for creating a stable environment for sperm storage in the sperm duct. Higher variability of certain seminal plasma characteristics, such as protein concentration and antiproteinase activity, suggests that these characteristics are related to individual semen features of particular males. A strong correlation of seminal plasma zinc concentration with protein concentration may reflect an importance of zinc in semen biology. Cryopreservation caused a significant release of protein and acid phosphatase from spermatozoa. Our results did not reveal any single characteristic of semen collected by catheter that could be used as a powerful predictor of cryopreservation success, presumably because all samples were of high quality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.2000.00400.x
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  • 4
    Electronic Resource
    Electronic Resource
    Nutritional effects of protein source in starter diets for channel catfish (Ictalurus punctatus Rafinesque) in suboptimal water temperature (2000)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 31 (2000), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Intensive tank rearing of channel catfish (Ictalurus punctatus Rafinesque) fry can be successfully accomplished with commonly available ‘salmonid’ starter diets. Ingredient substitution in starter diets is less important from the cost perspective but growth, survival and health of fish are major concerns. Several combinations of fish meals and animal protein substitutes were evaluated in diet formulations for hatchery rearing of catfish fry. Sub-optimal thermal conditions were used which are characteristic for the north-central USA where catfish culture is important for stocking purposes and live-fish markets. A diet formulated on the basis of menhaden fish meal (29.1%), herring fish meal (25.1%) and animal by-product mixture (16.38%) gave numerically the highest growth rate after 13 weeks of feeding, although growth reductions in fish fed diets exclusively with mehaden meal (77.6%) as protein or substituted with 50% animal by-product protein were not significant. Instantaneous mortality rates were the highest between weeks 2 and 4 of rearing and increased almost proportionally with the increased fish meal protein substitution. A diet based on menhaden fish meal had the highest concentration of phosphorus and several other essential minerals, but these were not reflected in the mineral composition of the fish body at the termination of feeding. Among activities of digestive enzymes, trypsin was depressed in fish offered diets with 75–100% fish meal protein replacement. A diet superior in terms of fish performance was defined in the present study and it was concluded that the initial feeding can greatly affect physiological status of juvenile channel catfish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.2000.00494.x
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  • 5
    Electronic Resource
    Electronic Resource
    The dynamics of gonad growth and ascorbate status in yellow perch, Perca flavescens (Mitchill) (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 27 (1996), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Yellow perch, Perca flavescens (Mitchill), caught in the wild (Grand St Marys Lake, Ohio) and cultured in the laboratory were used to examine the relationship between gonad development and the concentration of ascorbic acid in ovaries, testes, liver and kidney. In wild fish the ovary had concentrations of ascorbate twice as high (75-102 μg g-1) as the testis (28-48 μg g-1), and when the differences in gonadosomatic indices between sexes were accounted for, females deposited 10-fold more of this essential nutrient in gonads than did males. Yellow perch cultured intensively throughout the gonadal recrudescence had shown a decrease of ascorbate concentration in the kidney, liver and ovary during winter, most likely due to the low dietary level of the vitamin. Diet enrichment with ascorbic acid resulted in a dramatic increase of ascorbate in ovary and other tissues. Incorporation of ascorbic acid may take place during the late vitellogenesis, and this vitamin deserves to be studied as a quality indicator in fish eggs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2109.1996.tb01284.x
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  • 6
    Electronic Resource
    Electronic Resource
    Mass-marking of coregonid larvae and fry by tetracycline tagging of otoliths (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 19 (1988), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Larvae and juveniles of two species of Coregouns sp. were immersed in tetracycline (TC) solutions (200–800)mg/1) and fluorescent marks in the otoliths from fish were identified under a UV-light microscope. Whitefish. Coregonus Iavaretus (L.). juveniles (average weight 191 mg) immersed in TC solution retained their marking until the 127th day, hut 40% of the population lost their TC marking after wintering. Whitefish and peled. C. peled Gmelin, larvae retained TC marking from the TC solution (400 mg/1) if water temperature was higher than 5°C, Whitefish juveniles retained clear marking in the otolith after 120 days of post-immersion rearing. Peled larvae immersed in TC solution were grown in a pond and the fluorescent otolith centre of 55·4-g fish was well visible after processing. Nearly 100% of peled larvae grown for 176 days can he identified based on fluoresceent marks observed under a UV-lighl microscope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2109.1988.tb00420.x
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  • 7
    Electronic Resource
    Electronic Resource
    Ascorbic acid and reproduction in fish: endocrine regulation and gamete quality (2001)
    Oxford, UK : Blackwell Science Ltd
    Aquaculture research 32 (2001), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: High ascorbic acid concentrations have been associated with gonad and brain tissues in teleost fishes. Although a direct dietary effect on gamete quality has been given some attention recently, the mechanism of action of ascorbate along the cascade of reproductive events in the hypothalamus, pituitary and gonads has not been defined. Data relating to gamete production and quality, as well as a possible protective role for ascorbate against cumulative genetic defects during gametogenesis and congenital malformation during gestation (embryonic development) is reviewed. It is suggested that the gonad growth in response to gonadotropin stimulation involves direct interaction between catecholamines and steroid hormones and their receptor sites. This interaction acts as a regulatory mechanism of ascorbate absorption, transfer and metabolism (degradation and/or renewal) in the reproductive system. We conclude that ascorbic acid is a leading nutrient in reproductive tissue functions and further research is needed on: (1) its antioxidant effect on gametes' (sperm and ova) capacity to prevent DNA damage occurring prior to (endogenous) and after spawning (environmental insults); (2) its dietary requirement to optimize survival and physiological recovery in multiple spawners; (3) the integration mechanism of ascorbic acid action as part of the overall endocrine regulation of neurohormonal–hormonal pathway in fish reproduction; and (4) the possible role for ascorbate in regulating fish maturation and/or infertility in the presence of enhanced UV-radiation or conditions of intensive aquaculture (hypoxia, oxygen supersaturation, dietary pro–, and antioxidants).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.2001.00598.x
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  • 8
    Electronic Resource
    Electronic Resource
    Ascorbate concentration in fish ontogeny (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 40 (1992), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The ontogenetic trend of ascorbate has been quantified in three freshwater fishes: roach (Rutilus rutilus), whitefish (Coregonus lavaretus) and Arctic charr (Salvelinus alpinus). Total ascorbate (reduced and oxidized) declined from 150 to μg g−1 as newly hatched larvae grew to become several-months-old juveniles. Declining total ascorbate with increasing size of metamorphosing fish could not be reversed by feeding on brine shrimp, Artemia salina nauplii, zooplanktonic food containing 〉 74μg g−1 total ascorbate. The proportion of reduced ascorbate in total ascorbate increases with fish size/age. The physiological mechanism of the changes in transferable ascorbate forms remains unknown, but high dehydroascorbate concentrations suggest high vulnerability of larval fish to oxidation stress. This is the first report on quantity of vitamin C retained in actively-feeding larval and juvenile fish. The efficiency of ascorbate transfer from zooplankters to larval fish amounted to 5–20%. The ecological significance of larval fish feeding on various zooplankters and/or phytoplankton may reflect a trend toward maximum transfer of this vitamin in freshwater food webs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1992.tb02572.x
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  • 9
    Electronic Resource
    Electronic Resource
    Tetracycline tagging in coregonid embryos and larvae (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 29 (1986), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Coregonus peled (Gmelin) embryos at the eyed stage were immersed in tetracycline hydrochloride (TC) solution (600 mg l−1) and fluorescent marks on the otoliths from fish were identified under a UV light microscope. Three weeks after treatment, when the larval fish had hatched, multiple primordia of the sagitta had fluorescent bands whose locations suggest that calcification begins before formation of the otolith's core. Upon hatching, increments were few or absent, and daily increments started forming after hatching. In coregonid larvae immersed in TC solution immediately after hatching, the fluorescent band was only 1 day's growth increment wide in the otolith. The age of larvae based on ring counts after marking corresponded to the actual age, but further studies are required. Triple marks due to 35-h immersions in TC solution separated by 5–7 day feeding periods were clearly readable in the otoliths. One month after treatment the fluorescent marks were identified under UV light on otoliths from every fish. In treated embryos, 38% of fish had marks 3 months after TC immersion, whereas in treated larvae 60–80% of fish grown up to 38.7 mm were marked.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1986.tb04985.x
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  • 10
    Electronic Resource
    Electronic Resource
    The influence of light environment on depth of visual feeding by larvae and fry of Coregonus pollan (Thompson) in Lough Neagh (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 25 (1984), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The depth limits for visual feeding by pollan larvae and fry, Coregonus pollan, were determined in Lough Neagh, Northern Ireland, by combining laboratory estimates of the minimum light threshold for feeding activity with field measurements of spectral, diurnal and seasonal changes in light penetration. Although feeding thresholds were lowest in the blue light (400–490 nm), the rapid attenuation of this region in the lake meant that the depth limits of feeding in situ were determined by response to the green region (490–595 nm). Effects of changes in irradiance and light penetration on the depth of feeding are considered during a seasonal study. Increased sensitivity, as the juvenile stages develop, may be offset by reduced light penetration due to algal growth. Over an annual period the maximum feeding depth for pollan varied between 2.6 and 4.1 m. In the juvenile stages of two other predatory species from the lake, perch, Perca fluviatilis, and pike, Esox lucius, the corresponding ranges were 1.1–1.9 m and 2.7–4.6 m respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1984.tb04864.x
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