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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the World Aquaculture Society 35 (2004), S. 0 
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Artificially induced maturation of 10 male eels Anguilla anguilla L. weighing 170 ± 30-3 g was followed for 6 wk with in vivo CT scanning in a repeated manner. Since testis tissue has a well defined X-ray density value, the volumetric development could be described. Parallel with this process, a strong decrease of the abdominal fat volume was measured and depicted with the applied surface smoothing method. As an affect of the hCG treatment (250 IU/week per eel) at the third wk, the testis could clearly be recognized on the images. From that time the average testis volume values of the 10 eels were 4,975, 6345, 11,583 and 14,553 mmJ respectively. At the sixth wk, the relative testis volume in the abdomen was 25%. In the fillet a characteristic shift (from -10 to -20 Hounsfield units) of the density histogram towards the fat interval was detected. The average density value of the fillet was found to be zero; this was supported furthermore by the histological analysis of the fillet (fat to muscle rate 0.35-0.40). On the basis of the above findings, the applied CT scanning method was proven to be suitable to follow in vivo the maturation process of male eels.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The crude fat and protein content of the total body was estimated by X-ray computer tomography (CT) and determined by chemical analyses during a feeding experiment with sexually matured common carp. Between 21 and 35 serial scans were taken of altogether 41 fish and samples from the homogenized body were prepared for chemical analyses. Experimental fish with an average body weight of 1453 g originated from a commercial stock of mirror carp. Two feeding regimes (carp feed and carp feed+ad libitum maize) were applied for 57 days and followed by a fasting period of 27 days. Both feeding regimes significantly increased the crude fat content of the whole body that did not decrease during fasting in spite of high water temperature (22°C). No significant changes were observed in crude protein content. The variables used for producing the prediction equations were taken from the density values of the Hounsfield scale, on a range between −90 and +160, by summing the frequencies within each interval of 10 values. Whole body fat content could be estimated with R2=0.89−0.91 accuracy with the principal component analysis using data of all (seven) body regions and only dorsal fin region respectively. Adequate linear regression model could not be calculated by the same procedure for crude protein. Three-dimensional ‘volumetric’ estimation of fat tissue was also carried out on the basis of fat index showing high correlation with measured fat content. The changes of body composition of individual fish can be followed by sequential CT scanning.
    Type of Medium: Electronic Resource
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