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  • 1
    Electronic Resource
    Electronic Resource
    A review of genetic improvement in growth rate in redclaw crayfish Cherax quadricarinatus (von Martens) (Decapoda: Parastacidae) (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: This paper provides a review and summary of strain comparison and selective breeding work carried out on redclaw crayfish Cherax quadricarinatus (von Martens) at the Queensland Department of Primary Industries, Freshwater Fisheries and Aquaculture Centre, Walkamin. Redclaw crayfish are a highly marketable, environmentally tolerant, freshwater crayfish with a moderately fast, but variable, growth rate. Five strains of the species were assessed morphologically and in terms of age at maturity. A non-replicated production trial was also carried out before two strains, from the Gilbert and Flinders rivers in North Queensland, were chosen to be part of an experimental selective breeding programme for improved growth. Initially, 14 families of each strain were randomly mated and grown out. At this point, a size-related selection took place, with the largest animals from each family forming a selected line, and individuals from around the mean forming a control line. Within-family selection and reciprocal mating between families was performed. Data were collected after each of two generations of growout and analysed by analysis of variance. Significant differences (P 〈 0.05) were measured between strains, sexes and between selected and control lines. Selected individuals grew 9.5% faster than the controls. Recommendations for selective breeding research involving freshwater crayfish are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.2000.00430.x
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in growth, appetite, food conversion efficiency and body composition in mice selected for high post-weaning weight gain on restricted feeding (1980)
    Springer
    Theoretical and applied genetics 57 (1980), S. 49-56 
    Details
    ISSN: 1432-2242
    Keywords: Protein deposition ; Fat deposition ; Appetite ; Food conversion ; ad libitum feeding ; Post-weaning period ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study aimed to test the hypothesis that if animals were fed the same amount over the same time period, selection of the fastest growers would result in a change in the partitioning of metabolisable energy toward more protein and less fat deposition. Two mouse lines (S1 and S2) were selected for high 5 to 9 week weight gain corrected to mean 5 week weight. Appetite variation between mice was eliminated by feeding a fixed amount to each mouse daily. After 6 generations of selection, the lines were compared with an unselected control (C) on restricted and ad libitum levels of feeding for growth rate, appetite, food conversion efficiency and chemical body composition. Realised heritabilities of 5 to 9 week gain were 0.36+ 0.05 and 0.19±0.04 for S1 and S2 respectively. Nine week weights were increased by an average of 13% on both feeding levels. Most of this increase, particularly in S2, occurred before 5 weeks and was therefore outside the period of measurement used in selection. On ad libitum feeding, selection increased food intake per unit time by 6% but there was no increase per unit body weight. Food conversion efficiency (gain/food) increased by 12%. Compared with controls at 9 weeks, 3% more of the body weights of selected mice was fat and 1% less was protein. These differences were reduced but were still in the same direction when comparisons were made at the same body weight. Thus the expected change in energy partitioning toward greater protein and less fat deposition in the S lines did not occur. It was concluded that the increased growth and energy retention in the S lines was brought about by a reduction in maintenance requirement. To achieve the desired change in energy partitioning using a similar selection scheme, higher levels of dietary protein should be fed, and some measure of protein deposition rather than growth rate used as the selection criterion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276400
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  • 3
    Electronic Resource
    Electronic Resource
    Growth and body composition changes in mice selected for high post-weaning weight gain on two levels of feeding (1987)
    Springer
    Theoretical and applied genetics 73 (1987), S. 926-931 
    Details
    ISSN: 1432-2242
    Keywords: Selection ; Feeding levels ; Growth ; Body composition ; Mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two lines of mice were selected for high post-weaning weight gain (3 to 6 weeks) adjusted for 3 week weight. One line (F) was grown on freely available food and the other (S) on a feeding scale set at the same level for all mice. Food intake of the S line averaged 80% of the F line. The realised heritabilities after 6 generations of selection were 0.38±0.06 and 0.33±0.07 for the F and S lines, respectively. In generation 7, mice from the F and S lines and from an unselected control line (C) were compared on both free and set levels of feeding from 3 weeks to 9 weeks of age. Measurements taken were growth rate, appetite, food conversion efficiency (weight gain/food intake) and body composition (fat, protein, ash, water). The F and S lines grew more rapidly and efficiently than the C line on both levels of feeding, each line performing best on the level of feeding on which it was selected. The average genetic correlation between growth rates of the same line on the two feeding levels was 0.54±0.10. The F line grew 19% faster and was 9% more efficient than the S line on free feeding but the S line grew 15% faster and was 15% more efficient than the F line on set feeding. Relative to the C line, food intake per day on free feeding was 4% higher in the F line and 6% lower in the S line. There was no difference between the lines in food intake/g body weight. The rate of deposition of all body components increased in both selection lines. In the F, S and C lines respectively, efficiencies of gains in body components (102x gain/food) were 1.79, 1.31 and 1.06 for fat, 1.53, 1.63 and 1.22 for protein and 5.88, 6.45 and 4.98 for protein + water. Apparently energy lost as heat was reduced in both the F and S lines. The partitioning of energy retained was altered in favour of more fat in the F line and more protein in the S line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00289400
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  • 4
    Electronic Resource
    Electronic Resource
    Changes in the body composition of mice selected for high and low eight week weight (1976)
    Springer
    Theoretical and applied genetics 47 (1976), S. 21-26 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Body composition was studied in three lines of mice, one selected for high (H) and one for low (L) 8 week weight, and one maintained as an unselected control (C). After 25 generations 8 week weights were 41.2g, 30.6 g and 20.5g for the H, C and L lines. Mice were sampled from the lines and analysed for fat, protein, ash and water at generations 14 and 25. Apart from fat in the H line, there was little alteration due to selection in the relationships between individual body components and total body weight. In the H line, the contribution of fat to body weight gain was considerably increased. Although leaner than the C and L mice at low body weights, H line mice rapidly became fatter with increasing body weight. Selection appeared to reduce the body weight at which fat was deposited at its maximum rate in the H line. The H and C lines were equally fat at body weights of 29.0 g and 21.6 g at generations 14 and 25 respectively. Body weights at points of inflection of the growth curves of the H, C and L lines at generation 25 were 18.3 g, 14.3 g and 12.8 g. The implications of these findings for meat species slaughtered at set weights are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00277400
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  • 5
    Electronic Resource
    Electronic Resource
    Changes in growth, appetite, food conversion efficiency and body composition in mice selected for high post-weaning weight gain on restricted feeding (1980)
    Springer
    Theoretical and applied genetics 57 (1980), S. 49-56 
    Details
    ISSN: 1432-2242
    Keywords: Protein deposition ; Fat deposition ; Appetite ; Food conversion ; ad libitum feeding ; Post-weaning period ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study aimed to test the hypothesis that if animals were fed the same amount over the same time period, selection of the fastest growers would result in a change in the partitioning of metabolisable energy toward more protein and less fat deposition. Two mouse lines (S1 and S2) were selected for high 5 to 9 week weight gain corrected to mean 5 week weight. Appetite variation between mice was eliminated by feeding a fixed amount to each mouse daily. After 6 generations of selection, the lines were compared with an unselected control (C) on restricted and ad libitum levels of feeding for growth rate, appetite, food conversion efficiency and chemical body composition. Realised heritabilities of 5 to 9 week gain were 0.36+ 0.05 and 0.19±0.04 for S1 and S2 respectively. Nine week weights were increased by an average of 13% on both feeding levels. Most of this increase, particularly in S2, occurred before 5 weeks and was therefore outside the period of measurement used in selection. On ad libitum feeding, selection increased food intake per unit time by 6% but there was no increase per unit body weight. Food conversion efficiency (gain/food) increased by 12%. Compared with controls at 9 weeks, 3% more of the body weights of selected mice was fat and 1% less was protein. These differences were reduced but were still in the same direction when comparisons were made at the same body weight. Thus the expected change in energy partitioning toward greater protein and less fat deposition in the S lines did not occur. It was concluded that the increased growth and energy retention in the S lines was brought about by a reduction in maintenance requirement. To achieve the desired change in energy partitioning using a similar selection scheme, higher levels of dietary protein should be fed, and some measure of protein deposition rather than growth rate used as the selection criterion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00745028
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    The contributions of the second and third chromosomes to selection response in Drosophila melanogaster (1971)
    Springer
    Theoretical and applied genetics 41 (1971), S. 25-30 
    Details
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new approach was made to comparing the contributions to response of chromosomes 2 and 3 of Drosophila in lines selected for high and low sternopleural bristle number. Separate response curves for chromosomes 2 and 3 were obtained from changes in the effect of standard second and third chromosomes marked Cy and Mé which were kept segregating with their wild-type homologues during selection. Dominance interaction between marker and wild chromosomes caused some bias in estimating responses in each direction, but the amount by which the responses diverged in the two directions of selection was relatively free from bias. On a log. scale divergences of chromosomes 2 and 3 were in the ratio 1∶1.7 and their heritabilities realised early in selection were 0.14 and 0.26 respectively. There was interaction between the Cy and the Mé chromosomes which was not altered by the selection. Almost all the responses in the lines could be accounted for by addition of the responses in single chromosomes 2 and 3, chromosomes 1 and 4 making a negligible contribution. Sampling, as a cause of variation between selection lines, was reflected in the variation between them in response in chromosomes 2 and 3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00279295
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