MILK YIELD IN LINES OF MICE SELECTED FOR GROWTH OR MATERNAL ABILITY

1975 ◽  
Vol 17 (2) ◽  
pp. 263-268 ◽  
Author(s):  
J. M. White
Keyword(s):  
Milk Yield ◽  
Body Weight Gain ◽  
Correlated Response ◽  
Response To Selection ◽  
Litter Weight ◽  
Average Production ◽  
Before And After ◽  
Selection For ◽  
And Control ◽  
Gain Line

Two experiments were conducted to measure milk yield as a correlated response to selection for increased 12-day litter weight (maternal lines) for 13 generations and increased and decreased body weight gain from 21 to 42 days of age (postweaning gain lines) for 12 to 14 generations. Milk yield was measured from day 6 to day 21 of lactation by separating litters from their dams for 6 h, then weighing litters before and after a 1.5 h suckling period. Average total milk production was 30.3 ± 0.9 g and 28.6 ± 1.1 g in maternal and control lines, respectively. This difference was not significant (P > 0.05). Differences among gain lines were significant (P < 0.01) in the second experiment with average production of 44.1 ± 1.4 g for increased gain lines, 22.5 ± 0.9 g for the decreased gain line and 31.2 ± 1.0 g for the control. These results indicated that response to selection for increased 12-day litter weight was not associated with increases in milk yield, but sizable changes in milk yield accompanied bi-directional selection for early postweaning gain.

Correlated response to selection for litter size in pigs: II. Carcass, meat, and fat quality traits

2002 ◽  
Vol 80 (10) ◽  
pp. 2566 ◽  
Author(s):  
J. Estany ◽  
D. Villalba ◽  
M. Tor ◽  
D. Cubiló ◽  
J. L. Noguera
Keyword(s):  
Litter Size ◽  
Correlated Response ◽  
Quality Traits ◽  
Response To Selection ◽  
Fat Quality ◽  
Selection For

Group feeding behavior of brown trout is a correlated response to selection for growth shaped by the environment

2007 ◽  
Vol 37 (3) ◽  
pp. 525-534 ◽  
Author(s):  
Thierry Boujard ◽  
Julien Ramezi ◽  
Marc Vandeputte ◽  
Laurent Labbé ◽  
Muriel Mambrini
Keyword(s):  
Feeding Behavior ◽  
Brown Trout ◽  
Correlated Response ◽  
Response To Selection ◽  
Group Feeding ◽  
Selection For

scholarly journals Responses to divergent selection for plasma concentrations of insulin-like growth factor-1 in mice

1989 ◽  
Vol 53 (3) ◽  
pp. 187-192 ◽  
Author(s):  
H. T. Blair ◽  
S. N. McCutcheon ◽  
D. D. S. Mackenzie ◽  
P. D. Gluckman ◽  
J. E. Ormsby ◽  
...  
Keyword(s):  
Growth Factor ◽  
Plasma Concentrations ◽  
Selection Criterion ◽  
Divergent Selection ◽  
Correlated Response ◽  
Insulin Like Growth Factor ◽  
Family Selection ◽  
Selection For ◽  
High Control ◽  
And Control

SummaryA divergent selection experiment with mice, using plasma concentrations of insulin-like growth factor-1 (IGF-1) at 42 days of age as the selection criterion, was undertaken for 7 generations. Lines were not replicated. To obtain sufficient plasma for the IGF-1 assay, blood from four individuals was volumetrically bulked to obtain a litter mean IGF-1 concentration. This necessitated the use of between family selection. Although inbreeding accumulated in a linear fashion in each of the high, control and low lines, the rates were different for each line (3·6, 1·6 and 5·3% per generation for the high, control and low lines, respectively). As a consequence, the effects of selection and inbreeding are confounded in this experiment. Divergence between the high and low lines in plasma concentrations of IGF-1 continued steadily until generation 5. In generations 6 and 7, there was a reduced degree of divergence and this contributed towards the low realized heritability value of 0.15 ± 0.12. Six-week liveweight showed a steady positive correlated response to selection for or against plasma concentrations of IGF-1 until generation 4 (high-low difference = 1·7 g = 12%). In generation 5, a substantial drop in 6-week liveweight in the low line relative to both the high and control lines occurred (high-low difference, 3·9; g, 25%). This difference was maintained until generation 7.This experiment suggests that genetic variation exists at 6 weeks of age in plasma concentrations of IGF-1 in mice. Furthermore, genetic covariation between plasma IGF-1 concentrations and liveweight at 6 weeks of age is likely to be positive. Further experiments have been initiated to examine these theories.

scholarly journals The genetic analysis of the direct and correlated response to selection for chaetae in Drosophila melanogaster

1973 ◽  
Vol 22 (1) ◽  
pp. 1-7
Author(s):  
W. R. Scowcroft
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Genetic Correlation ◽  
Statistical Approach ◽  
Correlated Response ◽  
Minor Importance ◽  
Response To Selection ◽  
Genetic Changes ◽  
Selection For ◽  
Selection Of

SUMMARYThe direct and correlated response to selection of scutellar microchaetae and scutellar bristles has been analysed by determining the contribution of the three major chromosomes, alone and in combination with each other, to the overall response. The results of the analysis confirm a previous finding, based on a formal statistical approach, that response to selection for microchaetae had highly pleiotropic effects on scutellar bristles. In lines selected, each for high and low microchaetae, genetic changes in the 2nd and 3rd chromosomes are pre-eminent and essentially equal. Inter-chromosomal interactions are of relatively minor importance in interpreting the response to selection for microchaetae but assume greater importance with respect to the correlated character. The results are discussed in terms of the genetic correlation between fitness and the character measured.

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