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1

The effect of selection for traits of low heritability conducted in noninbred populations on the basis of progeny or performance tests

100%
Sobczynska M., Kownacki M.
Journal of Applied Genetics
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1995
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vol. 36
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issue 2
169-175
EN
The ivestigations were carried out to compare selection conducted on the basis of progeny with that on the basis of animals' own performance.Selection was conducted for the body weight at weaning (at the age of 21 days), which is a trait of low heritability.It was run throghout 15 generations,whereas in generation 13 and 14 three experimental replices were crossed to obtain population free of inbreeding.A cumulated response to selection was higher in the group selected on the basis of animals'own performance, but after crossing the replicas it decreased clearly in the both groups.The cumulated selection differential was higher in the group selected on the basis of animals'own performance.However, a statistical analysis of the obtained results showed no significant difference between the two selection method.
2

Genetic aspects of racing performance in Polish pure bred Arab horses. II.Genetic trends

100%
Sobczynska M., Kownacki M.
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vol. 38
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issue 3
303-308
EN
The objective of this study was to estimate genetic trends in the Polish Arab horses population. Annual earnings and rank at finish in flat races of Polish Arab horses from 1951 to 1993 were analysed with a BLUP animal model. The collected data included 2,234 records of 1,640 4 and 5 year old horses from 143 sires. Only races, in which horses of at least two mentioned age groups took part, were taken into consideration. The model included an individual additive genetic effect as random, the year of race, herd, sex, age, number of starts and the year of race ? age effects as fixed effects. Genetic trends were estimated from differences between horses belonging to different age groups and racing in the same year. The annual genetic gains from 1951 to 1993 were 3.5% and 12.3% of the genetic standard deviation for the log of earnings and rank at finish, respectively. Although the main role in breeding Arab horses is played by beauty and exterior, small genetic progress in the log of earnings and rank at finish was obtained.
3

A correlated response to selection of mice based on progeny or performance test

100%
Sobczynska M., Kownacki M.
|
EN
A comparison was made of a correlated response to selection between populations of mice selected for body weight at weaning on the basis of their own performance or their progeny.Selection was conducted throughout 15 generations andduring the last two generations, three replicas were crossed within each group.A correlated response to selection of the body weight on day 42, weights gains between day 21 and 42 and litter size at birth was significantly higher in the group of mice evaluated on the basis of their progeny.A negative correlated response occured in the litter size at birth in the group evaluated on the basis of animals' own performance.The realized genetic correlations in the group evaluated on the basis of animals' own performance was 0.9, 0.1 and 0.8 respectively, between the body weight on day 21 and 42, body weight on day 21 and weight gains between day 21 and 42, body weight on day 21 and litter size at birth.
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