Long-term selection for litter size in swine results in shifts in allelic frequency in regions involved in reproductive processes

2016 ◽  
Vol 47 (5) ◽  
pp. 534-542 ◽  
Author(s):  
M. D. Trenhaile ◽  
J. L. Petersen ◽  
S. D. Kachman ◽  
R. K. Johnson ◽  
D. C. Ciobanu
Keyword(s):  
Litter Size ◽  
Allelic Frequency ◽  
Term Selection ◽  
Selection For ◽  
Reproductive Processes

Reproduction and Body Weight of Mice after Long-Term Selection for Large Litter Size

1978 ◽  
Vol 46 (6) ◽  
pp. 1572-1580 ◽  
Author(s):  
H. Bakker ◽  
J. H. Wallinga ◽  
R. D. Politiek
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Term Selection ◽  
Large Litter ◽  
Selection For

Comparative performance of Omani goats and sheep

1996 ◽  
Vol 127 (1) ◽  
pp. 117-121 ◽  
Author(s):  
F. M. S. Al-Nakib ◽  
E. S. S. Al-Shukaily ◽  
S. S. S. Al-Hanai ◽  
S. A. M. Al-Nabhani
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Performance Test ◽  
Comparative Performance ◽  
Rhodes Grass ◽  
Sheep Industry ◽  
Body Weights ◽  
Selection For ◽  
Performance Trial

SUMMARYAs part of a long-term breeding programme aimed at improving the performance of Omani goats and sheep, a 3-year performance trial was carried out between 1991 and 1993 to evaluate the reproductive and productive performance of three breeds of goat: Batinah (BT), Dhofari (DH) and Jabal Akhdar (JA), and one breed of local Omani sheep. In each year, flushing started on 1 September, mating started on 1 October and terminated on 15 November, and the kidding/lambing season started on average on 1 March. Kids and lambs were weaned at c. 3 months of age, then put on a 3-month performance test, fed on concentrates ad libitum and Rhodes grass hay. Some 3706 dam and 3011 progeny performance records were available over a 3-year period from 1991 to 1993. Ewes were lighter in body weight and lower in litter size weaned but higher in fertility than the does. Although the lambs had lighter birth weights, they were heavier at weaning and at 6 months of age. Among the goats, the DH does had lighter body weight but higher litter size weaned than both the BT and the JA goats. DH kids were somewhat lighter at birth, weaning and 6-month body weights than the other two breeds but had higher survival.The sheep had higher output per ewe exposed (3·28 kg, 33%) and per ewe lambed (3·27 kg, 26%) and were 35% more efficient in production than the goats. Although the DH goats had a lower output per doe exposed than the BT and JA goats (0·9 kg, 9 % and 0·76 kg, 7% respectively) and per doe kidded (1·11 kg, 9% and 1·29 kg, 10%), they had higher efficiency of production than both BT (0·05 units, 6%) and JA (0·11 units, 14%).In view of these results, attention should be paid to the sheep industry through the introduction of promotion schemes. The DH goats would be even more useful if involved in a crossbreeding scheme and the JA goats would benefit from selection for maternal care.

scholarly journals Optimum selection intensities in artificial selection programmes: an experimental evaluation

1977 ◽  
Vol 30 (2) ◽  
pp. 115-119 ◽  
Author(s):  
R. Frankham
Keyword(s):  
Experimental Evaluation ◽  
Selection Intensity ◽  
Effective Population ◽  
Term Selection ◽  
Optimum Selection ◽  
Selection For ◽  
Selection Intensities ◽  
Selection Of ◽  
Better Than

SUMMARYAn experimental evaluation of Robertson's (1970) theory concerning optimum intensities of selection for selection of varying durations has been carried out using published results from a long term selection study in Drosophila. Agreement of predicted rankings of treatments with expectations was excellent for low values of t/T (generations/total number scored) but poor for larger values of t/T. This was due to the 20% selection intensity treatments responding worse than expected and the 40% treatments relatively better than expected. Several possible reasons for the discrepancies exist but the most likely explanation is considered to be the greater reduction in effective population size due to selection in treatments with more intense selection.

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