پژوهشهای علوم دامی ایران (Jan 2015)
Impact of applying sex sorted semen in heifers on genetic improvement of dam of dams selection pathway
Abstract
The objective of the current study was to examine the extent of variation of genetic improvement in dam of dams genetic pathway after insemination of heifers with sex sorted semen. For this purpose three different sexed semen based strategies were examined including 1: continuous use of sex sorted semen (strategy CS), 2: use of sex sorted semen for the first and the second inseminations and use of conventional semen for the third and later inseminations (strategy S2) and 3: use of sex sorted semen for the first insemination and use of conventional semen for the second and later inseminations (strategy S1). Predicted values of genetic improvement resulted from the referred strategies were compared to its related values in the case of utilizing conventional semen. Changes in the selection proportion and selection intensity and its effect on genetic improvement were achieved in different scenarios under different conception rates. In all scenarios, genetic improvement of CS strategy was greater than its value in other strategies. Genetic improvement varied in additive genetic standard deviation unit from 0.31 to 0.32 in CS strategy, from 0.23 to 0.30 in S2 strategy and from 0.20 to 0.27 in S1 strategy. Furthermore, predicted genetic improvement in sexed semen based strategies was about 5.82 to 39.65 % greater than its related value when continuous utilization of conventional semen was applied. In spite of enhancing genetic improvement in dam of dams pathway after utilizing sex sorted semen in heifers, changes were not considerable compared with the obtained genetic improvement from other genetic pathways; And a greater genetic improvement is expected from other genetic pathways.
