عنوان مقاله [English]
Investigating the genetic gain resulted from use of sexed sorted semen in embryo transfer program in dairy cattle
Background and objectives
In dairy cattle industry, there is a great interest in pre-selecting the sex of offspring. Use of sex-sorted sperm is instrumental method for production of female offspring. This reproductive technique could lead to more genetic progress and more economic profitability. On the other hand, the use of sex-sorted sperm in multiple ovulation and embryo transfer (MOET) programs is regarded because of its potential for producing more female progeny from superior dams. The aim of this study was to investigate the effect of using sexed semen in MOET program on the genetic gain in Holstein dairy cattle.
Materials and methods
True breeding values (TBVs) and estimated breeding values (EBVs) of a herd with 30,000 heifers, 24,900 cows in parity 1 and 19,671 cows in parity 2 were simulated in Visual Basic 6. The traditional evaluation (TE) and genomic evaluation (GE) methods were considered for genetic evaluation. Four strategies were assumed. In the first strategy, 750 heifers were considered as donors and sexed semen was used for inseminating these donors. In the second strategy, 750 superior heifers, 622 superior cows in parity 1 and 492 superior cows in parity 2 were donors and conventional semen was used for inseminating these donors. In the third strategy the number of donors was the same as those described for strategy 2 but in this strategy conventional semen was used for inseminating all donors. In strategy 4, sexed semen was considered for insemination of heifer donors and conventional semen was used for other donors.
The genetic gain of strategy 4 was more than other strategies. For example, using traditional evaluation, genetic gain of strategies 1 to 4 was 51/7, 75/6, 102/4 and 110/5 Kg, respectively. Using sexed semen for insemination of heifer donors had positive effect on genetic gain, but when cows in parity 1 and 2 were donors, using conventional semen had more potential to increase the genetic gain. Our results also showed that the improved genetic gain resulted from reproductive techniques, is lower than the genetic gain of sire selection in dairy herds.
In conclusion, use of sexed sorted semen in combination with MOET for heifer donors improved the genetic gain in the herd but when cows in parity 1 and 2 were donors, using sexed semen was not profitable.
Conventional semen, Female offspring, Sexed sorted semen, Embryo transfer and Genetic gain.