Application of in vitro production-embryo transfer in the protection and development of lactational potential of superior cows
This study was carried out to investigate if the technology of in vitro embryo production can be used for protection and development of milk productivity potential of the superior cattle via ablation. The ovaries of the superior cattle selected for ablation were collected immediately after slaughter. Bovine immature oocytes were then used for in vitro maturation/fertilization and the presumptive zygote were then cultured for about eight days in Vero-TCM culture medium before being transferred into previously synchronized heifers of low genetic merits. From 21 culled superior cattle, the highest causes of culling were related to reproductive problems (33.3%), lowest milk production was related to systemic diseases (7824), highest average of offspring production expected and number of offspring production were 9.2 and 7.4 in old cows, respectively and the highest average of unproduced offspring were three in reproductive problem cows. The highest average oocytes collection was related to old cows and rate of cleavage was significant in each four groups. Systemic diseases group was significantly lower (34.2%) than the reproductive problems (69.6%) and mastitis (60.6%) groups in 5 to 8 cells stage. Systemic diseases group was significantly lower (36.6) than the reproductive problem (73.9) groups in 8 to 16 cells. Morula rate was 71.8% in the reproductive problems group and the rate of blastocysts old cows was significantly higher (34.2%) than those of the other groups. Two established pregnancies (25%) and one viable offspring (50%) resulted from eight blastocysts transferred. The advances of assisted reproductive technology (ART) can effectively protect and multiply the superior genes of lactation and reproduction within the dairy farms.
Key words: In vitro production, embryo transfer, genetics potential, dairy cattle.