Akademik Veri Yönetim Sistemi
4th International Eurasian Conference on Science, Engineering and Technology (EurasianSciEnTech 2022), Ankara, Türkiye, 14 - 16 Aralık 2022, cilt.4, ss.81
Traditional selection for economically important traits in farm animals has been performed based on phenotypic records for
many years. Significant progress has been made in animal breeding in the following years, and effective statistical approaches
have been adopted in calculating the estimated breeding value in dairy cattle. With the development of methodologies such
as daughter-dam comparisons and best linear unbiased prediction (BLUP), the accuracy was increased by including records
of different traits or multiple records of the same animal on different days/periods. However, the desired genetic progress was
not achieved until the effective incorporation of molecular genetic techniques into assessments. Advances in marker-assisted
selection (MAS) and quantitative trait loci (QTL) studies have enabled the transfer of DNA-level information to selection
programs. However, the traits of interest in livestock production were much more complex than expected. Polygenic and
pleiotropic dynamics have been one of the major limitations encountered in establishing a highly successful selection program
using individual gene effects. Hence, the genotypic interactions between marker loci should be more carefully investigated as
such combined effects may account for differences in genotype responses across populations. On the other hand, intensive
selection focused on milk yield has led to serious decreases in fertility and health characteristics in dairy cattle. Implementing
genomic selection in dairy cattle has resulted in an increased genetic gain. The genome-wide association studies (GWAS)
have led to the development of new perspectives in dairy farming, as well as achieving a more desirable level of longevity by
including fertility/health characteristics in the selection indexes. This study aims to make a retrospective evaluation of dairy
cattle breeding, from traditional phenotypic selection to current genome-supported applications, and to assess the cumulative
data obtained from current genetic studies on milk production characteristics and fertility. Moreover, future directions for
genomic selection will be discussed.