Research Information System
ULUSLARARASI AKADEMİK VE BİLİMSEL ÇALIŞMALAR VE ARAŞTIRMALAR Kongresi, Ankara, Turkey, 21 - 23 February 2022, pp.18-20
Fertility is one of the most important criteria that determines the sustainability of animal
production. A successful pregnancy and the resulting milk and the exact number of pregnancies
in a cow's lifetime are essential to maintaining the profitability of a modern dairy industry. After
the phenotypic view has been used for a long time in selection of bulls, selection of
characteristics related to reproductive performance has been difficult due to low heritability.
On the one hand, inbreeding reduces reproductive efficiency, on the other hand, increasing
lineage relatedness has led to the spread of genetic problems. Studies of some of the most
qualified bulls in the history of the dairy industry have shown the presence of fertility-affecting
mutations that are spreading rapidly in the population. In recent years, several of these
mutations have been identified. More studies are needed to determine the relationship between
male fertility and female fertility and to obtain genetic parameters for both sexes. Genome-wide
association analysis is a powerful tool to explain phenotypic effects on the genome. New
recessive genes were discovered in Holsteins through haplotype testing, which had a high gene
frequency in the population but was never homozygous. Holstein haplotype (HH) 1, 3 and 4 are
lethal mutations responsible for early embryonic loss in Holstein cattle worldwide. In this
review, the genetic backround of paternal fertility in Holstein cattle and SNP detection methods
of HH1, HH3, HH4 mutant genes and studies related to these were examined. When studies on
this subject are examined, it has been seen that these genes are directly related to male fertility.
Overall, female lineage studies, and haplotype findings reveal genetic variants and pathways
that affect Holstein bull fertility. However, the necessity of field studies has emerged for safer
data analysis. In this direction, the development of new genomic strategies to improve bull
fertility in Holstein cattle may contribute. In general, with integrative genomic studies, low
fertility rates are not only evaluated with female phenotype and genotype, but also it can be
concluded that it is necessary to consider the bull effect on fertility brought about by mutations
which belong to Peptide activating factor 1 (APAF1), Structural Maintenance of Chromosomes
2 (SMC2) and Glycinamide ribonucleotide transformylase (GART) genes.