Genomic study for pregnancy loss in Brahman cattle

Area of Science:

• Animal Genetics
• Reproductive Biology
• Genomics

Background:

• Reproductive efficiency significantly impacts beef cattle productivity and profitability.
• Pregnancy loss (PL) is a major economic concern in cattle operations, affecting herd efficiency.
• Understanding the genetic basis of PL is essential for developing effective breeding strategies.

Purpose of the Study:

• To estimate variance components for PL in Brahman cattle.
• To identify genomic regions and candidate genes associated with PL.
• To explore genetic factors influencing reproductive success in beef cattle.

Main Methods:

• Utilized 29,905 phenotypic records (pregnancies and abortions).
• Genotyped 921 animals using a medium-density SNP chip (52K markers).
• Applied a single-step genomic BLUP with a threshold model for variance component estimation and GWAS.

Main Results:

• Estimated low heritability for PL (0.11), indicating genetic variance is present.
• Identified 17 candidate regions on various chromosomes (BTA4, 7-9, 11, 12, 16, 18, 19, 21, 22, 29) containing 92 genes.
• Discovered genes linked to embryonic development, implantation, fertilization, and signaling pathways, with human and rodent orthologs.

Conclusions:

• Genetic selection for improved reproductive performance in Brahman cattle is feasible.
• Candidate regions and genes provide targets for marker-assisted selection to reduce PL.
• Findings enhance understanding of genetic and physiological mechanisms of pregnancy retention in cattle.