Sequence level genome-wide associations for bull production and fertility traits in tropically adapted bulls

Wei Liang Andre Tan; Laercio Ribeiro Porto Neto; Antonio Reverter; Michael McGowan; Marina Rufino Salinas Fortes

doi:10.1186/s12864-023-09475-2

Sequence level genome-wide associations for bull production and fertility traits in tropically adapted bulls

BMC Genomics. 2023 Jun 29;24(1):365. doi: 10.1186/s12864-023-09475-2.

Authors

Wei Liang Andre Tan¹, Laercio Ribeiro Porto Neto², Antonio Reverter², Michael McGowan³, Marina Rufino Salinas Fortes⁴

Affiliations

¹ School of Chemistry and Molecular Biosciences, The University of Queensland, Chemistry Bld, 68 Cooper Rd, Brisbane City, QLD, 4072, Australia. weiliangandre.tan@uq.net.au.
² CSIRO Agriculture and Food, 306 Carmody Road, St Lucia, QLD, 4067, Australia.
³ School of Veterinary Science, The University of Queensland, Gatton, QLD, 4343, Australia.
⁴ School of Chemistry and Molecular Biosciences, The University of Queensland, Chemistry Bld, 68 Cooper Rd, Brisbane City, QLD, 4072, Australia.

Abstract

Background: The genetics of male fertility is complex and not fully understood. Male subfertility can adversely affect the economics of livestock production. For example, inadvertently mating bulls with poor fertility can result in reduced annual liveweight production and suboptimal husbandry management. Fertility traits, such as scrotal circumference and semen quality are commonly used to select bulls before mating and can be targeted in genomic studies. In this study, we conducted genome-wide association analyses using sequence-level data targeting seven bull production and fertility traits measured in a multi-breed population of 6,422 tropically adapted bulls. The beef bull production and fertility traits included body weight (Weight), body condition score (CS), scrotal circumference (SC), sheath score (Sheath), percentage of normal spermatozoa (PNS), percentage of spermatozoa with mid-piece abnormalities (MP) and percentage of spermatozoa with proximal droplets (PD).

Results: After quality control, 13,398,171 polymorphisms were tested for their associations with each trait in a mixed-model approach, fitting a multi-breed genomic relationship matrix. A Bonferroni genome-wide significance threshold of 5 × 10^{- 8} was imposed. This effort led to identifying genetic variants and candidate genes underpinning bull fertility and production traits. Genetic variants in Bos taurus autosome (BTA) 5 were associated with SC, Sheath, PNS, PD and MP. Whereas chromosome X was significant for SC, PNS, and PD. The traits we studied are highly polygenic and had significant results across the genome (BTA 1, 2, 4, 6, 7, 8, 11, 12, 14, 16, 18, 19, 23, 28, and 29). We also highlighted potential high-impact variants and candidate genes associated with Scrotal Circumference (SC) and Sheath Score (Sheath), which warrants further investigation in future studies.

Conclusion: The work presented here is a step closer to identifying molecular mechanisms that underpin bull fertility and production. Our work also emphasises the importance of including the X chromosome in genomic analyses. Future research aims to investigate potential causative variants and genes in downstream analyses.

Keywords: Bull fertility; Genome-wide Association study; Quantitative trait loci; Sequence-level.

MeSH terms

Animals
Cattle / genetics
Fertility / genetics
Genome-Wide Association Study*
Genomics
Male
Reproduction
Semen Analysis* / veterinary

Abstract

MeSH terms

Grants and funding