Genome study of Nellore cattle finds shared regions for growth and female fertility traits

Researchers analysed phenotypes of 905,316 Nellore cattle recorded from 1984 to 2020 and mapped genomic regions linked to growth and early fertility, according to a study in BMC Genomics. biomedcentral.comBMC Genomicsbiomedcentral.comOpen source ↗ Whole-genome sequence was imputed for 42,591 of the animals; after quality control the dataset held 2,591,217 variants. The team applied weighted single-step genome-wide association analysis.

The traits were average daily gain (ADG), yearling weight (YW), scrotal circumference (SC), heifer early pregnancy at 16 months (HP) and heifer rebreeding (HR). The authors note that growth and early fertility matter for beef-cattle efficiency and are shaped by endocrine, metabolic and developmental processes.

Shared regions and genetic correlations

Genomic regions explaining more than 1% of the additive genetic variance connected growth traits (ADG and YW) with female reproductive traits (HP and HR). No region was shared with SC.

Genetic correlations followed the same pattern. They were higher within growth traits (ADG–YW, 0.65 ± 0.04) and within female reproductive traits (HP–HR, 0.57 ± 0.04). Between growth and early fertility they were moderate, most notably ADG–HP at 0.39 ± 0.07. Correlations of HR with growth traits or SC were weak. biomedcentral.comBMC Genomicsbiomedcentral.comOpen source ↗

Shared windows were found on chromosomes BTA14 and BTA7. Enrichment analyses pointed to hormone signaling, MAPK-related processes, growth hormone signaling, cholesterol metabolism and placental development.

Candidate genes by trait

Growth traits were mainly associated with endocrine and metabolic regulation, involving IGF1R, GHRH, GHRHR, INSR, LPL, MYBPC1 and MYO5B. Regions linked to SC highlighted genes involved in testicular development and cellular homeostasis: SLC9B1, SLC9B2 and UBE2D3.

For HP, the regions indicated roles of IGF and hormone signaling, ovarian development and metabolic health, with genes such as IGFBP2, IGFBP5, GNRHR, INSR and FIGLA. HR-associated regions suggested contributions from endocrine recovery, developmental competence and early placental support, highlighting LEP, FIGLA, GHRH, SOX13, KCNQ1 and DHCR7. biomedcentral.comBMC Genomicsbiomedcentral.comOpen source ↗

The authors describe the identified genes as candidates for functional validation. They state that the findings may support genomic selection strategies that jointly improve productivity and reproductive efficiency. The work is an association study, so causal roles of the regions and genes remain to be confirmed.