Polledness in Argentinean Creole cattle, five centuries surviving

Area of Science:

• Genetics and Animal Breeding
• Livestock Genomics
• Bovine Genetics

Background:

• Polledness is an autosomal dominant trait mapped to BTA1, contrasting with the horned phenotype common in Argentinean Creole cattle.
• Historical records indicate the presence of polled native animals predating modern European breed introductions.
• Understanding the origin of polled mutations is crucial for livestock genetic management and breed characterization.

Purpose of the Study:

• To investigate the origin of the polled mutation in a specific Creole cattle line from northwest Argentina.
• To determine if the polled trait is due to an independent mutation or introgression from other breeds.
• To identify the genetic region and specific alleles responsible for polledness in this population.

Main Methods:

• Genotyping of 65 Creole cattle (39 polled, 26 horned) using high-density SNP microarrays.
• Analysis of three previously reported genetic markers (P202ID, P80kbID, PG).
• Application of genome-wide association study (GWAS), selection signature analysis, linkage disequilibrium (LD) analysis, and copy number variation (CNV) analysis.

Main Results:

• The polled locus in the Leales herd mapped to the 1.23-2.13 Mb interval on BTA1, overlapping with regions found in European breeds.
• Previously identified variants PF and PG were absent, ruling out Holstein-Friesian and Nellore origins for the polled phenotype.
• The Celtic variant PC was detected with near-complete co-segregation, and cluster analysis rejected recent introgression.

Conclusions:

• The polled phenotype in this Argentinean Creole cattle line is likely due to the segregation of an ancient Celtic variant.
• The genetic data suggests the polled mutation is not a result of recent introgression from common European or Nellore breeds.
• Findings support the historical presence of polled Creole cattle and provide insights into the genetic diversity of native South American breeds.