Differential proportion of ancestral MHC haplotypes in Brangus breed

GOSZCZYNSKI DE; CORBI-BOTTO CM; MORALES DURAND H; POSIK DM; VILLEGAS CASTAGNASSO EE; MUNILLA LEGUIZAMÓN S; PERAL GARCIA P; ROGBERG MUÑOZ A; CANTET RJC; GIOVAMBATTISTA G

Salt Lake City

Conferencia; 35th International Society for Animal Genetics Conference; 2016

International Society for Animal Genetics

Brangus breed was developed to use the superior characteristics of both founder breeds. The breed maintains the high adaptability to tropical and sub-tropicalenvironments, disease resistance and rusticity from Zebu cattle, and the high reproductive capability, production and meat quality traits from Angus. It has been studied that the major histocompatibility complex (MHC), located on BTA23, encodes genes implicated in the adaptive immune response, and may beresponsible for the adaptation to those environments. The objectives of this work were to study the MHC ancestral haplotypes in a Brangussample to detect thebreed of origin (Angus or Brahman) of each genotype, and then determine if there is a divergence from the overall genomic proportion. For this, a total of 169animals (99 Brangus, 48 Angus and 22 Brahman) were genotyped using Affymetrix BOS1 (640K) Chip. Structure software v2.3.4 was used to estimate thewhole genome fraction of each founding breed that emained in the sampled Brangus animals, with a subset of 5K SNPs evenly spaced over the 29 autosomes.The SNPs included in the MHC BTA23 region (5585 SNPs within 7013,913?28,998,760 bp) were primarily phased with ShapeIT2 algorithm, for further haplotypeorigin assessment with LAMP-LD package. Two other regions demonstrated for coat color (MC1R gene on BTA18: 1682,065?2,046,164bp) and polled trait (BTA1: 14,038,121?14,991,286bp) were selected for Proof of Concept, as those traits were selected in Brangus for the Angus phenotype (solid coat color and polled). The result obtained for the whole genome composition of Brangus was 34.7% Brahman, ranging from 22.3% to 81.1%, while for the MHC region, thehaplotypes appear to have originated from Brahman in 55.3% of the chromosomes. As expected, the Proof of Control regions showed that the Angus haplotypeswere nearly fixed, which supports the hypothesis that the divergence of the haplotypes of the MHC region may have originated in a selection process to promote adaptation to tropical and sub-tropical environments.