Differential Proportion of Ancestral MHC Haplotypes in Brangus Breed

GOSZCZYNSKI D; CORBI BOTTO, C; MORALES, H; POSIK, D; VILLEGAS-CASTAGNASSO E.; MUNILLA, S; ROGBERG-MUÑOZ, A; CANTET, R; DIAZ, S; KALEMKERIAM, P; PENA, N; MANGARANE, M; VILLEGAS CASTAGNASSO, E; KIENAST, M; GIOVAMBATTISTA, G; PERAL GARCÍA, P

Utah

Congreso; 35th Conference of the International Society for Animal Genetics.; 2016

International Society for Animal Genetics

Brangus breed was developed to use the superior characteristicsof both founder breeds. The breed maintainsthe high adaptability to tropical and sub-tropicalenvironments, disease resistance and rusticity fromZebu cattle, and the high reproductive capability,production and meat quality traits from Angus. It hasbeen studied that the major histocompatibility complex(MHC), located on BTA23, encodes genes implicatedin the adaptive immune response, and may beresponsible for the adaptation to those environments.The objectives of this work were to study the MHCancestral haplotypes in a Brangussample to detect thebreed of origin (Angus or Brahman) of each genotype,and then determine if there is a divergence from theoverall 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 thatremained in the sampled Brangus animals, with a subsetof 5K SNPs evenly spaced over the 29 autosomes.The SNPs included in the MHC BTA23 region (5585SNPs within 7013,913?28,998,760 bp) were primarilyphased with ShapeIT2 algorithm, for further haplotypeorigin assessment with LAMP-LD package.Two other regions demonstrated for coat color (MC1Rgene on BTA18: 1682,065?2,046,164bp) and polledtrait (BTA1: 14,038,121?14,991,286bp) were selectedfor Proof of Concept, as those traits were selected inBrangus for the Angus phenotype (solid coat colorand polled). The result obtained for the whole genomecomposition of Brangus was 34.7% Brahman, rangingfrom 22.3% to 81.1%, while for the MHC region, thehaplotypes appear to have originated from Brahmanin 55.3% of the chromosomes. As expected, the Proofof Control regions showed that the Angus haplotypeswere nearly fixed, which supports the hypothesis thatthe divergence of the haplotypes of the MHC regionmay have originated in a selection process to promoteadaptation to tropical and sub-tropical environments.