Genome-wide association analysis of body conformation traits in Mexican Holstein cattle using a mix of sampled and imputed SNP genotypes.

In arid and semi-arid zones, animal health and production are closely correlated with body conformation traits. These selected traits, in turn, allow livestock to adapt unfavorable soil and environmental conditions. The primary objective of this study was to perform a genome-wide association analysis for a set of sampled and imputed SNPs with 16 conformation traits in a population of Holstein cows from a desert area of Northwestern Mexico. Imputation from 6K to 50K SNPs was performed as a low-cost optimization strategy. Results show eight SNPs associated with two conformation traits. The Udder Depth trait resulted in seven associated SNPs from chromosome 10, that related to Marbling Score, Milk Yield, Fat Yield, Protein Yield, and Protein Percentage Quantitative Trait Loci (QTLs). The Body Depth trait resulted in one associated SNP from chromosome 2, although no QTL relation was found. The discovery of genes associated with conformation traits may be indicative of the adaptive selection pressures the Holstein breed has undergone in response to the extreme weather conditions found in the northwestern areas of Mexico. Results of this study indicate that traits such as stature and body depth may be used as indicators of cows' potential genetic merits for milk, fat, and protein production.