Abstract
Studies are being conducted on the applicability of genomic data to improve the accuracy of the selection process in livestock, and genome-wide association studies (GWAS) provide valuable information to enhance the understanding on the genetics of complex traits. The aim of this study was to identify genomic regions and genes that play roles in birth weight (BW), weaning weight adjusted for 210 days of age (WW), and long-yearling weight adjusted for 420 days of age (LYW) in Canchim cattle. GWAS were performed by means of the Generalized Quasi-Likelihood Score (GQLS) method using genotypes from the BovineHD BeadChip and estimated breeding values for BW, WW, and LYW. Data consisted of 285 animals from the Canchim breed and 114 from the MA genetic group (derived from crossings between Charolais sires and ½ Canchim + ½ Zebu dams). After applying a false discovery rate correction at a 10% significance level, a total of 4, 12, and 10 SNPs were significantly associated with BW, WW, and LYW, respectively. These SNPs were surveyed to their corresponding genes or to surrounding genes within a distance of 250 kb. The genes DPP6 (dipeptidyl-peptidase 6) and CLEC3B (C-type lectin domain family 3 member B) were highlighted, considering its functions on the development of the brain and skeletal system, respectively. The GQLS method identified regions on chromosome associated with birth weight, weaning weight, and long-yearling weight in Canchim and MA animals. New candidate regions for body weight traits were detected and some of them have interesting biological functions, of which most have not been previously reported. The observation of QTL reports for body weight traits, covering areas surrounding the genes (SNPs) herein identified provides more evidence for these associations. Future studies targeting these areas could provide further knowledge to uncover the genetic architecture underlying growth traits in Canchim cattle.
Highlights
Growth traits are traditionally included in selection criteria in beef cattle breeding programs, due to their association with meat production, and are of great economic importance for both breeders and the industry [1]
Data on estimated breeding values (EBVs) for birth weight (BW), weaning weight adjusted for 210 days of age (WW), and long-yearling weight adjusted for 420 days of age (LYW) were provided by the National Association of Canchim Breeders (ABCCAN) and by the Embrapa-Geneplus Beef Cattle Breeding Program
As our individuals were a sample from a larger population, it was expected that the mean EBV for each trait was different than zero
Summary
Growth traits are traditionally included in selection criteria in beef cattle breeding programs, due to their association with meat production, and are of great economic importance for both breeders and the industry [1]. The most common type of growth trait used in the selection process is the body weight measurement, which can be taken from birth and throughout an animal’s life. These traits are used for evaluation of growth and development, and for decision making about reproduction, nutritional, and prophylactic management. There are several SNP panel densities commercially available from Illumina [5] and Affymetrix [6], varying from a few thousand to more than 3 million SNPs [7], which are applicable for genome-wide association and genomic selection studies. If candidate regions are identified it could be useful for livestock improvement through GS by focusing on relevant genomic regions [10,11]
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