Genomic study on infection rate of Babesia bovis and association with resistance of tick in Hereford and Braford cattle

Abstract

Tick and tick-borne diseases, including the babesia (B. bovis), constitutes a major drawback to improve productivity of beef cattle in the tropics, especially for systems where taurine animals and their crosses are used. The eradication and control of ticks by acaricide is made difficult the possibility of babesiosis outbreaks that that may cause high mortality rate. This study will aim to estimate genetic parameters and to evaluate predictive ability and the adequacy of applying genomic selection for control the infection rate of B.bovis in Hereford and Braford breeds animals and verify the associatin of this trait with resistance of tick. Genome wide association studies (GWAS) will also be carried out and candidate genes will be prospected if GWAS results highlight regions highly associated with the studied trait. For this to happen, approximately 800 Hereford and Braford breeds yearling animals, from different farms and raised in two different years, phenotypes observed for tick count and blood sample collected with EDTA anti coagulant for DNA extraction will be used. B. bovis quantification will be performed using the qPCR technique from genomic DNA of each animal with specific primers for this protozoan and the absolute quantification method. Animals were genotyped using SNPs Illumina BovineSNP50 panel. Results from genomic selection and GWAS analyses will help to evaluate the possibility to incorporate the trait infection rate of babesia in Brazilian Hereford and Braford breeding programs, together with resistance of tick trait.