Advanced search
Start date
Betweenand

Identification of genomic regions and physiological pathways associated with susceptibility to ruminal acidosis in feedlot Nellore cattle.

Abstract

When beef cattle are fed high-concentrate diets, there may be a high risk of metabolic disorders, such as acidosis, especially in cattle from Bos taurus indicus genotypes, which have shown to be more sensitive to this disease in some studies. In addition, it is well documented in the literature that there's great variation among animals, and each animal responds differently in order to cope with this disorder, especially when related to feed preferences, that is, the same diet may lead some animals to acidosis and others may not present any clinical signs. Therefore, this study will aim to identify genomic regions responsible for the ruminal acidosis in Nellore cattle. It will be used 700 bulls that will be fed diets containing concentrate levels higher than 85%. Genotyping will be performed on samples of cattle tail hair by using GGP-LD panel (Geneseek® Genomic Profiler Bovine 30K). The SNPs markers presenting unknown genomic position and monomorphic markers, as well as those showing MAF (frequency of less common alleles) lower than 0.05, will be deleted. In addition, it will be excluded from the analysis the SNPs that show allocation rate of genotypes (Call Freq) lower than 93%, and also those containing excess of heterozygous genotypes (Het Excess). Segments containing genes or near genes that could explain the variability in the expression of characteristics such as average daily gain, dry matter intake, particle sorting, rumenites incidence and morphometric measurements of the rumen will be identified. The effects and variances of the SNPs will be estimated by ssGWAS methodology and the effects of the markers will be obtained from genomic values estimated by ssGBLUP model. (AU)