Study of the genetic variability of meat fatty acid profile in Nelore cattle finished in feedlot

Abstract

Among the attributes of beef meat, the fatty acid profile is important because it affects not only the meat palatability, but also the human health. In recent years, fatty acids harmful to human health have received considerable attention. Several studies, working with taurine breeds, showed that there is genetic variability for meat fatty acid profile and, therefore the possibility of genetic improvement of fatty acid composition in beef cattle. Moreover, the results of these studies showed favorable genetic correlations estimates between fatty acids. However, genetic parameter estimates for fatty acid profile in zebu cattle are scarce. The meat fatty acid profile is difficult and costly to measure. For this type of trait is indicated the application of genomic selection, which is a type of marker-assisted selection. Despite the major advances in genetic molecular techniques that allow the genotyping of hundreds of animals in less time and in an automated fashion, there are still being developed methodologies that allow the incorporation of genomic information in animal breeding programs. The objective of this project is to study the genetic variability of meat fatty acid profile in Nelore cattle finished in feedlot conditions, and implement models and methods that use genomic information to improve the fatty acid composition of beef meat. To attain this objective we propose the following specific objectives: 1) Study and characterize the profile of meat fatty acids of Nelore cattle finished in feedlot 2) Estimate genetic parameters for meat fatty acid composition in Nelore cattle finished in feedlot 3) Implement genome wide association studies between single nucleotide polymorphisms markers (SNPs) with meat fatty acid composition 4) Predict the genomic breeding values for meat fatty acid profile considering different models 5) Verified the expression patterns of genes involved in lipid metabolism and fatty acid synthesis 6) Study the influence of polymorphisms (functional polymorphisms) on the expression of several genes of interest. Approximately from 800 to 1,000 Nelore males finished in feedlot conditions (minimum 90 days), aged around two years old, it were utilized. From the individual concentration of fatty acids, it will be calculated the proportion of saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids, the ratio of polyunsaturated fatty acids and saturated fatty acids, fatty acids of n-6 and n-3 series and the n-6/n-3 ratio. In addition, the desaturation index (ID) (adding a double bond) and elongation index (IE) (conversion from 16 to 18 carbon chains atoms) will be calculated. The genetic parameter and (co)variance estimates for these traits will be estimated by restricted maximum likelihood method. The Bovine HD SNP BeadChip, with more than 777,000 SNP, will be utilized to genotyped the animals. To perform the genome wide association analyses, single and multiple regression analyses, will be done. These analyses will allow a genome scan in seeking areas of interest in the genome. Then, SNPs with significant effects obtained in the multiple regression analysis, it will be analyzed by an animal model including the effects of SNPs in the model. The genomic breeding values for meat fatty acid profile will be predicted using different a prior distributions for variances and SNPs effects. The estimation of SNP effects will be performed with BLUP, BayesB and BayesLasso models. The results of this project will establish new elements to differentiate, develop and promote the attributes of Brazilian beef meat on the basis of a solid scientific and technical support. In addition, this project will allow the formation, training and qualification of students and teachers that will be important for future research and for teaching in undergraduate and graduate courses. (AU)