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| Author(s): |
Laiza Helena de Souza Iung
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2014-07-17 |
| Examining board members: |
Decio Barbin;
Maria Gabriela Campolina Diniz Peixoto
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| Advisor: | Gerson Barreto Mourão |
| Abstract | |
Bovine milk is an essential food in human nutrition, especially for younger people for being as important source of proteins, minerals and vitamins. The growing for quantity and quality for milk in recent years has stimulated numerous studies, especially regarding the fatty acid profile by differ substantially of human requirements. Nutrition and animal breeding are the main factors which would enhance change the nutritional quality of cow milk. For a long time the changes achieved by animal breeding were obtained purely based on quantitative genetics, but from 90 the interest in this area came to be divided with molecular genetics. The advances made in the molecular biology obtained through the mapping and sequencing of the genomes of different species and genome-wide association studies is helping to explain more about the genetic background of quantitative traits. Currently, most of genome-wide association studies were designed to estimate additive genetic effects only at a single locus, excluding additional effects. However, part of the observed variation in these phenotypes result from the interaction between genes or loci, thus, such studies are also important for the understanding of the origin of biological variation of these traits, such as their metabolic and biochemical pathways. The aims of this study were: I) Associate single nucleotide polymorphisms (SNPs) with production traits and fatty acid profile in milk; and II) Identify interactions between SNPs associated with these traits in milk from Holstein cows. Phenotype adjusted of 760 cows for the fixed effects of contemporary group and covariates days in milk, age at measurement and milk yield, and information from 6,553 SNPs were considered for performing the association using single SNP regression method. A total of nine SNPs were associated with one or more traits related to the fat percentage and fatty acid profile. Some of these associations showed the presence of epistasis and/or pleiotropy between these regions. To identify interaction between SNPs, models that consider the individual effects (additive and dominance); and individual and interaction effects between the nine SNPs for comparison using the likelihood ratio test (LRT). Additive x dominance epistatic effect (P < 0.01) was observed only between markers ARS-BFGL-NGS- 71749 and ARS-BFGL-NGS-34135, both located on chromosome 14 (Bos taurus autossome, BTA14), for fat percentage (FP), saturated fatty acids (SFA) and palmitic acid (C16:0). For a better understanding of its biological interaction there is a need for greater knowledge of the metabolic pathways in with these genes identified these markers are located. More studies will enable these chromosomal regions expand knowledge about genes and their interactions. (AU) | |
| FAPESP's process: | 12/24788-3 - Epistatic interactions between SNPs associated with composition and fatty acid profile in bovine milk |
| Grantee: | Laiza Helena de Souza Iung |
| Support Opportunities: | Scholarships in Brazil - Master |