Captulo II
Holstein and Jersey cattle breeds are two of the most important dairy breeds and the majors in our country. The aim of this study was to conduct an exploratory analysis that could identify allelic variants associated with milk production on a commercial herd with Holstein and Holstein x Jersey cross...
Guardado en:
| Autor principal: | |
|---|---|
| Otros Autores: | |
| Formato: | Tesis doctoral acceptedVersion |
| Lenguaje: | Español |
| Publicado: |
Universidad de Buenos Aires. Facultad de Ciencias Veterinarias
2015
|
| Materias: | |
| Acceso en línea: | http://repositoriouba.sisbi.uba.ar/gsdl/cgi-bin/library.cgi?a=d&c=avaposgra&cl=CL1&d=HWA_1874 https://repositoriouba.sisbi.uba.ar/gsdl/collect/avaposgra/index/assoc/HWA_1874.dir/1874.PDF |
| Aporte de: |
| Sumario: | Holstein and Jersey cattle breeds are two of the most important dairy breeds and the majors in our country. The aim of this study was to conduct an exploratory analysis that could identify allelic variants associated with milk production on a commercial herd with Holstein and Holstein x Jersey crossbred cows. The material used consisted in a database containing information about dairy production and pedigree records of 1,859 animals belonging to 25 half-sib families from 16 dairy farms located in the central dairy area of Argentina. Through a candidate gene approach, 1,859 animals were genotyped for 56 SNPs in selected genes, using the SNPlex® system. Those genes were selected for being related to productivity and milk quality in cattle. Moreover, in 821 animals, 12,460 SNPs genotypes included in a medium-density microarray and located in chromosomal regions containing the candidate genes selected previously, were determined. With the genotypic data and estimated breeding values (EBV) for first-lactation 305-days milk yield, estimated through a linear mixed model, an association analysis was performed using the FASTA-GC strategy of GenABEL package in R. After performing the respective genotypes quality controls, 10,227 SNPs were used in the association analysis. This analysis allowed the detection of 12 SNPs associated with EBVs for milk yield in BTAs 1, 20, 23 and 24. Due to its proximity to these SNPs and for being related to milk production or composition, specific regions of PRMT2, BTN1A1 and S100B genes were sequenced in 34 cows with extreme EBVs. The obtained sequences were used to explore the presence of polymorphisms that could contribute to the observed differences in the studied population EBVs for milk yield. For PRMT2, BTN1A1_A and BTN1A1_B regions, the 7%, 22% and 24% of the SNPs previously reported were obtained, respectively, while in S100B none SNP was found. Nine of BTN1A1 gene SNPs generate missense mutations. Some of the SNPs found showed significant differences in allele frequencies in animals with opposite phenotypes (lower and higher EBV values for milk yield). This analysis has revealed trends that would be interesting to study in a larger population, especially in the case of SNPs in coding regions that result in a change in the protein structure that may affect milk yield and compositional characteristics. The results obtained are of interest for the genotypic characterization of Argentinean Holstein and Holstein x Jersey cattle, because the studied population is representative of the genetic currently used in the dairy industry and could form part of a reference population to use the Genomic Selection methodology in dairy breeding cattle programs in the country. |
|---|