Navegando por Autor "Silva, Raphael Steinberg da"
Agora exibindo 1 - 2 de 2
Resultados por página
Opções de Ordenação
Item Genetic diversity and population genetic structure of a guzerá (Bos indicus) meta-population.(2021) Peixoto, Maria Gabriela Campolina Diniz; Carvalho, Maria Raquel Santos; Egito, Andréa Alves do; Silva, Raphael Steinberg da; Bruneli, Frank Angelo Tomita; Machado, Marco Antônio; Santos, Fernanda Caroline dos; Cruz, Izinara Rosse da; Fonseca, Pablo Augusto S.The Brazilian Guzerá population originated from a few founders introduced from India. These animals adapted well to the harsh environments in Brazil, were selected for beef, milk, or dual-purpose (beef and milk), and were extensively used to produce crossbred animals. Here, the impact of these historical events with regard to the population structure and genetic diversity in a Guzerá meta-population was evaluated. DNA samples of 744 animals (one dairy, nine dual-purpose, and five beef herds) were genotyped for 21 microsatellite loci. Ho, He, PIC, Fis, Fit, and Fst estimates were obtained considering either farms or lineages as subpopulations. Mean Ho (0.73) and PIC (0.75) suggest that genetic diversity was efficiently conserved. Fit, Fis and Fst values (95% CI) pointed to a low fixation index, and large genetic diversity: Fit (Farms = 0.021–0.100; lineages = 0.021–0.100), Fis (Farms = –0.007–0.076; lineages = −0.014–0.070), and Fst (Farms = 0.0237–0.032; lineages = 0.029– 0.038). The dual-purpose herds/selection lines are the most uniform subpopulation, while the beef one preserved larger amounts of genetic diversity among herds. In addition, the dairy herd showed to be genetically distant from other herds. Taken together, these results suggest that this Guzerá meta-population has high genetic diversity, a low degree of population subdivision, and a low inbreeding level.Item Polymorphisms in genes coding milk proteins and protein hormones involved in milk production traits in Brazilian Guzerá cattle.(2022) Silva, Raphael Steinberg da; Carvalho, Maria Raquel Santos; Cruz, Izinara Rosse da; Machado, Marco Antônio; Peixoto, Maria Gabriela Campolina DinizResearch on genes affecting phenotypic variation in milk production and composition from indicine (Bos indicus) cattle is imperative, since these breeds are important tropical genetic resources, and there have been few studies investigating the genetic basis of these traits. We identified polymorphisms in -casein (CSN3), -lactoglobulin (LGB), thyroglobulin (TG) and prolactin (PRL) and examined their effect on milk and composition traits in the Guzerá breed. DNA samples of 260 Guzerá cattle selected for dual purpose use were genotyped. Allele frequencies observed for the A allele were 0.83, 0.18 and 0.25 respectively for CSN3, LGB and PRL genes, while for the TG gene T allele had an allele frequency of 0.09. For all polymorphisms evaluated, observed genotypic frequencies were in agreement with those expected according to the Hardy- Weinberg Equilibrium hypothesis. A polymorphism association study evaluated breeding values (BV) for 305-day milk (BV-M), fat (BV- F), and protein (BV-P) production, employing the allele substitution model using a sample of 139 cows belonged to 27 full and half-sib families of a MOET (multiple ovulation and embryo transfer) selection nucleus. Association was found between the LGB polymorphism and BV-M, BV-F and BV-P. Animals with LGB AA genotype have, on average, higher BV when compared to animals with LGB AB and BB genotypes (277.85 kg for BV-M, 12.09 kg for BV-F and 9.33 kg for BV-P). These findings contribute to a better understanding on the influence of these polymorphisms on milk production traits in Guzerá cattle.