Comparison of Marker Effects and Breeding Values at Two Levels at THI for Milk Yield and Quality Traits in Brazilian Holstein Cows

Autor(es)

Carrara, Eula Regina ; Dauria, Brayan Dias ; Gervasio, Izally Carvalho ; Silveira, Robson Mateus Freitas ; Rovadoski, Gregori Alberto ; Petrini, Juliana ; Salvian, Mayara ; Machado, Paulo Fernando ; Mourao, Gerson Barreto

• Tipo de documento: Artigo Científico
• Fonte: GENES; v. 14, n. 1, p. 11-pg., 2023-01-01.

Resumo

Genomic tools can help in the selection of animals genetically resistant to heat stress, especially the genome-wide association studies (GWAS). The objective of this study was to compare the variance explained by SNPs and direct genomic breeding values (DGVs) at two levels of a temperature and humidity index (THI). Records of milk yield (MY), somatic cell score (SCS), and percentages of casein (CAS), saturated fatty acids (SFA), and unsaturated fatty acids (UFA) in milk from 1157 Holstein cows were used. Traditional breeding values (EBV) were determined in a previous study and used as pseudo-phenotypes. Two levels of THI (heat comfort zone and heat stress zone) were used as environments and were treated as "traits" in a bi-trait model. The GWAS was performed using the genomic best linear unbiased prediction (GBLUP) method. Considering the top 50 SNPs, a total of 36 SNPs were not common between environments, eight of which were located in gene regions related to the evaluated traits. Even for those SNPs that had differences in their explained variances between the two environments, the differences were very small. The animals showed virtually no rank order, with rank correlation values of 0.90, 0.88, 1.00, 0.88, and 0.97 for MY, CAS, SCS, SFA, and UFA, respectively. The small difference between the environments studied can be attributed to the small difference in the pseudo-phenotypes used between the environments, on-farm acclimation, the polygenic nature of the traits, and the THI values studied near the threshold between comfort and heat stress. It is recommended that future studies be conducted with a larger number of animals and at more extreme THI levels. (AU)

• Processo FAPESP: 12/15948-7 - Incorporação de informações genômicas no desenvolvimento de índices econômicos para a seleção de bovinos leiteiros
• Beneficiário: Juliana Petrini
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 10/12929-6 - Análise genética quantitativo-molecular para características de produção, perfil de ácidos graxos e qualidade do leite
• Beneficiário: Gerson Barreto Mourão
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 16/15066-5 - Estresse térmico e a qualidade do leite em vacas da raça Holandesa: uma abordagem genômica
• Beneficiário: Eula Regina Carrara
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 12/24788-3 - Interações epistáticas entre SNPs associados à composição e perfil de ácidos graxos no leite bovino
• Beneficiário: Laiza Helena de Souza Iung
• Modalidade de apoio: Bolsas no Brasil - Mestrado