Genetic parameters for milk yield and quality traits of Brazilian Holstein cows as a function of temperature and humidity index

Autor(es)

Carrara, Eula Regina ^[1] ; Petrini, Juliana ^[1] ; Salvian, Mayara ^[1] ; de Oliveira, Hinayah Rojas ^[2] ; Rovadoscki, Gregori Alberto ^[1] ; Iung, Laiza Helena de Souza ^[1] ; Miquilini, Marina ^[1] ; Machado, Paulo Fernando ^[1] ; Mourao, Gerson Barreto ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Anim Sci, Piracicaba - Brazil

^[2] Univ Guelph, Ctr Genet Improvement Livestock, Dept Anim Biosci, Guelph, ON - Canada

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ANIMAL BREEDING AND GENETICS; v. 138, n. 6 JUN 2021.
• Citações Web of Science: 0

Resumo

Measurements of milk yield (MY), somatic cell score (SCS), percentage of fat (FP), protein (PP), lactose (LP), casein (CP) and percentage of palmitic (C16:0), stearic (C18:0), oleic (C18:1), total saturated (SFA), unsaturated (UFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in milk from 5,224 Holstein cows were evaluated as a function of a temperature and humidity index (THI). Legendre orthogonal polynomials from second to seventh order were tested. The best fit order for MY, PP and C18:0 was the third, whereas the second for all other traits. The heritability estimates decreased for MY (0.31 to 0.14), FP (0.28 to 0.16), LP (0.43 to 0.30), SCS (0.14 to 0.09), SFA (0.33 to 0.22) and C16:0 (0.31 to 0.26), whereas increased for CP (0.32 to 0.42), MUFA (0.08 to 0.13), UFA (0.07 to 0.11) and C18:1 (0.07 to 0.11) as the THI level increased. For PP, heritabilities (0.26 to 0.39) presented larger values in intermediate THI. For PUFA and C18:0, heritabilities were approximately constant (0.13 to 0.14 and 0.15, respectively). However, the greatest variations may have been the result of the limitations of Legendre polynomials at the extreme points of the curve, and the pattern of heritabilities curves was approximately constant for the evaluated traits. Spearman's rank correlations between breeding values in extreme THI levels were greater than 0.80 for all traits considering all animals, only cows and only bulls. When considering the top 1% and the top 50% animals (only cows, only bulls and all), Spearman correlations smaller than 0.70 were found, suggesting reranking of the animals. Although there was little variation in the variance components over THI, it is possible that there is no heat stress in the animals studied, because, on average, there was no great impact of the thermal load on the traits. One possible explanation is the use of herds with little climatic difference among herds, as well as the use of fans and sprinklers into the barns. However, the THI levels may be important factors in the selection process, as reranking of animals was verified. (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: 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
• 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