| Full text | |
| Author(s): Show less - |
Salvian, Mayara
;
Silveira, Robson Mateus Freitas
;
Petrini, Julina
;
Rovadoscki, Gregori Alberto
;
Iung, Laiza Helena de Souza
;
Ramirez-Diaz, Johanna
;
Carrara, Eula Regina
;
Pertile, Simone Fernanda Nedel
;
Cassoli, Laerte Dagher
;
Machado, Paulo Fernando
;
Mourao, Gerson Barreto
Total Authors: 11
|
| Document type: | Journal article |
| Source: | INTERNATIONAL JOURNAL OF BIOMETEOROLOGY; v. 67, n. 2, p. 8-pg., 2022-12-29. |
| Abstract | |
Due to the high milk production of Holstein cows, many countries have chosen to import semen to improve local dairy herds. This strategy would be more effective if this semen was used in the same environment conditions in which the bulls were selected. If the effect of genotype by environment (G x E) interaction is not considered, the estimated breeding values (EBVs) may vary, potentially reducing the selection response. We evaluate the impact of heat stress on selection for milk yield and composition of Holstein cows using random regression models. To verify the interference of heat stress in milk yield (MY) and composition traits (fat, protein, total saturated, and total unsaturated fatty acids content in milk), temperature-humidity index (THI) on test-day milk records was used. The threshold value to divide the environments using test-day information from Brazilian Holstein cows was 72 units of THI, i.e., < 72 represented no heat stress and > 72 represented heat stress. Legendre polynomials of second-order (Leg 2) model and two lactation points (33 and 122 DIM) were used to estimate heritabilities and EBVs for five important dairy traits. The heritabilities of milk components and fatty acids were low (0.09-0.29), regardless of lactation period and degree of heat stress, with the exception of protein content (0.30-0.35). Fat content was the only milk component that was reduced according to the degree of heat stress and lactation period. The EBVs tended to decrease in heat stress conditions, thus animals with high genetic potential demonstrated evidence of G x E interaction. However, acclimatization of dairy cows to heat stress in the farm production systems may have been responsible for the low differences among genetic parameters and EBVs with and without heat stress found in this study. (AU) | |
| FAPESP's process: | 12/15948-7 - Inclusion of genomic information in the development of economic index for dairy cattle selection |
| Grantee: | Juliana Petrini |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 10/12929-6 - Quantitative-molecular genetic analysis for production traits, fatty acid profile and milk quality |
| Grantee: | Gerson Barreto Mourão |
| Support Opportunities: | Regular Research Grants |
| 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 |