Data/hora: 01/06/2024 02:10:51

Provedor de dados: | 74
País: | Brazil
Título: | Genetic parameters of test day milk yields of Holstein cows
Autores: | Machado,S.G.; Freitas,M.A.R.; Gadini,C.H.
Data: | 1999-09-01
Ano: | 1999
Resumo: | Data were obtained from 17,968 records from 2,130 first lactations of Holstein cows calving between 1988 and 1991. The subjects were daughters of 136 sires monitored by Brazilian Breeders Association, Animal Science Institute, Department of Agriculture, a branch of the State of São Paulo. Data were divided into 10 subsets based on the number of days in milk yield. Test day milk yields (M1 to M10) and 305-day milk yield (M305) were the traits studied. These traits were adjusted for several environmental effects: class of cow age at calving, interval from calving to first test day, and herd-year-season. Restricted maximum likelihood estimates of (co)variance components were obtained from one and two-traits analysis under a sire model. Estimates of heritabilities for M ranged from 0.04 to 0.32. The highest values were found in the second half of lactation (M5 to M7). Heritability estimate for M305 was 0.32. Genetic correlations between individual test days and M305 ranged from 0.78 to 1.00. Results suggested that test day milk yields, mainly in mid-lactation, can be used instead of 305-day milk yield in genetic evaluations, because estimates of these two-trait heritabilities are nearly alike. Moreover, early selection can reduce generation intervals.
Tipo: | Info:eu-repo/semantics/article
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47571999000300016
Editor: | Sociedade Brasileira de Genética
Relação: | 10.1590/S1415-47571999000300016
Formato: | text/html
Fonte: | Genetics and Molecular Biology  v.22 n.3 1999
Fonte: | info:eu-repo/semantics/openAccess