| Autor: |
H. Farhangfar, H. Naeemipour, R. Lotfi |
| Jazyk: |
perština |
| Rok vydání: |
2008 |
| Předmět: |
|
| Zdroj: |
Tulīd va Farāvarī-i Maḥṣūlāt-i Zirā̒ī va Bāghī, Vol 12, Iss 43, Pp 533-543 (2008) |
| Druh dokumentu: |
article |
| ISSN: |
2251-8517 |
| Popis: |
This study was undertaken to estimate genetic trend and parameters of Holstein cattle in Khorasan province for milk yield using a spline random regression test day animal model. A total of 32854 monthly test day milk records (twice and thrice a day milking) obtained from 3842 Holstein heifers (progeny of 466 sires) distributed in 125 herds and calved from 2001 to 2005 was used to predict breeding value of individual animals. In the model, fixed effects of herd including year-month of recording, milking times, age at calving (linear and quadratic covariables), Holstein gene percentage (linear covariable) as well as random effects of additive genetic and permanent environment were studied. To take account of the shape of the lactation curve at genetic and environmental levels, cubic spline polynomials were also included in the test day model. Bayesian method by applying Gibbs sampling technique (100000 chains applying RRGIBBS software) was utilized to obtain posterior means of predicted breeding value of animals for milk yield at individual month of lactation. The results showed that mean of breeding value for 305-day milk yield was 52.90 kg (p |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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