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Paper Information

Journal:   THE SCIENTIFIC JOURNAL OF AGRICULTURE (SJA)   MARCH 2008 , Volume 30 , Number 4-A; Page(s) 101 To 107.
 
Paper: 

ESTIMATION OF GENETIC PARAMETERS FOR MONTHLY TEST DAY MILK PRODUCTION IN IRANIAN HOLSTEINS

 
 
Author(s):  FARHANGFAR H.*, REZAEI H.
 
* AGRICULTURE FACULTY, BIRJAND UNIVERSITY, BIRJAND, IRAN
 
Abstract: 

In this study, a total of 179460 monthly test day milk records (thrice a day with 10 test day records for each cow) obtained from 17946 Iranian Holstein cows at first lactation and distributed in 287 dairy herds and calved between 1986 and 2001 were used to estimate genetic parameters of milk yields during the lactation period. An animal model implementing covariance function methodology (orthogonal Legendre polynomials) was used for genetic analysis of monthly test day milk records. The results revealed that milk production of the second half of the lactation is on average more heritable than the first half of the lactation. The lowest and highest heritabilities were found for first (0.063) and seventh (0.299) month of lactation, respectively. The results also showed that genetic correlations among monthly test day milk yields decreased when the interval between them increased so that milk yields at first and last month of the lactation period had the lowest genetic correlation (0.398).

 
Keyword(s): GENETIC PARAMETERS, COVARIANCE FUNCTION, IRANIAN HOLSTEIN
 
References: 
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