Author/Authors :
ÜNALAN, Adnan Niğde Üniversitesi - Ulukışla Meslek Yüksekokulu - Bitkisel ve Hayvansal Üretim Bölümü, Turkey , ÇANKAYA, Soner Ondokuz Mayıs Üniversitesi, Kurupelit - Ziraat Fakültesi - Zootekni Bölümü, Turkey
Abstract :
In dairy cattle management, the estimation of variance components and genetic parameters related to milk yield by using unbiased methods is very important. In this study, 3630 lactation milk yield records of Jersey cattle herd in the Karakoy Agricultural State Farm between the years 1984-2008 were obtained, and variance components and genetic parameters related to milk yield were estimated by ANOVA, ML, REML and MIVQUE methods. Variance ratios (σ^2 α / σ^2 e) were taken as a criteria in the comparison of unbiasedness and effectiveness of the estimates. Despite all of the variance ratios obtained from ANOVA, ML, REML and MIVQUE methods by sire model were found less than 0.50, ML and REML results were very similar. Therefore, REML method was found to be more effective than the other methods in this study, because the variance ratio obtained from DFREML by animal model was greater than 0.50. While the heritability estimates for ANOVA, ML, REML and MIVQUE methods by sire model were determined to be 0.317, 0.459, 0.477 and 0.135, respectively, it was obtained as 0.481 from DFREML by animal model.
NaturalLanguageKeyword :
Jersey cattle , milk yield , variance components , genetic parameter , estimation methods
