Estimation of the Repeatability of Holstein Milk Yields via Various Statistical Methods

Öz

This study aims at estimation the repeatability of vital yield characteristics through the Restricted Maximum Likelihood (REML) method by the way of using data with regards to the calving intervals, lactation period, lactation milk yield, dry period and recovered milk yield (2x305 Max.) related to the Holstein herd raised in Ceylanpınar Agriculture Enterprise and comparing the repeatability estimates determined with the help of the REML method, Minimum Quadratic Unbiased Estimation (MQUE), Variance Analysis (VA) and Maximum Likelihood (ML) method. The number of records used for milk yield in the statistical analysis is 1457. The repeatability related to the milk yield characteristics was estimated to be between 0,005 and 0,244. Because of the fact that the repeatability was estimated to be low; it is believed that it might be useful to make the selection based on the mean of two or more records. Estimating the repeatability; the Minimum Quadratic Unbiased Estimation method is most likely to give reliable results for the calving period, dry period and lactation period that meets the r>2Sr condition while REML and ML methods are most likely to give the most reliable results for lactation milk yield and MQUE, VA, REML and ML methods are most likely to give the best results for the adjusted milk yield (2x350 Max.).

Anahtar Kelimeler

• Milk yield
• repeatability
• parameter estimations
• restricted maximum likelihood
• maximum likelihood
• minimum quadratic unbiased estimation
• variance analysis

Kaynakça

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