Estimation of heritability and breeding values using single test day records of first lactation milk yield of Holstein cows [electronic resource].

By: Language: English Summary language: Arabic Description: p.121-128Other title:
  • تقدير العمق الوراثى والقيم التربوية باستخدام سجلات يوم الاختبار الفردية لموسم الحليب الاول فى ابقار الهولشتين [Added title page title]
Uniform titles:
  • Egyptian journal of animal production, 2003 v. 40 (2) [electronic resource].
Subject(s): In: Egyptian journal of animal production 2003.v.40(2)Summary: Data used in this study comprised 10945 test day (TD) milk records oj 1163 first lactation Holstein cows belonging to a commercial farm. The objective was to estimate heritability and breeding values for cows and sires using both single test day and 305-day milk records. Additive genetic variance, heritability and breeding values were estimated using DF-REML (Meyer,1998). Heritability estimates of single TD records, except the first, sixth and ninth, were higher than those estimated for 305-days. The highest estimates oj heritability were observed for the second and third TD milk records. The product-moment and rank correlations between breeding values, of both sires and cows, estimated from 305-day and single TD milk records were positive and significant. Shifts in rank for various top cows and sires. ranked by their breeding values for 305-day and single TD milk yields, showed that extreme changes in ranks occurred in cows than in sires.
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Data used in this study comprised 10945 test day (TD) milk records oj 1163 first lactation Holstein cows belonging to a commercial farm. The objective was to estimate heritability and breeding values for cows and sires using both single test day and 305-day milk records. Additive genetic variance, heritability and breeding values were estimated using DF-REML (Meyer,1998). Heritability estimates of single TD records, except the first, sixth and ninth, were higher than those estimated for 305-days. The highest estimates oj heritability were observed for the second and third TD milk records. The product-moment and rank correlations between breeding values, of both sires and cows, estimated from 305-day and single TD milk records were positive and significant. Shifts in rank for various top cows and sires. ranked by their breeding values for 305-day and single TD milk yields, showed that extreme changes in ranks occurred in cows than in sires.

Summary in Arabic.

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