| Registro completo |
| Provedor de dados: |
OAK
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| País: |
Japan
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| Título: |
Genetic Correlations of Milk Production and Type Traits with Somatic Cell Score from Holstein Cows in Hokkaido
北海道の乳牛集団における体細胞スコアと産乳および体型形質との遺伝相関
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| Autores: |
三浦, 伸也
鈴木, 三義
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| Data: |
2005
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| Ano: |
2005
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| Palavras-chave: |
Somatic cell score
Genetic correlation
Type trait
Milk production
Holstein
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| Resumo: |
(社)北海道酪農検定検査協会の検定日記録および(社)日本ホルスタイン登録協会北海道支局の体型記録を用い，体細胞スコアと泌乳形質および体型形質との遺伝相関を推定した．各体型形質の記録数は審査開始時期の違いにより異なるが，多くの形質に共通な記録数を示すと，初産が181,291記録であり，2産が104,105記録，3産が30,973記録であった．遺伝相関の推定には，2形質分析モデルを用いた．母数効果としては，体細胞に対して，牛群・検定日，分娩月齢，分娩後日数の1次の回帰，分娩後日数に対するWilminkの指数項，体型形質に対しては，牛群・審査日，審査時月齢，泌乳ステージ，審査員の各効果を考慮し，さらに変量効果として両形質について，相加的遺伝効果と残差を含むモデルを用いた．体細胞スコアと乳生産形質との遺伝相関は−0.22〜0.15と低い値が推定され，初産において正の相関，2産以降では負の相関となる傾向が示された．体型形質と体細胞スコアとの遺伝相関は，産次により値が変動し，正負の符号の逆転が認められた．これは，加齢による体型変化に起因していると考えられる．体型形質の中で，乳房の深さ（−0.29〜−0.19）および前乳房の付着（−0.25〜−0.07）において，負の遺伝相関が推定された．これらの体型形質は生涯生産性，在群期間とも遺伝的な関連があり，これらの体型形質を改良することにより，体細胞スコアを低減することが可能であり，結果として生涯生産量の増加が期待できる．
Genetic correlations between somatic cell score (SCS) and other traits (milk, fat, SNF and protein yields, and type traits) were estimated using test-day records from Hokkaido Dairy Cattle Milk Recording and Testing Association and conformation records from Hokkaido Holstein Agricultural Cooperation. The numbers of records used for estimation of genetic correlation in most type traits were 181291, 104105, and 30973 records on first to third lactation, respectively. The bi-variate statistical model contained additive genetic effects and residual errors as random effects, and they also contained fixed effects for herd-test-day, age of calving, linear regression on days after calving, and Wilmilk’s function of days after calving in somatic cell score and herd-classification, age of classification, stage of lactation, and classifier in type traits. Genetic correlations estimated between SCS and milk production traits were low (from -0.22 to 0.15), and were positive in the first lactation and negative in later lactations. Genetic correlations among SCS and conformation traits were also estimated. Signs of the correlations changed across the parities, most likely depending on the growth. Higher negative genetic correlations with SCS were estimated for udder depth (from -0.29 to -0.19) and for fore udder attachment (from -0.25 to -0.07). These conformation traits were associated with the lifetime production and herd life ; thus, genetic improvement of these conformation traits may reduce SCS, further increasing lifetime production.
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| Idioma: |
Japonês
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| Identificador: |
http://ir.obihiro.ac.jp/dspace/handle/10322/2597
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| Editor: |
日本畜産学会
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| Formato: |
application/pdf
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| Direitos: |
日本畜産学会
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