Consulta: subjectFacets:"Age at first calving"
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Data/hora: 09/06/2024 14:49:43

A deterministic simulation study of embryo marker-assisted selection for age at first calving in Nellore (Bos indicus) beef cattle
Provedor de dados: 74
Autores: Rosa,Artur J.M.; Bijma,Piter; Oliveira,Henrique N.; Lôbo,Raysildo B.; van Arendonk,Johan A.M.
We used deterministic simulation of four alternative multiple ovulation and embryo manipulation (MOET) closed nucleus schemes to investigate the benefits of using marker-assisted selection (MAS) of Nellore (Bos indicus) beef cattle embryos prior to transplantation to reduce the age at first calving (AFC). We found that MAS resulted in increased genetic gain as compared to selection without AFC quantitative trait loci (AFC-QTL) information. With single-stage selection the genetic response (GR) increased as follows: GR = 0.68% when the AFC-QTL explained 0.02 of the AFC additive genetic variance (sigma2A); GR = 1.76% for AFC-QTL explaining 0.05 sigma2A; GR = 3.7% for AFC-QTL explaining 0.1 sigma2A; and GR = 55.76% for AFC-QTL explaining 0.95 sigma2A. At the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Age at first calving; Beef cattle; Marker-assisted selection; Pre-selection; Quantitative trait loci.
Ano: 2007
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572007000400008

Genetic relationships of age at first calving, and reproductive traits of cows and yield traits for Holsteins in Hokkaido
Provedor de dados: 19
Autores: 阿部, 隼人; 増田, 豊; 鈴木, 三義; MASUDA, Yutaka; SUZUKI, Mitsuyoshi.
初産分娩月齢と3産までの経産牛繁殖形質ならびに生産形質間について，AIREML法を用いた2形質アニマルモデルにより，遺伝的パラメータを推定した．記録は，(社)北海道酪農検定検査協会に集積された繁殖ならびに乳期記録，および(社)日本ホルスタイン登録協会北海道支局に集積された血統記録である．計算機の能力の制約からすべての記録を同時に分析することは困難であったため，牛群単位の無作為抽出により10万記録程度のサブセットを10個生成し，各サブセットに対し分析を行なった．遺伝率は，初産分娩月齢に対し0.22，経産牛繁殖形質に対し0.03～0.05と推定された．初産分娩月齢と経産牛繁殖形質との遺伝相関は絶対値で0.2を上回らなかった一方，生産形質との遺伝相関は2産以降で－0.3から－0.4と比較的高かった．2産以降の生産形質との好ましい関連から，初産分娩月齢の改良による長期的な生産性の向上の可能性が示された．
Palavras-chave: Age at first calving; Genetic correlation; Holstein; Reproductive traits of cows; Yield traits.
Ano: 2008
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/3942

Genetic associations between reproductive and linear-type traits of Holstein cows in Brazil
Provedor de dados: 96
Autores: Almeida,Tatiana Prestes; Kern,Elisandra Lurdes; Daltro,Darlene dos Santos; Braccini Neto,José; McManus,Concepta; Thaler Neto,André; Cobuci,Jaime Araujo.
ABSTRACT This study aimed to estimate heritability, genetic, and residual correlations between reproductive traits such as age at first calving, calving interval, dry period, and first service period and linear type traits measured in Holstein cows born between the years 1990 and 2008 in Brazil. The (co)variance components were estimated by restricted maximum likelihood, using the MTDFREML software. The heritability for reproductive traits and linear-type traits ranged from 0.02 to 0.03 and from 0.07 to 0.40, respectively. Estimates of genetic correlations between reproductive and linear-type traits ranged from -0.23 (top line) to 0.28 (angularity) to age at first calving, from -0.54 (final score) to 0.34 (foot angle) to calving interval, from -0.23...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Age at first calving; Dairy cattle; Genetic parameters; Reproductive efficiency.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-35982017000200091