Article

Environmental and Genetic Parameters for Type Traits in Holstein Cows1

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Abstract

Data consisted of 11 type appraisal traits for 51,044 Holstein first calf heif- ers with age at classification from 25 to 36 me. Effects of 10 rounds, 12 monthly ages at classification, 12 monthly stages of lactation, and 12 months (season) of classification were analyzed by least- squares. Effects of these four environ- mental factors were significant in most eases although the squared multiple cor- relation for the complete model ranged from 1 to 3?0 for various type traits. Heritabilities from adjusted and unad- justed data were final score .19, .33; final classification .27, .28; general appearance .27, .28; dairy character .22, .23; body capacity .31, .31; mammary system .17, .19; fore udder .14, .17; rear udder .15, .16; legs and feet .07, .08; rump .33, .34; and body size .52, .55. Genetic correla- tions among type traits were positive and ranged from .06 between dairy charac- ter and legs and feet to 1.18 between final score and final classification. Pheno- typic correlations were generally smaller than genetic correlations.

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... Para aumentar a produção leiteira por meio da seleção de animais funcionais e produtivos é necessário identificar e quantificar os fatores de meio ambiente que influenciam as características consideradas na classificação linear para tipo. Estudos mostram que há influência dos fatores de meio como rebanho, ano e estação de classificação, estádio da lactação, idade ou ordem do parto, classificador, dentre outros, sobre as características lineares de tipo (Wilcox et al., 1959;Norman e Vanvleck, 1972a;Rennie et al., 1974;Thompson et al., 1983;Lawstuen et al., 1987). Lucas et al. (1984) e Funk et al. (1991) estudaram os efeitos de meio sobre as características de conformação em vacas da raça Holandesa, encontrando efeitos significativos da idade da vaca, do estádio da lactação e do classificador sobre algumas características de tipo. ...
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... Para aumentar a produção leiteira por meio da seleção de animais funcionais e produtivos é necessário identificar e quantificar os fatores de meio ambiente que influenciam as características consideradas na classificação linear para tipo. Estudos mostram que há influência dos fatores de meio como rebanho, ano e estação de classificação, estádio da lactação, idade ou ordem do parto, classificador, dentre outros, sobre as características lineares de tipo (Wilcox et al., 1959;Norman e Vanvleck, 1972a;Rennie et al., 1974;Thompson et al., 1983;Lawstuen et al., 1987). Lucas et al. (1984) e Funk et al. (1991) estudaram os efeitos de meio sobre as características de conformação em vacas da raça Holandesa, encontrando efeitos significativos da idade da vaca, do estádio da lactação e do classificador sobre algumas características de tipo. ...
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