Estimates of genetic parameters for visual scores and daily weight gain in Brangus animals

Queiroz, Salete Linhares; Oliveira, João Ademir de; Costa, G. Z.; Fries, L. A.

doi:10.1017/s1751731110002442

Cited by 17 publications

(12 citation statements)

References 9 publications

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“…Walker et al (2015) observed that heifers from heavier dams showed that a positive correlation existed between dam and heifer body weight that can affect selection goals for replacement heifers. Our data suggest a close agreement with other studies about beef breeds, in which visual appraisal were measured on live animals (Robinson et al, 1993;Queiroz et al, 2011).…”

Section: Discussionsupporting

confidence: 92%

Relationship of post-weaning growth and age at puberty in crossbred beef heifers

et al. 2017

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-This study was intended to evaluate body size structure and growth parameters of crossbred heifers fed at four nutritional levels to achieve puberty earlier. Animals were classified depending on their level of crossing between Nelore and Hereford and subjected to four nutritional levels (kg day -1 ) as follows: 0.5 (light; n = 32), 0.75 (medium; n = 32), 1.00 (high; n = 29), and 1.25 (very high; n = 27). Heifers at puberty and at weaning were individually classified for growth parameters. The fat thickness and longissimus muscle area throughout the experimental period were determined by ultrasonography. The height, heart girth, frame, and weight:height ratio were variables used to evaluate body traits. Univariate analysis of variance using the GLIM MIXED procedure os SPSS was performed and the significance level was set at 0.05. Age and body weight at puberty were 388±1.9 days and 331.4±1.3 kg, respectively. Body condition score demonstrated an interaction between nutritional level and crossbred degree. Heifers with the highest degree of Nelore had higher fat thickness and lower weight:height ratio compared with other racial groups at puberty. Pearson correlation coefficient showed a negative association for body condition score (-0.34) and fat thickness (-0.58) compared with age at puberty. The increased fat thickness at younger ages at puberty was observed in all racial groups. The increased weight:height ratio at younger ages at puberty was observed in all racial groups. We observed higher values for a frame in animals at the higher level of supplementation. There is a greater correlation between live weight gain and phenotypic traits during weaning to achieve puberty at an earlier age in crossbred heifers.

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Section: Discussionsupporting

confidence: 92%

Relationship of post-weaning growth and age at puberty in crossbred beef heifers

et al. 2017

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“…P and M scores showed similar heritability estimates for all models considered and larger than those estimated for C. The heritability estimates for C, P and M obtained in this study were close to those for Nellore breed reported by Eler et al (1996) of 0.34, 0.29 and0.33, andVan Melis et al (2003) of 0.22, 0.21 and 0.22, respectively, and higher than those found by Koury Filho et al (2010) of 0.13, 0.25 and 0.23, respectively, for the Nellore breed, and those found by Queiroz et al (2011) of 0.12, 0.14 and 0.13, respectively, for Brangus cattle.…”

Section: Resultssupporting

confidence: 89%

“…Environmental effects can be divided into unpredictable, as the classificatory effect of contemporary group, and predictable, which are often used as covariates such as age at first calving, animal age and animal weight (CARDOSO et al, 2004). However, for the traits C, P and M, measured by visual scores, there is no consensus in the literature on which environmental effects should be considered in the statistical models for the genetic evaluation of animals (DAL-FARRA et al, 2002;QUEIROZ et al, 2011). This study evaluates the influence of age of dam at calving (AC), long yearling age (YA) and long yearling weight (YW) on scores of C, P and M at long yearling age and estimates the heritability of these scores using different models, with the aim of improving Nellore breeding programs.…”

Section: Introductionmentioning

confidence: 99%

Genetic and environmental effects on scores of conformation, precocity and muscling in long yearling Nellore cattle

et al. 2015

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The visual scores for conformation (C), precocity (P) and muscle (M) are used to indirectly assess traits related to termination and carcass composition. This study analyzes how age of dam at calving (AC), long yearling age (YA) and long yearling weight (YW) of the animal affect the scores of Nellore cattle, and estimates their heritability. Regression functions were estimated to determine the AC, YA and YW effects on C, P and M scores after the contemporary group (CG) effect being absorbed. The heritabilities were estimated by restricted maximum likelihood using four different models that included animal additive genetic effect as random and different covariates (AC, YA and YW) as fixed effects. The regression analysis showed that the covariates, either linear or quadratic, significantly influenced the scores of C, P and M. The determination coefficients of the models for YA and AC were small, probably due to the CG bias removal. The heritability estimates for the scores ranged from 0.13 to 0.36 for C; 0.32 to 0.36 for P; and, 0.35 to 0.38 for M, for all models, indicating that C, P and M respond to direct selection. The classification of animals according to their breeding values, especially in relation to C, varied according to the environmental effects included in the models. Key words: Calving age, genetic evaluation, heritability, long yearling age, long yearling weight ResumoOs escores visuais de conformação (C), precocidade (P) e musculosidade (M) são usados para acessar indiretamente características relacionadas à terminação e composição de carcaça. Neste estudo, objetivou-se analisar como a idade da vaca ao parto (AC), idade (YA) e peso do animal ao sobreano (YW) influenciam os escores de bovinos da raça Nelore, além de estimar suas herdabilidades. Foram estimadas funções de regressão dos efeitos de AC, YA e YW sobre os escores C, P e M, após a absorção do efeito de grupo de contemporâneos (CG verossimilhança restrita, considerando-se quatro diferentes modelos que incluíram o efeito genético aditivo de animal como aleatório, e diferentes covariáveis (AC, YA e YW) como efeitos fixos. Nas análises de regressão, as covariáveis, tanto linear como quadrática, influenciaram significativamente os escores C, P e M. Os coeficientes de determinação dos modelos para YA e AC foram de pequena magnitude, provavelmente devido à absorção do efeito de CG. As estimativas de herdabilidade para os escores variaram de 0,13 a 0,36 para C, de 0,32 a 0,36 para P, e de 0,35 a 0,38 para M, considerando todos os modelos utilizados, indicando que C, P e M respondem à seleção direta. A classificação dos animais de acordo com seus valores genéticos, principalmente em relação a C, variou de acordo com os efeitos de ambiente incluídos nos modelos. Palavras-chave: Avaliação genética, herdabilidade, idade ao sobreano, idade da vaca ao parto, peso ao sobreano

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“…Sturges' formula was again used to define the calf weaning weight classes. Visual scores of calf conformation and early finishing at weaning were divided into five phenotypic classes, according to the methodology described by Queiroz et al (2011). A score of 1 was assigned to the worst performing animal, and a score of 5 was assigned to the calf with the best conformation or finishing (Table 1).…”

Section: Data Setmentioning

confidence: 99%

Body condition score of Nellore beef cows: a heritable measure to improve the selection of reproductive and maternal traits

Fernandes

Neves

Carvalheiro

et al. 2015

Animal

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Despite the economic importance of beef cattle production in Brazil, female reproductive performance, which is strongly associated with production efficiency, is not included in the selection index of most breeding programmes due to low heritability and difficulty in measure. The body condition score (BCS) could be used as an indicator of these traits. However, so far little is known about the feasibility of using BCS as a selection tool for reproductive performance in beef cattle. In this study, we investigated the sources of variation in the BCS of Nellore beef cows, quantified its association with reproductive and maternal traits and estimated its heritability. BCS was analysed using a logistic model that included the following effects: contemporary group at weaning, cow weight and hip height, calving order, reconception together with the weight and scores of conformation and early finishing assigned to calves at weaning. In the genetic analysis, variance components of BCS were estimated through Bayesian inference by fitting an animal model that also included the aforementioned effects. The results showed that BCS was significantly associated with all of the reproductive and maternal variables analysed. The estimated posterior mean of heritability of BCS was 0.24 (highest posterior density interval at 95%: 0.093 to 0.385), indicating an involvement of additive gene action in its determination. The present findings show that BCS can be used as a selection criterion for Nellore females.

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Estimates of genetic parameters for visual scores and daily weight gain in Brangus animals

Cited by 17 publications

References 9 publications

Relationship of post-weaning growth and age at puberty in crossbred beef heifers

Relationship of post-weaning growth and age at puberty in crossbred beef heifers

Genetic and environmental effects on scores of conformation, precocity and muscling in long yearling Nellore cattle

Body condition score of Nellore beef cows: a heritable measure to improve the selection of reproductive and maternal traits

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