Genetic parameters and environmental effects on temperament score and reproductive traits of Nellore cattle

Barrozo, D.; Buzanskas, Marcos Eli; Oliveira, João Ademir de; Munari, Danísio Prado; Neves, Haroldo Henrique de Rezende; Queiroz, Salete Linhares

doi:10.1017/s1751731111001169

Cited by 39 publications

(43 citation statements)

References 14 publications

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“…The values estimated for genetic variance (3.602, Table 3) and heritability (0.52 ± 0.019, Table 3) for SC, as usually described in literature (e.g. Barrozo et al, 2012), indicate the possibility of good responses when selection is applied to this trait. Weak genetic correlations were estimated between female reproductive traits and SC; therefore, no effective genetic response in those traits through SC selection is expected.…”

Section: Resultsmentioning

confidence: 70%

Genetic relationship among reproductive traits in Nellore cattle

Guarini¹,

Neves²,

Schenkel

et al. 2015

Animal

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In order to achieve improvements in production efficiency in livestock, herds of high sexual precocity and good fertility are needed. These traits increase the availability of animals in herd, either for sale or selection, allowing both greater selective intensity and greater genetic progress. This study aimed at estimating genetic parameters for reproductive traits measured directly in females in order to verify whether they could be used as selection criteria for genetic improvement in Nellore cows, as well as estimating the genetic relationship among these traits and scrotal circumference (SC), the traditional selection criterion for sexual precocity in cattle. In addition to SC, stayability (STAY), number of calvings at 53 months (NC53) and heifers rebreeding (HR) were studied. The (co)variances and genetic parameters were estimated using Bayesian inference. STAY, NC53 and HR were analyzed assuming a threshold model, whereas SC was analyzed with a linear model. Heritability estimated for NC53 was 0.22, and this trait was strongly and positively correlated with STAY, meaning selection for NC53 would improve productive longevity of Nellore cows. Correlations estimated between HR and STAY (≈0.97) and between HR and NC53 (≈0.99) allow an improvement on HR rates if selection was applied to traits related to longevity. Genetic correlations among SC and female reproductive traits were positive but weak, suggesting the need to use reproductive traits directly measured in females in order to obtain greater improvements in sexual precocity and longevity.

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Section: Resultsmentioning

confidence: 70%

Genetic relationship among reproductive traits in Nellore cattle

Guarini¹,

Neves²,

Schenkel

et al. 2015

Animal

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“…Una característica que puede ser usada como criterio de selección de los machos con el objetivo de aumentar la fertilidad de los rebaños, es la circunferencia escrotal (CE). Este parámetro presenta una estimativa de heredabilidad de moderada a alta (Barrozo et al, 2012), es de fácil medición y presenta correlación genética favorable con la tasa reproductiva de las hembras (Mello, 2014). El peso testicular está en función directa con la cantidad de epitelio seminífero productor de esperma y por lo tanto, con la concentración espermática del eyaculado.…”

Section: Introductionunclassified

Evaluación del desarrollo testicular y medidas morfométricas en ovinos de pelo colombiano

2018

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The sheep body measurements are useful indicators of type and function that allow improving the selection. Biometric studies have shown in sheep a relationship between these measures with some productive variables. The main purpose of this study was to evaluate the testicular development and their relationship with morphometric parameters on Colombian hairy sheep of Sampués, Sucre, Colombia. Weaned males (n=12) born between February and April of 2014 were used, and the following measures were taken every twenty-eight days: scrotal circumference (CS), body weight (PC), rump height (AG), withers height (AC), and right and left testicular length (LTD and LTL).The sheep were between three to twelve months old. A multiple regression analysis (RA) was done from PC; AG; AC; TL. To describe the variation of LT, the model included only the variables PC; AG; AC. The grade of association between the studied variables was performed by a Pearson correlation. Scrotal circumference showed a high correlation with the evaluated morphometric parameters. In the RA analysis, the PC influenced the variable CE (p<0.05), while other variables did not have a significant influence. According to the regression coefficient associated to the measurement, per each kg of PC that an animal gained in weight, there was a corresponding increase of 0,09 cm in the CS.

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“…This evaluation was carried out following the procedure described by Barrozo et al (2012), such that the animals had their temperament classified according to:…”

Section: Animals and Datamentioning

confidence: 99%

“…Therefore, it is necessary to use appropriate statistical models to correctly evaluate this trait in animal breeding programs that adopt temperament as a selection criterion. Several studies have reported heritability estimates for temperament scores in cattle ranging from 0.13 to 0.40 (Burrow, 2001;Kadel et al, 2006;Barrozo et al, 2012); linear models were used in most of these studies to estimate the genetic parameters. However, given the categorical nature of temperament scores and their asymmetric distribution, it is possible that some assumptions, such as the normality and homoscedasticity of residuals, would not be met when analyzing this trait using linear models.…”

Section: Introductionmentioning

confidence: 99%

Genetic analysis of the temperament of Nellore cattle using linear and threshold models

Lucena¹,

Neves²,

Carvalheiro³

et al. 2015

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Temperament is an important trait for the management and welfare of animals and for reducing accidents involving people who work with cattle. The present study aimed to estimate the genetic parameters related to the temperament score (T) and weaning weight (WW) of Nellore cattle, reared in a beef cattle breeding program in Brazil. Data were analyzed using two different two-trait statistical models, both considering WW and T: (1) a linear-linear model in which variance components (VCs) were estimated using restricted maximum likelihood; and (2) a linear-threshold model in which VCs were estimated via Bayesian inference. WW was included in the analyses of T to minimize any possible effects of sequential selection and to allow for estimation of the genetic correlation between these two traits. The heritability estimates for T were 0.21 ± 0.003 (model 1) and 0.26 (model 2, with a 95% credibility interval (95% CI) of 0.21 to 0.32). The estimated genetic correlations between WW and T were of a moderate magnitude (−0.33 ± 0.01 (model 1) and − 0.34 (95% CI: − 0.40, − 0.28, model 2). The genetic correlations between the estimated breeding values (EBVs) obtained for the animals based on the two models were high (>0.92). The use of different models had little influence on the classification of animals based on EBVs or the accuracy of the EBVs.Keywords: beef production, categorical trait, genetic parameter, performance trait ImplicationsAnimal temperament is a trait that exerts a marked influence on the beef production system in tropical regions, because the management applied on the herds has direct repercussions on the profitability of the enterprises. Given the categorical nature of the temperament scores (T) and their asymmetric distribution, two statistical models were applied to study this trait in cattle, with the aim of assessing the differences and possible advantages of using a threshold model compared with a linear model for estimating variance components. The two models produced similar estimates of genetic parameters, classification of animals based on estimated breeding values (EBVs) and accuracy of the EBVs. The variability observed for T and the favorable association of this score with weaning weight, a trait related to maternal ability, support the inclusion of T as a selection criterion for the breeding program.

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Genetic parameters and environmental effects on temperament score and reproductive traits of Nellore cattle

Cited by 39 publications

References 14 publications

Genetic relationship among reproductive traits in Nellore cattle

Genetic relationship among reproductive traits in Nellore cattle

Evaluación del desarrollo testicular y medidas morfométricas en ovinos de pelo colombiano

Genetic analysis of the temperament of Nellore cattle using linear and threshold models

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