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The objective of this study was to estimate adjustment factors of scrotal circumference for growth traits in Nellore cattle. Measurement at post-yearling of scrotal circumference from 100,107 Nellore was adjusted for six traits: age (A), body weight (BW), hip height (HH), conformation (C), precocity (P), musculature (M), and simultaneously for age and the other five traits (A-BW, A-HH, A-C, A-P, A-M), body weight and the other four traits (BW-HH, BW-C, BW-P, BW-M), and hip height and the other three traits (HH-C, HH-P, HH-M). Standard values were 500 days, 300 kg, 135 cm, and 3, for age, body weight, hip height, and visual scores, respectively. Amplitudes of adjustment factor of scrotal circumference for age, body weight, and hip height were 0.6028, 0.4869, and 0.1572, respectively. Scrotal circumference is expected to grow, on average, 8.71 cm per 100 days of age, 6.51 cm per 100 kg of body weight, and 4.81 cm per 10 cm of hip height. The results showed higher amplitude in the adjustment factor of scrotal circumference for age and body weight (0.3429) compared with age and hip height and body weight and hip height (0.1271 and 0.0443, respectively). The amplitude observed in adjustment factor of scrotal circumference for conformation, precocity, and musculature were 0.1328, 0.1175, and 0.1160, respectively. Considering different adjustment factors of scrotal circumference can be useful for identifying better selection criteria for growth and/or sexual precocity in Nellore.(AU)

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Background: Reactivity in livestock species has been assessed in relation to the behavioral reactions of animals, through restrained and non-restrained tests. Environmental and genetic parameters for reactivity traits have been reported for farm animals, as sheep, providing support for the possibility of direct selection. Despite evidences, there is little information on how genetic and environmental factors affect the expression of reactivity in sheep during and after weighing. Therefore, this study aimed to estimate the environmental and genetic effects of reactivity traits in Île-de-France x Texel crossbred lambs.Materials, Methods & Results: Reactivity traits from 188 Île-de-France x Texel cross lambs, aged between 28 and 110 days-old, were assessed in two situations: 1- During weighing: a. vocalization (VOC), b. movement (MOV), c. tension (TEN), d. exploratory behavior (EB) and e. ears posture (EP), and 2- After exiting the weighing crate, in a chute, through: a. gait speed (GS) and b. flight speed (FS) tests. For the study of environmental effects the model considered the fixed effects of month of assessment, sex and management group and as covariates, the linear effects of type of birth, age of dam and age of lamb. The (co)variance and genetic parameters were estimated using REML in univariate analysis and the direct additive genetic effect was considered in the model as a random effect. From all the environmental effects, month of assessment was statistically important over all the reactivity traits. Similarly, the effects of age of dam and age of lamb were significant for almost all variables.[...]

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Background: Reactivity in livestock species has been assessed in relation to the behavioral reactions of animals, through restrained and non-restrained tests. Environmental and genetic parameters for reactivity traits have been reported for farm animals, as sheep, providing support for the possibility of direct selection. Despite evidences, there is little information on how genetic and environmental factors affect the expression of reactivity in sheep during and after weighing. Therefore, this study aimed to estimate the environmental and genetic effects of reactivity traits in Île-de-France x Texel crossbred lambs.Materials, Methods & Results: Reactivity traits from 188 Île-de-France x Texel cross lambs, aged between 28 and 110 days-old, were assessed in two situations: 1- During weighing: a. vocalization (VOC), b. movement (MOV), c. tension (TEN), d. exploratory behavior (EB) and e. ears posture (EP), and 2- After exiting the weighing crate, in a chute, through: a. gait speed (GS) and b. flight speed (FS) tests. For the study of environmental effects the model considered the fixed effects of month of assessment, sex and management group and as covariates, the linear effects of type of birth, age of dam and age of lamb. The (co)variance and genetic parameters were estimated using REML in univariate analysis and the direct additive genetic effect was considered in the model as a random effect. From all the environmental effects, month of assessment was statistically important over all the reactivity traits. Similarly, the effects of age of dam and age of lamb were significant for almost all variables.[...](AU)

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Objetivou-se estimar as correlações fenotípicas (r) entre os escores comportamentais de reatividade aplicados durante e após a pesagem e os ganhos médios diários de peso (GMD) de cordeiros cruzados Suffolk x Île-de-France, aos 30, 60 e 90 dias de idade, bem como estudar o efeito da habituação dos animais ao manejo. As variáveis avaliadas por meio de escores foram: interferência do avaliador para o animal entrar na balança (INT), vocalização (VOC), movimentação (MOV), tensão (TEN), movimentos exploratórios (ME), postura de orelhas (ORE) e o teste de tipos de marcha (TM). Os resultados das correlações de Spearman obtidos entre os escores indicam que VOC, MOV e TEN podem ser consideradas como características importantes na expressão da reatividade de ovinos em ambiente de restrição. Já o GMD parece não estar associado com a reatividade dos cordeiros avaliados. Por fim, aos 90 dias de idade, os cordeiros apresentaram-se menos reativos, em função do aprendizado por habituação.

The aim of this study was to estimate the phenotypic correlations (r) between behavioral reactivity scores obtained during and after weighing, and the average daily weight gains (ADG) of Suffolk x Île-de-France cross lambs, at 30, 60 and 90 days of age, as well as to study the effect of habituation towards handling. The variables assessed through scores were: interference of the observer for the animal to enter the weighing crate (INT), vocalization (VOC), movement (MOV), tension (TEN), exploratory movements (EM), ears posture (EP) and the gait speed test (qualitative flight time test) (GS). The results of the Spearman correlations indicate that VOC, MOV and TEN may be considered important traits in the expression of reactivity in sheep assessed while restrained. On the contrary, ADG does not seem to be correlated with reactivity. Finally, at 90 days of age, the lambs were less reactive, due to learning by habituation.

RESUMO

Objetivou-se estimar as correlações fenotípicas (r) entre os escores comportamentais de reatividade aplicados durante e após a pesagem e os ganhos médios diários de peso (GMD) de cordeiros cruzados Suffolk x Île-de-France, aos 30, 60 e 90 dias de idade, bem como estudar o efeito da habituação dos animais ao manejo. As variáveis avaliadas por meio de escores foram: interferência do avaliador para o animal entrar na balança (INT), vocalização (VOC), movimentação (MOV), tensão (TEN), movimentos exploratórios (ME), postura de orelhas (ORE) e o teste de tipos de marcha (TM). Os resultados das correlações de Spearman obtidos entre os escores indicam que VOC, MOV e TEN podem ser consideradas como características importantes na expressão da reatividade de ovinos em ambiente de restrição. Já o GMD parece não estar associado com a reatividade dos cordeiros avaliados. Por fim, aos 90 dias de idade, os cordeiros apresentaram-se menos reativos, em função do aprendizado por habituação.(AU)

The aim of this study was to estimate the phenotypic correlations (r) between behavioral reactivity scores obtained during and after weighing, and the average daily weight gains (ADG) of Suffolk x Île-de-France cross lambs, at 30, 60 and 90 days of age, as well as to study the effect of habituation towards handling. The variables assessed through scores were: interference of the observer for the animal to enter the weighing crate (INT), vocalization (VOC), movement (MOV), tension (TEN), exploratory movements (EM), ears posture (EP) and the gait speed test (qualitative flight time test) (GS). The results of the Spearman correlations indicate that VOC, MOV and TEN may be considered important traits in the expression of reactivity in sheep assessed while restrained. On the contrary, ADG does not seem to be correlated with reactivity. Finally, at 90 days of age, the lambs were less reactive, due to learning by habituation.(AU)

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This study aimed to investigate the following environmental effects in Suffolk lambing: contemporary groups, type of birth, and age of animal and age of dam at lambing on conformation (C), precocity (P), musculature (M), and body weight at postweaning (W), and the heritability coefficients and genetic correlations among these traits. Contemporary groups, type of birth, and age of animal and age of dam at lambing were significant for W. For C, all the effects studied were significant, except linear and quadratic effects of age of the animal. For P, all effects studied were significant, except the quadratic effect of age of the animal. For M, the effects of contemporary group, type of birth, and the linear effect of the age of the animal were significant. Heritability estimates were 0.07 ± 0.03, 0.14 ± 0.03, 0.09 ± 0.03, and 0.11 ± 0.03 for C, P, M, and W, respectively, indicating a positive low response for direct selection. Estimates of genetic correlations among the visual scores (C, P, and M) and W were moderate to highly favorable and positive, ranging from 0.48 to 0.90. These results indicate that selection for visual scores will increase body weight.

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