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Temperament of crossbred Angus Nellore bovine and its relationship with level of stress to management and performance


The aim of this study is to analyze the relationships between the reactivity during management, using three methods of evaluation, the level of stress and the performance of crossbred Angus Nellore. During weighing, the temperament will be recorded by the Crush Score Tests in squeeze chute (CS), Flight Speed (FS) and Qualitative Behavior Assessment (QBA), and the plasmatic cortisol concentration. Three hundred and twenty male steers Angus Nellore crossbreed with an average initial weight of 325 kg, 17 months old, will be housed in 8 confinement pens with an area of 800 m2 each, providing 20 m2 of free area, 6 m2 of artificial shading and 50 linear cm of feeding trough per animal, during 130 days of collective feedlot. In addition, the social behavior of the cattle will be evaluated during 72 continuous hours, aiming to analyze the hierarchy of each group and its possible relationship with the reactivity of the individuals. The average daily gain, carcass and meat quality will be recorded to detect possible temperament influences on performance. The cortisol and performance data will be processed by a model adjusted from generalized linear model theory through the SAS GENMOD considering the effects of confinement time (0, 28, 56, 84, 112 days) and of animals as a repeated measure. To evaluate the daily behavior and hierarchy will be considered the effects of evaluation days, times, batch and their interactions. At the end, Spearman correlations will be performed between the parameters of reactivity, cortisol and performance. (AU)

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