Comportamento social de bovinos confinados

Abstract

The present study evaluated the effect of the familiarization to the group and the food, before entering in the confinement, in the social behavior of cattle. A total of 900 male Nellore bulls with initial mean live weight of 420 ± 30 kg and 30 months of age were used. Twenty-one days before entering in the confinement, 450 animals, from different groups, were randomly divided into three groups of 150 animals. Each one was housed in a pasture with 30 ha and received 3 kg of concentrate/animal daily. On the day of entry into the feedlot, the remaining 450 animals, also from different groups, were randomly divided into three groups of 150 (unfamiliar) animals. Subsequently, each of the six lots was accommodated in a confinement pen with one water trough shared between two pens. The animals were fed four times a day, twice in the morning (07h0min and 10h30min) and two in the afternoon (14h30min and 16h30min) and had ad libitum access to water. The evaluation of the social behavior was performed by recording the number of heads with displacement (D), mounts (M), fights (F) and head-play (HP), when they occurred up to 10 meters from the feed trough. During the first two weeks of confinement, the evaluations of the variables were performed at intervals of two days and then fortnightly, in the period between 7:00 a.m. and 11:00 a.m. All analyzes were performed using the statistical package SAS (SAS Inst. Inc., Cary, NC) and the results were considered significant when p < 0.05. To evaluate the effects of treatment (familiar and unfamiliar) on F, M, D and HP, the PROC MIXED command was used in a repeated measure analysis over the confinement days for the adaptation period (1, 3 5, 7, 10, 11 and 13 days) and for the post-adaptation period (28 °, 43 °, 58 °, 73 ° days). Comparisons between averages were performed using the Tukey's test. The frequency of M, D and F differed significantly between treatments in the adaptation period, with unfamiliar animals presenting higher mean values than those familiarized (p < 0.05). Within the postadaptation period, there was no significant interaction for any of the social behavior variables (p> 0.05). The results showed that the familiarization of the cattle to the group and the feeding before entering the confinement reduces the attempts of mounts, fights and displacements during the first ten days of confinement, positively impacting the well-being of the animals.