Influence of progesterone ear implant on behavior, physiological parameters, and carcass injuries of Nellore females reared in an intensive system

ABSTRACT The objective of this study was to evaluate the influence of a synthetic progesterone ear implant on the behavior, physiological responses, and number of carcass injuries of Nellore females. Twenty-eight Nellore heifers with an average initial weight of 240.89 kg were used in the experiment. All animals received the same dietary management, in an intensive rearing system with mineral salt and water ad libitum. Heifers were distributed in a completely randomized design with two treatments (with and without progesterone ear implant) and seven replications, in 14 stalls. Analyses of variance and correlation were performed. In the evaluation of the feeding, rumination, rest, sleeping, social, and body-care behaviors, no significant differences were observed. The use of ear implant did not change weight gain or the number of injuries on the carcass of Nellore females. There was a greater incidence of anomalous behavior for the animals without the implant. Other behaviors were not affected by the hormone. As regards the physiological responses, only respiratory frequency was influenced by the implant. The behavior and performance of heifers are not influenced by progesterone ear implant.