Restricted suckling: Are calves less reactive when subjected to an aversive handling?

Abstract

The restricted suckling requires the daily handling of calves and cows for their separation, increasing the frequency of contact with humans. Thus, when subjected to aversive handling procedures such as fire branding, it is expected that these individuals present lower reactivity due to their close intimacy with humans. The aim of this study was to evaluate the effect of fire branding procedure on the flight speed of calves subjected or not the restricted suckling. We used 70 calves from Nellore, Guzerath purebreds and their crosses, allocated into two treatments: Permanent suckling (PS) - 17 females and 18 males aged 212 (± 33.27) days, remained continuously with their dams and; restricted suckling (RS) - 16 females and 19 males aged 232 (± 42.39) days, daily separated from their dams during the breeding season (90 days of duration). A handling was done (D0) to evaluate the flight speed (FS) of the calves, this handling consisted only of physical restraint on the squeeze chute, followed by the release and recording of the speed (in m/s) at which the animals exited the chute to a pen of the corral. The next day (D1) a second handling was carried out with the same individuals, performing the aversive handling that consisted of physical restraining in the chute, fire branding and, only on females, the application of brucellosis vaccine (according to the IN n.33, 24th August 2007, MAPA-Brazil), after this handling the FS was recorded using the same procedure described above. For statistical analysis we used the analysis of variance with a generalized linear model (PROC GLM, SAS) that included FS as dependent variable and the effects of aversive handling (D0 or D1), type of suckling (permanent or restricted), sex ( male or female), and the interaction between aversive handling and the type of suckling. There was a trend of females (2.53 ± 0.12 m/s) had higher FS than males (2.24 ± 0.12 m/s) (F = 0.10, P = 0.09) and, a trend of increasing FS of calves when they were subjected to the aversive handling (D0: 2.23 ± 0.12 and D1: 2.54 ± 0.12 m/s, F = 2.95, P = 0.07). There was no significant effect of type of suckling (F = 3.39, P> 0.05) nor of interaction between type of suckling and aversive handling (F = 0.24, P> 0.05) on FS. The results of this study confirmed that the fire branding is aversive to the calves that responded increasing the speed at which they exited the squeeze chute. We concluded that the fire branding changes the behavioral response of calves to the handling and the restricted suckling is not able to reduce the higher reactivity caused by the exposition to aversive handlings.