Effects of acclimation to handling on performance, reproductive, and physiological responses of Brahman-crossbred heifers

Abstract

The objective of this study was to evaluate the effects of acclimation to handling on growth, plasma concentrations of progesterone (P4) and cortisol, temperament, and reproductive performance of Brahman-crossbred heifers. Over 2 consecutive years, 37 Braford and 43 Brahman x Angus heifers were initially evaluated, within 30 d after weaning, for BW and puberty status via transrectal ultrasonography and plasma P4 concentrations (d 0 and 10), and for temperament by measurements of chute score, pen score, and exit velocity (d 10 only). On d 11, heifers were stratified by breed, puberty status, temperament score, BW, and age and randomly assigned to receive or not (control) the acclimation treatment. Acclimated heifers were exposed to a handling process 3 times weekly (Mondays, Wednesdays, and Fridays) for 4 wk (d 11 to 39 of the experiment). The acclimation treatment was applied individually to heifers by processing them through a handling facility, whereas control heifers remained undisturbed on pasture. Heifer puberty status, evaluated via plasma P4 concentrations and transrectal ultrasonography, and BW were assessed again on d 40 and 50, d 80 and 90, and d 120 and 130. Blood samples collected before (d 10) and at the end of the acclimation period (d 40) were also analyzed for plasma concentrations of cortisol. Heifer temperament was assessed again on d 40 of the study. No interactions containing the effects of treatment, breed, and year were detected. Acclimated heifers had reduced (P< 0.01) ADG compared with control heifers (0.50 vs. 0.58 kg/d, respectively). Attainment of puberty and pregnancy, however, was hastened (P = 0.02 and 0.04, respectively) in acclimated heifers compared with control. Acclimated heifers had reduced chute score (P < 0.01) and concentrations of cortisol (P < 0.01) and P4 (P = 0.03; prepubertal heifers only) compared with control heifers after the acclimation period (1.37 vs. 1.84 for chute score; 37.8 vs. 50.5 ng/mL of cortisol; 0.52 vs. 0.78 ng/mL of P4). Results from this study indicated that, although acclimation to handling decreased ADG, it resulted in decreased chute score, reduced plasma concentrations of cortisol and prepubertal P4, and enhanced reproductive performance of Brahman-crossbred heifers.

Effect of anabolic implants on adrenal cortisol synthesis in feedlot beef cattle implanted early or late in the finishing phase

“…Furthermore, recent studies examining the relationship between cortisol levels and anxiety behavior in beef cattle support the link between anxiety-related behavior and serum cortisol concentrations [25]. Additionally, increased cortisol release is reported in response to the social stress accompanying mixing beef cattle [26], while acclimated feeder cattle are reported to have reduced plasma cortisol compared with controls [27,28]. The data provided herein demonstrate that common production practices used in feeder cattle production can influence endogenous secretion of cortisol.…”

Effect of a topical anaesthetic formulation on the cortisol response to surgical castration of unweaned beef calves

“…This may reflect the stress of separation from mothers (Loberg et al, 2008), handling through a race, and restraint in a head bale (Cooke et al, 2009) before treatment. Cortisol concentration further increased from 0 to 0.5 h to reach a peak, with the rise more apparent in C and CTA calves than CON calves (Table 1).…”

GROWTH AND DEVELOPMENT SYMPOSIUM: Impacts of inflammation on cattle growth and carcass merit1,2

“…Because the APR can be stimulated by eortisol (Cooke and Bohnert, 2011), it might be diffieult to distinguish between increased concentrations of APP in response to animal handling vs. increased concentrations due to illness. It is clear that increased APP are associated with decreased ADG (Qui et al, 2007;Cooke et al, 2009), and the APR and inflammatory responses, regardless of initiator, likely alter metabolic function in a variety of tissues. Future studies are needed to determine how long the APR is sustained in ealves that naturally acquire BRD, and if the APR, inflammatory cytokines, or other mechanisms are responsible for long-term decreased growth and carcass characteristics.…”