EFFECT OF TRANSPORTATION ON CORTISOL CONCENTRATIONS AND ON THE CIRCADIAN-RHYTHM OF CORTISOL IN GILTS

Abstract

A study was conducted to determine whether the circadian rhythm of cortisol in gilts is disrupted or altered by transport. Ovariectomized gilts (16) with indwelling jugular catheters were individually penned in an enclosed building (location 1). Blood samples were collected at 0700 and 1900 h for 6 days. On day 7, gilts in groups of 4 were transported 5.6 km to environmentally controlled chambers (25 C) and were individually penned (location 2). On the day of transport, samples were collected at 0700 h at location 1, immediately before and after transport in a trailer, after unloading at location 2, and at 1900 h at location 2. For the first 6 days at location 2, blood samples were collected daily at 0700 and 1900 h. For the 6 days at location 1, circadian rhythm was evidenced by higher cortisol concentrations in the AM hours than in the PM hours. During transport, serum cortisol concentrations increased (P < 0.01). Highest concentrations developed at 0.5 h after unloading; concentrations declined thereafter. During the first 6 days at location 2, circadian rhythm was evidenced by higher serum cortisol concentrations in the AM hours than in the PM hours. Therefore, the transportation of gilts 5.6 km to new pens was a transient stress causing a temporary increase in serum cortisol concentrations, but did not cause a disruption in the endogenous rhythm of cortisol.