Effect of electro-ejaculation on the serum cortisol response of Criollo goats (Capra hircus)

Abstract

Concern has been expressed on animal welfare in the use of electro-ejaculation (EE) as a semen collection technique. Furthermore, even though breed differences in stress response have been demonstrated in goats, a lack of background information characterizes the Criollo genotype. Therefore, in the present experiment, changes in concentrations of serum cortisol in serial blood samples were used to quantify stress response to EE in Criollo goats. Twenty intact Criollo bucks aged 1.5-3 years and weighing between 33 and 40 kg were randomly assigned to one of two treatments: bucks that were electro-ejaculated (T1) compared to males that a rectal probe was inserted without EE (T0). Blood samples were collected by venipuncture at 0 (immediately before inserting the rectal probe), 20, 40, 60 and 90 min after the onset of the experiment. To compare blood cortisol concentrations between treatments and the sequential data recorded on the same set of animals, a repeated measures analysis of variance model was used. The increases in concentrations of serum cortisol were significantly higher (P < 0.05) for EE animals in comparison with the T0 group, 20 min after EE (10.76 +/- 4.45 and 2.93 +/- 0.83 ng/ml in T1 and T0, respectively) and then declined to pre-EE levels 40 min post-EE (2.86 +/- 1.06 and 2.00 +/- 0.00 ng/ml for T1 and T0, respectively). It could be concluded that a > 350% increase in serum cortisol concentration 20 min after EE indicates an acute stress response despite the peak values being only slightly above the basal serum cortisol levels found in other goat breeds. (c) 2006 Elsevier B.V. All rights reserved.