Sedation or anaesthesia decrease the stress response to electroejaculation and improve the quality of the collected semen in goat bucks

Abstract

Electroejaculation (EE) is stressful and probably painful; thus the administration of anaesthesia is recommended to decrease those negative effects. However, anaesthesia has a direct risk of provoking death, but sedation is less risky than anaesthesia. At the same time, α2-adrenergic agonists may improve semen quality. Therefore, the aim of the present study was to compare the physiological and behavioural responses indicative of stress and possibly pain, and the semen quality in electroejaculated untreated, anaesthetised or sedated goat bucks. Semen was collected from eight bucks using three different procedures in all them (EE in untreated bucks, EE under sedation or EE under general anaesthesia). The number of vocalizations during EE and the behavioural pattern before and after procedures were recorded. Pain visual analogue scale (VAS) score was also determined during EE. Rectal temperature, heart rate, serum cortisol concentration, biochemical and haematological parameters were measured before and after each procedure, and sperm characteristics were determined. Bucks vocalised more often when untreated than sedated or anaesthetised (P<0.02). The pain VAS score was greater when bucks were untreated than sedated or anaesthetised (P<0.002). The rectal temperature, heart rate, total protein, albumin and haemoglobin concentrations were greater when bucks were untreated than anaesthetised or sedated (P<0.02). Serum cortisol increased after EE (P=0.0006), without differences between procedures. The frequency and duration of lying down after EE were greater when bucks were anaesthetised than sedated or untreated (P<0.05), and were also greater when bucks were sedated than untreated (P<0.05). The number of times that the animal tried to stand up after EE was greater when bucks were anaesthetised than sedated or untreated (P<0.02). The sperm mass motility was greater when bucks were anaesthetised or sedated than when they were untreated (P=0.048). When animals were sedated, the ejaculate contained more spermatozoa with functional plasma membrane (P=0.03) and morphologically normal (P=0.05) than when they were untreated. In conclusion, general anaesthesia and sedation decreased the stress and probably the pain response provoked by EE and especially sedation improved the quality of the semen collected.