Once deposited in the female tract, sperm face a series of challenges that must be overcome to ensure the presence of an adequate normal sperm population close to the site of fertilization. Our aim was to evaluate the influence of the uterine milieu on boar sperm morphology. In experiment 1, sperm morphology was evaluated in the backflow (60 min after insemination) and within the uterotubal junction (UTJ) (collected ~24 h after insemination) following intrauterine sperm deposition (n = 6) and compared with the morphology of the sperm in the insemination dose. In experiment 2, the influence of the uterine fluid (UF) on sperm morphological modifications was evaluated. For this purpose, ejaculated (n = 4) and epididymal (n = 4) sperm were in vitro incubated with or without UF for 2 and 24 h. In both experiments, sperm were classified as normal, having a cytoplasmic droplet (proximal or distal) or having tail defects. The results of experiment 1 pointed to an increase in morphologically abnormal sperm collected in the backflow (27.70%) and a reduction of the same in the UTJ (2.12%) compared with the insemination dose (17.75%) (P < 0.05). In experiment 2, incubation of ejaculated sperm with UF did not provoke any morphological modifications; however, when epididymal sperm were incubated with UF, a pronounced increase in the percentage of normal sperm was evident after 24 h compared with the initial dose (from 25.77% to 53.58%, P < 0.05), mainly due to distal cytoplasmatic droplet shedding (53.22 vs. 20.20%). In conclusion, almost all the sperm that colonize the UTJ had a normal morphology, with part of the abnormal sperm having been discarded in the backflow and part selected/modified on their way to the oviduct. UF seems to influence cytoplasmic distal droplet removal, as demonstrated previously in seminal plasma.

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.

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Electroejaculation procedures (EEPs) provoke stress; nevertheless, ejaculation produces physiological changes similar as those usually used to measure stress responses. The application of EEP to animals that cannot ejaculate-as ewes-may be useful to discriminate the responses induced by ejaculation from those provoked by EEP. The aim was to determine the stress response to EEP in rams and ewes. The EEPs were applied to 10 rams and 10 ewes during the non-breeding season, and the number of vocalizations, the heart rate, rectal temperature, serum cortisol concentration, biochemical and haematological parameters were measured. Overall, EEP provoked increases in cortisol concentration, glycaemia, rectal temperature and concentration of creatine kinase (all them: p < .0001) as well as relative concentration of granulocytes (p = .003) and absolute granulocyte concentration (p = .0002) in both, rams and ewes. Heart rate, relative concentration of lymphocytes (p = .001), haematocrit (p = .02) and haemoglobin (p = .045) decreased in animals from both genders after EEP. Besides, cortisol (p < .0001), rectal temperature (p = .002) and glycaemia (p = .001) were greater in ewes than rams, and creatine kinase also tended to be greater in ewes than rams (p = .054). On the other hand, the number of animals that vocalized (p = .006), white blood cells (p = .02) and absolute lymphocytes (p = .02) were greater in rams than ewes. The general trends show a similar pattern of stress responses in animals from both genders. Therefore, we concluded that ejaculation does not contribute to the stress response provoked by the EEP. This procedure also provokes muscular damage and probably pain.