Seasonality of the stress response in goat bucks when there is use of electroejaculation for semen collection

Abstract

Electroejaculation (EE) is frequently used to collect semen, but this procedure is both stressful and painful. In seasonal-breeding species the sensitivity to stressors might vary with season of the year when semen collection occurs, therefore, the present study was conducted to compare the responses when imposing the EE procedure, stress response to EE and fresh semen characteristics in goat bucks throughout the year. Semen was collected using EE from goat bucks once in autumn (mid-breeding season), winter (transition to the non-breeding season), spring (non-breeding season), and summer (beginning of the breeding season). The number of pulses applied during ejaculation was larger in the autumn and spring than winter and summer months. The number of vocalizations/pulse while bucks were ejaculating was greater in the summer than winter and spring months. The increase in heart rate was greater in spring than summer months. Cortisol concentration was least in the autumn, and concentration of creatine kinase (CK) was greatest in summer. Sperm mass motility was greater in autumn than spring months. Spermatozoa concentration, total number of spermatozoa ejaculated, motile spermatozoa ejaculated, and progressively motile spermatozoa were greater in the autumn and spring than in the winter and summer months. The bucks were less stressed by imposing EE procedures in the autumn, and buck responses were greater in the spring-summer period. Bucks had a greater incremental increase in serum CK and number of vocalizations in the summer months, indicating there was a greater muscular damage and quite likely pain associated with lesser semen quality.