Abstract
Seven mature boars and 8 peripubertal boars were used to study the effects of elevated testicular temperature. The scrotum of the boars was covered by a textile-aluminium foil insulation device for 100 hours. Insulation of the scrotum in the peripubertal boars took place at an age of 100 days. Pronounced changes in sperm characteristics, e.g. decreased sperm motility and high numbers of proximal cytoplasmic droplets, abnormal sperm head shapes and abnormal acrosomes, were seen during week 3 to 5 after scrotal insulation in the mature boars. An "immature" semen picture, i.e. low sperm motility, low total sperm count and high numbers of proximal cytoplasmic droplets and abnormal sperm head shapes, was seen in the first ejaculates in the peripubertal experimental boars. The semen picture was normal in the control boars. A maturation of the semen picture over time was seen in the experimental boars. However, remaining abnormalities in the sperm morphology together with the testicular histology indicate lasting pathological changes in the testes.