Note: relationship between scrotal temperature and sperm morta lity of the New Zealand White rabbit
Eight mature New Zealand White bucks (3049 ± 247g líve weight) were randomly allocated to one of 4 groups in descending order of the density of their semen. Rabbits were raised at 20ºC except during a single short period of 8 hours when they were introduced in a climatic chamber (CC) regulated at 20ºC (control], 32ºC, 32ºC + infrared heating al 1,9MJ/m2/h or 34ºC (groups 1 to 4). Semen quality was evaluated before treatment and then once a week during 8 consecutive weeks. During the stay in the CC, scrotal temperature increased rapidly within the first hour. Average scrotal temperature increased (P < 0.05) with each shortterm environmental temperature increase: 34.1 º - 36.5º - 37.0º and 37.9ºC for groups 1 to 4 respectively. The maximum level of dead sperm was recorded at the first week after hotroom exposure in each of the 3 experimental groups. Between temperatures, the highest level of mortality (16.3%) was recorded in the 34ºC group, followed by 32ºC + i.r. and 32ºC (11.3 and 7.8%). lt was only 1 % in the control group. A total of 3 weeks after treatment was required for the incidence of sperm mortality to return to normal. As a whole, it can be concluded that the exposure of bucks to short-term high ambient temperature is followed by a significant degree of seminal degeneration.
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