THE EFFECT OF FREQUENCY OF EJACULATION ON SEMEN CHARACTERISTICS AND SPERM OUTPUT THE RABBIT [French]

摘要

The aim of this work was to assess the effect of ejaculation frequency on a set of semen characteristics including massal and individual motility percentage of live spermatozoa, semen volume, concentration, number of live or total spermatozoa per ejaculate. Two experiments were carried out at the station of animal genetics (Toulouse, France). In a first experiment, an extensive frequency (2 ejaculates about 15 mn apart once a week) was compared to an intensive one (2 ejaculates on Monday, Wednesday and Friday). This experiment lasted 52 weeks; 12 and 9 males, respectively, were included in the analysis. In the 2nd experiment, which lasted 14 weeks, the same extensive frequency was compared with an intermediate one (2 successive ejaculates on Tuesday and Friday). The number of males used in the analysis was, respectively, 14 and 13. Motility and percentage of live spermatozoa were estimated using an optic microscope. Concentration was determined by the Hemocytometer method. Standard procedures of SAS were used for the calculations of the linear correlations between traits, the comparison of means using the T-test, and maximum likelihood estimation of components of variance for the within-buck repeatability of traits. All the traits of the ejaculate were significantly improved (P < 0.01) by the extensive frequency when compared to the intensive or intermediate ones (tables I, II); for example, sperm number per ejaculate was, respectively, 136 and 65% greater. Nevertheless, the weekly sperm cutout was greater (P < 0.01) when the ejaculation frequency was intermediate or intensive (tables VI, VII), but the increase did not exceed about 28% compared with the extensive one. The correlation coefficients (table III) showed that the increase of semen concentration improved sperm motility (r = 0.57). The values of within-buck repeatability differed with ejaculation frequency (tables IV, V). The repeatability of motility and percentage of live spermatozoa was greater with intermediate or intensive frequency, whereas the repeatability of semen volume, concentration, and sperm number per ejaculate was greater with the extensive frequency.