Evidence for heterosis and maternal effects on rabbit semen characteristics

Abstract

The analysis concerned 546 ejaculates from 65 bucks from two strains ('1601', a duplicate of the 'Verde' strain from INIA-Valencia, Spain-and '2066' from INRA, France) and their two reciprocal crosses, recorded during a 210 day period spanning from August 1996 to February 1997. Two ejaculates were collected from each buck every three weeks and semen traits were recorded every six weeks when the semen was used for insemination. All semen traits were recorded for both ejaculates except concentration, which was recorded only for the ejaculate selected for insemination (the better of the two ejaculates for mass motility). On average, mass motility (scale of Petitjean, 1965 [24]) was 6.75 (standard deviation 1.01), pH 7.28 (0.33), volume 0.62 mL (0.19 mL), percent of motile spermatozoa (PMS) 70.1% (7.5%), concentration 492 10 6 spzmL -1 (142 10 6 ), the total number of spermatozoa per ejaculate (TSE) 321 10 6 (110 10 6 ) and the number of motile sperms per ejaculate (MSE) 231 10 6 (83 10 6 ). Both strains had similar performances except for the volume of the ejaculate (1601: 0.67 0.04 mL; 2066: 0.52 0.04 mL) and PMS (1601: 69.8 1.4%; 2066: 66.4 1.4%). There was a significant heterosis effect for concentration (37.5% of the parental average), mass motility (6.8%) and PMS (4.1%). Heterosis for the synthetic criteria TSE and MSE amounted to 37.6% and 42.3%, respectively. Strain differences in maternal effects were evidenced: strain 1601 exhibited favourable maternal effects on volume, PMS and mass motility. rabbit / semen / heterosis / maternal effects Rsum -Htrosis et effets maternels sur les caractristiques de la semence de lapin. L'analyse concerne 546 jaculats issus de 65 mles de deux souches ('1601', issue par duplication de la souche 'Verde'de l' INIA-Valencia, Espagne-et '2066'de l'INRA, France) et de leurs deux croisements rciproques, contrls pendant 210 jours entre aot 1996 et fvrier 1997. Les mles sont prlevs toutes les 3 semaines (2 jaculats), mais les caractristiques de la semence sont mesures toutes les 6 semaines, lors de l'insmination. Tous les caractres sont contrls sur les 2 jaculats sauf la concentration, mesure uniquement sur l'jaculat slectionn pour l'insmination (le meilleur des 2 sur la motilit 433