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 × 106 spz·mL-1 (142 × 106), the total number of spermatozoa per ejaculate (TSE) 321 × 106 (110 × 106) and the number of motile sperms per ejaculate (MSE) 231 × 106 (83 × 106). 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.