Relationships between rabbit semen characteristics and fertilising ability after insemination

Abstract

This study aimed to analyse the relationship between rabbit semen characteristics and semen fertilising ability after insemination, which is generally found to be weak. Our hypothesis was that using high semen dilutions (1 : 19), non-oestrus-stimulated does, and homospermic inseminations would make it easier to predict semen fertilising ability. Semen characteristics were evaluated on 275 ejaculates of 128 INRA1001 bucks, distributed into five successive batches. A total of 1970 inseminations were performed. The continuous semen variables were subdivided into three classes of similar size to account for any non-linear relationship between semen characteristics and fertilising ability. Mass motility was divided into two classes according to the presence or absence of waves under microscope observation. Libido, the presence or absence of gel, volume, percentage of progressive sperms, curvilinear velocity, beat frequency of the flagellum, and straightness and linearity of sperm movement did not affect fertility, prolificacy or productivity. It was confirmed that mass motility, estimated by visual observation under the microscope, significantly influenced fertility as well as the percentage of motile and of rapid sperms, and the amplitude of lateral head displacement, estimated by a computer-assisted semen analysis system. To a lesser extent, the percentage of motile cells and of rapid cells significantly influenced prolificacy. Consequently, mass motility and the percentage of motile cells significantly influenced rabbit doe productivity (+1 live births/AI when the semen showed at least a beginning of wave movement, or when the percentage of motile cells was >84%). Interestingly, a gain of 1.5 rabbits was observed when the percentage of rapid cells changed from 64% to 79%, whereas productivity significantly dropped beyond 83% of rapid cells, reflecting a non-linear relationship.Keywords: rabbit, semen characteristics, fertilising ability ImplicationsThe relationship between rabbit semen characteristics and semen fertilising ability is generally found to be weak. Nevertheless, our results obtained using a high dilution and homospermic inseminations on rabbit does not stimulated for oestrus show that a simple selection on mass motility allows increasing productivity by one rabbit born alive per insemination, when the semen shows at least a beginning of wave movement. Moreover, computer-assisted semen evaluation provides additional markers of fertilising ability (such as the percentage of rapid sperms, and the amplitude of lateral head displacement) possibly non-linearly related to fertilising ability.

Can feed supplementation of the refined vegetable oils enhance the seminal quality of rabbit bucks (Oryctolagus cuniculus)?

“…This conclusion was actually based on the analytical findings of the seminal samples collected once a week from rabbit bucks fed on ration treated with soybean and sunflower oils. According to Castellini and Lattaioli (1999), estimating semen quality is important in determining the reproductive efficiency in rabbit bucks, where it has been documented to be correlated with sperm fertilizing ability (Castellini et al, 2000;Brun et al, 2002;Hagen et al, 2002;Castellini, 2007;Piles et al, 2013;Theau-Clément et al, 2016). The present data indicated that semen collected from rabbit bucks supplemented with vegetable oils had higher sperm concentration, total sperm output, percentage of motile sperms, as well as lower percentages of dead and altered acrosomal sperms than the control bucks.…”

Artificial insemination in rabbits: factors that interfere in assessing its results

“…According to Araujo et al (2013), using suitable insemination dose and dilution rate are very important because very small volumes may result in less effective mechanical drainage, while highly concentrate semen may be more irritating because of more contacts between spermatozoa and endometrium, resulting in an intense inflammatory response. Theau-Clément et al (2016) showed that the presence or absence of gel, volume, percentage of progressive sperms, curvilinear velocity and beat frequency of the flagellum, did not affect fertility or productivity of inseminated INRA1001 rabbit doe. However, mass motility and the percentage of motile cells (>84%) significantly influenced rabbit doe productivity, but there was a non-linear relationship.…”

Antimicrobials in a rabbit semen extender: effects on reproduction

“…The main factors related to the quality of the semen are fertility in females (proportion of pregnant females after AI), and prolificacy (number of offspring per litter), as pointed out by IRRG (2005). Indeed, a correlation between sperm motility, concentration and female reproductive performance has been demonstrated in several studies (Brun et al, 2002;Theau-Clément et al, 2016).…”

“…The other 8.5 mL of the semen pools were used to carry out the insemination doses in 0.5 mL straws (IMV Technologies, L'Aigle, France) with a total of around 24 million sperm cells per dose (484.5±122.2 million spermatozoa/mL in raw ejaculates) (Theau-Clément et al, 2016). Doses were prepared only from semen pools with a total motility above 70% (Daniel and Renard, 2010) and diluted in the medium with the original antibiotic composition (original) or new antibiotic composition (gentamicin 0.3 g/L; New).…”