Semen evaluation of two selected lines of rabbit bucks

[EN] Twenty rabbit bucks of 9 months of age were used to evaluate semen quality of two lines of New Zealand rabbit bucks selected for litter size at weaning (A line) and growth rate from weaning to slaughter (R line). The morphological semen characteristics indicated that the A line spermatozoa had greater acrosome integrity (+3.6 percentage units; P<0.01) and smaller sperm head size (for example, ¿1.46 ¿m2 for sperm head area) than in the R line. Seminal functional traits were also significantly higher for the A line (+13.4 percentage units for viability, +10.6 percentage units for hypo-osmotic swelling test (HOST) and +3.3 g/L for seminal plasma protein. However, no differences were detected between lines for motility parameters and seminal plasma protein electrophoretic profiles. Both lines had the same twelve bands with the following molecular weights to the nearest 1 kD: 124, 117, 99, 86, 75, 62, 40, 32, 21, 19, 10 and 6 kD. A relationship (r=0.308 for A line and 0.359 for R line; P<0.01) was found between the integrity of the plasmatic membrane (viability rate) and tail membrane (HOST) of the spermatozoa in the A line, but not in the R line, which had greater sperm head size. There was also a significant positive correlation coefficient between sperm concentration and either viability or some kinetic traits (r=0.567 and 0.575 for VCL, r=0.584 and 0.561 for VSL and r=0.588 and 0.588 for VAP, for A and R lines, respectively; P<0.001). We concluded that the A line seems to have better semen characteristics than the R line. We also found an interesting correlation among the seminal morphological, functional and kinetic traits, which could possibly be used to facilitate semen evaluation.Hosam M. Safaa was supported by a grant from ICSC-World Laboratory, Switzerland. This work has been supported by the Spanish Research Project (CICYT AGL2004-02710/GAN). The authors are indebted to F. Marco-Jiménez, Universidad Politécnica de Valencia, Valencia, Spain, and G.M.K. Mehaisen, Department of Animal Production, Faculty of Agricultural, Cairo University, Giza, Egypt, for their excellent cooperation throughout this study and to D.A.A. El-Sayed, Faculty of Agricultural, Cairo University, Giza, Egypt, for her help in preparing the manuscript.Safaa, H.; Vicente, J.; Lavara, R.; Viudes De Castro, M. (2008). Semen evaluation of two selected lines of rabbit bucks. World Rabbit Science. 16(3). doi:10.4995/wrs.2008.62216

Does the inclusion of protease inhibitors in the insemination extender affect rabbit reproductive performance?

[EN] The bioavailability of buserelin acetate when added to the seminal dose appears to be determined by the activity of the existing aminopeptidases. Thus, the addition of amino peptidase inhibitors to rabbit semen extenders could be a solution to decrease the hormone degradation. This study was conducted to evaluate the effect of the protease activity inhibition on rabbit semen quality parameters and reproductive performance after artificial insemination. Seminal quality was not affected by the incubation with protease inhibitors, being the values of motility, viability, and acrosome integrity not significantly different between the protease inhibitors and the control group. In addition, seminal plasma aminopeptidase activity was inhibited in a 55.1% by the protease inhibitors. On the other hand, regarding the effect of protease inhibitors on reproductive performance, our results showed that the presence of protease inhibitors affected the prolificacy rate (9.2 +/- 0.26 and 9.3 +/- 0.23 vs. 8.2 +/- 0.22 total born per litter for negative control, positive control, and aminopeptidase inhibitors group, respectively; P < 0.05), having this group one kit less per delivery. We conclude that the addition of a wide variety of protease inhibitors in the rabbit semen extender negatively affects prolificacy rate. Therefore, the development of new extenders with specific aminopeptidase inhibitors would be one of the strategies to increase the bioavailability of GnRH analogues without affecting the litter size. (C) 2016 Elsevier Inc. All rights reserved.This research was supported in part by the RTA2013-00058-00-00 from INIA, the European Social Fund and the European FEDER Funds. L Casares-Crespo is supported by a scholarship from Institute Valenciano de Investigaciones Agrarias (IVIA) and the European Social Fund.Casares-Crespo, L.; Vicente Antón, JS.; Talavan, A.; Viudes De Castro, MP. (2016). Does the inclusion of protease inhibitors in the insemination extender affect rabbit reproductive performance?. Theriogenology. 85(5):928-932. doi:10.1016/j.theriogenology.2015.10.044S92893285

EFFECT OF SYNTHETIC PROSTAGLANDIN F2ct ANALOGUE (CLOPROSTENOL) ON LITTER SIZE AND WEIGHT IN A RABBIT LINE SELECTED BY GROWTH RATE

[EN] The effect of a treatment with a synthetic analogue of prostaglandin F2a (cloprostenol) administrated intramuscularly on day 28 of pregnancy in does belonging to a synthetic rabbit line selected by growth rate (line R) was studied. A reduction in gestation length was observed after treatrnent with prostaglandins (31.3±0.1 vs 32.4±0.1 days, for treated and control groups, respectively, P<0.05). Litter size at birth, and live-born pups were not affected by the treatment. Individual weight of young rabbits at birth was significantly different between treatrnent groups (52±1 vs 58±1 g, in treatment and control group respectively, P<0.05). In the control group, young rabbits born from multiparous does were heavier than those from pnm1parous (53±2 vs 63±1 g, in primiparous and multiparous does respectively, P<0.05). There were not differences in birth weight of kits from treated multiparous and primiparous does. At weaning, individual weight was not affected by treatrnent (578±12 and 561±10 g, in control and treatment group respectively), and differences were observed in reproductive status (513±12 vs 626±9 g, in primiparous and multiparous does respectively, P<0.05). An increase in mortality was observed during lactation period after treatrnent with PGF2a (48% vs 26%, in cloprostenol and control group respectively, P<0.01).[FR] L'objet de ce travail est d'étudier l'effet de l'injection intramusculaire d'un analogue synthétique de la prostaglandine PGF2a {Cloprostenol) au 28éme jour de gestation a des lapines appartenant a une lignée synthétique sélectionnée sur la vitesse de croissance {lignée R). La durée de 9estation est réduite aprés traitement avec les prosta9landines (31.3±0.1 vs 32.4±0.1 jours, respectivement pour le lot traité et le lot témoin, P<0.05). La taille de portée a la naissance et le nombre de nés vivants ne sont pas modifiés par le traitement. Le poids individue! des jeunes lapereaux a la naissance est si9nificativement différent entre les lots (52±1 vs 58±19, respectivement pour le lot traité et le lot témoin, P<0.05). Dans le lot témoin, les jeunes lapereaux nés de lapines multipares sont plus lourds que ceux issus de primipares (53±2 vs 63±19, respectivement pour les primipares et les multipares, P<0.05). Dans le lot traité, le poids des lapereaux a la naissance ne varie pas selon qu'ils sont issus de lapines multipares ou primipares. Au sevra9e, le poids individue! des lapereaux n'est pas modifié par le traitement (578±12 et 561±109, respectivement pour le lot témoin et le lot traité) mais des différences sont observées selon la parité des lapines (513±12 vs 626±9g, respectivement pour les primipares et les multipares, P<0.05). Cependant, le traitement avec PGF2., s'accompa9ne d'une au9mentation de la mortalité pendan! la lactation (48% vs 26%, respectivement pour le lot traité au Cloprostenol et le lot témoin, P<0.01 ).This work was supported by CICYT project nº AGL2000-0595-C03-01. The authors thank Mr. Neil Macowan for revising the English versionLavara, R.; Viudes-De-Castro, M.; Vicente, J.; Mocé, E. (2002). EFFECT OF SYNTHETIC PROSTAGLANDIN F2ct ANALOGUE (CLOPROSTENOL) ON LITTER SIZE AND WEIGHT IN A RABBIT LINE SELECTED BY GROWTH RATE. World Rabbit Science. 10(1). https://doi.org/10.4995/wrs.2002.470SWORD10