High plasmatic progesterone levels at insemination depress reproductive performances of rabbit does

The aim of this experiment was to quantify the frequency of the high progesterone syndrome at the moment of insemination and to study the influence of progesterone level (P4) on receptivity and reproductive performances of primiparous and secondiparous rabbit does. A total of 422 primiparous INRA 0067 were inseminated twice at an interval of 42 days. Prior to artificial insemination (AI), sexual receptivity of the does was tested in the presence of a vasectomised buck and, just after AI, blood samples were collected to determine progesterone concentration by RIA. The mean plasma progesterone concentration was 1.8\ub13.4 ng/ml and significantly depended on parity (primiparous: 2.2\ub13.7 ng/ml, secondiparous: 0.9\ub12.2 ng/ml, P<0.001). At the following AI, 78% of pseudopregnant rabbit does returned to the basal level of oestrous condition, demonstrating that the pseudopregnancy is a reversible process. The overall percentage of pseudopregnant does (P4 651 ng/ml) was 25.9%, but it was differently (P<0.001) distributed between primiparous (31.2%) and secondiparous does (12.2%). Moreover, primiparous lactating females were more frequently pseudopregnant than non-lactating ones (36.5 vs. 18.9% respectively, P<0.001). The progesterone level of primiparous does was related to the lactation status (2.5\ub13.8 vs. 1.5\ub13.2 ng/ml, respectively for lactating and non-lactating, P<0.001). The receptivity was highly related to the level of progesterone (P4<1: 74.1%, 1 64P4<6: 79.1% vs. P4>6: 56.3%, P=0.006). Also the kindling rate was significantly influenced by progesterone concentrations. Non-pseudopregnant does (P<1 ng/ml) had the highest fertility rate (79.0%) but when the progesterone concentration increased from 1 64P4<6 to P4>6 ng/ml, the fertility decreased from 68.1 to 37.4%, respectively (P<0.001). Consequently, the productivity at birth was highly depressed when the progesterone level was over 6 ng/ml (9.5 and 8.6 vs. 4.5 number of born alive rabbits/AI, for P4<1, 1 64P4<6 and P4>6 respectively, P<0.001). The productivity of pseudopregnant and nonreceptive females was very poor in comparison with pseudopregnant receptive does (0.4 vs. 9.5 born alive rabbits/AI). The productivity at birth was also highly (P<0.001) influenced by the physiological status of the does. Primiparous non-lactating does produced the highest number of born alive rabbits/AI, whereas primiparous lactating does had the lowest productivity at birth (9.9 vs. 5.6), secondiparous lactating being intermediate (7.1). In conclusion, the high progesterone syndrome evaluated at the moment of insemination occurred in 25.9% of females and had a strong negative impact on receptivity and reproductive performance of rabbit does

Reproductive performance of male rabbits of algerian local population

[EN] A total of 267 rabbit does and 46 bucks from a local Algerian population were controlled during 6 generations (from G0 to G5) at the experimental farm of the University of Tizi-Ouzou. Natural mating was used and 1412 presentations were analysed. Reproductive and growing performance were analysedtaking into account the effect of the buck, its age, the generation, the season of mating (or kindling) and the physiological status of does at the moment of the mating. The buck influenced the acceptance rate(P<0.001), kindling rate (P=0.032), litter size at birth and at weaning (P<0.001), litter weight at birth (P<0.001)and at weaning (P=0.034), the mean weaning weight (P=0.018) and consequently the ponderal productivity at weaning (weight of rabbits produced at weaning/mating, P<0.001). Nevertheless, the ponderal productivity was also influenced by the age of bucks, the generation, the season and the physiological status of does at the moment of mating. The highest acceptation rate was recorded in autumn in non lactating does (primiparous and multiparous). Productivity was higher for bucks 5-10 mo old but decreased thereafter.Productivity was higher in spring, particularly for multiparous and lactating does and highly varied with the generation, evidencing the importance of environmental conditions.Dj, C.; M, T.; N, Z.; M, B. (2013). Reproductive performance of male rabbits of algerian local population. World Rabbit Science. 21(2):91-99. doi:10.4995/wrs.2013.1173.SWORD919921

Selection for ovulation rate in rabbits: Direct and correlated responses estimated with a cryopreserved control population1

The aim of this work was to evaluate the response in 10 generations of selection for ovulation rate in rabbits using a cryopreserved control population. Selection was based on the phenotypic value of ovulation rate estimated at d 12 of second gestation by laparoscopy. To produce the control population, embryos from 50 donor females and 18 males, belonging to the base generation of the line selected for ovulation rate, were recovered. A total of 467 embryos (72-h embryos) were vitrifi ed and stored in liquid N2 for 10 generations. The size of both populations was approximately 10 males and 50 females. The number of records used to analyze the different traits ranged from 99 to 340. Data were analyzed using Bayesian methodology. A difference between the selected and the control populations of 2.1 ova (highest posterior density interval (HPD95%) [1.3, 2.9]) was observed in ovulation rate (OR), but it was not accompanied by a correlated response in litter size (LS; &#8722;0.3; HPD95% [&#8722;1.1, 0.5]). The number of implanted embryos (IE) increased with selection in 1.0 embryo (HPD95% [&#8722;0.6, 2.0]), but this increase was not relevant. Prenatal survival, embryonic survival, and fetal survival (FS) were calculated as LS/OR, IE/OR, and LS/IE, respectively. Prenatal survival was reduced with selection (&#8722;0.12; HPD95% [&#8722;0.20, &#8722;0.04]), basically because of a decrease in FS (&#8722;0.12; HPD95% [&#8722;0.19, &#8722;0.06]). Embryonic survival could have slightly decreased (&#8722;0.05; HPD95% [&#8722;0.12, 0.02]). In summary, comparison with a control population showed that ovulation rate in rabbits increased with selection without any correlated response in litter size, basically because of a decrease in fetal survival.This study was supported by the Comision Interministerial de Ciencia y Tecnologia CICYT-AGL2005-07624-C03-01 and by funds from the Generalitat Valenciana research program (Prometeo 2009/125). The authors are grateful to Wagdy Mekkawy for letting us use his programs.Laborda Vidal, P.; Santacreu Jerez, MA.; Blasco Mateu, A.; Mocé Cervera, ML. (2015). Selection for ovulation rate in rabbits: Direct and correlated responses estimated with a cryopreserved control population1. Journal of Animal Science. 90(10):3392-3397. https://doi.org/10.2527/jas.2011-4837S33923397901

Genetic selection for ovulation rate and litter size in rabbits: estimation of genetic parameters and direct and correlated responses

The aim of this work was to estimate direct and correlated responses in survival rates in an experiment of selection for ovulation rate (OR) and litter size (LS) in a line of rabbits (OR_LS). From generation 0 to 6 (first selection period), females were selected only for second gestation OR estimated by laparoscopy. From generation 7 to 13 (second selection period), a 2-stage selection for OR and LS was performed. In stage 1, females having the greatest OR at second gestation were selected. In stage 2, selection was for the greatest average LS of the first 2 parities of the females selected in stage 1. Total selection pressure in females was about 30%. The line had approximately 17 males and 75 females per generation. Traits recorded were OR estimated as the number of corpora lutea in both ovaries, number of implanted embryos (IE) estimated as the number of implantation sites, LS estimated as total number of rabbits born recorded at each parity, embryo survival (ES) estimated as IE/OR, fetal survival (FS) estimated as LS/IE, and prenatal survival (PS) estimated as LS/OR. Data were analyzed using Bayesian methodology. The estimated heritabilities of LS, OR, IE, ES, FS, and PS were 0.07, 0.21, 0.10, 0.07, 0.12, and 0.16, respectively. Direct and correlated responses from this study were estimated in each period of selection as the difference between the average genetic values of last and first generation. In the first selection period, OR increased 1.36 ova, but no correlated response was observed in LS due to a decrease on FS. Correlated responses for IE, ES, FS, and PS in the first selection period were 1.11, 0.00, -0.04, and -0.01, respectively. After 7 generations of 2-stage selection for OR and LS, OR increased 1.0 ova and response in LS was 0.9 kits. Correlated responses for IE, ES, FS, and PS in the second selection period were 1.14, 0.02, 0.02, and 0.07, respectively. Two-stage selection for OR and LS can be a promising procedure to improve LS in rabbits.This study was supported by the Comision Interministerial de Ciencia y Tecnologia CICYT-AGL2005-07624-C03-01 CICYT-AGL2008-05514-C02-01 and by funds from Generalitat Valenciana research programme (Prometeo 2009/125).Ziadi, C.; Mocé Cervera, ML.; Laborda Vidal, P.; Blasco Mateu, A.; Santacreu Jerez, MA. (2013). Genetic selection for ovulation rate and litter size in rabbits: estimation of genetic parameters and direct and correlated responses. Journal of Animal Science. 91(7):3113-3120. https://doi.org/10.2527/jas.2012-6043S3113312091

EFFECT OF A SYSTEMATIC PMSG TREATMENT 48 HOURS BEFORE ARTIFICIAL INSEMINATION ON THE PRODUCTIVE PERFORMANCE OF RABBIT DOES

[EN] A total of 148 multiparous rabbit does were distributed into two equal groups. Two days before insemination, the animals of the treated group received 25 IU of PMSG (Ciclogonine PROCHENA). The animals of the control group received no injection. At the end of the 9-month experiment, the does went on breeding according to the same protocol (artificial insemination (Al] 10-11 days after each kindling), except injections of PMSG, in order to study the possible remanent effects of the treatment. This postexperimental stage !asted for 7 months. During the experiment, PMSG improved the percentage of receptiva does (72.0 vs 38.4 %, P = 0.001) and its efficiency was not reduced with time; the percentage of kindling through Al was however improved only far the first tour inseminations (78.7 vs 66.2 %, P = 0.024), PMSG treatment was without significant effect far the following inseminations. Moreover, PMSG significantly improved the fertility of the lactating does at the time of insemination (+ 18.4 %) but did not improve the fertility of the non lactating does (+ 1.3 %). PMSG treatment improved the number of total born young per kindling by 7.4 % but, for a similar level of receptivity, the treatment did not improve the numerical productivity but decreased the mean weight at weaning (658.4 vs 674.9 g, P = 0.044). PMSG treatment made it possible to improve the global productivity of the rabbit does (number of weaned young per insemination) by + 28.4 % following the first tour inseminations; there was no improvement far the following inseminations. The improvement of this criterium depended on the physiological stage of the does at the time of insemination. In lactating does indeed the increase in the number of weaned young per insemination in the treated does persisted throughout the trial (beginning: + 44.6 %, end: + 48.0 %) while the molecule had no effect on the non lactating does whatever the experimental stage. The use of PMSG in non lactating does is thus unjustified. lt was also demonstrated that when treatment was over the productivity of the does which were previously treated was identical to that of the control group.[FR] Cent quarante huit tapines multipares ont été également réparties en 2 lots. Deux jours avant insémination, les tapines du lot traité (lot PMSG) recevaient 25 U./. de PMSG (Ciclogonine Prochena). Les tapines du lot témoin ne recevaient aucune injection. A /'issue de la période expérimentale de 9 mois, le troupeau a continué de produire selon le meme protocole (/A 10-11 jours apres chaque mise bas), a l'exclusion des injections de PMSG, afín d'étudier les éventuels arrieres effets du traitement. Cette phase post expérimenta/e a duré . 7 mois. Au cours de la période expérimentale, la PMSG a amélioré le pourcentage de tapines réceptives (72,0 vs 38,4 %, P = 0,001) sans réduction d'efficacité avec le temps ; par contre, le pourcentage de mises bas par /A a été amé/ioré uniquement sur /'ensemble des 4 premieres inséminations (78,7 vs 66,2 %, P = 0,024), le traitement par PMSG est resté sans effet significatif ensuite. Par ailfeurs, la PMSG a amélioré significativement la fertilité des tapines allaitantes au moment de l'insémination (+ 18,4 %}, mais pas ce/le des tapines non allaitantes (+ 1,3 %). Le traitement par PMSG a amélioré de 7,4% le nombre de /apereaux nés totaux par mise bas, mais a niveau de réceptivité identique, il n'a pas amélioré la productivité numérique mais il a diminué te poids moyen au sevrage (658,4 vs 674,9 g, P = 0,044). Le traitement par PMSG a permis d'améliorer de + 28,4 % la productivité globale des tapines (nombre de /apereaux sevrés par /A) a la suite des 4 premieres inséminations ; il n'y pas eu d'amélioration pour les inséminations suivantes. Cependant, l'amélioration de ce critere dépend du stade physiologique des tapines au moment de l'insémination. En effet, chez les tapines a/laitantes, l'amélioration du nombre de /apereaux sevrés par insémination chez les tapines traitées est démontrée tout au long de l'expérience (début: + 44,6 %, fin : + 48,0 %) a/ors que chez les tapines non allaitantes, la molécule est sans effet significatif que/fe que soit la phase expérimenta/e. L'utilisation de PMSG chez les tapines non af/aitantes n'est done pas justifiée. ll a été enfin démontré qu'apres arret du traitement, la productivité des tapines antérieurement traitées, ne differe pas de ce/le des tapines du lot témoin.Theau-Clement, M.; Lebas, F. (1996). EFFECT OF A SYSTEMATIC PMSG TREATMENT 48 HOURS BEFORE ARTIFICIAL INSEMINATION ON THE PRODUCTIVE PERFORMANCE OF RABBIT DOES. World Rabbit Science. 04(2). doi:10.4995/wrs.1996.270SWORD04

EFFECT OF THE GENOTYPE, DAY LENGTH, SEASON AND PHYSIOLOGYCAL STAGE ON THE REPRODUCTIVE PERFORMANCE OF DOE RABBITS REARED IN GUADELOUPE (F.W.I.)

[EN] The aim of this study was to compare under tropical climate conditions the reproductive performance of doe rabbits as affected by the genotype (NZ vs NZXCAL), lighting conditions (11 h of natural light + 5h of artificial light per day vs 11 h of natural light), the season (hot and wet vs cool and dry) and the physiological stage (nursing or non nursing females at mating ). A total of 272 matings were analysed. Fertility was not affected by any of these factors. The litter size of crossbred females (NZXCAL) was higher than that of purebred ones (NZ) (8.2 vs 7.1; P<0.05). However, this superiority was only observed during the dry and cool season (P<0.05). The analysis also showed the effects of significant interactions between the genotype and the physiological stage for the mean live weight at weaning (P<0.01 ). lncreasing the day length enhanced the litter size at birth (8.4 vs 6.9; P<0.001) and at weaning (6.6 vs 5.5; P<0.05). However, the beneficia! effect of lighting conditions was only observed during a dry and cool birth season (P<0.05). The wet and hot season (May-November) had an unfavourable effect on the litter size at birth and at weaning (7.1 vs 8.2; P<0.05 and 5.5 vs 6.6; P<0.05). Moreover, the physiological stage affected the mean birth weight of the young, the mortinatality and the post-natal mortality. lt was concluded that the genotype and lighting conditions were efficient means of improving the reproductive performance of doe rabbits during the dry and cool season in a tropical environment. However, they were not sufficient to counterbalance the unfavourable effects of the wet and hot season.[FR] L'objectif de cette étude est de comparer, en milieu tropical, les performances de reproduction de lapines en fonction du type génétique (NZ vs NZxCAL), du traitement lumineux (lumiare naturelle + 5h de complément en lumiare artificielle par jour vs lumiare naturel/e), de la saison (chaude et humide vs fra1che et sache) et du stade physiologique au moment de la saillie (allaitante vs non allaitante). 272 saillies sont analysées dans cette expérience. La fertilité n'est influencée par aucun des effets étudiés. Les feme/les NZXCAL ont une taille de portée a la naissance plus élevée que les NZ (8,2 vs 7, 1; P<0,05). Cependant, la supériorité de la taille de portée a la naissance ne s'exprime qu'en saison sache et fra1che (P<0,05). L'analyse met également en évidence des effets d'interactions significatifs entre le type génétique et le stade physiologique pour le poids moyen au sevrage (P<0,01). L'allongement de la durée d'éclairement augmente la taille de portée a la naissance (8,4 vs 6,9; P<0,001) et au sevrage (6,6 vs 5,5; P<0,05). Cependant, l'effet bénéfique du traitement lumineux ne s'exprime que pour la saison sache et fra1che (P<0,05). La saison humide et chaude (Mai-Novembre) influence défavorablement la tail/e de portée a la naissance et au sevrage (7, 1 vs 8,2; P<0,05 et 5,5 vs 6,6; P<0,05). Par ajlleurs, notre étude montre que le poids moyen des lapereaux a la naissance, la mortinatalité et la mortalité postnatale sont inf/uencés par le stade physiologique. On peut done conclure que le type génétique et l'allongement de la durée d'éclairement sont des moyens utiles pour améliorer la productivité des lapines pendant la saison sache et fra1che en milieu tropical. Cependant, leurs effets ne sont pas assez puissants pour neutra/iser les effets défavorables de la saison humide et chaude.Depres, E.; Theau-Clement, M.; Lorvelec, O. (1996). EFFECT OF THE GENOTYPE, DAY LENGTH, SEASON AND PHYSIOLOGYCAL STAGE ON THE REPRODUCTIVE PERFORMANCE OF DOE RABBITS REARED IN GUADELOUPE (F.W.I.). World Rabbit Science. 04(4). doi:10.4995/wrs.1996.292SWORD04

Reproductive physiopathology of the rabbit doe.

The main components of the female sexual function will be discussed in this chapter, with an emphasis on those reproductive disorders best characterised as having an impact on the reproductive efficiency of rabbit

PRODUCTION OF ANTI-PMSG ANTIBODIES AND ITS RELATION TO THE PRODUCTIVITY OF RABBIT DOES

[EN] A batch of 100 female rabbits of the Hyplus breed were subjected to artificial insemination (A.I.) for a period of 9 months. With the goal of inducing the sexual receptivity of the does, half of them received systematic doses of 25 1.U .. of PMSG (Ciclogonine PROCHENA), 48 hours before A.I.. The other half were not injected (Control group). Following this experimental period (40 days after the last injection), blood samples of all the does were taken, in order to assay the anti-PMSG antibodies and to study the relationship between the production of antibodies, and the receptivity and productivity of the does observad for the previous litter. For the PMSG group, we classified the results of the does according to their level of immunity which either has a low binding rate (::::; 4 %) ora high one (> 4 %). 30,6% of the does from the group treated with PMSG produced antiPMSG antibodies with a high binding rate. In no way related to the level of production of the antibodies, the PMSG treated does were found to be significantly more receptiva than the does in the control group (respectively 70.6 - 66.7 vs 42.0%, P = 0.023), while the fertility did not appear to have been either improved or decreased by the PMSG treatment. The total number of young born, born alive and weaned rabbits per litter did not vary according to the treatment or the intensity of antibody production. Likewise the weight of the litter and also the individual mean weight of the weaned young did not vary significantly according to the group. However, inside of the group treated with PMSG, the individual weight at weaning was the highest for the young from hyper- immune mothers (710 vs 639g, P = 0.035). For 29 does from the PMSG group, a second blood sample was taken 12 weeks after the previous one. Only 3 does showed a decreased level of antibodies, 4 months after the last injection. The study showed that one third of the does developed an immune reaction following injections of PMSG; however the proportion of antibodies produced did not appear related to either their sexual receptivity or productivity.[FR] Un troupeau de 100 lapines de souche Hyplus a été conduit en insémination artificielle (l.A) pendant 9 mois. Dans l'objectif d'induire la réceptivité sexuelle des lapines, la moitié d'entre elles recevait systématiquement 48 heures avant 1.A, 25 u.i de PMSG (Ciclogonine PROCHENA), l'autre moitié ne recevait aucune injection (Lot témoin). A l'issue de cette période expérimentale (40 jours aprés la derniére injection), un prélévement de sang a été réalisé sur toutes les lapines, afín de doser les anticorps anti-PMSG et d'étudier la relation entre la production d'anticorps, la réceptivité et la productivité des lapines lors de la portée précédente. Pour le lot PMSG, nous avons distingué les résultats des lapines selon leur niveau immunitaire qui se traduit par un taux de liaison faible (f'4 %) ou fort (> 4 %). 30,6 % des lapines du lot traité a la PMSG produisent des anticorps anti-PMSG ayant un taux de liaison fort. Sans relation avec le niveau de production d'anticorps, les lapines traitées sont significativement plus réceptives, que les lapines du lot témoin (respectivement 70,6- 66,7 vs 42,0 %, P = 0,023), la fertilité ne semble ni améliorée, ni détériorée par le traitement PMSG. Le nombre de nés totaux, nés vivants et sevrés par portée ne varia pas selon le traitement ou selon l'intensité de la production d'anticorps. De mame, le poids de portée ainsi que le poids moyen de lapereaux sevrés ne varient pas significativement en fonction du lot. En revancha, au sein du lot traité a la PMSG, le poids moyen au sevrage est plus élevé pour les lapereaux issus de meres hyperimmunes (71 o vs 639 g, p = 0,035). Sur 29 lapines du lot PMSG, un deuxiéme prélévement de sang a été réalisé 12 semaines aprés le précédent. Seules 3 lapines (sur 29 étudiées) ont eu une production d'anticorps diminuée, 4 mois aprés la derniére injection. Ce travail montre qu'un tiers des lapines développe une réaction immunitaire suite a des injections de PMSG cependant, le taux d'anticorps produit ne semble affecter ni la réceptivité sexuelle, ni la productivité des lapines.Lebas, F.; Theau-Clement, M.; Remy, B.; Drion, P.; Beckers, J. (1996). PRODUCTION OF ANTI-PMSG ANTIBODIES AND ITS RELATION TO THE PRODUCTIVITY OF RABBIT DOES. World Rabbit Science. 04(2). https://doi.org/10.4995/wrs.1996.27104

Absence of relation between the production of anti-PMSG antibodies and the receptivity or productivity of rabbit does

peer reviewe