Influence of different eCG doses on sexual receptivity and productivity of rabbit does

[EN] The aim of this study was to examine sexual receptivity and productivity of does injected 48 h before insemination with 8 or 25 IU of eCG (groups 8 and 25, respectively) in comparison with a control group (no injection, group 0). One hundred twenty four does were inseminated during 11 consecutive cycles (reproduction rythm: 35 d; inseminations: 4 d post partum and weaning: 28 d post partum). In comparison with the control group, eCG signifi cantly improves the receptivity of does (60.3 vs 80.5 and 79.8%; P<0.001), kindling rate (70.4 vs 80.9 and 79.4%; P=0.030) and the number of weaned rabbits/insemination (5.9 vs 7.1 and 7.1; P=0.008) for group 0, 8 and 25 respectively, during the whole experiment. eCG effi ciency is not obviously demonstrated for primiparous and non-lactating does. Authors conclude that only an 8 IU dose is able to improve 62% the productivity (measured as weaned rabbits per insemination) of multiparous and lactating does inseminated 4 d post partum.Theau-Clément, M.; Lebas, F.; Boiti, C.; G. Brecchia, G.; Mercier, P. (2010). Influence of different eCG doses on sexual receptivity and productivity of rabbit does. World Rabbit Science. 16(2). doi:10.4995/wrs.2008.62816

Milk production of pseudopregnant multiparous does

The aim of the experiment was to evaluate the milk production of pseudopregnant does. In this experiment, data of multiparous, inseminated, pregnant (IP, n=15) does and two groups of presumably pseudopregnant multiparous does: inseminated, non-pregnant (INP, n=17) and induced to ovulation by GnRH (1.5 microgram per animal) at the day of insemination (11 d after parturition) (non-inseminated, ovulating: NIO, n=15) were analysed. The progesterone level was measured at the 12th d after treatment to determine if females were pseudopregnant. All IP and NIO does were pregnant and pseudopregnant, respectively. Within the INP group, 10 and 7 does were diagnosed as positive (INPO) or negative (INPNO) for pseudopregnancy. Two of the INPNO does perished during lactation. The average milk production of groups IP, INP and NIO was 212, 92 and 72 g/d, respectively (P160 g in the various groups were: IP=0, 0, 0, 0 and 100%, NIO=20, 13, 27, 40 and 0%, INP=15, 15, 15, 55 and 0%, respectively. The daily milk yield of the 5 INPNO does was 2, 6, 27, 84 and 139 g, respectively. These results demonstrated that multiparous empty does, pseudopregnant or non-pseudopregnant, can produce milk, but in lower quantities than multiparous does after kindling.Szendrö, Z.; Matics, Z.; Brecchia, G.; Theau-Clément, M.; Nagy, Z.; Princz, Z.; Biró-Németh, E.... (2010). Milk production of pseudopregnant multiparous does. World Rabbit Science. 18(2). doi:10.4995/WRS.2010.18.1018

Effects of parity order and reproductive management on the efficiency of rabbit productive systems.

The aim of this work was to study the effect of parity order and reproductive management systems on rabbit production performance. A total of 73 rabbit does (I group) were submitted to a 35-day intensive rhythm [artificial insemination (AI) on day 4 post-partum (pp) and weaning at 25 days of lactation], and 108 rabbit does (SI group) were submitted to a 42-day semi-intensive rhythm (AI on day 11 pp and weaning at 35 days of lactation) during 9 months. Primiparous does had the lowest live body weight at parturition (P < 0.0001) and at 21 days of lactation (P < 0.0001). They also had lower milk production (P < 0.0001) than does with later parities. I group animals needed a higher number of AI than SI group to become pregnant (1.70 ± 0.03 vs. 1.39 ± 0.03; P < 0.0001: especially after the third). Prolificacy was not affected by the management system. Parturition interval (PI) was longer than expected in both groups [56.0 ± 1.4 and 50.9 ± 1.38 days in I and SI groups, respectively (P < 0.05)]. Mean productivity, estimated as number of weaned rabbits per female and year, was 12 kits higher in rabbit does of the SI group (P < 0.05). From the third parturition onward, an increase in live body weight of kits at different ages was observed. At 21 (P < 0.05) and 25 days of age (P < 0.01), kits from the I group rabbit does weighed more than those from the SI group; however, the latter showed a higher weight at 35 (P < 0.05) and 60 days of age (P < 0.05). Rabbit does with two or three parturitions had higher litter size at 21 and 25 days of age (P < 0.0001 and P < 0.001, respectively). Kit mortality between 21 and 25 days of age and between 35 and 60 days of age was not affected by treatments but was higher in the I group between 25 and 35 days (18.2 vs. 5.03% in the I and SI groups, respectively; P < 0.0001) and as age of does increased (P < 0.05). In light of these results, we could conclude that long term doe reproductive performance is negatively affected and litter viability decreased when using intensive compared to a semi-intensive reproductive management

Preparation of the rabbit doe to insemination: a review

[EN] This review analyses the main factors of success of insemination as well as the methods suitable for oestrus induction in order to improve reproductive efficiency of rabbit does in term of fecundity (combining fertility and prolificacy). Parity, lactation status, pseudopregnancy as well as sexual receptivity at the time of insemination highly influence reproductive performance. Pseudopregnancy (ovulation non-induced by GnRH or mating) strongly depresses fertility, but its cause is still unknown. The routine use of eCG (or PMSG) on lactating does consistently increases the proportion of receptive does at the time of AI and, therefore, their long-term productivity, without any important side-effect. Applied just before insemination, different alternative methods have been studied: animal manipulation (a change of cage, does gathering), buck effect, short dam litter separation, feeding programmes and light stimulations. Some of these methods improve the fecundity, but they sometimes also decrease kits growth (dam-litter separation, lighting programmes...). Consequently, for an optimal application in farms, it is important to consider long-term effects, such as global productivity and persistency of the effects. However, a better knowledge of the underlying physiological mechanisms would allow a better control of reproduction in rabbit farms.Theau-Clément, M. (2007). Preparation of the rabbit doe to insemination: a review. World Rabbit Science. 15(2). doi:10.4995/wrs.2007.60415

"BIOSTIMULATION METHODS" FOR BREEDING RABBIT DOES: SYNTHESIS OF THE FIRST RESULTS

[EN] In this short synthesis the authors triad to drive sorne conclusions from 4 studies on breeding rabbit does biostimulation, conducted within the lnternational Rabbit Reproduction Group (IRRG). The aim of these biostimulations was the improvement of does' fertility after artificial insemination (Al). Ali experiments were conducted according a 42 days reproduction rhythm. The trial of flushing, i.e. momentary improvement of the energy balance of does 4 days before Al, failed to improve fertility. The main reason was the low palatability of the experimental diet : the daily energy intake was lower than with control diet. Transfer of does to another caga, 2 days befare Al, can improve fertility of adults does, but in opposition with literatura, was inefficient in nulliparous does. However this technique is difficult to manage in larga commercial rabbitries. Efficiency of biostimulation through separation of mother from her litter for a short period depends of the timing and duration of the stimulus. A 36 to 48 hours separatlon just befare Al may improve fertility by 7 to 30 points ; but kits' weaning weight is reduced by 5% to 10%. Finally, further experiments are needed to know the practica! interest of a long term utilisation of such biostimulations, and to know the physiological mechanism.[FR] Dans ce bref artícle de synthiJse, les auteurs tentent de tirar les enseígnements de 4 études portant sur la "bíostimulatíon" de la reproduction chez la lapine, études conduites dans le cadre du Groupe lntemational sur la Reproduction (IRRG). Les différentes biostímulatlons étudiées avaient toutes pour objectif de favoriser la fertílité de tapines inséminées artificiellement dans le cadre d'une conduite en bandas selon un rythme a 42 jours. L'essai de f/ushing par distributlon d'un aliment plus concentré n'a pas donné les résultats espérés en raison d'une sous-consommation relativa de /'aliment expérimental initialement destiné a stimuler l'ingestion énergétique des femelles. Un simple changement de caga des tapines pendant les 2 jours précédant /'/A permet d'améliorer significativement la fertílité (+14 points), sauf pour les femelles nullipares. Toutefois, cette technique est difficile a app/iquer dans des élevages commerciaux. Enfin, la biostimulation de la reproduction par séparation de la mere et de sa portée donne des résu/tats dépendants de la durée et du moment de la séparation par rapport a l'IA. Une séparation de 36 a 48 heures juste avant l'IA permet d'accroitre la fertílité des tapines de 7 a 30 points, mais elle réduit d'environ 5% a 10% le poids des lapereaux au sevrage. De nouvelles expérimentations sont nécessaires pour validar /'efficacité de ces biostimulations a long terma et é/ucider le mécanisme de leur action.Theau- Clément, M.; Boiti, C. (1998). "BIOSTIMULATION METHODS" FOR BREEDING RABBIT DOES: SYNTHESIS OF THE FIRST RESULTS. World Rabbit Science. 06(1). doi:10.4995/wrs.1998.344SWORD06

EFFECT OF A 24 HOUR DOE-LITTER SEPARATION ON RABBIT DOE REPRODUCTIVE PERFORMANCE AND GROWTH OF THE YOUNG

Abstract not available.[EN] The aim of this work was to study the effect of a 24h doe-litter separation (nest-boxes closed) on reproductive performance of rabbit does and growth of their young, in comparison with a control group (nest-boxes always opened). Two series of artificial insemination (A.I) were studied (123 A.I). Separated does were more fertile (94,9 vs 82.3 %, P = 0.003). Litter size at birth and at weaning, as well as litter weight at weaning were not influenced by the biostimulation. At weaning, the mean weight of young rabbits from the experimental does was lower (559 vs 593 g, P = 0.002). Nevertheless, a 24h doe-litter separation on the tenth day of lactation just before insemination improved the productivity of does (+ 19.5 %).[FR] L'objectif de cette expérience était d'étudier en comparaison avec un lo! témoin (allaitement libre), l'influence d'une séparation mére-jeunes 24 heures avant l'insémination (fermeture ponctuelle des boíles a nid), sur les performances de reproduction des lapines et la croissance des lapereaux. Deux sérles d'insémination ont été réalisées et 123 l.A ont été analysées. Les lapines du lot expérimental ont été plus fertiles (94,9 vs 82,3 %, P = 0,003). Les tailles de portée a la naissance et au sevrage, le poids total de portée au sevrage n'ont pas été influencés par la méthode utilisée pour stimuler les lapines. En revanche, le poids moyen des lapereaux au sevrage du lot expérimental a été réduit (559 vs 593 g, P = 0,002). Cependant, la séparation mére-jeunes 24 heures avant l'insémination, a permis d'améliorer la productivité des lapines au stade 11 jours de lactation de 19,5 %.Theau- Clément, M.; Mercier, P. (1999). EFFECT OF A 24 HOUR DOE-LITTER SEPARATION ON RABBIT DOE REPRODUCTIVE PERFORMANCE AND GROWTH OF THE YOUNG. http://hdl.handle.net/10251/10285.SWORD07

INFLUENCE DE LA DURÉE D'ÉCLAIREMENT SUR LES PERFORMANCES DE REPRODUCTION DE LAPINES NULLIPARES ÉLEVÉES EN GUADELOUPE (F.W.I.)

[EN] In the present experiment, we compared reproductive performance of nulliparous rabbit does exposed to one of two light treatments designated as experimental group (N = 41 ) and control group (N = 40). In the experimental group, rabbits were exposed to 7 days extended light (+ 6 hours) befare mating. Control group were exposed to natural photoperiod (12 L. : 12 D.). Receptivity to the male, colour and size of the vulva were tested every days far 4 days. Receptivity to the male, the proportion of coloured and size of the vulva were significantly higher among the experimental group than the control. However, the breeding performance were not significantly different. lt was concluded that the exposure of young female rabbit to extended light may serve as useful technique to improve management of the first mating in the tropics.[FR] Dans cette expérience, nous avons comparé les performances de reproduction de tapines nullipares soumises a deux régimes /umineux. Les animaux du lot témoin étaient placés sous des conditions photopériodiques naturelles, alors que les tapines du lot expérimental étaient soumises, 7 jours avant la saillie, a un complément d'éclairement artificiel quotidien de 6 heures. La réceptivité au mate, la couleur de la vulve étaient observées pendant les 4 jours de présentation. Les résultats indiquent que le pourcentage de tapines qui acceptent l'accouplement, le pourcentage ayant la vulve colorée et turgescente étaient significativement plus élevés chez les feme/les du lot expérimental comparé au lot témoin. Cependant, les performances de reproduction étaient équivalentes que/ que soit le lot. On peut conclure que l'exposition de tapines nullipares a une modification de la durée d'éclairement peut etre un mayen utile pour mieux synchroniser la mise a la reproduction des jeunes feme/les elevées en milieu tropical.Deprés, E.; Theau-Clément, M.; Lorvelec, O. (1994). INFLUENCE DE LA DURÉE D'ÉCLAIREMENT SUR LES PERFORMANCES DE REPRODUCTION DE LAPINES NULLIPARES ÉLEVÉES EN GUADELOUPE (F.W.I.). World Rabbit Science. 2(2). doi:10.4995/wrs.1994.218SWORD2

Effect of change in nursing method on the performance of rabbit does

[EN] To study the effect of nursing method on reproduction, 232 primiparous and multiparous lactating Pannon White and NZW rabbit does were distributed proportionately among four experimental groups: FF: free nursing from kindling until weaning; FC: free nursing from day 1 to 7 and controlled nursing from day 8 to 17; CF: controlled nursing from day 1 to 7 and free nursing from day 8 to 17; CC: controlled nursing from day 1 to 17. After the 17th day of lactation, free nursing was used in all groups until weaning at 35 days of age. In controlled nursing the females could visit the nest box between 8 and 9 a.m. every day. Artificial inseminations (AI, n = 482) with 42d intervals were performed on day 10 post partum, within 15 minutes after nursing. The results of three consecutive kindlings were evaluated. In conclusion, it is not recommended to follow controlled nursing between 1-17th days of lactation because productivity traits were relatively poorer than in the other groups. The change from controlled to free nursing before AI did not increase productivity parameters. Conversely, the switch over from free to controlled nursing did increase the number of 21 day-old young per insemination (3.0, 4.2, 3.4 and 3.1 for FF, FC, CF and CC, respectively, P<0.05) suggesting that such a change in nursing two days before AI can be an efficient biostimulation tool for improving productivity. However, young body weight at 21 days of age was considerably impaired, especially by numerically larger litters (432, 401, 414 and 417 g in FF, FC, CF and CC, respectively, P<0.05), which suggests that the duration of controlled nursing must be shortened to avoid a detrimental effect on growth. Therefore, further studies are needed to determine the optimum form of controlled nursing and its long term effect on productivity.Financial support for the research was obtained from the Ministry of Agriculture and Regional Development (project no. KF-173/4/00).Eiben, C.; Kustos, K.; Gódor-Surmann, K.; Theau-Clément, M.; Szendrõ, Z. (2004). Effect of change in nursing method on the performance of rabbit does. World Rabbit Science. 12(3):173-183. https://doi.org/10.4995/wrs.2004.572SWORD17318312

BIOSTIMULATIONS APPLIED TO RABBIT REPRODUCTION: THEORY AND PRACTICE

[EN] Rabbit artificial insemination is now commonly practised in European countrles. In arder to maintain a "natural image" of rabbit meat and to be consistent with animal welfare, authors discuss the interest of biostimulation methods defined in opposition with "gonadotrophin treatment" to improve sexual receptivity of does at the moment of insemination. They first comment how at a physiological level biostimulations can improve reproduction performance. In a second part, they draw up the balance-sheet of their use in zootechnical species and rabbits. They concluded that these methods have to be easy to apply, inexpensive, consistent with animal welfare and have to improve also general productivity. Ughting programs, controlled lactation through temporary mother-litter separatlon and feeding programs seem the most interesting ways to explore.[FR] Dans ce bref artícle de synthiJse, les auteurs tentent de tirar les enseígnements de 4 études portant sur la "bíostimulatíon" de la reproduction chez la lapine, études conduites dans le cadre du Groupe lntemational sur la Reproduction (IRRG). Les différentes biostímulatlons étudiées avaient toutes pour objectif de favoriser la fertílité de tapines inséminées artificiellement dans le cadre d'une conduite en bandas selon un rythme a 42 jours. L'essai de f/ushing par distributlon d'un aliment plus concentré n'a pas donné les résultats espérés en raison d'une sous-consommation relativa de /'aliment expérimental initialement destiné a stimuler l'ingestion énergétique des femelles. Un simple changement de caga des tapines pendant les 2 jours précédant /'/A permet d'améliorer significativement la fertílité (+14 points), sauf pour les femelles nullipares. Toutefois, cette technique est difficile a app/iquer dans des élevages commerciaux. Enfin, la biostimulation de la reproduction par séparation de la mere et de sa portée donne des résu/tats dépendants de la durée et du moment de la séparation par rapport a l'IA. Une séparation de 36 a 48 heures juste avant l'IA permet d'accroitre la fertílité des tapines de 7 a 30 points, mais elle réduit d'environ 5% a 10% le poids des lapereaux au sevrage. De nouvelles expérimentations sont nécessaires pour validar /'efficacité de ces biostimulations a long terma et é/ucider le mécanisme de leur action.Theau- Clément, M.; Castellini, C.; Maertens, L.; Boiti, C. (1998). BIOSTIMULATIONS APPLIED TO RABBIT REPRODUCTION: THEORY AND PRACTICE. World Rabbit Science. 06(1). doi:10.4995/wrs.1998.339SWORD06