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Il contributo intende affrontare la prassi statutaria dei più recenti partiti politici, al fine di evidenziare la "crisi" della democrazia interna delle organizzazioni politiche. Ciò, almeno, sotto un duplica aspetto. Da un lato sono codificate regole che attribuiscono ampi poteri a pochi soggetti. Dall'altro, vi è la tendenza a superare le regole statutarie, privilegiando le scelte e ed i diktat di coloro che guidano il partito politico. Nella parte finale del contributo si dialoga con il futuro legislatore al fine di individuare alcune linee guida per una disciplina organica dei partiti politici.

OBJECTIVE: To provide a prospective developmental model for behavioral outcomes in preterm infants in relation to developmental care (DC) practices and postnatal maternal depression. STUDY DESIGN: A longitudinal, multicenter, follow-up study conducted in 25 Italian tertiary neonatal intensive care units (NICUs). Participants were 162 healthy very preterm infants and their mothers. The level of quality of DC was assessed for each hospital. Infant's neurobehavioral profile was evaluated twice: at discharge (T1) and at 18 months for behavioral problems (T3). Maternal depressive symptomatology was measured at T1 and at 6 months (T2). RESULTS: Low-quality DC in NICUs was associated with lower levels of infant neurobehavioral adaptability and higher levels of maternal depressive symptoms. Maternal depressive symptomatology in conjunction with higher infant dysregulation predicted more internalizing problems at 18 months of age. CONCLUSION: DC interventions and postnatal maternal depression, as well as infant behavior have an impact on short- and long-term infant outcomes.

[EN] Sexual receptivity of rabbit does at insemination greatly influences fertility and is generally induced by hormones or techniques known as “biostimulation”. Searching for more sustainable farming systems, an original alternative would be to utilise the genetic pathway to increase the does’receptivity. The purpose of the present study was to identify genetic and non-genetic factors that influence rabbit doe sexual receptivity, in the context of a divergent selection experiment over 1 generation. The experiment spanned 2 generations: the founder generation (G0) consisting of 140 rabbit does, and the G1 generation comprising 2 divergently selected lines (L and H lines) with 70 does each and 2 successive batches from each generation. The selection rate of the G0 females to form the G1 lines was 24/140. The selection tests consisted of 16 to 18 successive receptivity tests at the rate of 3 tests per week. On the basis of 4716 tests from 275 females, the average receptivity was 56.6±48.2%. A batch effect and a test operator effect were revealed. The contribution of females to the total variance was 20.0%, whereas that of bucks was only 1.1%. Throughout the experiment, 18.2% of does expressed a low receptivity (< 34%), 50.7% a medium one and 33.1% a high one (>66%). Some does were frequently receptive, whereas others were rarely receptive. The repeatability of sexual receptivity was approximately 20%. The results confirmed the high variability of sexual receptivity of non-lactating rabbit does maintained without any biostimulation or hormonal treatment. A lack of selection response on receptivity was observed. Accordingly, the heritability of receptivity was estimated at 0.01±0.02 from an animal model and at 0.02±0.03 from a sire and dam model. The heritability of the average receptivity of a doe was calculated as 0.04. In agreement with the low estimated heritability, the heritability determined was no different from zero. Nevertheless, the occurrence of pseudopregn

[EN] Sexual receptivity of rabbit does at insemination greatly influences fertility and is generally induced by hormones or techniques known as “biostimulation”. Searching for more sustainable farming systems, an original alternative would be to utilise the genetic pathway to increase the does’receptivity. The purpose of the present study was to identify genetic and non-genetic factors that influence rabbit doe sexual receptivity, in the context of a divergent selection experiment over 1 generation. The experiment spanned 2 generations: the founder generation (G0) consisting of 140 rabbit does, and the G1 generation comprising 2 divergently selected lines (L and H lines) with 70 does each and 2 successive batches from each generation. The selection rate of the G0 females to form the G1 lines was 24/140. The selection tests consisted of 16 to 18 successive receptivity tests at the rate of 3 tests per week. On the basis of 4716 tests from 275 females, the average receptivity was 56.6±48.2%. A batch effect and a test operator effect were revealed. The contribution of females to the total variance was 20.0%, whereas that of bucks was only 1.1%. Throughout the experiment, 18.2% of does expressed a low receptivity (< 34%), 50.7% a medium one and 33.1% a high one (>66%). Some does were frequently receptive, whereas others were rarely receptive. The repeatability of sexual receptivity was approximately 20%. The results confirmed the high variability of sexual receptivity of non-lactating rabbit does maintained without any biostimulation or hormonal treatment. A lack of selection response on receptivity was observed. Accordingly, the heritability of receptivity was estimated at 0.01±0.02 from an animal model and at 0.02±0.03 from a sire and dam model. The heritability of the average receptivity of a doe was calculated as 0.04. In agreement with the low estimated heritability, the heritability determined was no different from zero. Nevertheless, the occurrence of pseudopregn

[EN] Sexual receptivity of rabbit does at insemination greatly influences fertility and is generally induced by hormones or techniques known as “biostimulation”. Searching for more sustainable farming systems, an original alternative would be to utilise the genetic pathway to increase the does’receptivity. The purpose of the present study was to identify genetic and non-genetic factors that influence rabbit doe sexual receptivity, in the context of a divergent selection experiment over 1 generation. The experiment spanned 2 generations: the founder generation (G0) consisting of 140 rabbit does, and the G1 generation comprising 2 divergently selected lines (L and H lines) with 70 does each and 2 successive batches from each generation. The selection rate of the G0 females to form the G1 lines was 24/140. The selection tests consisted of 16 to 18 successive receptivity tests at the rate of 3 tests per week. On the basis of 4716 tests from 275 females, the average receptivity was 56.6±48.2%. A batch effect and a test operator effect were revealed. The contribution of females to the total variance was 20.0%, whereas that of bucks was only 1.1%. Throughout the experiment, 18.2% of does expressed a low receptivity (< 34%), 50.7% a medium one and 33.1% a high one (>66%). Some does were frequently receptive, whereas others were rarely receptive. The repeatability of sexual receptivity was approximately 20%. The results confirmed the high variability of sexual receptivity of non-lactating rabbit does maintained without any biostimulation or hormonal treatment. A lack of selection response on receptivity was observed. Accordingly, the heritability of receptivity was estimated at 0.01±0.02 from an animal model and at 0.02±0.03 from a sire and dam model. The heritability of the average receptivity of a doe was calculated as 0.04. In agreement with the low estimated heritability, the heritability determined was no different from zero. Nevertheless, the occurrence of pseudopregn

[EN] Sexual receptivity of rabbit does at insemination greatly influences fertility and is generally induced by hormones or techniques known as “biostimulation”. Searching for more sustainable farming systems, an original alternative would be to utilise the genetic pathway to increase the does’receptivity. The purpose of the present study was to identify genetic and non-genetic factors that influence rabbit doe sexual receptivity, in the context of a divergent selection experiment over 1 generation. The experiment spanned 2 generations: the founder generation (G0) consisting of 140 rabbit does, and the G1 generation comprising 2 divergently selected lines (L and H lines) with 70 does each and 2 successive batches from each generation. The selection rate of the G0 females to form the G1 lines was 24/140. The selection tests consisted of 16 to 18 successive receptivity tests at the rate of 3 tests per week. On the basis of 4716 tests from 275 females, the average receptivity was 56.6±48.2%. A batch effect and a test operator effect were revealed. The contribution of females to the total variance was 20.0%, whereas that of bucks was only 1.1%. Throughout the experiment, 18.2% of does expressed a low receptivity (< 34%), 50.7% a medium one and 33.1% a high one (>66%). Some does were frequently receptive, whereas others were rarely receptive. The repeatability of sexual receptivity was approximately 20%. The results confirmed the high variability of sexual receptivity of non-lactating rabbit does maintained without any biostimulation or hormonal treatment. A lack of selection response on receptivity was observed. Accordingly, the heritability of receptivity was estimated at 0.01±0.02 from an animal model and at 0.02±0.03 from a sire and dam model. The heritability of the average receptivity of a doe was calculated as 0.04. In agreement with the low estimated heritability, the heritability determined was no different from zero. Nevertheless, the occurrence of pseudopregn

[EN] Sexual receptivity of rabbit does at insemination greatly influences fertility and is generally induced by hormones or techniques known as “biostimulation”. Searching for more sustainable farming systems, an original alternative would be to utilise the genetic pathway to increase the does’receptivity. The purpose of the present study was to identify genetic and non-genetic factors that influence rabbit doe sexual receptivity, in the context of a divergent selection experiment over 1 generation. The experiment spanned 2 generations: the founder generation (G0) consisting of 140 rabbit does, and the G1 generation comprising 2 divergently selected lines (L and H lines) with 70 does each and 2 successive batches from each generation. The selection rate of the G0 females to form the G1 lines was 24/140. The selection tests consisted of 16 to 18 successive receptivity tests at the rate of 3 tests per week. On the basis of 4716 tests from 275 females, the average receptivity was 56.6±48.2%. A batch effect and a test operator effect were revealed. The contribution of females to the total variance was 20.0%, whereas that of bucks was only 1.1%. Throughout the experiment, 18.2% of does expressed a low receptivity (< 34%), 50.7% a medium one and 33.1% a high one (>66%). Some does were frequently receptive, whereas others were rarely receptive. The repeatability of sexual receptivity was approximately 20%. The results confirmed the high variability of sexual receptivity of non-lactating rabbit does maintained without any biostimulation or hormonal treatment. A lack of selection response on receptivity was observed. Accordingly, the heritability of receptivity was estimated at 0.01±0.02 from an animal model and at 0.02±0.03 from a sire and dam model. The heritability of the average receptivity of a doe was calculated as 0.04. In agreement with the low estimated heritability, the heritability determined was no different from zero. Nevertheless, the occurrence of pseudopregn

[EN] Sexual receptivity of rabbit does at insemination greatly influences fertility and is generally induced by hormones or techniques known as “biostimulation”. Searching for more sustainable farming systems, an original alternative would be to utilise the genetic pathway to increase the does’receptivity. The purpose of the present study was to identify genetic and non-genetic factors that influence rabbit doe sexual receptivity, in the context of a divergent selection experiment over 1 generation. The experiment spanned 2 generations: the founder generation (G0) consisting of 140 rabbit does, and the G1 generation comprising 2 divergently selected lines (L and H lines) with 70 does each and 2 successive batches from each generation. The selection rate of the G0 females to form the G1 lines was 24/140. The selection tests consisted of 16 to 18 successive receptivity tests at the rate of 3 tests per week. On the basis of 4716 tests from 275 females, the average receptivity was 56.6±48.2%. A batch effect and a test operator effect were revealed. The contribution of females to the total variance was 20.0%, whereas that of bucks was only 1.1%. Throughout the experiment, 18.2% of does expressed a low receptivity (< 34%), 50.7% a medium one and 33.1% a high one (>66%). Some does were frequently receptive, whereas others were rarely receptive. The repeatability of sexual receptivity was approximately 20%. The results confirmed the high variability of sexual receptivity of non-lactating rabbit does maintained without any biostimulation or hormonal treatment. A lack of selection response on receptivity was observed. Accordingly, the heritability of receptivity was estimated at 0.01±0.02 from an animal model and at 0.02±0.03 from a sire and dam model. The heritability of the average receptivity of a doe was calculated as 0.04. In agreement with the low estimated heritability, the heritability determined was no different from zero. Nevertheless, the occurrence of pseudopregn

We introduce the wave front set WF*P(u) with respect to the iterates of a hypoelliptic linear partial differential operator with constant coefficients of a classical distribution u is an element of D' (Omega) in an open set Omega in the setting of ultradifferentiable classes of Braun, Meise, and Taylor. We state a version of the microlocal regularity theorem of Hormander for this new type of wave front set and give some examples and applications of the former result.

[EN] Primiparous does express low mating acceptance during lactation and different oestrus induction methods are employed to improve sexual receptivity. The aim of this work was to study the effect of a biostimulation, a 48 h doe-litter separation (DLS), in primiparous lactating rabbits on mating acceptance, external characteristics of the vulva and plasma concentrations of estradiol, testosterone, progesterone and cortisol. Seventy primiparous does from local population were divided on day 1 after kindling into 2 equal groups: control (C, n=35), where does always had free access to the nest-box, and DLS (n=35), where free suckling was adopted, except from day 9 to day 11 post-partum (PP). Litter size was equalised to 6-7 kits. Before mating, blood samples were obtained from 10 does per group on 9th and 11th d post-partum (dpp). The results showed that the DLS treatment improved the mating acceptance on 11th dpp (88.5 vs. 54.2%; P<0.01) and the frequency of red or pink and turgid vulva (54.3 vs. 20%; P<0.01). The sexual receptivity of DLS does depended on the time for which the female was presented to the male: 60% refused mating before opening the nest-box, while 80.9% of them accepted the male after the nursing episode. Plasma levels of estradiol, testosterone and progesterone in DLS group rose from 9th to 11th dpp (+44.4; +59.2 and +82%, respectively; P<0.01) compared to C group (+6.7; -3.9 and +33.4%, respectively; P>0.05). In contrast, cortisol plasma levels were not affected by the DLS treatment (-12.4 and -14.4% for control and DLS group; P>0.05). At day 11 PP, higher plasma E2 and P4 levels were described in DLS in comparison to C, although no significant difference was found, while plasma testosterone concentrations tended to be higher in DLS (165.5±27.1 vs. 114.9±31.9 pg/mL, for DLS and C, respectively; P=0.075). In summary, the 48 h doe-litter-separation acted as an efficient oestrus inductor in primiparous lactating rabbits. Insemination of biostimulated

[EN] Primiparous does express low mating acceptance during lactation and different oestrus induction methods are employed to improve sexual receptivity. The aim of this work was to study the effect of a biostimulation, a 48 h doe-litter separation (DLS), in primiparous lactating rabbits on mating acceptance, external characteristics of the vulva and plasma concentrations of estradiol, testosterone, progesterone and cortisol. Seventy primiparous does from local population were divided on day 1 after kindling into 2 equal groups: control (C, n=35), where does always had free access to the nest-box, and DLS (n=35), where free suckling was adopted, except from day 9 to day 11 post-partum (PP). Litter size was equalised to 6-7 kits. Before mating, blood samples were obtained from 10 does per group on 9th and 11th d post-partum (dpp). The results showed that the DLS treatment improved the mating acceptance on 11th dpp (88.5 vs. 54.2%; P<0.01) and the frequency of red or pink and turgid vulva (54.3 vs. 20%; P<0.01). The sexual receptivity of DLS does depended on the time for which the female was presented to the male: 60% refused mating before opening the nest-box, while 80.9% of them accepted the male after the nursing episode. Plasma levels of estradiol, testosterone and progesterone in DLS group rose from 9th to 11th dpp (+44.4; +59.2 and +82%, respectively; P<0.01) compared to C group (+6.7; -3.9 and +33.4%, respectively; P>0.05). In contrast, cortisol plasma levels were not affected by the DLS treatment (-12.4 and -14.4% for control and DLS group; P>0.05). At day 11 PP, higher plasma E2 and P4 levels were described in DLS in comparison to C, although no significant difference was found, while plasma testosterone concentrations tended to be higher in DLS (165.5±27.1 vs. 114.9±31.9 pg/mL, for DLS and C, respectively; P=0.075). In summary, the 48 h doe-litter-separation acted as an efficient oestrus inductor in primiparous lactating rabbits. Insemination of biostimulated

[EN] Primiparous does express low mating acceptance during lactation and different oestrus induction methods are employed to improve sexual receptivity. The aim of this work was to study the effect of a biostimulation, a 48 h doe-litter separation (DLS), in primiparous lactating rabbits on mating acceptance, external characteristics of the vulva and plasma concentrations of estradiol, testosterone, progesterone and cortisol. Seventy primiparous does from local population were divided on day 1 after kindling into 2 equal groups: control (C, n=35), where does always had free access to the nest-box, and DLS (n=35), where free suckling was adopted, except from day 9 to day 11 post-partum (PP). Litter size was equalised to 6-7 kits. Before mating, blood samples were obtained from 10 does per group on 9th and 11th d post-partum (dpp). The results showed that the DLS treatment improved the mating acceptance on 11th dpp (88.5 vs. 54.2%; P<0.01) and the frequency of red or pink and turgid vulva (54.3 vs. 20%; P<0.01). The sexual receptivity of DLS does depended on the time for which the female was presented to the male: 60% refused mating before opening the nest-box, while 80.9% of them accepted the male after the nursing episode. Plasma levels of estradiol, testosterone and progesterone in DLS group rose from 9th to 11th dpp (+44.4; +59.2 and +82%, respectively; P<0.01) compared to C group (+6.7; -3.9 and +33.4%, respectively; P>0.05). In contrast, cortisol plasma levels were not affected by the DLS treatment (-12.4 and -14.4% for control and DLS group; P>0.05). At day 11 PP, higher plasma E2 and P4 levels were described in DLS in comparison to C, although no significant difference was found, while plasma testosterone concentrations tended to be higher in DLS (165.5±27.1 vs. 114.9±31.9 pg/mL, for DLS and C, respectively; P=0.075). In summary, the 48 h doe-litter-separation acted as an efficient oestrus inductor in primiparous lactating rabbits. Insemination of biostimulated

[EN] Primiparous does express low mating acceptance during lactation and different oestrus induction methods are employed to improve sexual receptivity. The aim of this work was to study the effect of a biostimulation, a 48 h doe-litter separation (DLS), in primiparous lactating rabbits on mating acceptance, external characteristics of the vulva and plasma concentrations of estradiol, testosterone, progesterone and cortisol. Seventy primiparous does from local population were divided on day 1 after kindling into 2 equal groups: control (C, n=35), where does always had free access to the nest-box, and DLS (n=35), where free suckling was adopted, except from day 9 to day 11 post-partum (PP). Litter size was equalised to 6-7 kits. Before mating, blood samples were obtained from 10 does per group on 9th and 11th d post-partum (dpp). The results showed that the DLS treatment improved the mating acceptance on 11th dpp (88.5 vs. 54.2%; P<0.01) and the frequency of red or pink and turgid vulva (54.3 vs. 20%; P<0.01). The sexual receptivity of DLS does depended on the time for which the female was presented to the male: 60% refused mating before opening the nest-box, while 80.9% of them accepted the male after the nursing episode. Plasma levels of estradiol, testosterone and progesterone in DLS group rose from 9th to 11th dpp (+44.4; +59.2 and +82%, respectively; P<0.01) compared to C group (+6.7; -3.9 and +33.4%, respectively; P>0.05). In contrast, cortisol plasma levels were not affected by the DLS treatment (-12.4 and -14.4% for control and DLS group; P>0.05). At day 11 PP, higher plasma E2 and P4 levels were described in DLS in comparison to C, although no significant difference was found, while plasma testosterone concentrations tended to be higher in DLS (165.5±27.1 vs. 114.9±31.9 pg/mL, for DLS and C, respectively; P=0.075). In summary, the 48 h doe-litter-separation acted as an efficient oestrus inductor in primiparous lactating rabbits. Insemination of biostimulated

[EN] Primiparous does express low mating acceptance during lactation and different oestrus induction methods are employed to improve sexual receptivity. The aim of this work was to study the effect of a biostimulation, a 48 h doe-litter separation (DLS), in primiparous lactating rabbits on mating acceptance, external characteristics of the vulva and plasma concentrations of estradiol, testosterone, progesterone and cortisol. Seventy primiparous does from local population were divided on day 1 after kindling into 2 equal groups: control (C, n=35), where does always had free access to the nest-box, and DLS (n=35), where free suckling was adopted, except from day 9 to day 11 post-partum (PP). Litter size was equalised to 6-7 kits. Before mating, blood samples were obtained from 10 does per group on 9th and 11th d post-partum (dpp). The results showed that the DLS treatment improved the mating acceptance on 11th dpp (88.5 vs. 54.2%; P<0.01) and the frequency of red or pink and turgid vulva (54.3 vs. 20%; P<0.01). The sexual receptivity of DLS does depended on the time for which the female was presented to the male: 60% refused mating before opening the nest-box, while 80.9% of them accepted the male after the nursing episode. Plasma levels of estradiol, testosterone and progesterone in DLS group rose from 9th to 11th dpp (+44.4; +59.2 and +82%, respectively; P<0.01) compared to C group (+6.7; -3.9 and +33.4%, respectively; P>0.05). In contrast, cortisol plasma levels were not affected by the DLS treatment (-12.4 and -14.4% for control and DLS group; P>0.05). At day 11 PP, higher plasma E2 and P4 levels were described in DLS in comparison to C, although no significant difference was found, while plasma testosterone concentrations tended to be higher in DLS (165.5±27.1 vs. 114.9±31.9 pg/mL, for DLS and C, respectively; P=0.075). In summary, the 48 h doe-litter-separation acted as an efficient oestrus inductor in primiparous lactating rabbits. Insemination of biostimulated

[EN] Primiparous does express low mating acceptance during lactation and different oestrus induction methods are employed to improve sexual receptivity. The aim of this work was to study the effect of a biostimulation, a 48 h doe-litter separation (DLS), in primiparous lactating rabbits on mating acceptance, external characteristics of the vulva and plasma concentrations of estradiol, testosterone, progesterone and cortisol. Seventy primiparous does from local population were divided on day 1 after kindling into 2 equal groups: control (C, n=35), where does always had free access to the nest-box, and DLS (n=35), where free suckling was adopted, except from day 9 to day 11 post-partum (PP). Litter size was equalised to 6-7 kits. Before mating, blood samples were obtained from 10 does per group on 9th and 11th d post-partum (dpp). The results showed that the DLS treatment improved the mating acceptance on 11th dpp (88.5 vs. 54.2%; P<0.01) and the frequency of red or pink and turgid vulva (54.3 vs. 20%; P<0.01). The sexual receptivity of DLS does depended on the time for which the female was presented to the male: 60% refused mating before opening the nest-box, while 80.9% of them accepted the male after the nursing episode. Plasma levels of estradiol, testosterone and progesterone in DLS group rose from 9th to 11th dpp (+44.4; +59.2 and +82%, respectively; P<0.01) compared to C group (+6.7; -3.9 and +33.4%, respectively; P>0.05). In contrast, cortisol plasma levels were not affected by the DLS treatment (-12.4 and -14.4% for control and DLS group; P>0.05). At day 11 PP, higher plasma E2 and P4 levels were described in DLS in comparison to C, although no significant difference was found, while plasma testosterone concentrations tended to be higher in DLS (165.5±27.1 vs. 114.9±31.9 pg/mL, for DLS and C, respectively; P=0.075). In summary, the 48 h doe-litter-separation acted as an efficient oestrus inductor in primiparous lactating rabbits. Insemination of biostimulated

[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.

[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.

[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.

[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.

[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.

This study compared reproductive performance and behaviour of does raised in a group-housing system and in a regular cage system. The group-housing pen was divided into different functional areas for suckling, resting, and eating and special hiding areas for kits when they had left the nest-boxes and does to favour the species specific behavioural traits. Does had access to their nest-box by means of an individual Electronic Nest-box Recognition System (ENRS) activated by a coded transponder placed in their eartags. Eight does were housed in each pen. Natural mating (NM, with a buck in the group) or artificial inseminations (AI) were applied. Litter size, kit mortality and kit weight at 14 d of age were similar for group-housing and cages when NM were applied. With a natural reproduction rhythm group-housing led to an increase of +38% of litters. However, from a management point of view, a cycled production system with AI is preferred. With AI and group-housing, a lower kindling rate and a lower kit weight at weaning were found. The lower kindling rate was partly caused by pseudo-pregnancies that were found in 23% (P <0.01) of the does in the group-housing system against 0% in the control group. Sixteen to 20% of the does in the group-housing system had skin injuries, which is an indicator for aggression among does. Most of the injuries were seen on the body and most of them were superficial bites. Based on the results of this study, it can be concluded that group-housing of rabbit does seems possible, but more research is needed to solve the problems of the decreased kindling rate and occurrence of pseudo-pregnancies, the lower weight at weaning and aggressiveness among does.

An experiment was performed to assess the metabolic adaptation and hormonal regulation in young female rabbits during long-term food restriction and subsequent compensatory growth during rearing. Feeding level was either ad libitum (AL, no. = 52) or restricted (R, no. = 52). From 6 to 12 weeks of age, food intake of R was kept at a constant level. This resulted in an increase in relative restriction as compared with AL to 0.54of AL intake at 12 weeks of age (restriction period). Thereafter food intake gradually increased to 0.95 of AL at 17 weeks of age (recovery period). During the last 5 days before insemination at 17.5 weeks of age, all animals were fed to appetite. Blood samples were taken weekly from 6 to 17 weeks of age from 11 animals in each group. Growth rate of R was reduced during the restricted period (29 (s.d. 2) v. 44 (s.d. 5) g/day for R and AL, respectively; P <0.05), but was higher in the recovery period (30 (s.d. 3) v. 27 (s.d. 4) g/day, respectively; P <0.05). At first insemination, AL rabbits were heavier than R (4202 (s.d. 388) v. 3798 (s.d. 220) g, respectively; P <0.001). During the restricted period, plasma glucose was constantly lower (P <0.05) in R. Insulin levels paralleled those of glucose, being lower (P <0.05) in R than in AL. Restriction reduced CP <0.05) circulating corticosterone and tri-iodothyronine (T3) levels in R. Leptin, non-esterified fatty acids, and plasma urea nitrogen levels were similar for AL and R during food restriction, whereas triglycerides were similar until 10 weeks of age, after which the levels were lower in R. During the recovery period, the food intake of the R but not AL rabbits increased. Insulin was the only hormone in R rabbits that had returned to levels found in AL rabbits by the 2nd week of the recovery period. Glucose, T3, and corticosterone levels returned to levels found in AL rabbits between 3 to 4 weeks after refeeding. Non-esterified fatty acids, triglycerides, and leptin were higher (P <0.05) in A

[EN] The aim of this study was to verify the effectiveness of post partum pharmacological oestrus synchronisation with alfaprostol or eCG in improving rabbit doe reproductive performances and to evaluate the incidence of pseudopregnancy in this species. One hundred and eighty commercial hybrid rabbit does, multiparous and lactating, were randomly divided into three groups (n=60) and treated on day 8 post partum (pp) as follows: Group A, 1 mL s.c. vitaminic solution with 200 mg alfaprostol, a synthetic analogue of PGF2a; Group B, 1 mL sc vitaminic solution with 20 I.U eCG; Group C (Control) 1 mL sc vitaminic solution. On day 11 pp (3 days after treatment), all the rabbits were artificially inseminated (AI), and injected with 0.8 mg of buserelin i.m. to induce ovulation. Concurrently, blood samples were taken for progesterone (P4) analysis by RIA with the following schedule: day 8 pp (before treatment), day 11 pp (before AI and the induction of ovulation) and day 16 pp (5 days after AI). Fertility was not influenced by hormonal treatments (71.7% and 71.2% respectively) compared to control (66.1%). Conversely, both PGF2a and eCG hormonal synchronisation treatments increased (P<0.05) litter size. P4 values before treatment on day 8 pp testify to the absence of functional CL (P4<2 ng/mL) in the early post partum period in 98.9% of the does in this breeding farm. Before AI and the induction of ovulation on day 11 pp 5.6% of the does had P4 concentrations, indicating non-oestral status (P4>1 ng/mL). On day 5 after insemination 95.5% had P4 values, which attest to the presence of functional corpora lutea (CL) (P4>2 ng/mL). The results of this study show that as long as rabbitry is properly managed zootechnically and sanitarily, drugs such as alfaprostol and eCG, while not ameliorating fertility rate when used for post partum oestrus sychronisation, can increase litter size.

[EN] The aim of this study was to verify the effectiveness of post partum pharmacological oestrus synchronisation with alfaprostol or eCG in improving rabbit doe reproductive performances and to evaluate the incidence of pseudopregnancy in this species. One hundred and eighty commercial hybrid rabbit does, multiparous and lactating, were randomly divided into three groups (n=60) and treated on day 8 post partum (pp) as follows: Group A, 1 mL s.c. vitaminic solution with 200 mg alfaprostol, a synthetic analogue of PGF2a; Group B, 1 mL sc vitaminic solution with 20 I.U eCG; Group C (Control) 1 mL sc vitaminic solution. On day 11 pp (3 days after treatment), all the rabbits were artificially inseminated (AI), and injected with 0.8 mg of buserelin i.m. to induce ovulation. Concurrently, blood samples were taken for progesterone (P4) analysis by RIA with the following schedule: day 8 pp (before treatment), day 11 pp (before AI and the induction of ovulation) and day 16 pp (5 days after AI). Fertility was not influenced by hormonal treatments (71.7% and 71.2% respectively) compared to control (66.1%). Conversely, both PGF2a and eCG hormonal synchronisation treatments increased (P<0.05) litter size. P4 values before treatment on day 8 pp testify to the absence of functional CL (P4<2 ng/mL) in the early post partum period in 98.9% of the does in this breeding farm. Before AI and the induction of ovulation on day 11 pp 5.6% of the does had P4 concentrations, indicating non-oestral status (P4>1 ng/mL). On day 5 after insemination 95.5% had P4 values, which attest to the presence of functional corpora lutea (CL) (P4>2 ng/mL). The results of this study show that as long as rabbitry is properly managed zootechnically and sanitarily, drugs such as alfaprostol and eCG, while not ameliorating fertility rate when used for post partum oestrus sychronisation, can increase litter size.

[EN] The aim of this study was to verify the effectiveness of post partum pharmacological oestrus synchronisation with alfaprostol or eCG in improving rabbit doe reproductive performances and to evaluate the incidence of pseudopregnancy in this species. One hundred and eighty commercial hybrid rabbit does, multiparous and lactating, were randomly divided into three groups (n=60) and treated on day 8 post partum (pp) as follows: Group A, 1 mL s.c. vitaminic solution with 200 mg alfaprostol, a synthetic analogue of PGF2a; Group B, 1 mL sc vitaminic solution with 20 I.U eCG; Group C (Control) 1 mL sc vitaminic solution. On day 11 pp (3 days after treatment), all the rabbits were artificially inseminated (AI), and injected with 0.8 mg of buserelin i.m. to induce ovulation. Concurrently, blood samples were taken for progesterone (P4) analysis by RIA with the following schedule: day 8 pp (before treatment), day 11 pp (before AI and the induction of ovulation) and day 16 pp (5 days after AI). Fertility was not influenced by hormonal treatments (71.7% and 71.2% respectively) compared to control (66.1%). Conversely, both PGF2a and eCG hormonal synchronisation treatments increased (P<0.05) litter size. P4 values before treatment on day 8 pp testify to the absence of functional CL (P4<2 ng/mL) in the early post partum period in 98.9% of the does in this breeding farm. Before AI and the induction of ovulation on day 11 pp 5.6% of the does had P4 concentrations, indicating non-oestral status (P4>1 ng/mL). On day 5 after insemination 95.5% had P4 values, which attest to the presence of functional corpora lutea (CL) (P4>2 ng/mL). The results of this study show that as long as rabbitry is properly managed zootechnically and sanitarily, drugs such as alfaprostol and eCG, while not ameliorating fertility rate when used for post partum oestrus sychronisation, can increase litter size.

[EN] The aim of this study was to verify the effectiveness of post partum pharmacological oestrus synchronisation with alfaprostol or eCG in improving rabbit doe reproductive performances and to evaluate the incidence of pseudopregnancy in this species. One hundred and eighty commercial hybrid rabbit does, multiparous and lactating, were randomly divided into three groups (n=60) and treated on day 8 post partum (pp) as follows: Group A, 1 mL s.c. vitaminic solution with 200 mg alfaprostol, a synthetic analogue of PGF2a; Group B, 1 mL sc vitaminic solution with 20 I.U eCG; Group C (Control) 1 mL sc vitaminic solution. On day 11 pp (3 days after treatment), all the rabbits were artificially inseminated (AI), and injected with 0.8 mg of buserelin i.m. to induce ovulation. Concurrently, blood samples were taken for progesterone (P4) analysis by RIA with the following schedule: day 8 pp (before treatment), day 11 pp (before AI and the induction of ovulation) and day 16 pp (5 days after AI). Fertility was not influenced by hormonal treatments (71.7% and 71.2% respectively) compared to control (66.1%). Conversely, both PGF2a and eCG hormonal synchronisation treatments increased (P<0.05) litter size. P4 values before treatment on day 8 pp testify to the absence of functional CL (P4<2 ng/mL) in the early post partum period in 98.9% of the does in this breeding farm. Before AI and the induction of ovulation on day 11 pp 5.6% of the does had P4 concentrations, indicating non-oestral status (P4>1 ng/mL). On day 5 after insemination 95.5% had P4 values, which attest to the presence of functional corpora lutea (CL) (P4>2 ng/mL). The results of this study show that as long as rabbitry is properly managed zootechnically and sanitarily, drugs such as alfaprostol and eCG, while not ameliorating fertility rate when used for post partum oestrus sychronisation, can increase litter size.

[EN] The aim of this study was to verify the effectiveness of post partum pharmacological oestrus synchronisation with alfaprostol or eCG in improving rabbit doe reproductive performances and to evaluate the incidence of pseudopregnancy in this species. One hundred and eighty commercial hybrid rabbit does, multiparous and lactating, were randomly divided into three groups (n=60) and treated on day 8 post partum (pp) as follows: Group A, 1 mL s.c. vitaminic solution with 200 mg alfaprostol, a synthetic analogue of PGF2a; Group B, 1 mL sc vitaminic solution with 20 I.U eCG; Group C (Control) 1 mL sc vitaminic solution. On day 11 pp (3 days after treatment), all the rabbits were artificially inseminated (AI), and injected with 0.8 mg of buserelin i.m. to induce ovulation. Concurrently, blood samples were taken for progesterone (P4) analysis by RIA with the following schedule: day 8 pp (before treatment), day 11 pp (before AI and the induction of ovulation) and day 16 pp (5 days after AI). Fertility was not influenced by hormonal treatments (71.7% and 71.2% respectively) compared to control (66.1%). Conversely, both PGF2a and eCG hormonal synchronisation treatments increased (P<0.05) litter size. P4 values before treatment on day 8 pp testify to the absence of functional CL (P4<2 ng/mL) in the early post partum period in 98.9% of the does in this breeding farm. Before AI and the induction of ovulation on day 11 pp 5.6% of the does had P4 concentrations, indicating non-oestral status (P4>1 ng/mL). On day 5 after insemination 95.5% had P4 values, which attest to the presence of functional corpora lutea (CL) (P4>2 ng/mL). The results of this study show that as long as rabbitry is properly managed zootechnically and sanitarily, drugs such as alfaprostol and eCG, while not ameliorating fertility rate when used for post partum oestrus sychronisation, can increase litter size.

[EN] The aim of this study was to verify the effectiveness of post partum pharmacological oestrus synchronisation with alfaprostol or eCG in improving rabbit doe reproductive performances and to evaluate the incidence of pseudopregnancy in this species. One hundred and eighty commercial hybrid rabbit does, multiparous and lactating, were randomly divided into three groups (n=60) and treated on day 8 post partum (pp) as follows: Group A, 1 mL s.c. vitaminic solution with 200 mg alfaprostol, a synthetic analogue of PGF2a; Group B, 1 mL sc vitaminic solution with 20 I.U eCG; Group C (Control) 1 mL sc vitaminic solution. On day 11 pp (3 days after treatment), all the rabbits were artificially inseminated (AI), and injected with 0.8 mg of buserelin i.m. to induce ovulation. Concurrently, blood samples were taken for progesterone (P4) analysis by RIA with the following schedule: day 8 pp (before treatment), day 11 pp (before AI and the induction of ovulation) and day 16 pp (5 days after AI). Fertility was not influenced by hormonal treatments (71.7% and 71.2% respectively) compared to control (66.1%). Conversely, both PGF2a and eCG hormonal synchronisation treatments increased (P<0.05) litter size. P4 values before treatment on day 8 pp testify to the absence of functional CL (P4<2 ng/mL) in the early post partum period in 98.9% of the does in this breeding farm. Before AI and the induction of ovulation on day 11 pp 5.6% of the does had P4 concentrations, indicating non-oestral status (P4>1 ng/mL). On day 5 after insemination 95.5% had P4 values, which attest to the presence of functional corpora lutea (CL) (P4>2 ng/mL). The results of this study show that as long as rabbitry is properly managed zootechnically and sanitarily, drugs such as alfaprostol and eCG, while not ameliorating fertility rate when used for post partum oestrus sychronisation, can increase litter size.

[EN] Using data from three different experiments, the effects of oestrus synchronisation by doe-litter separation (DLS), applied 48 hours befare artificial insemination from day 9 to day 11 post partum, on productive performance of free nursing rabbit does and their litters in relation to parity and number of successive DLS treatments were evaluated. lnitially, 200 New Zealand White does of different parity were homogeneously and definitively distributed in two groups (DLS and Control). On the whole, DLS improved fertility (+23.9%, Ps0.001 ), but reduced the growth of young rabbits from day 9 to weaning (-1.7 g/d, Ps0.01) and their weaning weight (-38 g, Ps0.01) at day 35. DLS also increased by 19.2%, 32.5% and 35.0% (Ps0.01) the fertility rate of does from parity 1 to 3, respectively. but was ineffective on does of parity <:4. When DLS was repeatedly applied to does with more than 3 parity, fertility progressively dropped and, after the first still successful application, it was similar to !ha! of controls. The results suggested that the effect of DLS on fertility of does and growth of suckling rabbit could depend on number of successive treatments rather !han on parity. The hypothesis !ha! severa! DLS treatments could induce a condi!ion of behavioural/psychological and/or physiological adaptation, depressing both fertility and milk yield thereafter, while tempting, remains to be tested., [FR] En utilisant des données de trois expériences différentes, nous avons évalué J'effet de la synchronisation de l'oestrus par séparation mere-jeune (SMJ), réalisée 48 heures avant insémination artificielle, du 9eme (J9) au 11 eme jour (J11) apres la mise bas, sur la productivité de lapines en allaitement libre et de leurs portées, en fonction de la parité et du nombre de SMJ successives. Deux cents lapines Néo Zélandais Blanc, de parité variable, ont été réparties de fa9on homogene et définitive en deux groupes (SMJ et témoin). Globalement, SMJ a amélioré Ja fertilité (+23.9%, P<0.001 ), mais a réduit la croissance des Japereaux de J9 au sevrage (-1, 7 g/j, P<0.01) et leur poids au sevrage a 35 jours (-38 g, P<0.01 ). SMJ a augmenté le taux de fertilité des parités 1 a 3 de 19,2%, 32,5% et 35,0% (P<0.01 ), respectivement, mais a été inefficace a partir de la parité 4. Quand SMJ était appliquée a plusieurs reprises a des femelles ayant ·eu plus de trois portées, la fertilité diminuait progressivement et, apres le premier traitement encare efficace, elle é!ait identique a celle des témoins. Ces résultats suggerent que J'effet de SMJ sur la fertilité des lapines et la croissance des Japereaux pourrait dépendre du nombre de traitements successifs plutot que de la parité. L'hypothese que plusieurs traitements de SMJ pourraient induire un état d'adaptation comportementale/psychologique et/ou physiologique, réduisant a la fois la fertilité et la production laitiere reste a vérifier.

[EN] Using data from three different experiments, the effects of oestrus synchronisation by doe-litter separation (DLS), applied 48 hours befare artificial insemination from day 9 to day 11 post partum, on productive performance of free nursing rabbit does and their litters in relation to parity and number of successive DLS treatments were evaluated. lnitially, 200 New Zealand White does of different parity were homogeneously and definitively distributed in two groups (DLS and Control). On the whole, DLS improved fertility (+23.9%, Ps0.001 ), but reduced the growth of young rabbits from day 9 to weaning (-1.7 g/d, Ps0.01) and their weaning weight (-38 g, Ps0.01) at day 35. DLS also increased by 19.2%, 32.5% and 35.0% (Ps0.01) the fertility rate of does from parity 1 to 3, respectively. but was ineffective on does of parity <:4. When DLS was repeatedly applied to does with more than 3 parity, fertility progressively dropped and, after the first still successful application, it was similar to !ha! of controls. The results suggested that the effect of DLS on fertility of does and growth of suckling rabbit could depend on number of successive treatments rather !han on parity. The hypothesis !ha! severa! DLS treatments could induce a condi!ion of behavioural/psychological and/or physiological adaptation, depressing both fertility and milk yield thereafter, while tempting, remains to be tested., [FR] En utilisant des données de trois expériences différentes, nous avons évalué J'effet de la synchronisation de l'oestrus par séparation mere-jeune (SMJ), réalisée 48 heures avant insémination artificielle, du 9eme (J9) au 11 eme jour (J11) apres la mise bas, sur la productivité de lapines en allaitement libre et de leurs portées, en fonction de la parité et du nombre de SMJ successives. Deux cents lapines Néo Zélandais Blanc, de parité variable, ont été réparties de fa9on homogene et définitive en deux groupes (SMJ et témoin). Globalement, SMJ a amélioré Ja fertilité (+23.9%, P<0.001 ), mais a réduit la croissance des Japereaux de J9 au sevrage (-1, 7 g/j, P<0.01) et leur poids au sevrage a 35 jours (-38 g, P<0.01 ). SMJ a augmenté le taux de fertilité des parités 1 a 3 de 19,2%, 32,5% et 35,0% (P<0.01 ), respectivement, mais a été inefficace a partir de la parité 4. Quand SMJ était appliquée a plusieurs reprises a des femelles ayant ·eu plus de trois portées, la fertilité diminuait progressivement et, apres le premier traitement encare efficace, elle é!ait identique a celle des témoins. Ces résultats suggerent que J'effet de SMJ sur la fertilité des lapines et la croissance des Japereaux pourrait dépendre du nombre de traitements successifs plutot que de la parité. L'hypothese que plusieurs traitements de SMJ pourraient induire un état d'adaptation comportementale/psychologique et/ou physiologique, réduisant a la fois la fertilité et la production laitiere reste a vérifier.

[EN] Using data from three different experiments, the effects of oestrus synchronisation by doe-litter separation (DLS), applied 48 hours befare artificial insemination from day 9 to day 11 post partum, on productive performance of free nursing rabbit does and their litters in relation to parity and number of successive DLS treatments were evaluated. lnitially, 200 New Zealand White does of different parity were homogeneously and definitively distributed in two groups (DLS and Control). On the whole, DLS improved fertility (+23.9%, Ps0.001 ), but reduced the growth of young rabbits from day 9 to weaning (-1.7 g/d, Ps0.01) and their weaning weight (-38 g, Ps0.01) at day 35. DLS also increased by 19.2%, 32.5% and 35.0% (Ps0.01) the fertility rate of does from parity 1 to 3, respectively. but was ineffective on does of parity <:4. When DLS was repeatedly applied to does with more than 3 parity, fertility progressively dropped and, after the first still successful application, it was similar to !ha! of controls. The results suggested that the effect of DLS on fertility of does and growth of suckling rabbit could depend on number of successive treatments rather !han on parity. The hypothesis !ha! severa! DLS treatments could induce a condi!ion of behavioural/psychological and/or physiological adaptation, depressing both fertility and milk yield thereafter, while tempting, remains to be tested., [FR] En utilisant des données de trois expériences différentes, nous avons évalué J'effet de la synchronisation de l'oestrus par séparation mere-jeune (SMJ), réalisée 48 heures avant insémination artificielle, du 9eme (J9) au 11 eme jour (J11) apres la mise bas, sur la productivité de lapines en allaitement libre et de leurs portées, en fonction de la parité et du nombre de SMJ successives. Deux cents lapines Néo Zélandais Blanc, de parité variable, ont été réparties de fa9on homogene et définitive en deux groupes (SMJ et témoin). Globalement, SMJ a amélioré Ja fertilité (+23.9%, P<0.001 ), mais a réduit la croissance des Japereaux de J9 au sevrage (-1, 7 g/j, P<0.01) et leur poids au sevrage a 35 jours (-38 g, P<0.01 ). SMJ a augmenté le taux de fertilité des parités 1 a 3 de 19,2%, 32,5% et 35,0% (P<0.01 ), respectivement, mais a été inefficace a partir de la parité 4. Quand SMJ était appliquée a plusieurs reprises a des femelles ayant ·eu plus de trois portées, la fertilité diminuait progressivement et, apres le premier traitement encare efficace, elle é!ait identique a celle des témoins. Ces résultats suggerent que J'effet de SMJ sur la fertilité des lapines et la croissance des Japereaux pourrait dépendre du nombre de traitements successifs plutot que de la parité. L'hypothese que plusieurs traitements de SMJ pourraient induire un état d'adaptation comportementale/psychologique et/ou physiologique, réduisant a la fois la fertilité et la production laitiere reste a vérifier.

[EN] Using data from three different experiments, the effects of oestrus synchronisation by doe-litter separation (DLS), applied 48 hours befare artificial insemination from day 9 to day 11 post partum, on productive performance of free nursing rabbit does and their litters in relation to parity and number of successive DLS treatments were evaluated. lnitially, 200 New Zealand White does of different parity were homogeneously and definitively distributed in two groups (DLS and Control). On the whole, DLS improved fertility (+23.9%, Ps0.001 ), but reduced the growth of young rabbits from day 9 to weaning (-1.7 g/d, Ps0.01) and their weaning weight (-38 g, Ps0.01) at day 35. DLS also increased by 19.2%, 32.5% and 35.0% (Ps0.01) the fertility rate of does from parity 1 to 3, respectively. but was ineffective on does of parity <:4. When DLS was repeatedly applied to does with more than 3 parity, fertility progressively dropped and, after the first still successful application, it was similar to !ha! of controls. The results suggested that the effect of DLS on fertility of does and growth of suckling rabbit could depend on number of successive treatments rather !han on parity. The hypothesis !ha! severa! DLS treatments could induce a condi!ion of behavioural/psychological and/or physiological adaptation, depressing both fertility and milk yield thereafter, while tempting, remains to be tested., [FR] En utilisant des données de trois expériences différentes, nous avons évalué J'effet de la synchronisation de l'oestrus par séparation mere-jeune (SMJ), réalisée 48 heures avant insémination artificielle, du 9eme (J9) au 11 eme jour (J11) apres la mise bas, sur la productivité de lapines en allaitement libre et de leurs portées, en fonction de la parité et du nombre de SMJ successives. Deux cents lapines Néo Zélandais Blanc, de parité variable, ont été réparties de fa9on homogene et définitive en deux groupes (SMJ et témoin). Globalement, SMJ a amélioré Ja fertilité (+23.9%, P<0.001 ), mais a réduit la croissance des Japereaux de J9 au sevrage (-1, 7 g/j, P<0.01) et leur poids au sevrage a 35 jours (-38 g, P<0.01 ). SMJ a augmenté le taux de fertilité des parités 1 a 3 de 19,2%, 32,5% et 35,0% (P<0.01 ), respectivement, mais a été inefficace a partir de la parité 4. Quand SMJ était appliquée a plusieurs reprises a des femelles ayant ·eu plus de trois portées, la fertilité diminuait progressivement et, apres le premier traitement encare efficace, elle é!ait identique a celle des témoins. Ces résultats suggerent que J'effet de SMJ sur la fertilité des lapines et la croissance des Japereaux pourrait dépendre du nombre de traitements successifs plutot que de la parité. L'hypothese que plusieurs traitements de SMJ pourraient induire un état d'adaptation comportementale/psychologique et/ou physiologique, réduisant a la fois la fertilité et la production laitiere reste a vérifier.

[EN] Using data from three different experiments, the effects of oestrus synchronisation by doe-litter separation (DLS), applied 48 hours befare artificial insemination from day 9 to day 11 post partum, on productive performance of free nursing rabbit does and their litters in relation to parity and number of successive DLS treatments were evaluated. lnitially, 200 New Zealand White does of different parity were homogeneously and definitively distributed in two groups (DLS and Control). On the whole, DLS improved fertility (+23.9%, Ps0.001 ), but reduced the growth of young rabbits from day 9 to weaning (-1.7 g/d, Ps0.01) and their weaning weight (-38 g, Ps0.01) at day 35. DLS also increased by 19.2%, 32.5% and 35.0% (Ps0.01) the fertility rate of does from parity 1 to 3, respectively. but was ineffective on does of parity <:4. When DLS was repeatedly applied to does with more than 3 parity, fertility progressively dropped and, after the first still successful application, it was similar to !ha! of controls. The results suggested that the effect of DLS on fertility of does and growth of suckling rabbit could depend on number of successive treatments rather !han on parity. The hypothesis !ha! severa! DLS treatments could induce a condi!ion of behavioural/psychological and/or physiological adaptation, depressing both fertility and milk yield thereafter, while tempting, remains to be tested., [FR] En utilisant des données de trois expériences différentes, nous avons évalué J'effet de la synchronisation de l'oestrus par séparation mere-jeune (SMJ), réalisée 48 heures avant insémination artificielle, du 9eme (J9) au 11 eme jour (J11) apres la mise bas, sur la productivité de lapines en allaitement libre et de leurs portées, en fonction de la parité et du nombre de SMJ successives. Deux cents lapines Néo Zélandais Blanc, de parité variable, ont été réparties de fa9on homogene et définitive en deux groupes (SMJ et témoin). Globalement, SMJ a amélioré Ja fertilité (+23.9%, P<0.001 ), mais a réduit la croissance des Japereaux de J9 au sevrage (-1, 7 g/j, P<0.01) et leur poids au sevrage a 35 jours (-38 g, P<0.01 ). SMJ a augmenté le taux de fertilité des parités 1 a 3 de 19,2%, 32,5% et 35,0% (P<0.01 ), respectivement, mais a été inefficace a partir de la parité 4. Quand SMJ était appliquée a plusieurs reprises a des femelles ayant ·eu plus de trois portées, la fertilité diminuait progressivement et, apres le premier traitement encare efficace, elle é!ait identique a celle des témoins. Ces résultats suggerent que J'effet de SMJ sur la fertilité des lapines et la croissance des Japereaux pourrait dépendre du nombre de traitements successifs plutot que de la parité. L'hypothese que plusieurs traitements de SMJ pourraient induire un état d'adaptation comportementale/psychologique et/ou physiologique, réduisant a la fois la fertilité et la production laitiere reste a vérifier.

[EN] Using data from three different experiments, the effects of oestrus synchronisation by doe-litter separation (DLS), applied 48 hours befare artificial insemination from day 9 to day 11 post partum, on productive performance of free nursing rabbit does and their litters in relation to parity and number of successive DLS treatments were evaluated. lnitially, 200 New Zealand White does of different parity were homogeneously and definitively distributed in two groups (DLS and Control). On the whole, DLS improved fertility (+23.9%, Ps0.001 ), but reduced the growth of young rabbits from day 9 to weaning (-1.7 g/d, Ps0.01) and their weaning weight (-38 g, Ps0.01) at day 35. DLS also increased by 19.2%, 32.5% and 35.0% (Ps0.01) the fertility rate of does from parity 1 to 3, respectively. but was ineffective on does of parity <:4. When DLS was repeatedly applied to does with more than 3 parity, fertility progressively dropped and, after the first still successful application, it was similar to !ha! of controls. The results suggested that the effect of DLS on fertility of does and growth of suckling rabbit could depend on number of successive treatments rather !han on parity. The hypothesis !ha! severa! DLS treatments could induce a condi!ion of behavioural/psychological and/or physiological adaptation, depressing both fertility and milk yield thereafter, while tempting, remains to be tested., [FR] En utilisant des données de trois expériences différentes, nous avons évalué J'effet de la synchronisation de l'oestrus par séparation mere-jeune (SMJ), réalisée 48 heures avant insémination artificielle, du 9eme (J9) au 11 eme jour (J11) apres la mise bas, sur la productivité de lapines en allaitement libre et de leurs portées, en fonction de la parité et du nombre de SMJ successives. Deux cents lapines Néo Zélandais Blanc, de parité variable, ont été réparties de fa9on homogene et définitive en deux groupes (SMJ et témoin). Globalement, SMJ a amélioré Ja fertilité (+23.9%, P<0.001 ), mais a réduit la croissance des Japereaux de J9 au sevrage (-1, 7 g/j, P<0.01) et leur poids au sevrage a 35 jours (-38 g, P<0.01 ). SMJ a augmenté le taux de fertilité des parités 1 a 3 de 19,2%, 32,5% et 35,0% (P<0.01 ), respectivement, mais a été inefficace a partir de la parité 4. Quand SMJ était appliquée a plusieurs reprises a des femelles ayant ·eu plus de trois portées, la fertilité diminuait progressivement et, apres le premier traitement encare efficace, elle é!ait identique a celle des témoins. Ces résultats suggerent que J'effet de SMJ sur la fertilité des lapines et la croissance des Japereaux pourrait dépendre du nombre de traitements successifs plutot que de la parité. L'hypothese que plusieurs traitements de SMJ pourraient induire un état d'adaptation comportementale/psychologique et/ou physiologique, réduisant a la fois la fertilité et la production laitiere reste a vérifier.

[EN] For many years prostaglandin E2 and prostaglandin F2a have been known to exert luteotrophic and luteolytic actions on the corpus luteum (CL) of most mammalian species. Although the modalities by which the CL regulates normal reproductive cycles and maintenance of pregnancy are basically similar, increasing evidence suggests that severa! unique mechanisms regulating the growth and regression of CL exist between different species. In this respect, the corpus luteum of rabbits has not been as extensively studied as that of other farm or laboratory animals and very often the experimental data conflict. This reviews presents what is currently known about the actions of these two prostaglandins by critically examining their in vivo and in vitro effects. In non-pregnant and normally cycling animals, uterine PGF2a causes the CL to spontaneously regress at approximately 14-16 days post-ovulation depending on the species. Exogenous PGF2a administration may be used to cause CL regression and thus control the ovarian cycle. In the rabbit, however, because it does not have a defined cycle, this luteolytic mechanism comes into play only in the case of pseudopregnancy or pregnancy. The PGF2a analogue, alfaprostol, will reduce the diestrous phase at day 9 of pseudopregnancy In pregnant rabbits, PGF2a (and its synthetic analogues) is the hormone of choice for induction and synchronisation of kindling, having beneficia! effects on postpartum fertility., [FR] Depuis de nombreuses années, les effets lutéotrophiques et lutéolytiques exercés par les prostaglandines E2 et F2a sur les corps jaunes (CL) de la plupart des mammiféres sont bien connus. Bien que les modalités qui permettent aux CL de réguler les cycles normal de reproduction et le maintien de la gestation soient similaires, un nombre de plus en plus grand d'évidences suggére que plusieurs mécanismes particuliers, régulant la croissance et la régression des CL, existen! chez différentes espéces. En ce qui concerne les lapines, les corps jaunes n'ont pas été aussi largement étudiés que ceux d'autres animaux d'élevage ou de laboratoire, et les résultats expérimentaux sont tres souvent contradictoires. Cette revue actualise les connaissances concernant les actions de ces deux prostaglandines grace a !'examen critique de leurs actions in vivo et in vitro. Chez les femelles non gravides et ayant un cycle normal, la PGF2" utérine produit une régression spontanée des CL approximativement au 14-16éme jours aprés l'ovulation selon les espéces. L'administration de PGF2a peut étre utilisée pour provoquer la régression des CL et contrOler ainsi le cycle ovarien. Cependant, chez la lapine qui n'a pas de cycle défini, ce mécanisme lutéolytique entre en jeu seulement en cas de pseudogestation ou de gestation. L'alfaprostol, un analogue de PGF2a, peut réduire a 9 jours l'anoestrus de pseudogestation. Chez la lapine, PGF2a (et ses analogues synthétiques) est l'hormone de choix pour l'induction et la synchronisation des mise-bas, avec un effet bénéfique sur la fertilité post partum.

[EN] For many years prostaglandin E2 and prostaglandin F2a have been known to exert luteotrophic and luteolytic actions on the corpus luteum (CL) of most mammalian species. Although the modalities by which the CL regulates normal reproductive cycles and maintenance of pregnancy are basically similar, increasing evidence suggests that severa! unique mechanisms regulating the growth and regression of CL exist between different species. In this respect, the corpus luteum of rabbits has not been as extensively studied as that of other farm or laboratory animals and very often the experimental data conflict. This reviews presents what is currently known about the actions of these two prostaglandins by critically examining their in vivo and in vitro effects. In non-pregnant and normally cycling animals, uterine PGF2a causes the CL to spontaneously regress at approximately 14-16 days post-ovulation depending on the species. Exogenous PGF2a administration may be used to cause CL regression and thus control the ovarian cycle. In the rabbit, however, because it does not have a defined cycle, this luteolytic mechanism comes into play only in the case of pseudopregnancy or pregnancy. The PGF2a analogue, alfaprostol, will reduce the diestrous phase at day 9 of pseudopregnancy In pregnant rabbits, PGF2a (and its synthetic analogues) is the hormone of choice for induction and synchronisation of kindling, having beneficia! effects on postpartum fertility., [FR] Depuis de nombreuses années, les effets lutéotrophiques et lutéolytiques exercés par les prostaglandines E2 et F2a sur les corps jaunes (CL) de la plupart des mammiféres sont bien connus. Bien que les modalités qui permettent aux CL de réguler les cycles normal de reproduction et le maintien de la gestation soient similaires, un nombre de plus en plus grand d'évidences suggére que plusieurs mécanismes particuliers, régulant la croissance et la régression des CL, existen! chez différentes espéces. En ce qui concerne les lapines, les corps jaunes n'ont pas été aussi largement étudiés que ceux d'autres animaux d'élevage ou de laboratoire, et les résultats expérimentaux sont tres souvent contradictoires. Cette revue actualise les connaissances concernant les actions de ces deux prostaglandines grace a !'examen critique de leurs actions in vivo et in vitro. Chez les femelles non gravides et ayant un cycle normal, la PGF2" utérine produit une régression spontanée des CL approximativement au 14-16éme jours aprés l'ovulation selon les espéces. L'administration de PGF2a peut étre utilisée pour provoquer la régression des CL et contrOler ainsi le cycle ovarien. Cependant, chez la lapine qui n'a pas de cycle défini, ce mécanisme lutéolytique entre en jeu seulement en cas de pseudogestation ou de gestation. L'alfaprostol, un analogue de PGF2a, peut réduire a 9 jours l'anoestrus de pseudogestation. Chez la lapine, PGF2a (et ses analogues synthétiques) est l'hormone de choix pour l'induction et la synchronisation des mise-bas, avec un effet bénéfique sur la fertilité post partum.

[EN] For many years prostaglandin E2 and prostaglandin F2a have been known to exert luteotrophic and luteolytic actions on the corpus luteum (CL) of most mammalian species. Although the modalities by which the CL regulates normal reproductive cycles and maintenance of pregnancy are basically similar, increasing evidence suggests that severa! unique mechanisms regulating the growth and regression of CL exist between different species. In this respect, the corpus luteum of rabbits has not been as extensively studied as that of other farm or laboratory animals and very often the experimental data conflict. This reviews presents what is currently known about the actions of these two prostaglandins by critically examining their in vivo and in vitro effects. In non-pregnant and normally cycling animals, uterine PGF2a causes the CL to spontaneously regress at approximately 14-16 days post-ovulation depending on the species. Exogenous PGF2a administration may be used to cause CL regression and thus control the ovarian cycle. In the rabbit, however, because it does not have a defined cycle, this luteolytic mechanism comes into play only in the case of pseudopregnancy or pregnancy. The PGF2a analogue, alfaprostol, will reduce the diestrous phase at day 9 of pseudopregnancy In pregnant rabbits, PGF2a (and its synthetic analogues) is the hormone of choice for induction and synchronisation of kindling, having beneficia! effects on postpartum fertility., [FR] Depuis de nombreuses années, les effets lutéotrophiques et lutéolytiques exercés par les prostaglandines E2 et F2a sur les corps jaunes (CL) de la plupart des mammiféres sont bien connus. Bien que les modalités qui permettent aux CL de réguler les cycles normal de reproduction et le maintien de la gestation soient similaires, un nombre de plus en plus grand d'évidences suggére que plusieurs mécanismes particuliers, régulant la croissance et la régression des CL, existen! chez différentes espéces. En ce qui concerne les lapines, les corps jaunes n'ont pas été aussi largement étudiés que ceux d'autres animaux d'élevage ou de laboratoire, et les résultats expérimentaux sont tres souvent contradictoires. Cette revue actualise les connaissances concernant les actions de ces deux prostaglandines grace a !'examen critique de leurs actions in vivo et in vitro. Chez les femelles non gravides et ayant un cycle normal, la PGF2" utérine produit une régression spontanée des CL approximativement au 14-16éme jours aprés l'ovulation selon les espéces. L'administration de PGF2a peut étre utilisée pour provoquer la régression des CL et contrOler ainsi le cycle ovarien. Cependant, chez la lapine qui n'a pas de cycle défini, ce mécanisme lutéolytique entre en jeu seulement en cas de pseudogestation ou de gestation. L'alfaprostol, un analogue de PGF2a, peut réduire a 9 jours l'anoestrus de pseudogestation. Chez la lapine, PGF2a (et ses analogues synthétiques) est l'hormone de choix pour l'induction et la synchronisation des mise-bas, avec un effet bénéfique sur la fertilité post partum.

[EN] For many years prostaglandin E2 and prostaglandin F2a have been known to exert luteotrophic and luteolytic actions on the corpus luteum (CL) of most mammalian species. Although the modalities by which the CL regulates normal reproductive cycles and maintenance of pregnancy are basically similar, increasing evidence suggests that severa! unique mechanisms regulating the growth and regression of CL exist between different species. In this respect, the corpus luteum of rabbits has not been as extensively studied as that of other farm or laboratory animals and very often the experimental data conflict. This reviews presents what is currently known about the actions of these two prostaglandins by critically examining their in vivo and in vitro effects. In non-pregnant and normally cycling animals, uterine PGF2a causes the CL to spontaneously regress at approximately 14-16 days post-ovulation depending on the species. Exogenous PGF2a administration may be used to cause CL regression and thus control the ovarian cycle. In the rabbit, however, because it does not have a defined cycle, this luteolytic mechanism comes into play only in the case of pseudopregnancy or pregnancy. The PGF2a analogue, alfaprostol, will reduce the diestrous phase at day 9 of pseudopregnancy In pregnant rabbits, PGF2a (and its synthetic analogues) is the hormone of choice for induction and synchronisation of kindling, having beneficia! effects on postpartum fertility., [FR] Depuis de nombreuses années, les effets lutéotrophiques et lutéolytiques exercés par les prostaglandines E2 et F2a sur les corps jaunes (CL) de la plupart des mammiféres sont bien connus. Bien que les modalités qui permettent aux CL de réguler les cycles normal de reproduction et le maintien de la gestation soient similaires, un nombre de plus en plus grand d'évidences suggére que plusieurs mécanismes particuliers, régulant la croissance et la régression des CL, existen! chez différentes espéces. En ce qui concerne les lapines, les corps jaunes n'ont pas été aussi largement étudiés que ceux d'autres animaux d'élevage ou de laboratoire, et les résultats expérimentaux sont tres souvent contradictoires. Cette revue actualise les connaissances concernant les actions de ces deux prostaglandines grace a !'examen critique de leurs actions in vivo et in vitro. Chez les femelles non gravides et ayant un cycle normal, la PGF2" utérine produit une régression spontanée des CL approximativement au 14-16éme jours aprés l'ovulation selon les espéces. L'administration de PGF2a peut étre utilisée pour provoquer la régression des CL et contrOler ainsi le cycle ovarien. Cependant, chez la lapine qui n'a pas de cycle défini, ce mécanisme lutéolytique entre en jeu seulement en cas de pseudogestation ou de gestation. L'alfaprostol, un analogue de PGF2a, peut réduire a 9 jours l'anoestrus de pseudogestation. Chez la lapine, PGF2a (et ses analogues synthétiques) est l'hormone de choix pour l'induction et la synchronisation des mise-bas, avec un effet bénéfique sur la fertilité post partum.

[EN] For many years prostaglandin E2 and prostaglandin F2a have been known to exert luteotrophic and luteolytic actions on the corpus luteum (CL) of most mammalian species. Although the modalities by which the CL regulates normal reproductive cycles and maintenance of pregnancy are basically similar, increasing evidence suggests that severa! unique mechanisms regulating the growth and regression of CL exist between different species. In this respect, the corpus luteum of rabbits has not been as extensively studied as that of other farm or laboratory animals and very often the experimental data conflict. This reviews presents what is currently known about the actions of these two prostaglandins by critically examining their in vivo and in vitro effects. In non-pregnant and normally cycling animals, uterine PGF2a causes the CL to spontaneously regress at approximately 14-16 days post-ovulation depending on the species. Exogenous PGF2a administration may be used to cause CL regression and thus control the ovarian cycle. In the rabbit, however, because it does not have a defined cycle, this luteolytic mechanism comes into play only in the case of pseudopregnancy or pregnancy. The PGF2a analogue, alfaprostol, will reduce the diestrous phase at day 9 of pseudopregnancy In pregnant rabbits, PGF2a (and its synthetic analogues) is the hormone of choice for induction and synchronisation of kindling, having beneficia! effects on postpartum fertility., [FR] Depuis de nombreuses années, les effets lutéotrophiques et lutéolytiques exercés par les prostaglandines E2 et F2a sur les corps jaunes (CL) de la plupart des mammiféres sont bien connus. Bien que les modalités qui permettent aux CL de réguler les cycles normal de reproduction et le maintien de la gestation soient similaires, un nombre de plus en plus grand d'évidences suggére que plusieurs mécanismes particuliers, régulant la croissance et la régression des CL, existen! chez différentes espéces. En ce qui concerne les lapines, les corps jaunes n'ont pas été aussi largement étudiés que ceux d'autres animaux d'élevage ou de laboratoire, et les résultats expérimentaux sont tres souvent contradictoires. Cette revue actualise les connaissances concernant les actions de ces deux prostaglandines grace a !'examen critique de leurs actions in vivo et in vitro. Chez les femelles non gravides et ayant un cycle normal, la PGF2" utérine produit une régression spontanée des CL approximativement au 14-16éme jours aprés l'ovulation selon les espéces. L'administration de PGF2a peut étre utilisée pour provoquer la régression des CL et contrOler ainsi le cycle ovarien. Cependant, chez la lapine qui n'a pas de cycle défini, ce mécanisme lutéolytique entre en jeu seulement en cas de pseudogestation ou de gestation. L'alfaprostol, un analogue de PGF2a, peut réduire a 9 jours l'anoestrus de pseudogestation. Chez la lapine, PGF2a (et ses analogues synthétiques) est l'hormone de choix pour l'induction et la synchronisation des mise-bas, avec un effet bénéfique sur la fertilité post partum.

[EN] For many years prostaglandin E2 and prostaglandin F2a have been known to exert luteotrophic and luteolytic actions on the corpus luteum (CL) of most mammalian species. Although the modalities by which the CL regulates normal reproductive cycles and maintenance of pregnancy are basically similar, increasing evidence suggests that severa! unique mechanisms regulating the growth and regression of CL exist between different species. In this respect, the corpus luteum of rabbits has not been as extensively studied as that of other farm or laboratory animals and very often the experimental data conflict. This reviews presents what is currently known about the actions of these two prostaglandins by critically examining their in vivo and in vitro effects. In non-pregnant and normally cycling animals, uterine PGF2a causes the CL to spontaneously regress at approximately 14-16 days post-ovulation depending on the species. Exogenous PGF2a administration may be used to cause CL regression and thus control the ovarian cycle. In the rabbit, however, because it does not have a defined cycle, this luteolytic mechanism comes into play only in the case of pseudopregnancy or pregnancy. The PGF2a analogue, alfaprostol, will reduce the diestrous phase at day 9 of pseudopregnancy In pregnant rabbits, PGF2a (and its synthetic analogues) is the hormone of choice for induction and synchronisation of kindling, having beneficia! effects on postpartum fertility., [FR] Depuis de nombreuses années, les effets lutéotrophiques et lutéolytiques exercés par les prostaglandines E2 et F2a sur les corps jaunes (CL) de la plupart des mammiféres sont bien connus. Bien que les modalités qui permettent aux CL de réguler les cycles normal de reproduction et le maintien de la gestation soient similaires, un nombre de plus en plus grand d'évidences suggére que plusieurs mécanismes particuliers, régulant la croissance et la régression des CL, existen! chez différentes espéces. En ce qui concerne les lapines, les corps jaunes n'ont pas été aussi largement étudiés que ceux d'autres animaux d'élevage ou de laboratoire, et les résultats expérimentaux sont tres souvent contradictoires. Cette revue actualise les connaissances concernant les actions de ces deux prostaglandines grace a !'examen critique de leurs actions in vivo et in vitro. Chez les femelles non gravides et ayant un cycle normal, la PGF2" utérine produit une régression spontanée des CL approximativement au 14-16éme jours aprés l'ovulation selon les espéces. L'administration de PGF2a peut étre utilisée pour provoquer la régression des CL et contrOler ainsi le cycle ovarien. Cependant, chez la lapine qui n'a pas de cycle défini, ce mécanisme lutéolytique entre en jeu seulement en cas de pseudogestation ou de gestation. L'alfaprostol, un analogue de PGF2a, peut réduire a 9 jours l'anoestrus de pseudogestation. Chez la lapine, PGF2a (et ses analogues synthétiques) est l'hormone de choix pour l'induction et la synchronisation des mise-bas, avec un effet bénéfique sur la fertilité post partum.

[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.

not available.

[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.

[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.

[EN] The effect of 2 different techniques of mother-litter separation on rabbit doe performance was analysed. In the first experiment, executed in a commercial rabbitry, multiparous lactating hybrid does were successively artificially inseminated (620 Al) while in the second, a flock of 100 nulliparous was followed (524 Al). Does Nere submitted to one of the following treatments: control no treatment; 24 hours of mother-litter separation, 3 days befare Al, with 2 different procedures: closing the nestbox (Experiment 1) and change of caga (Experiment 2). AH the does were inseminated 11 days after kindling. Mother-litter separation did not significantly affect reproductiva results while, as expected, sexual receptivity and physiological status strongly influenced it. Probably longar stimuli are necessary to induce oestrus, particularly when does are in lactation. Nulliparous and multiparous non-lactating does showed a significant positiva reaction to biostimulation (Experiment 2 - gain of fertillty rata: 12.9% and 14.0%, respectively)., [FR] Deux techniques différentes de séparation de la mere et de sa portée ont été étudiées. Dans la premiare expérience menée dans un élevage industrie/, des lapínes hybrídes plurípares a/laítantes ont été inséminées artificiellement (620 JA) tandis que dans la deuxieme expérimentation un groupe de 100 lapines ont été contr61ées jusqu'a obtenir 524 JA. Les traitements suivants ont été appliqués : groupe controle sans traitement, 24 heures de séparation mere-portée trois iours avant /'/A selon deux méthodes - fermeture de la boíte a níd (expérience 1) - changement de cage (expérience 2). Toutes les lapines ont été inséminées 11 jours apres la mise bas. La séparation mere-portée n'a pas significatívement influencé les performances de reproductíon tandis que la réceptivité sexual/e et le statut physiologique ont été fortement ínfluencés. De plus· longues stimulatíons sont sans doute nécessaires pour induire l'oestrus, particulierement quand les feme/les sont allaitantes. Les lapines non allaitantes nullípares ou pluripares montrent une réaction positiva significativa a la biostimulation (expérience 2: augmentation du taux de fertilité: 12,9 et 14,0 %, respectivement)

not available.

[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.

[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.

[EN] The effect of 2 different techniques of mother-litter separation on rabbit doe performance was analysed. In the first experiment, executed in a commercial rabbitry, multiparous lactating hybrid does were successively artificially inseminated (620 Al) while in the second, a flock of 100 nulliparous was followed (524 Al). Does Nere submitted to one of the following treatments: control no treatment; 24 hours of mother-litter separation, 3 days befare Al, with 2 different procedures: closing the nestbox (Experiment 1) and change of caga (Experiment 2). AH the does were inseminated 11 days after kindling. Mother-litter separation did not significantly affect reproductiva results while, as expected, sexual receptivity and physiological status strongly influenced it. Probably longar stimuli are necessary to induce oestrus, particularly when does are in lactation. Nulliparous and multiparous non-lactating does showed a significant positiva reaction to biostimulation (Experiment 2 - gain of fertillty rata: 12.9% and 14.0%, respectively)., [FR] Deux techniques différentes de séparation de la mere et de sa portée ont été étudiées. Dans la premiare expérience menée dans un élevage industrie/, des lapínes hybrídes plurípares a/laítantes ont été inséminées artificiellement (620 JA) tandis que dans la deuxieme expérimentation un groupe de 100 lapines ont été contr61ées jusqu'a obtenir 524 JA. Les traitements suivants ont été appliqués : groupe controle sans traitement, 24 heures de séparation mere-portée trois iours avant /'/A selon deux méthodes - fermeture de la boíte a níd (expérience 1) - changement de cage (expérience 2). Toutes les lapines ont été inséminées 11 jours apres la mise bas. La séparation mere-portée n'a pas significatívement influencé les performances de reproductíon tandis que la réceptivité sexual/e et le statut physiologique ont été fortement ínfluencés. De plus· longues stimulatíons sont sans doute nécessaires pour induire l'oestrus, particulierement quand les feme/les sont allaitantes. Les lapines non allaitantes nullípares ou pluripares montrent une réaction positiva significativa a la biostimulation (expérience 2: augmentation du taux de fertilité: 12,9 et 14,0 %, respectivement)

[EN] The effect of 2 different techniques of mother-litter separation on rabbit doe performance was analysed. In the first experiment, executed in a commercial rabbitry, multiparous lactating hybrid does were successively artificially inseminated (620 Al) while in the second, a flock of 100 nulliparous was followed (524 Al). Does Nere submitted to one of the following treatments: control no treatment; 24 hours of mother-litter separation, 3 days befare Al, with 2 different procedures: closing the nestbox (Experiment 1) and change of caga (Experiment 2). AH the does were inseminated 11 days after kindling. Mother-litter separation did not significantly affect reproductiva results while, as expected, sexual receptivity and physiological status strongly influenced it. Probably longar stimuli are necessary to induce oestrus, particularly when does are in lactation. Nulliparous and multiparous non-lactating does showed a significant positiva reaction to biostimulation (Experiment 2 - gain of fertillty rata: 12.9% and 14.0%, respectively)., [FR] Deux techniques différentes de séparation de la mere et de sa portée ont été étudiées. Dans la premiare expérience menée dans un élevage industrie/, des lapínes hybrídes plurípares a/laítantes ont été inséminées artificiellement (620 JA) tandis que dans la deuxieme expérimentation un groupe de 100 lapines ont été contr61ées jusqu'a obtenir 524 JA. Les traitements suivants ont été appliqués : groupe controle sans traitement, 24 heures de séparation mere-portée trois iours avant /'/A selon deux méthodes - fermeture de la boíte a níd (expérience 1) - changement de cage (expérience 2). Toutes les lapines ont été inséminées 11 jours apres la mise bas. La séparation mere-portée n'a pas significatívement influencé les performances de reproductíon tandis que la réceptivité sexual/e et le statut physiologique ont été fortement ínfluencés. De plus· longues stimulatíons sont sans doute nécessaires pour induire l'oestrus, particulierement quand les feme/les sont allaitantes. Les lapines non allaitantes nullípares ou pluripares montrent une réaction positiva significativa a la biostimulation (expérience 2: augmentation du taux de fertilité: 12,9 et 14,0 %, respectivement)