Efecto de la adición de acido fórmico en el control de las infecciones entéricas del conejo

Sin resume

Control del déficit energético y actividad ovárica de conejas primíparas sometidas a destete temprano

El objetivo de este estudio fue estudiar el efecto de un destete temprano, realizado a los 25 días post-parto (dpp), con el fin de reducir el déficit energético de las conejas primíparas y mejorar su eficacia reproductiva. Para ello, se estudió el efecto sobre las reservas corporales y la actividad ovárica de 34 conejas primíparas lactantes. Se sacrificó un grupo (n=10) a los 25 dpp (L25), otro (n=13) se destetó a los 25 dpp y se sacrificó a los 32 dpp (NL32) y un tercero (n=11), no se destetó y se sacrificó a los 32 dpp (L32). El peso vivo de los animales, las concentraciones de ácidos grasos no esterificados (AGNE) y de proteínas plasmáticas totales en el suero fueron similares en todos los grupos. Aunque el grupo NL32, después del destete, consumió menos alimento que el grupo L32 (122±23,5 vs. 402±26,7g/d, respectivamente; P < 0,001), sus contenidos estimados de lípidos (16,9±1,09%; P < 0,008), proteína (19,7±0,07%; P < 0,0001) y energía corporales (1147±42,7 MJ/kg; P < 0,006) fueron mayores, y sus concentraciones plasmáticas de glucosa (158±24,5mg/dl; P < 0,04) fueron menores que las del grupo L25 (11,9±1,3%, 18,5±0,08%, 942±51,3 MJ/kg y 212±27,9 mg/dl ) y que las del grupo L32, (13,4±1,03%, 18,5±0,1%, 993±40,4 MJ/kg and 259±29,5 mg/dl), respectivamente. El recuento de la población folicular en los ovarios fue similar en los tres grupos. La maduración nuclear (% de oocitos en metafase II) y la citoplásmica (% de gránulos corticales total o parcialmente migrados) fue significativamente menor en el grupo sacrificado a los 25 dpp (L25), que en los grupos NL32 y L32 (67 vs. 79,7 y 78,3%; P < 0,05; 16 vs. 38,3 y 60,0%; P<0,05, respectivamente). En conclusión, las reservas energéticas de la coneja primípara aumentan si es destetada a 25 dpp. Sin embargo, esta estrategia no es suficiente desde el punto de vista reproductivo, ya que a los 32 dpp, la actividad ovárica de las conejas es similar independientemente de si han sido destetadas previamente o no

Métodos de sincronización de celo en conejas primíparas lactantes a 25 días post-parto

La sincronización del celo es una técnica necesaria en las explotaciones cunícolas. En este trabajo se han utilizado un total de 60 conejas primíparas lactantes en día 25 post-parto (pp) distribuidas en 5 grupos de 12 animales: el grupo PG recibió un 2.5% de propilen glicol en el agua de bebida desde el día 22 pp, el grupo eCG se trató con 25 UI de eCG (i.m.) el día 23 pp, el grupo BIO fue separado transitoriamente de sus camadas durante 24 horas, el grupo PGBIO se suplementó con 2,5% de PG y además se le separó transitoriamente de su camada, y por último, el grupo C que no fue sincronizado. Estudiamos el efecto de estos tratamientos sobre el peso vivo, la composición corporal, el consumo de alimento, la concentración de los ácidos grasos no esterificados (AGNE), la glucosa y las proteínas plasmáticas, el crecimiento de los gazapos y la fisiología ovárica. Aunque todos los grupos tuvieron el mismo consumo de pienso, las conejas del grupo PG presentaron menos cantidad de proteína (P<0,003) y de grasa corporal (P<0,06) el día 25 pp que al principio del tratamiento. En los grupos PG y PGBIO, las concentraciones de AGNE no se modificaron y las concentraciones de proteínas plasmáticas eran más altas el día 22 que el 25 pp. En todos los grupos las concentraciones de glucosa aumentaron (P<0,001) y las camadas crecieron significativamente (P<0,001). Las poblaciones foliculares ováricas en el día 25 pp, así como la maduración nuclear in vitro de los oocitos no se vieron afectadas por ningún tratamiento. El grupo PG presentó una baja proporción de oocitos no madurados citoplásmicamente (P<0,05). En conclusión, ninguno de los tratamientos aplicados, incluido el hormonal, ha presentado resultados definitivamente mejores que el grupo control, por lo que es necesario estudiar otras combinaciones o métodos para poder conseguir mejorar sustancialmente los parámetros reproductivos en conejas primíparas lactantes en el día 25 pp

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

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

Study of failures in a rabbit line selected for growth rate

[EN] Selection for growth rate is negatively related with reproductive fitness. The aim of this work was to analyse the causes of fertility failure in rabbit does selected for growth rate and characterised for reproductive deficiencies (line R). In the experiment, 82 does were divided into 2 groups: naturally mated (NM) and artificially inseminated (AI), to relate luteinizing hormone (LH) concentration with ovulation induction and pregnancy rate by laparoscopic determination. Additionally, in 38 of these females ovulation rate and metabolites determination (leptin, NEFA, BOHB and glucose) were analysed and perirenal fat thickness measurement and live body weight (LBW) determined. The results showed that all ovulated does (both NM and AI) presented higher concentrations of LH than non-ovulated females. In addition, non-ovulated females showed high levels of leptin and BOHB, as well as LBW. Females from line R have an inherit reduced fertility due to ovulation failure as a consequence of a reduction in LH release, which could be explained by a heavier body weight and higher leptin concentrations.This work was supported by the Spanish Research Project AGL2011-30170-C02-01 (CICYT). Carmen Naturil-Alfonso was supported by a research grant from the Education Ministry of the Valencian Regional Government (programme VALi+d. ACIF/2013/296). English text version was revised by N. Macowan English Language Service.Naturil Alfonso, C.; Lavara García, R.; Millán, P.; Rebollar, P.; Vicente Antón, JS.; Marco Jiménez, F. (2016). Study of failures in a rabbit line selected for growth rate. World Rabbit Science. 24(1):47-53. https://doi.org/10.4995/wrs.2016.4016SWORD475324

Fertilidad, desarrollo embrionario y prolificidad de conejas nulíparas alimentadas con piensos enriquecidos en ácidos grasos poliinsaturados n-3

One hundred and five nulliparous rabbit does were fed ad libitum one month before and during pregnancy with two isofibrous, isoenergetic and isoproteic diets supplemented with two different fat sources: 0.75% lard for control diet (C group: n=53) or 1.5% of a supplement (Optomega-50; Optivite International Ltd., España) containing a 50% of ether extract and 38% of n-3 polyunsaturated fatty acids (PUFA) for experimental diet (group P n-3; n=52). Fertility after artificial insemination and induction of ovulation with 20 μg of Gonadorelina (Inducel-GnRH, Ovejero) at 4.5 months of age was assessed. At parturition, pregnancy length and prolificacy (number and weight of born alive and number of stillborn) were observed. A total of 8 pregnant does from each experimental group were chosen at random to study embryo and placenta dimensions by means of ultrasonography at 8, 15 and 22 days of pregnancy. PUFA n-3 supplementation did not affect any productive results due the success on reproductive features of nulliparous does which are difficult to improve. Neither, any differences in ultrasonographic meausrements were obtained; nevertheless we have defined useful physiological parameters of rabbit embryo and placenta to future studies in this specie.Un total de 105 conejas nulíparas se alimentaron ad libitum un mes antes y durante su primera gestación con dos piensos isofibrosos, isoenergéticos e isoproteicos suplementados con dos fuentes de grasa diferentes: 0,75% de manteca para la dieta control (grupo C; n=53) ó 1,5% de un suplemento (Optomega-50; Optivite International Ltd., España) que contenía un 50% de extracto etéreo y 38% de ácidos grasos poli-insaturados (AG n-3) para la dieta experimental (grupo P; n=52). A los 4,5 meses de edad se determinó la fertilidad después de ser inseminadas artificialmente y tratadas con 20 μg de Gonadorelina (Inducel-GnRH, Ovejero) para inducirles la ovulación. Al parto se determinó la duración de la gestación, el número y peso de los gazapos nacidos vivos y muertos. Se escogieron 16 conejas al azar, 8 de cada grupo, y se realizaron ecografías a los 8, 15 y 22 días de gestación en las que se determinó las dimensiones del embrión y de los anejos fetales. La suplementación con AG n-3 no afectó a los resultados productivos determinados ya que se trata de parámetros que en nulíparas son difíciles de mejorar y suelen ser altos. Tampoco se observaron diferencias en las determinaciones ecográficas pero se han podido definir medidas fisiológicas de los fetos y anejos placentarios de gran utilidad para futuros estudios en esta especie

Effects of feed restriction during pregnancy on maternal reproductive outcome, foetal hepatic IGF gene expression and offspring performance in the rabbit

Primiparous female rabbits have high nutritional requirements and, while it is recommended that they are subjected to an extensive reproductive rhythm, this could lead to overweight, affecting reproductive outcomes. We hypothesised that restricting food intake during the less energetic period of gestation could improve reproductive outcome without impairing offspring viability. This study compares two groups of primiparous rabbit does in an extensive reproductive programme, one in which feed was restricted from Day 0 to Day 21 of gestation (R021), and another in which does were fed ad libitum (control) throughout pregnancy. The mother and offspring variables compared were (1) mother reproductive outcomes at the time points pre-implantation (Day 3 postartificial insemination [AI]), preterm (Day 28 post-AI) and birth; and (2) the prenatal offspring characteristic IGF system gene expression in foetal liver, liver fibrosis and foetus sex ratio, and postnatal factor viability and growth at birth, and survival and growth until weaning. Feed restriction did not affect the conception rate, embryo survival, or the number of morulae and blastocysts recovered at Day 3 post-AI. Preterm placenta size and efficiency were similar in the two groups. However, both implantation rate (P < 0.001) and the number of foetuses (P = 0.05) were higher in the R021 mothers than controls, while there was no difference in foetal viability. Foetal size and weight, the weights of most organs, organ weight/BW ratios and sex ratio were unaffected by feed restriction; these variables were only affected by uterine position (P < 0.05). Conversely, in the R021 does, foetal liver IGBP1 and IGF2 gene expression were dysregulated despite no liver fibrosis and a normal liver structure. No effects of restricted feed intake were produced on maternal fertility, prolificacy, or offspring birth weight, but control females weaned more kits. Litter weight and mortality rate during the lactation period were also unaffected. In conclusion, pre-implantation events and foetal development were unaffected by feed restriction. While some genes of the foetal hepatic IGF system were dysregulated during pregnancy, liver morphology appeared normal, and the growth of foetuses and kits until weaning was unmodified. This strategy of feed restriction in extensive reproductive rhythms seems to have no significant adverse effects on dam reproductive outcome or offspring growth and viability until weaning

GROUPING OF RABBIT REPRODUCTION MANAGEMENT BY MEANS OF ARTIFICIAL INSEMINATION

[EN] One hundred and thirty does of the Californian x New Zealand breed were artificially inseminated on a fixed day of the week, during a thirteen months long study. All insemination were performed on Monday, using 1 mi diluted semen. Does with less than 8 youngs/litter (M1) were inseminated on day 3 or 4 post-partum (PP.), and rabbits with than 8 or more youngs/litter (M2) on day 1 O or 11 PP. All does found non pregnant were considered pseudopregnant and inseminated on day 24 PP. (M3). The first artificial insemination (A.I.) in nulliparous rabbits was performed at 4 months of age. 1679 A.I. were carried out during this experiment. Ovulation was induced with 20 μg of GnAH (Fertagyl, lntervet Lab.) in all rabbits, without considering their sexual receptivity. The overall conception rate (C.A.) obtained was 58.5 %. The lactation significatively influenced conception rate in animals inseminated in the post-partum period (P<0.001). Higher conception rate was observed in does inseminated after a first non-fertile insemination (type M3), (P<0.05). No difference between does M1 vs M2 was detected. C.R. in nulliparous does was higher compared to rabbits M2, and lower than rabbits M3 (P<0.05). Although rabbits were inseminated on a fixed day of the week, as a consequence of the pregnancy period variations, A.I. was finally performed between day 1 to 12 PP. Nevertheless, most of the inseminations were carried out on days 3, 4 and 10, 11 PP. Lower C.A. were obtained when comparing A.I. on days 3 to 5 and 9 to 12 PP., versus females inseminated on days 1 to 2 and 6 to 8 PP. (50.3 % and 48.9 % vs 69.5 % and 66.6 % respectively), (P<0.001). A significative interaction type of rabbit*lactation was detected when comparing non lactating rabbits inseminated on days 3 or 4, 1 O or 11, 24 or after PP., versus lactating does inseminated on the same days (71. 78 %, 68.9 %, 71.5 % vs 53.6 %, 48.7 %, 62.2 %, respectively, P<0.001). No influence on prolificacy was detected. The overall means obtained were : No. of youngs born/litter : 7.1 ± 0.1 ; No of youngs born dead/litter : 0.6 ± 0.05. Our results suggest a better reproductive management when A.I. was performed on one fixed day of the week. Practically all pregnancy diagnosis by abdominal palpation were carried out on Fridays (day 11 after A.1.), nest settings on Tuesdays (day 29 after A.1.), and parturition occurred on Thursdays and Fridays (day 31-32 after A.I.) of the same week. Nevertheless, the better C.A. observed in does A.I. on days 1 or 2 and 6 to 8 suggests that reproductive management could be organized on two fixed day of the week.[FR] Cent trente lapines Californiennes x Neo Zélandaises ont été artificiellement inséminées, un jour fixe de la semaine, durant une période d'étude de treize mois. Toutes les inséminations ont été pratiquées le Lundi, en utilisant 1 mi de semence diluée. Les lapines ayant moins de 8 lapereaux par portée (M1) ont été inséminees le 3 ou 4eme jour post partum (PP) et celles avec 8 lapereaux ou plus par portée (M2) le 1 O ou 11eme jour PP. Toutes les lapines reconnues non gestantes ont été considérées comme pseudo gestantes et inséminées le 24 eme jour PP (M3). La premiare insémination des lapines nullipares a été pratiquee a /'age de 4 mois. 1679 inséminations artificielles ont été pratiquées pendant cette expérimentation. L'ovulation était induite par 20μg de GnRH (Fertagyl, lntervet Lab.) pour toutes les lapines, sans tenir compte de leur réceptivité sexuelle. Le taux de fécondation globale a atteint 58.5 %. Le taux de fécondation était significativement influencé par la lactation pour les lapines inséminées PP (P<0.001). Le taux de fécondation le plus élevé a été observé chez les tapines inséminées apres un premiare insémination non fertile (type M3), (P<0.05). Entre les lapines M1 et M2 aucune différence n'a été détectée. Le taux de fécondation chez les tapines nullipares était supérieur comparé aux lapines M2 et inférieur comparé aux lapines M3 (P<0.05). A cause de la variation de la durée de gestation, et bien que les lapines aient été inséminées a jour fixe dans la semaine, - l'insémination artificielle a finalement été pratiquée entre le 1 er et le 12 eme jour PP.. Néanmoins, la majorité des inséminations ont ét pratiquées 3, 4 et 1O,11 jours PP.. Le taux de fécondation le plus bas concerne les inséminations 3 a 5 et 9 a 12 jours PP. comparés aux inséminations 1 a 2 et 6 a 8 jours PP. (50.53 % et 48.9 % vs 69.5 % et 66.6 % respectivement) (P<0.001). On remarque un interaction significative lapine/lactation lorsqu'on compare les tapines non allaitantes inséminées le 3, 4 et 1 Oeme jour ou les 11, 24eme jour et plus PP. et les tapines allaitantes inséminées les memes jours (71.7 %, 68.9 %, 71.5 % et 53.6 %, 48.7 %, 62.2 %, respectivement, P<0.001). Pas de différence de prolificité n'a été détectée. Les moyennes générales obtenues étaient : Nb de /apereaux nés / portée : 7. 1 ± O. 1 ; Nb de lapereaux morts / portée : 0.6 ± 0.05. Nos résultats suggerent une meilleur organisation de la reproduction lorsque l'insémination artificielle est pratiquée a jour fixe dans la semaine. Pratiquement tous les diagnostiques de gestation par palpation abdominale sont pratiqués le Vendredi (11 jours apres l.A. Les nids se font le Mardi (29 jours apres l.A.) et les mises bas surviennent le Jeudi ou le Vendredi (31 ou 32 jours apres l.A.) de la meme semaine. Néanmoins, le meilleur taux de fécondation étant observé chez les tapines inséminées le 1 er ou 2eme et les 6eme ou 8 eme jours, l'organisation de la reproduction peut etre envisagée sur deux jours fixes de la semaine.This work was supported by the CAYCIT (Madrid, Spain) as a part of the project GAN89-0127Rebollar, P.; Alvariño, J.; Ubilla, E. (1994). GROUPING OF RABBIT REPRODUCTION MANAGEMENT BY MEANS OF ARTIFICIAL INSEMINATION. World Rabbit Science. 2(3). https://doi.org/10.4995/wrs.1994.222SWORD2