Early deviations in performance, metabolic and immunological indicators affect stayability in rabbit females

[EN] The main purpose of this study was to find several early factors affecting stayability in rabbit females. To reach this goal, 203 females were used from their first artificial insemination to their sixth parturition. Throughout that period, 48 traits were recorded, considered to be performance, metabolic and immunological indicators. These traits were initially recorded in females' first reproductive cycle. Later, removed females due to death or culling and those that were non-removed were identified. A first analysis was used to explore whether it was possible to classify females between those reaching and those not reaching up to the mean lifespan of a rabbit female (the fifth reproductive) cycle using information from the first reproductive cycle. The analysis results showed that 97% of the non-removed females were classified correctly, whereas only 60% of the removed females were classified as animals to be removed. The reason for this difference lies in the model's characteristics, which was designed using early traits and was able to classify only the cases in which females would be removed due to performance, metabolic or immunologic imbalances in their early lives. Our results suggest that the model defines the necessary conditions, but not the sufficient ones, for females to remain alive in the herd. The aim of a second analysis was to find out the main early differences between the non-removed and removed females. The live weights records taken in the first cycle indicated that the females removed in their first cycle were lighter, while those removed in their second cycle were heavier with longer stayability (-203 and +202 g on average, respectively; P < 0.05). Non-removed females showed higher glucose and lower beta-hydroxybutyrate concentrations in the first cycle than the removed females (+4.8 and -10.7%, respectively; P < 0.05). The average lymphocytes B counts in the first cycle were 22.7% higher in the non-removed females group (P < 0.05). The females removed in the first reproductive cycle presented a higher granulocytes/lymphocytes ratio in this cycle than those that at least reached the second cycle (4.81 v. 1.66; P < 0.001). Consequently, non-removed females at sixth parturition offered adequate body development and energy levels, less immunological stress and a more mature immune function in the first reproductive cycle. The females that deviated from this pattern were at higher risk of being removed from the herd.This study was supported by the Interministerial Commission for Science and Technology (CICYT) of the Spanish Government (AGL2014-53405-C2-1-P, AGL2014-53405C2-2-P and AGL2017-85162-C2-1-R). The grants awarded to Mariola Penades and Alberto Arnau from the Spanish Ministry of Education, Culture and Sport (AP2010-3907 and BES-2012-052345, respectively) are also gratefully acknowledged.Penadés, M.; Arnau-Bonachera, A.; Selva, L.; Viana, D.; Larsen, T.; Corpa, JM.; Pascual Amorós, JJ.... (2020). Early deviations in performance, metabolic and immunological indicators affect stayability in rabbit females. Animal. 14(4):780-789. https://doi.org/10.1017/S1751731119002489S780789144Baselga M 2004. Genetic improvement of meat rabbits. Programmes and diffusion. In Proceedings of the 8th World Rabbit Congress, 7–10 September 2004, Puebla, Mexico, pp. 1–13.Bauman, D. E., & Bruce Currie, W. (1980). Partitioning of Nutrients During Pregnancy and Lactation: A Review of Mechanisms Involving Homeostasis and Homeorhesis. Journal of Dairy Science, 63(9), 1514-1529. doi:10.3168/jds.s0022-0302(80)83111-0Davis, A. K., Maney, D. L., & Maerz, J. C. (2008). The use of leukocyte profiles to measure stress in vertebrates: a review for ecologists. Functional Ecology, 22(5), 760-772. doi:10.1111/j.1365-2435.2008.01467.xDavis, W. C., & Hamilton, M. J. (2008). Use of flow cytometry to develop and characterize a set of monoclonal antibodies specific for rabbit leukocyte differentiation molecules. Journal of Veterinary Science, 9(1), 51. doi:10.4142/jvs.2008.9.1.51Dufort F 2012. Contribution of glucose metabolism to the B lymphocyte responses. PhD thesis, Boston College, Boston, MA, USA.Friggens, N. C., Brun-Lafleur, L., Faverdin, P., Sauvant, D., & Martin, O. (2013). Advances in predicting nutrient partitioning in the dairy cow: recognizing the central role of genotype and its expression through time. Animal, 7, 89-101. doi:10.1017/s1751731111001820García-Quirós, A., Arnau-Bonachera, A., Penadés, M., Cervera, C., Martínez-Paredes, E., Ródenas, L., … Pascual, J. J. (2014). A robust rabbit line increases leucocyte counts at weaning and reduces mortality by digestive disorder during fattening. Veterinary Immunology and Immunopathology, 161(3-4), 123-131. doi:10.1016/j.vetimm.2014.07.005Gross, W. B., & Siegel, H. S. (1983). Evaluation of the Heterophil/Lymphocyte Ratio as a Measure of Stress in Chickens. Avian Diseases, 27(4), 972. doi:10.2307/1590198Guerrero, I., Ferrian, S., Blas, E., Pascual, J. J., Cano, J. L., & Corpa, J. M. (2011). Evolution of the peripheral blood lymphocyte populations in multiparous rabbit does with two reproductive management rhythms. Veterinary Immunology and Immunopathology, 140(1-2), 75-81. doi:10.1016/j.vetimm.2010.11.017Harano, Y., Ohtsuki, M., Ida, M., Kojima, H., Harada, M., Okanishi, T., … Shigeta, Y. (1985). Direct automated assay method for serum or urine levels of ketone bodies. Clinica Chimica Acta, 151(2), 177-183. doi:10.1016/0009-8981(85)90321-3Jacobsen, C. N., Aasted, B., Broe, M. K., & Petersen, J. L. (1993). Reactivities of 20 anti-human monoclonal antibodies with leucocytes from ten different animal species. Veterinary Immunology and Immunopathology, 39(4), 461-466. doi:10.1016/0165-2427(93)90075-fJasper, P. J., Zhai, S.-K., Kalis, S. L., Kingzette, M., & Knight, K. L. (2003). B Lymphocyte Development in Rabbit: Progenitor B Cells and Waning of B Lymphopoiesis. The Journal of Immunology, 171(12), 6372-6380. doi:10.4049/jimmunol.171.12.6372Jeklova, E., Leva, L., & Faldyna, M. (2007). Lymphoid organ development in rabbits: Major lymphocyte subsets. Developmental & Comparative Immunology, 31(6), 632-644. doi:10.1016/j.dci.2006.10.002Jeklova, E., Leva, L., Knotigova, P., & Faldyna, M. (2009). Age-related changes in selected haematology parameters in rabbits. Research in Veterinary Science, 86(3), 525-528. doi:10.1016/j.rvsc.2008.10.007Jeklova, E., Leva, L., Kudlackova, H., & Faldyna, M. (2007). Functional development of immune response in rabbits. Veterinary Immunology and Immunopathology, 118(3-4), 221-228. doi:10.1016/j.vetimm.2007.05.003Kotani, M., Yamamura, Y., Tamatani, T., Kitamura, F., & Miyasaka, M. (1993). Generation and characterization of monoclomal antibodies against rabbit CD4, CD5 and CD11a antigens. Journal of Immunological Methods, 157(1-2), 241-252. doi:10.1016/0022-1759(93)90093-mKotani, M., Yamamura, Y., Tsudo, M., Tamatani, T., Kitamura, F., & Miyasaka, M. (1993). Generation of Monoclonal Antibodies to the Rabbit Interleukin-2 ReceptoraChain (CD25) and Its Distribution in HTLV-1-transformed Rabbit T Cells. Japanese Journal of Cancer Research, 84(7), 770-775. doi:10.1111/j.1349-7006.1993.tb02042.xMartin, O., & Sauvant, D. (2010). A teleonomic model describing performance (body, milk and intake) during growth and over repeated reproductive cycles throughout the lifespan of dairy cattle. 2. Voluntary intake and energy partitioning. 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Effect of housing enrichment and type of flooring on the performance and behaviour of female rabbits

[EN] This study investigated the effect of housing enrichments (scratching card, gnawing material and a platform), of a change in height and in the type of flooring on the live weight, reproductive performance and behaviour of female rabbits, as well as on the feed intake and spatial distribution of females and their kits. A total of 40 multiparous female rabbits were monitored in three consecutive reproductive cycles (48-d intervals). Four days before parturition in each reproductive cycle, the females were randomly assigned to one of the five types of housing: Control (CNT: 102×47×30 cm, L×W× H); Scratching card (SCT: containing a scratching card); Gnawing materials (GNW: CNT dimensions plus a compressed lucerne hay block and a wooden stick); Platform (PLT: 102×47×60 cm, including a platform with a plastic floor) and Combination (CBN: PLT dimensions with the scratching card, the gnawing materials and a platform). Data were only recorded during the first and third reproductive cycles. The living conditions did not significantly alter the females’ live weight (4889 g at housing; 4890 g at mid-lactation; 4867 g at weaning), reproductive performance (9.0 kits born alive), survival of the kits (90%), nor the feed intake of females and their litters (542 g/day). Providing animals with a gnawing block stimulated Gnawing behaviour (median frequency per group: CTL=0.00, SCT=0.00, GNW=4.69, PLT=0.00, and CBN=2.34; PRearing up behaviour (median frequencies per group: CTL=0.00, SCT=0.00, GNW=0.00, PLT=2.08, and CBN=3.12; P=0.06), and when a platform was present, the rabbits used it (mean values per group: CTL=0.00, SCT=0.00, GNW=0.00, PLT=1.79, and CBN=4.91; P=0.003). Regarding the type of floor, females appeared to prefer the plastic mesh flooring (31.2%) to the wire mesh flooring (18.8%). To sum up, providing female rabbits with simple enrichments appears to stimulate specific behaviours like Gnawing and Rearing up and may contribute to their wellbeing.Huang, Y.; Bréda, J.; Savietto, D.; Debrusse, A.; Bonnemère, J.; Gidenne, T.; Combes, S.... (2021). Effect of housing enrichment and type of flooring on the performance and behaviour of female rabbits. World Rabbit Science. 29(4):275-285. https://doi.org/10.4995/wrs.2021.15848OJS275285294Altmann J. 1974. Observational study of behavior: sampling methods. Behaviour, 49: 227-266. https://doi.org/10.1163/156853974X00534Animal Welfare Committee. 2009. Five Freedoms. Available at https://webarchive.nationalarchives.gov.uk/20110909181150/http://www.fawc.org.uk/freedoms.htm. Accessed February 2021.ANSES. 2018. ANSES proposes a definition of animal welfare and sets the foundation for its research and expert appraisal work. Available at https://www.anses.fr/en/content/ansesproposes-definition-animal-welfare-and-sets-foundation-itsresearch-and-expert. Accessed February 2021.Barge P., Masoero G., Chicco R. 2008. Raising rabbit does in platform cages. In Proc.: 9th World Rabbit Congress, 10-13 June, 2008. Verona, Italy. 1:1153-1158.Buijs S., Maertens L., Hermans K., Vangeyte J., Tuyttens F.A.M. 2015. Behaviour, wounds, weight loss and adrenal weight of rabbit does as affected by semigroup housing. Appl. Anim. Behav. Sci. 172: 44-51. https://doi.org/10.1016/j.applanim.2015.09.003Baumans, V. 2005. Environmental enrichment for laboratory rodents and rabbits: requirements of rodents, rabbits, and research. Ilar Journal, 46: 162-170. https://doi.org/10.1093/ilar.46.2.162Coureaud G., Fortun-Lamothe L., Rödel H.G., Monclús R., Schaal B. 2008. The developing rabbit: some data related to the behaviour, feeding and sensory capacities between birth and weaning. INRA-Prod. Anim. 21: 231-238. https://doi.org/10.20870/productions-animales.2008.21.3.3395Coureaud G., Rödel H.G., Le Normand B., Fortun-lamothe L. 2015. Habitat et Comportement. In: Gidenne T. (Eds), Le lapin de la biologie à l'élevage, Editions Quae, Versailles, France, pp. 107-136.Dixon L.M., Hardiman J.R., Cooper J.J. 2010. The effects of spatial restriction on the behavior of rabbits (Oryctolagus cuniculus). Journal of Veterinary Behavior: Clinical Applications and Research, 5: 302-308. https://doi.org/10.1016/j.jveb.2010.07.002EFSA AHAW Panel 2020. Scientific Opinion on the health and welfare of rabbits farmed in different production systems. EFSA Journal, 18: 5944. https://doi.org/10.2903/j.efsa.2020.5944Farkas T.P., Dal Bosco A., Szendro Z., Filiou E., Matics Z., Odermatt M., Radnai I., Paci G., Gerencser Z. 2016. Production of Growing Rabbits in Large Pens with and without Multilevel Platforms. In Proc.: 11th World Rabbit Congress, 15-18 June, 2016. Qingdao, China. 1: 663-666.Gerencsér Z., Farkas T.P., Dal Bosco A., Filiou E., Matics Z., Odermatt M., Paci G., Szendrő Z. 2016. The usage of multilevel platforms in growing rabbits housed in large pens as affected by platfor mmaterial (wire-mesh vs plastic-mesh). In Proc. 11th World Rabbit Congress, 15-18 June, 2016. Qingdao, China. 1: 671-674.Hawkins P., Hubrecht R., Buckwell A., Cubitt S., Howard B., Jackson A., Poirier, G. M. 2008. Refining rabbit care. A resource for those working with rabbits in research. RSPCA, West Sussex and UFAW, Hertfordshire.Huang Y., Breda J., Savietto D., Debrusse A., Combes S., Fortun-Lamothe L. 2021. Part-time grouping of rabbit does in enriched housing: effects on performances, injury occurrence and enrichment use. Animal. in press.Jordan D., Gorjanc G., Kermauner A., Štuhec I. 2011. The behaviour of individually housed growing rabbits and the influence of gnawing sticks as environmental enrichment on daily rhythm of behavioural patterns duration. Acta Agriculturae Slovenica, 98: 51-61.Jordan D., Gorjanc G., Štuhec I. 2008. Wooden sticks as environmental enrichment: effect on fattening and carcass traits of individually housed growing rabbits. World Rabbit Sci., 16: 237-243. https://doi.org/10.4995/wrs.2008.619Lang C., Hoy S. 2011. Investigations on the use of an elevated platform in group cages by growing rabbits. World Rabbit Sci., 19: 95-101. https://doi.org/10.4995/wrs.2011.800Leach M.C., Allweiler S., Richardson C., Roughan J.V., Narbe R., Flecknell P.A. 2009. Behavioural effects of ovariohysterectomy and oral administration of meloxicam in laboratory housed rabbits. Res. Vet. Sci., 87: 336-347. https://doi.org/10.1016/j.rvsc.2009.02.001Luzi F., Ferrante V., Heinzl E. Verga M. 2003. Effect of environmental enrichment on productive performance and welfare aspects in fattening rabbits. Ital. J. Anim. Sci., 2: 438-440.Matics Z., Farkas T. P., Dal Bosco A., Szendrő Z., Filiou E., Nagy I., Odermatt M., Paci G., Gerencsér Z. 2018. Comparison of pens without and with multilevel platforms for growing rabbits. Ital. J. Anim. Sci., 17: 469-476. https://doi.org/10.1080/1828051X.2017.1363640Mikó A., Matics Z., Gerencsér Z., Odermatt M., Radnai I., Nagy I., Szendrő K. Szendrő, Z. 2014. Performance and welfare of rabbit does in various caging systems. Animal, 8: 1146-1152. https://doi.org/10.1017/S1751731114001244Mirabito L., Buthon L., Cialdi G., Galliot P., Souchet C. 1999. Effet du logement des lapines en cages réhaussées avec plate-forme: Premiers resultats. In Proc.: 8èmes Journées de la Recherche Cunicole. 9-10 June, 1999. Paris, France. 1: 67-70.Mirabito L., Galliot P., Souchet C. 2000. Effect of different ways of cage enrichment on the productive traits and mortality of fattening rabbits. In Proc.: 7th World Rabbit Congress 4-7 July, 2000. Valencia, Spain. 1: 4-7.Monclús R., Rödel H. G. 2008. Different forms of vigilance in response to the presence of predators and conspecifics in a group-living mammal, the European Rabbit. Ethology, 114: 287-297. https://doi.org/10.1111/j.1439-0310.2007.01463.xMorton D.B., Jennings M., Batchelor G.R., Bell D., Birke L., Davies K., Eveleigh J.R., Gunn D., Heath M., Howard B., Koder P., Phillips J., Poole T., Sainsbury A.W., Sales G.D., Smith D.J.A., Stauffacher M., Turner R.J. 1993. Refinements in rabbit husbandry: Second report of the BVAAWF/FRAME/RSPCA/UFAW joint working group on refinement. Laboratory Animals, 27: 301-329. https://doi.org/10.1258/002367793780745633Podberscek A.L., Blackshaw J.K., Beattie A.W. 1991. The behaviour of group penned and individually caged laboratory rabbits. Appl. Anim. Behav. Sci., 28: 353-363. https://doi.org/10.1016/0168-1591(91)90167-VPrincz Z., Orova Z., Nagy I., Jordan D., Štuhec I., Luzi F., Verga M. Szendrő Z. 2007. Application of gnawing sticks in rabbit housing. World Rabbit Sci., 15: 29-36. https://doi.org/10.4995/wrs.2007.607Rommers J.M., Bracke M., Reuvekamp B., Gunnink H., de Jong I.C. 2014. Cage-enrichment: rabbit does prefer straw or a compressed wooden block. World Rabbit Sci., 22: 301-309. https://doi.org/10.4995/wrs.2014.1353Rommers J., de Greef K. H. 2018. Are combi parks just as useful as regular parks for fatteners for part-time group housing of rabbit does? World Rabbit Sci., 26: 299-305. https://doi.org/10.4995/wrs.2018.9587Rosell J.M., De la Fuente L.F. 2009. Effect of footrests on the incidence of ulcerative pododermatitis in domestic rabbit does. Animal Welfare, 18: 199-204.Rosell J.M., De la Fuente L. 2013. Assessing ulcerative pododermatitis of breeding rabbits. Animals, 3: 318-326. https://doi.org/10.3390/ani3020318Szendrő Z., Matics Z., Odermatt M., Gerencsér Z., Nagy I., Szendrő K., Dalle Zotte A. 2012. Use of different areas of pen by growing rabbits depending on the elevated platforms' floor-type. 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Hormones and Behavior, 52: 122-129. https://doi.org/10.1016/j.yhbeh.2007.03.02

Different resource allocation strategies result from selection for litter size at weaning in rabbit does

This study examined the effect of long-term selection of a maternal rabbit line, solely for a reproductive criterion, on the ability of female rabbits to deal with constrained environmental conditions. Female rabbits from generations 16 and 36 (n = 72 and 79, respectively) of a line founded and selected to increase litter size at weaning were compared simultaneously. Female rabbits were subjected to normal (NC), nutritional (NF) or heat (HC) challenging conditions from 1st to 3rd parturition. Animals in NC and NF were housed at normal room temperatures (18°C to 25°C) and respectively fed with control (11.6 MJ digestible energy (DE)/kg dry matter (DM), 126 g digestible protein (DP)/kg DM, and 168 g of ADF/kg DM) or low-energy fibrous diets (9.1 MJ DE/kg DM, 104 g DP/kg DM and 266 g ADF/kg DM), whereas those housed in HC were subjected to high room temperatures (25°C to 35°C) and the control diet. The litter size was lower for female rabbits housed in both NF and HC environments, but the extent and timing where this reduction took place differed between generations. In challenging conditions (NF and HC), the average reduction in the reproductive performance of female rabbits from generation 16, compared with NC, was &#8722;2.26 (P<0.05) and &#8722;0.51 kits born alive at 2nd and 3rd parturition, respectively. However, under these challenging conditions, the reproductive performance of female rabbits from generation 36 was less affected at 2nd parturition (&#8722;1.25 kits born alive), but showed a greater reduction at the 3rd parturition (&#8722;3.53 kits born alive; P<0.05) compared with NC. The results also showed differences between generations in digestible energy intake, milk yield and accretion, and use of body reserves throughout lactation in NC, HC and NF, which together indicate that there were different resource allocation strategies in the animals from the different generations. Selection to increase litter size at weaning led to increased reproductive robustness at the onset of an environmental constraint, but failure to sustain the reproductive liability when the challenge was maintained in the long term. This response could be directly related to the shortterm environmental fluctuations (less severe) that frequently occur in the environment where this line has been selected.The authors thank Professor Enrique Blas Ferrer for his valuable comments on the initial version of this document, Juan Carlos Moreno for his help in conducting the trial at the experimental farm, and the Ministry of Economy and Competitiveness (Project: AGL2011-30170-C02-01) for economic support.Savietto, D.; Cervera Fras, MC.; Ródenas Martínez, L.; Martínez Paredes, EM.; Baselga Izquierdo, M.; García Diego, FJ.; Larsen, T.... (2014). Different resource allocation strategies result from selection for litter size at weaning in rabbit does. Animal. 8(4):618-628. https://doi.org/10.1017/S1751731113002437S61862884García-Diego, F.-J., Pascual, J. J., & Marco, F. (2011). Technical Note: Design of a large variable temperature chamber for heat stress studies in rabbits. World Rabbit Science, 19(4). doi:10.4995/wrs.2011.938Ragab, M., & Baselga, M. (2011). A comparison of reproductive traits of four maternal lines of rabbits selected for litter size at weaning and founded on different criteria. Livestock Science, 136(2-3), 201-206. doi:10.1016/j.livsci.2010.09.009Friggens, N. C. (2003). Body lipid reserves and the reproductive cycle: towards a better understanding. Livestock Production Science, 83(2-3), 219-236. doi:10.1016/s0301-6226(03)00111-8Littell, R. C., Henry, P. R., & Ammerman, C. B. (1998). Statistical analysis of repeated measures data using SAS procedures. Journal of Animal Science, 76(4), 1216. doi:10.2527/1998.7641216xEstany, J., Baselga, M., Blasco, A., & Camacho, J. (1989). Mixed model methodology for the estimation of genetic response to selection in litter size of rabbits. Livestock Production Science, 21(1), 67-75. doi:10.1016/0301-6226(89)90021-3Fernández-Carmona, J., Alqedra, I., Cervera, C., Moya, J., & Pascual, J. J. (2003). Effect of lucerne-based diets on performance of reproductive rabbit does at two temperatures. Animal Science, 76(2), 283-295. doi:10.1017/s1357729800053534Fernández-Carmona, J., Cervera, C., Sabater, C., & Blas, E. (1995). Effect of diet composition on the production of rabbit breeding does housed in a traditional building and at 30°C. Animal Feed Science and Technology, 52(3-4), 289-297. doi:10.1016/0377-8401(94)00715-lHarano, Y., Ohtsuki, M., Ida, M., Kojima, H., Harada, M., Okanishi, T., … Shigeta, Y. (1985). Direct automated assay method for serum or urine levels of ketone bodies. Clinica Chimica Acta, 151(2), 177-183. doi:10.1016/0009-8981(85)90321-3Dauncey, M. J. (1990). Thyroid hormones and thermogenesis. Proceedings of the Nutrition Society, 49(2), 203-215. doi:10.1079/pns19900024Savietto, D., Blas, E., Cervera, C., Baselga, M., Friggens, N. C., Larsen, T., & Pascual, J. J. (2012). Digestive efficiency in rabbit does according to environment and genetic type. World Rabbit Science, 20(3). doi:10.4995/wrs.2012.1152Falconer, D. S. (1990). Selection in different environments: effects on environmental sensitivity (reaction norm) and on mean performance. Genetical Research, 56(1), 57-70. doi:10.1017/s0016672300028883Vicente, J., & García-Ximénez, F. (1993). Effects of strain and embryo transfer model (embryos from one versus two donor does/recipient) on results of cryopreservation in rabbit. Reproduction Nutrition Development, 33(1), 5-13. doi:10.1051/rnd:19930101Quiniou, N., Renaudeau, D., Dubois, S., & Noblet, J. (2000). Influence of high ambient temperatures on food intake and feeding behaviour of multiparous lactating sows. Animal Science, 70(3), 471-479. doi:10.1017/s1357729800051821Theilgaard, P., Sánchez, J. P., Pascual, J. J., Friggens, N. C., & Baselga, M. (2006). Effect of body fatness and selection for prolificacy on survival of rabbit does assessed using a cryopreserved control population. Livestock Science, 103(1-2), 65-73. doi:10.1016/j.livsci.2006.01.007Brecchia, G., Bonanno, A., Galeati, G., Federici, C., Maranesi, M., Gobbetti, A., … Boiti, C. (2006). Hormonal and metabolic adaptation to fasting: Effects on the hypothalamic–pituitary–ovarian axis and reproductive performance of rabbit does. Domestic Animal Endocrinology, 31(2), 105-122. doi:10.1016/j.domaniend.2005.09.006Piles, M., Garreau, H., Rafel, O., Larzul, C., Ramon, J., & Ducrocq, V. (2006). Survival analysis in two lines of rabbits selected for reproductive traits1. Journal of Animal Science, 84(7), 1658-1665. doi:10.2527/jas.2005-678Sanchez, J. P., Baselga, M., & Ducrocq, V. (2006). Genetic and environmental correlations between longevity and litter size in rabbits. Journal of Animal Breeding and Genetics, 123(3), 180-185. doi:10.1111/j.1439-0388.2006.00590.xQuevedo, F., Cervera, C., Blas, E., Baselga, M., & Pascual, J. J. (2006). Long-term effect of selection for litter size and feeding programme on the performance of reproductive rabbit does 2. Lactation and growing period. Animal Science, 82(5), 751-762. doi:10.1079/asc200688Vicente, J. S., & García-Ximénez, F. (1996). Direct transfer of vitrified rabbit embryos. Theriogenology, 45(4), 811-815. doi:10.1016/0093-691x(96)00010-6Coureaud, G., Fortun-Lamothe, L., Langlois, D., & Schaal, B. (2007). The reactivity of neonatal rabbits to the mammary pheromone as a probe for viability. animal, 1(7), 1026-1032. doi:10.1017/s1751731107000389Rommers, J. M., Boiti, C., Brecchia, G., Meijerhof, R., Noordhuizen, J. P. T. M., Decuypere, E., & Kemp, B. (2004). Metabolic adaptation and hormonal regulation in young rabbit does during long-term caloric restriction and subsequent compensatory growth. Animal Science, 79(2), 255-264. doi:10.1017/s1357729800090111Piles, M., García, M. L., Rafel, O., Ramon, J., & Baselga, M. (2006). Genetics of litter size in three maternal lines of rabbits: Repeatability versus multiple-trait models. Journal of Animal Science, 84(9), 2309-2315. doi:10.2527/jas.2005-622Garcı́a, M. L., & Baselga, M. (2002). Estimation of genetic response to selection in litter size of rabbits using a cryopreserved control population. Livestock Production Science, 74(1), 45-53. doi:10.1016/s0301-6226(01)00280-9Cervera, C., & Carmona, J. F. (s. f.). Nutrition and the climatic environment. Nutrition of the rabbit, 267-284. doi:10.1079/9781845936693.0267Nicodemus, N., Redondo, R., Pérez-Alba, L., Carabaño, R., De Blas, J. C., & García, J. (2010). Effect of level of fibre and type of grinding on the performance of rabbit does and their litters during the first three lactations. Livestock Science, 129(1-3), 186-193. doi:10.1016/j.livsci.2010.01.023Theilgaard, P., Sánchez, J., Pascual, J., Berg, P., Friggens, N. C., & Baselga, M. (2007). Late reproductive senescence in a rabbit line hyper selected for reproductive longevity, and its association with body reserves. Genetics Selection Evolution, 39(2), 207. doi:10.1186/1297-9686-39-2-207Martínez-Paredes, E., Ródenas, L., Martínez-Vallespín, B., Cervera, C., Blas, E., Brecchia, G., … Pascual, J. J. (2012). Effects of feeding programme on the performance and energy balance of nulliparous rabbit does. animal, 6(7), 1086-1095. doi:10.1017/s1751731111002643Baselga M 2004. Genetic improvement of meat rabbits. Programmes and diffusion. In Proceedings of 8th World Rabbit Science Congress, 5–7 September 2004, Puebla, Mexico, pp. 1–13

Extra-uterine (abdominal) full term foetus in a 15-day pregnant rabbit

[EN] Background: While ectopic pregnancies account for 1-2% of all pregnancies, abdominal pregnancy is extremely rare, accounting for approximately 1% of ectopic pregnancies. Extrauterine abdominal pregnancy is defined as the implantation and development of an embryo in the peritoneal cavity. The present report is the first of an incidental case of abdominal pregnancy within four full-term foetus simultaneously with 2 weeks of physiological gestation in a healthy doe rabbit. Case presentation: The doe was born on November 3, 2014 and the first partum took place on May 18, 2015. The doe had previously delivered and weaned an average of 12.0 +/- 1.41 live kits at birth (no stillbirths were recorded) during 5 consecutive pregnancies. The last mating was on December 18, 2015 and the detection of pregnancy failure post breeding (by abdominal palpation) on December 31, 2015. Then, the doe was artificially inseminated on January 27, 2016, diagnosed pregnant on February 11, 2016 and subsequently euthanized to recover the foetus. A ventral midline incision revealed a reproductive tract with 12 implantation sites with 15 days old foetus and 4 term foetus in abdominal cavity. There were two foetus floating on either side of the abdominal cavity and two suspended near the greater curvature of the stomach. They were attached to internal organs by means of one or 2 thread-like blood vessels that linked them to the abdominal surfaces. Conclusions: In our opinion a systematic monitoring of rabbit breeding should be included to fully understand and enhance current knowledge of this phenomenon of abdominal pregnancy.This work was supported by Spanish Research Project AGL2014-53405-C2-1-P (Interministerial Commission on Science and Technology).Marco-Jiménez, F.; Garcia-Dominguez, X.; Valdes-Hernández, J.; Vicente Antón, JS. (2017). Extra-uterine (abdominal) full term foetus in a 15-day pregnant rabbit. BMC Veterinary Research. 13:1-4. https://doi.org/10.1186/s12917-017-1229-7S1413Petracci M, Bianchi M, Cavani C. Development of rabbit meat products fortified with n-3 polyunsaturated fatty acids. Nutrients. 2009;1:111–8.FAOSTAT (Food and Agriculture Organization of the United Nations, authors). Available online: http://faostat.fao.org/site/569/DesktopDefault.aspx?PageID=569#ancor . Accessed Sept 2012.Segura Gil P, Peris Palau B, Martínez Martínez J, Ortega Porcel J, Corpa Arenas JM. Abdominal pregnancies in farm rabbits. Theriogenology. 2004;62:642–51.Rosell JM, de la Fuente LF. Culling and mortality in breeding rabbits. Prev Vet Med. 2009;88:120–7.Tena-Betancourt E, Tena-Betancourt CA, Zúniga-Muñoz AM, Hernández-Godínez B, Ibáñez-Contreras A, Graullera-Rivera V. Multiple extrauterine pregnancy with early and near full-term mummified foetuses in a New Zealand white rabbit (Oryctolagus Cuniculus). J Am Assoc Lab Anim Sci. 2014;53:204–7.Sánchez JP, Theilgaard P, Mínguez C, Baselga M. Constitution and evaluation of a long-lived productive rabbit line. J Anim Sci. 2008;86:515–25.Savietto D, Friggens NC, Pascual JJ. Reproductive robustness differs between generalist and specialist maternal rabbit lines: the role of acquisition and allocation of resources. Genet Sel Evol. 2015;47:2.Viudes-de-Castro MP, Vicente JS. Effect of sperm count on the fertility and prolificity rates of meat rabbits. Anim Reprod Sci. 1997;46:313–9.Marco-Jiménez F, Garcia-Dominguez X, Jimenez-Trigos E, Vera-Donoso CD, Vicente JS. Vitrification of kidney precursors as a new source for organ transplantation. Cryobiology. 2015;70:278–82.Garcia-Dominguez X, Vera-Donoso CD, Jimenez-Trigos E, Vicente JS, Marco-Jimenez. First steps towards organ banks: vitrification of renal primordial. Cryo Letters. 2016;37:47–52.Arvidsson A. Extra-uterine pregnancy in a rabbit. Vet Rec. 1998;142:176.Glišić A, Radunović N, Atanacković J. Methotrexate and fallopian tubes in ectopic pregnancy. Acta veterinaria. 2006;56:375–82.Nwobodo EI. Abdominal pregnancy. A case report. Ann Afr Med. 2004;3:195–6.Nassali MN, Benti TM, Bandani-Ntsabele M, Musinguzi E. A case report of an asymptomatic late term abdominal pregnancy with a live birth at 41 weeks of gestation. BMC Res Notes. 2016;9:31.Baffoe P, Fofie C, Gandau BN. Term abdominal pregnancy with healthy new-born: a case report. Ghana Med J. 2011;45:81–3.Eleje GU, Adewae O, Osuagwu IK, Obianika CE. Post-date extra-uterine abdominal pregnancy in a rhesus negative Nullipara with successful outcome: a case report. J Women's Health. 2013;6:2.Hong CC, Armstrong ML. Ectopic pregnancy in 2 guinea-pigs. Lab Anim. 1978;12:243–4.Peters LJ. Abdominal pregnancy in a golden hamster (Mesocricetus Auratus). Lab Anim Sci. 1982;32:392–3.Xiccato G, Trocino A, Boiti C, Brecchia G. Reproductive rhythm and litter weaning age as they affect rabbit doe performance and body energy balance. Anim Sci. 2005;81:289–96.Fortun-Lamothe L, De Rochambeau H, Lebas F, Tudela F. Influence of the number of suckling young on reproductive performance in intensively reared rabbits does. In: Blasco A, editor. Proceedings of the 7th world rabbit congress; 2002. p. 125–32

Environmental sensitivity differs between rabbit lines selectedfor reproductive intensity and longevity

To better understand the mechanisms that allow some animals to sustain their productive effort in harsh environmental conditions, rabbit does from two selection lines (LP and V) were housed in normal (NC), nutritional (NF) or heat (HC) challenging environmental conditions from first to third partum. The LP line (n=85) was founded on reproductive longevity criteria by selecting does from commercial farms that had a minimum of 25 partum with more than 7.5 kits born alive per parity. Line V (n=79) was constituted from four specialised maternal lines into a composite synthetic line and then selected by litter size at weaning for 36 generations. Female rabbits in NC and NF environments were housed at normal room temperature (18 degrees C to 24 degrees C) and fed with control [11.6 MJ digestible energy (DE)/kg dry matter (DM)] or low-energy diets (9.1 MJ DE/kg DM). HC does were housed at high room temperatures (25 degrees C to 35 degrees C) and fed the control diet. Female rabbits in the HC and NF environments ingested 11.5% and 6% less DE than NC does, respectively (P<0.05). These differences between environments occurred in both lines, with the differences being higher for LP than for V does (+6%; P<0.05). Milk yield responses followed those of energy intake also being higher for LP does (+21.3 g/day; P<0.05). The environmental conditions did not affect the perirenal fat thickness (PFT), but a genotype by environment interaction was observed. In NC and HC, the PFT was higher for line V (+0.23 and +0.35 mm, respectively; P<0.05) than for LP does, but this was not the case at NF (-0.01 mm). Moreover, the PFT evolution was different between them. In the NC environment, LP does used the accreted PFT in late lactation (-0.29 mm), whereas V does did not (-0.08 mm). Conversely, in the HC environment, LP does showed a flat PFT evolution in late lactation, whereas V does accumulated PFT. In the NF environment, LP and V does had a similar PFT evolution. There was also a litter size reduction for V does of -2.59 kits total born in HC and -1.78 kits total born in NF environments, whereas this was not observed for LP does. The results for LP does indicate a direct use of DE ingested for reproduction with little PFT change, whereas V does actively use the PFT reserves for reproduction.The authors thank Juan Carlos Moreno, Luis Rodenas and Eugenio Martinez-Paredes for their technical support and the Spanish Ministry of Education and Science (Project AGL2011-30170-C02-01) for the budget to conduct this study.Savietto, D.; Cervera Fras, MC.; Blas Ferrer, E.; Baselga Izquierdo, M.; Larsen, T.; Friggens, NC.; Pascual Amorós, JJ. (2013). Environmental sensitivity differs between rabbit lines selectedfor reproductive intensity and longevity. animal. 7(12):1969-1977. https://doi.org/10.1017/S175173111300178XS19691977712Vicente, J. S., Llobat, L., Viudes-de-Castro, M. P., Lavara, R., Baselga, M., & Marco-Jiménez, F. (2012). Gestational losses in a rabbit line selected for growth rate. Theriogenology, 77(1), 81-88. doi:10.1016/j.theriogenology.2011.07.019Theilgaard, P., Sánchez, J., Pascual, J., Berg, P., Friggens, N. C., & Baselga, M. (2007). Late reproductive senescence in a rabbit line hyper selected for reproductive longevity, and its association with body reserves. Genetics Selection Evolution, 39(2), 207. doi:10.1186/1297-9686-39-2-207Savietto, D., Blas, E., Cervera, C., Baselga, M., Friggens, N. C., Larsen, T., & Pascual, J. J. (2012). Digestive efficiency in rabbit does according to environment and genetic type. World Rabbit Science, 20(3). doi:10.4995/wrs.2012.1152Rosell, J. M., & de la Fuente, L. F. (2009). Culling and mortality in breeding rabbits. Preventive Veterinary Medicine, 88(2), 120-127. doi:10.1016/j.prevetmed.2008.08.003Sánchez, J. P., de la Fuente, L. F., & Rosell, J. M. (2012). Health and body condition of lactating females on rabbit farms1. Journal of Animal Science, 90(7), 2353-2361. doi:10.2527/jas.2011-4065Quevedo, F., Cervera, C., Blas, E., Baselga, M., Costa, C., & Pascual, J. J. (2005). Effect of selection for litter size and feeding programme on the performance of young rabbit females during rearing and first pregnancy. Animal Science, 80(2), 161-168. doi:10.1079/asc40850161Pascual, J. J., Motta, W., Cervera, C., Quevedo, F., Blas, E., & Fernández-Carmona, J. (2002). Effect of dietary energy source on the performance and perirenal fat thickness evolution of primiparous rabbit does. Animal Science, 75(2), 267-279. doi:10.1017/s1357729800053029Friggens, N. C., Brun-Lafleur, L., Faverdin, P., Sauvant, D., & Martin, O. (2011). Advances in predicting nutrient partitioning in the dairy cow: recognizing the central role of genotype and its expression through time. animal, 7(s1), 89-101. doi:10.1017/s1751731111001820Fernández-Carmona, J., Cervera, C., Sabater, C., & Blas, E. (1995). Effect of diet composition on the production of rabbit breeding does housed in a traditional building and at 30°C. Animal Feed Science and Technology, 52(3-4), 289-297. doi:10.1016/0377-8401(94)00715-lBlas, C. de, & Mateos, G. G. (s. f.). Feed formulation. Nutrition of the rabbit, 222-232. doi:10.1079/9781845936693.0222Brecchia, G., Bonanno, A., Galeati, G., Federici, C., Maranesi, M., Gobbetti, A., … Boiti, C. (2006). Hormonal and metabolic adaptation to fasting: Effects on the hypothalamic–pituitary–ovarian axis and reproductive performance of rabbit does. Domestic Animal Endocrinology, 31(2), 105-122. doi:10.1016/j.domaniend.2005.09.006Sánchez, J. P., Theilgaard, P., Mínguez, C., & Baselga, M. (2008). Constitution and evaluation of a long-lived productive rabbit line1. Journal of Animal Science, 86(3), 515-525. doi:10.2527/jas.2007-0217Mehaisen, G., Vicente, J., & Lavara, R. (2004). In Vivo Embryo Recovery Rate by Laparoscopic Technique from Rabbit Does Selected for Growth Rate. Reproduction in Domestic Animals, 39(5), 347-351. doi:10.1111/j.1439-0531.2004.00526.xHarano, Y., Ohtsuki, M., Ida, M., Kojima, H., Harada, M., Okanishi, T., … Shigeta, Y. (1985). Direct automated assay method for serum or urine levels of ketone bodies. Clinica Chimica Acta, 151(2), 177-183. doi:10.1016/0009-8981(85)90321-3Engblom, L., Lundeheim, N., Dalin, A.-M., & Andersson, K. (2007). Sow removal in Swedish commercial herds. Livestock Science, 106(1), 76-86. doi:10.1016/j.livsci.2006.07.002Fernández-Carmona, J., Alqedra, I., Cervera, C., Moya, J., & Pascual, J. J. (2003). Effect of lucerne-based diets on performance of reproductive rabbit does at two temperatures. Animal Science, 76(2), 283-295. doi:10.1017/s1357729800053534Piles, M., Garreau, H., Rafel, O., Larzul, C., Ramon, J., & Ducrocq, V. (2006). Survival analysis in two lines of rabbits selected for reproductive traits1. Journal of Animal Science, 84(7), 1658-1665. doi:10.2527/jas.2005-678Theilgaard, P., Baselga, M., Blas, E., Friggens, N. C., Cervera, C., & Pascual, J. J. (2009). Differences in productive robustness in rabbits selected for reproductive longevity or litter size. animal, 3(5), 637-646. doi:10.1017/s1751731109003838Ferrian, S., Blas, E., Larsen, T., Sánchez, J. P., Friggens, N. C., Corpa, J. M., … Pascual, J. J. (2013). Comparison of immune response to lipopolysaccharide of rabbit does selected for litter size at weaning or founded for reproductive longevity. Research in Veterinary Science, 94(3), 518-525. doi:10.1016/j.rvsc.2013.01.008Xiccato, G., Bernardini, M., Castellini, C., Dalle Zotte, A., Queaque, P. I., & Trocino, A. (1999). Effect of postweaning feeding on the performance and energy balance of female rabbits at different physiological states. Journal of Animal Science, 77(2), 416. doi:10.2527/1999.772416xRagab, M., & Baselga, M. (2011). A comparison of reproductive traits of four maternal lines of rabbits selected for litter size at weaning and founded on different criteria. Livestock Science, 136(2-3), 201-206. doi:10.1016/j.livsci.2010.09.009García-Diego, F.-J., Pascual, J. J., & Marco, F. (2011). Technical Note: Design of a large variable temperature chamber for heat stress studies in rabbits. World Rabbit Science, 19(4). doi:10.4995/wrs.2011.938Littell, R. C., Henry, P. R., & Ammerman, C. B. (1998). Statistical analysis of repeated measures data using SAS procedures. Journal of Animal Science, 76(4), 1216. doi:10.2527/1998.7641216xCervera, C., & Carmona, J. F. (s. f.). Nutrition and the climatic environment. Nutrition of the rabbit, 267-284. doi:10.1079/9781845936693.0267Sanchez, J. P., Baselga, M., & Ducrocq, V. (2006). Genetic and environmental correlations between longevity and litter size in rabbits. Journal of Animal Breeding and Genetics, 123(3), 180-185. doi:10.1111/j.1439-0388.2006.00590.xQuevedo, F., Cervera, C., Blas, E., Baselga, M., & Pascual, J. J. (2006). Long-term effect of selection for litter size and feeding programme on the performance of reproductive rabbit does 1. Pregnancy of multiparous does. Animal Science, 82(5), 739-750. doi:10.1079/asc200687Estany, J., Baselga, M., Blasco, A., & Camacho, J. (1989). Mixed model methodology for the estimation of genetic response to selection in litter size of rabbits. Livestock Production Science, 21(1), 67-75. doi:10.1016/0301-6226(89)90021-3Estany, J., Camacho, J., Baselga, M., & Blasco, A. (1992). Selection response of growth rate in rabbits for meat production. Genetics Selection Evolution, 24(6), 527. doi:10.1186/1297-9686-24-6-52

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

Gaia Data Release 1: Testing parallaxes with local Cepheids and RR Lyrae stars

Context. Parallaxes for 331 classical Cepheids, 31 Type II Cepheids, and 364 RR Lyrae stars in common between Gaia and the Hipparcos and Tycho-2 catalogues are published in Gaia Data Release 1 (DR1) as part of the Tycho-Gaia Astrometric Solution (TGAS). Aims. In order to test these first parallax measurements of the primary standard candles of the cosmological distance ladder, which involve astrometry collected by Gaia during the initial 14 months of science operation, we compared them with literature estimates and derived new period-luminosity (PL), period-Wesenheit (PW) relations for classical and Type II Cepheids and infrared PL, PL-metallicity (PLZ), and optical luminosity-metallicity (M V -[Fe/H]) relations for the RR Lyrae stars, with zero points based on TGAS. Methods. Classical Cepheids were carefully selected in order to discard known or suspected binary systems. The final sample comprises 102 fundamental mode pulsators with periods ranging from 1.68 to 51.66 days (of which 33 with σ Ω /Ω < 0.5). The Type II Cepheids include a total of 26 W Virginis and BL Herculis stars spanning the period range from 1.16 to 30.00 days (of which only 7 with σ Ω /Ω < 0.5). The RR Lyrae stars include 200 sources with pulsation period ranging from 0.27 to 0.80 days (of which 112 with σ Ω /Ω < 0.5). The new relations were computed using multi-band (V,I,J,K s ) photometry and spectroscopic metal abundances available in the literature, and by applying three alternative approaches: (i) linear least-squares fitting of the absolute magnitudes inferred from direct transformation of the TGAS parallaxes; (ii) adopting astrometry-based luminosities; and (iii) using a Bayesian fitting approach. The last two methods work in parallax space where parallaxes are used directly, thus maintaining symmetrical errors and allowing negative parallaxes to be used. The TGAS-based PL,PW,PLZ, and M V - [Fe/H] relations are discussed by comparing the distance to the Large Magellanic Cloud provided by different types of pulsating stars and alternative fitting methods. Results. Good agreement is found from direct comparison of the parallaxes of RR Lyrae stars for which both TGAS and HST measurements are available. Similarly, very good agreement is found between the TGAS values and the parallaxes inferred from the absolute magnitudes of Cepheids and RR Lyrae stars analysed with the Baade-Wesselink method. TGAS values also compare favourably with the parallaxes inferred by theoretical model fitting of the multi-band light curves for two of the three classical Cepheids and one RR Lyrae star, which were analysed with this technique in our samples. The K-band PL relations show the significant improvement of the TGAS parallaxes for Cepheids and RR Lyrae stars with respect to the Hipparcos measurements. This is particularly true for the RR Lyrae stars for which improvement in quality and statistics is impressive. Conclusions. TGAS parallaxes bring a significant added value to the previous Hipparcos estimates. The relations presented in this paper represent the first Gaia-calibrated relations and form a work-in-progress milestone report in the wait for Gaia-only parallaxes of which a first solution will become available with Gaia Data Release 2 (DR2) in 2018. © ESO, 2017

Gaia Data Release 1: Open cluster astrometry: performance, limitations, and future prospects

Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho-2 positions in 1991.25 as prior information.Aims. We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters.Methods. Mean cluster parallax and proper motion values are derived taking into account the error correlations within the astrometric solutions for individual stars, an estimate of the internal velocity dispersion in the cluster, and, where relevant, the effects of the depth of the cluster along the line of sight. Internal consistency of the TGAS data is assessed.Results. Values given for standard uncertainties are still inaccurate and may lead to unrealistic unit-weight standard deviations of least squares solutions for cluster parameters. Reconstructed mean cluster parallax and proper motion values are generally in very good agreement with earlier HIPPARCOS-based determination, although the Gaia mean parallax for the Pleiades is a significant exception. We have no current explanation for that discrepancy. Most clusters are observed to extend to nearly 15 pc from the cluster centre, and it will be up to future Gaia releases to establish whether those potential cluster-member stars are still dynamically bound to the clusters.Conclusions. The Gaia DR1 provides the means to examine open clusters far beyond their more easily visible cores, and can provide membership assessments based on proper motions and parallaxes. A combined HR diagram shows the same features as observed before using the HIPPARCOS data, with clearly increased luminosities for older A and F dwarfs

Gaia Data Release 2 Mapping the Milky Way disc kinematics

Context. The second Gaia data release (Gaia DR2) contains high-precision positions, parallaxes, and proper motions for 1.3 billion sources as well as line-of-sight velocities for 7.2 million stars brighter than G(RVS) = 12 mag. Both samples provide a full sky coverage. Aims. To illustrate the potential of Gaia DR2, we provide a first look at the kinematics of the Milky Way disc, within a radius of several kiloparsecs around the Sun. Methods. We benefit for the first time from a sample of 6.4 million F-G-K stars with full 6D phase-space coordinates, precise parallaxes (sigma((omega) over bar)/(omega) over bar Results. Gaia DR2 allows us to draw 3D maps of the Galactocentric median velocities and velocity dispersions with unprecedented accuracy, precision, and spatial resolution. The maps show the complexity and richness of the velocity field of the galactic disc. We observe streaming motions in all the components of the velocities as well as patterns in the velocity dispersions. For example, we confirm the previously reported negative and positive galactocentric radial velocity gradients in the inner and outer disc, respectively. Here, we see them as part of a non-axisymmetric kinematic oscillation, and we map its azimuthal and vertical behaviour. We also witness a new global arrangement of stars in the velocity plane of the solar neighbourhood and in distant regions in which stars are organised in thin substructures with the shape of circular arches that are oriented approximately along the horizontal direction in the U - V plane. Moreover, in distant regions, we see variations in the velocity substructures more clearly than ever before, in particular, variations in the velocity of the Hercules stream. Conclusions. Gaia DR2 provides the largest existing full 6D phase-space coordinates catalogue. It also vastly increases the number of available distances and transverse velocities with respect to Gaia DR1. Gaia DR2 offers a great wealth of information on the Milky Way and reveals clear non-axisymmetric kinematic signatures within the Galactic disc, for instance. It is now up to the astronomical community to explore its full potential.Peer reviewe