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