Environmental and genetic factors driving robustness in reproductive rabbit does

Selection strategies to increase productive traits of farm animals have been effective and highly specialized breeds and strains were obtained. At the same time, the effort made to obtain extremely high producing animals was accompanied by undesired effects, such as a reduced ability to sustain production, reproduction and health; especially under constrained conditions. The perception that selection was degrading robustness, lead to selection strategies aiming to improve the ability of animals to perform in a wider range of environmental constrain. However, at the present moment, the physiological mechanisms allowing farm animals to perform well in a wide range of environments, while others succumb, have not been described. The present thesis intended to address this question by describing the evolution of traits related to fitness, survival and to the adaptability to environmental constraints. Two maternal rabbit lines differing in their ability to face the environmental constraints, i.e. a `specialist¿ and a `generalist¿ maternal rabbit line were available. Additionally, two generations (20 generations apart) of the specialized line were simultaneously available. During the first two consecutive reproductive cycles, female rabbits were simultaneously subjected to three environmental conditions differing in the intensity and in the physiological constrain imposed. Digestive capacity, the acquisition of resources and the partitioning of resources into different function (i.e. litter size, milk yield, growth, body reserves, etc.) was also assessed. Results showed a greater acquisition capacity of `generalist¿ females in constrained conditions with respect to `specialist¿ females. Moreover, the greater acquisition capacity was not accompanied by a reduction in the digestive efficiency, allowing the `generalist¿ females a relative greater acquisition of digestible energy. The maintenance of reproductive performance by having a greater acquisition capacity, together with the avoidance of making an intensive use of body reserves were both related to the capacity of `generalist¿ females to sustain reproduction in a wide range of environmental conditions. Twenty generations of selection exclusively for reproduction (specialized line), was not accompanied by a higher acquisition capacity, but by a change in the relative priority between the litter being nursed (actual) and the litter being gestate (future litter). In this sense, females from the actual generation of selection for litter size at weaning had a greater milk yield in the first week of lactation (period of great importance to kits survival), reducing it by the end of lactation. The present thesis also evidenced the importance of the environment where the animals are being selected in the evolution of the interplay between competing functions.Savietto, D. (2014). Environmental and genetic factors driving robustness in reproductive rabbit does [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/37198TESISPremios Extraordinarios de tesis doctorale

Long-term implications of feed energy source in different genetic types of reproductive rabbit females: III. Fitness and productivity

[EN] The specialization process associated with genetic selection could be associated with functional disorders, affecting the reproductive success of females (fitness). We hypothesized that by modulating energy acquisition and allocation of females we could balance productivity and reproductive success. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66) maternal line specialized in prolificacy, LP (n=67) generalist maternal line, R (n=70) paternal line specialized in growth rate. We fed each genetic type with two diets specifically designed to promote milk yield (AF) or body reserves recovery (CS). We controlled females between their first and fifth reproductive cycles, recording traits related with productivity and fitness of females. H females fed CS had on average 11.2 +/- 0.43 kits with an individual weight of 54 +/- 1.2 g at birth and 525 +/- 11 g at weaning. Their conception rate when multiparous was 44% and their survival rate at the end of the experiment 30%. When they were fed AF, the individual weight of kits was 3.8 g heavier (P<0.05) at birth and 38 g heavier at weaning (P<0.05), the conception rate when multiparous increased 23 percentage points (P<0.05) and the survival rate at the end of the experiment 25 percentage points (P<0.05). LP females fed CS had on average 10.8 +/- 0.43 kits with an individual weight of 52 +/- 1.2 g at birth and 578 +/- 11 g at weaning. Their conception rate when multiparous was 79% and their survival rate at the end of the experiment 75%. When they were fed AF, it only increased individual weight of kits at weaning (+39 g; P<0.05). R females fed CS had on average 8.4 +/- 0.43 kits with an individual weight of 60 +/- 1.2 g at birth and 568 +/- 11 g at weaning. Their conception rate when multiparous was 60% and their survival rate at the end of the experiment 37%. When they were fed AF, they presented 1.4 kits less at birth (P<0.05) but heavier at birth (+4.9 g; P<0.05) and at weaning (+37 g; P<0.05). Therefore, we observed that genetic types prioritized different fitness components and that diets could affected them. In this sense, seems that more specialized genetic types, were more sensitive to diets than the more generalist type.This study was supported by the Interministerial Commission for Science and Technology (CICYT) of the Spanish Government (AGL2014-53405-C2-1-P). The authors thank Juan Carlos Moreno for his technical support. Grants for Alberto Arnau from the Ministry of Economy and Finance (BES-2012-052345) are also gratefully acknowledged.Arnau-Bonachera, A.; Savietto, D.; Pascual Amorós, JJ. (2018). Long-term implications of feed energy source in different genetic types of reproductive rabbit females: III. Fitness and productivity. animal. 12(9):1886-1894. https://doi.org/10.1017/S1751731117003305S1886189412

Early development and reproductive lifespan of rabbit females: implications of growth rate, rearing diet and body condition at first mating

[EN] Factors influencing early development such as birth weight, nest competition, and the diet received during rearing have been proposed as elements conditioning the future reproductive performance of European rabbit (Oryctolagus cuniculus) females. To evaluate their effects, we followed the life of 1513 females from birth to time of death, culling or censoring (animals alive at a fixed date). Between 0 and 63 days of age 353 females died. From the remaining 1160 females, 864 were chosen based on their birth weight to be transferred from the selection to the production farm. At this farm, 431 females received the control diet (184g of CP, 381 g of NDF and 11.8 MJ of DE per kg DM), while the other 433 received the fibrous diet (134 g of CP, 436g of NDF and 10.0 MJ of DE per kg DM). Throughout the rearing period, we checked for the individual live weight and body condition (perirenal fat thickness) at first artificial insemination. Reproductive lifespan was defined as the number of days between the first parturition and the time of death, culling or censoring. Birth weight affected the survival of newborn females during lactation and the presence of a milk spot at birth (related to nest competition) increased the survivability of newborns weighing <45g (P <0.001). Rearing diet altered the growth curve of females and their body condition at first insemination. The diet also altered the relative risk of death during the rearing period, which was lower among females fed on the fibrous diet (-12.5%; P < 0.001). Therefore, a higher number of females fed with this diet reached their reproductive life, directly affecting the productivity measured per housed female. Fatter females at first insemination had smaller litter sizes and a higher risk of being culled than lean ones (P < 0.05). In general, the fibrous diet reduced the risk of leaving the herd at early rearing, and both birth weight and perirenal fat thickness affected female's reproductive lifespan. An excess of fat (positive change in one unit of perirenal fat) at their first insemination represented an increased the risk of death or elimination of 13%.The authors acknowledge Cesar Villalba (Fabara, Spain), Luis Eroles (Valderrobres, Spain) for the technical support in managing the animals and for kindly providing a space to conduct our study. They also thank the Commission for Science and Technology (CICYT) of the Spanish Government (AGL2014-53405-C2-1-P) for the economic support to carry out this study.Martinez-Paredes, E.; Ródenas Martínez, L.; Pascual Amorós, JJ.; Savietto, D. (2018). Early development and reproductive lifespan of rabbit females: implications of growth rate, rearing diet and body condition at first mating. animal. 12(11):2347-2355. https://doi.org/10.1017/S1751731118000162S23472355121

A New Simplified Performance Referencing System Adapted To Organic Rabbit Farming

A referencing system to collect and analyse performances of French organic rabbit farms was created using an Excel sheet. Performances of reproduction were compilated on 6 farms over 3 years of production (2015-2017). Does are housed in movable cage on pasture or in individual paddock, the livestock size averages 33 does. The productive time of a doe averaged 374 d. and was variable (75%). Female mortality averaged 17% over the period, while culling reached 10%. With 4.8 matings, 2.7 parturitions per female/year were obtained (60% fertility rate), for a total of 21.6 rabbits born alive and 16.7 weaned (26% mortality from birth to weaning). The yearly turnover of a full-time rabbit farmer (80 females) would potentially be around 26.3k€/year. The database is actually extending to a larger number of farms, thanks to the deployment of a smartphone application (GAELA), that enable a management assistance of the rabbit farm and data collection, synchronized to a national securised database

Estimation of grass biomass consumed by rabbits housed in movable paddocks

Biomass allowance is a key feature in pasture-based rabbit production systems. It conditions not only the stock density (rabbits/m²) and/or the number of grazing days, it also influences the grazing behaviour of animals. When herbage restriction occurs, pelleted feed and/or cereal intake goes up. Inadequate pasture management may also impair the biomass quantity and quality if overgrazing occurs. To avoid the undesirable effects of overgrazing and better manage pellet and cereal intake, information on both biomass availability and rabbits’ grazing capacity are needed. Here, we present an adaptation of the rising plate meter method (developed for biomass intake measures for ruminants) for use in rabbit. To this end, we designed an experiment where two groups of 12 rabbits each were kept in two different fields: under an apple orchard (AO) or on fallow land (FL). We followed the animals for 5 consecutive weeks (from 45 to 80 d old). Rabbits lived in 25 m² movable paddocks, and every week a new paddock location (called paddock-spot) was made available for them. At each new paddock-spot, we measured the herbage height inside the paddocks and performed samplings of the available biomass (i.e. herbage cut after herbage height measurement) outside the paddocks. From this data we estimated the available biomass inside each paddock-spot by fitting linear regression equations of biomass to herbage height. Overall, rabbits in the AO and FL had access to 1328±65.7 and 1386±58.6 kg of dry matter (DM) per ha, respectively. In every field and paddock-spot, the biomass available was lower than the rabbits’ grazing capacity; overgrazing was the rule. Roughly, and under a restricted herbage allowance, rabbits in the AO ingested 45.2 g DM/d and rabbits in the FL 43.4 g DM/d. In the last week (64 to 80 d old), the biomass intake of rabbits in the AO and AL represented 26.4 and 23.5% of the total DM intake, respectively. These values, however, does not represent the real grazing capacity of growing rabbits. In this study, we provide some advice on the sampling method to obtain reliable biomass estimations and we mention two methods for handling influential observations in linear regression

Effect of early development on semen parameters and lifespan of rabbit males selected by high growth rate

[EN] Life history theory suggests that different body development dynamics may influence survival and future reproductive performance of organisms. The present work studied how these dynamics could influence seminal traits and lifespan of rabbit males selected for growth rate and intended for Al. To achieve this goal, a total of 550 rabbit males were controlled from birth, evaluated both during the testing phase (four consecutive weeks after reaching 147 days of life) and the productive phase (377 of them from the end of the testing phase until 2 years of life). In order to obtain individuals with different body development dynamics, we pre-selected males based on their live weight (LW) at 0, 28, 63 and 147 days and on their average daily gain (ADG) between each period (0-28, 28-63 and 63-147 days). Libido and main seminal traits (semen volume, motility, concentration, and production, as well as normal apical ridge and abnormalities of spermatozoa) were controlled during the testing phase. Semen volume, motility and concentration were subsequently controlled during the productive phase, as well as the length of the male life, calculated as the number of days a rabbit was present at the farm between age 147 and day of death, culling or censoring; set to 2 years of life). The birth weight, the ADG between 0 and 28 days and between 28 and 63 days were positively related to some seminal parameters measured during the testing phase (semen volume, concentration, production and motility; P<0.05), while the ADG between 63 and 147 days was negatively related to the seminal productivity throughout the productive life of the males (an increment of 10 g per day on ADG reduced the number of profitable ejaculates by 4.9%; P<0.05). In addition, a higher growth between 0 and 28 and between 63 and 147 days increased the risk of death or culling of males during the productive phase (P < 0.05). In conclusion, an adequate body development early in life seems to have a positive effect on the degree of sexual maturity with which male rabbits begin their reproductive life, but reaching the reproduction onset with excessive weight can reduce their reproductive performance and lifespan. (C) 2019 Elsevier Inc. All rights reserved.The authors would like to thank Jose Manuel Arias, owner of the selection centre El Adil Redondo S.L., (Carrizo de la Ribera, Leon, Spain), and his team for their help, as without their collaboration this work could not have been carried out. This study was supported by the Interministerial Commission for Science and Technology (CICYT) of the Spanish Government (AGL2017-85162-C2-1-R).Martinez-Paredes, E.; Llorens, J.; Ródenas Martínez, L.; Savietto, D.; Pascual Amorós, JJ. (2019). Effect of early development on semen parameters and lifespan of rabbit males selected by high growth rate. Theriogenology. 139:72-80. https://doi.org/10.1016/j.theriogenology.2019.07.014S728013

Reproductive robustness differs between generalist and specialist maternal rabbit lines: the role of acquisition and allocation of resources

[EN] Background: Farm animals are normally selected under highly controlled, non-limiting conditions to favour the expression of their genetic potential. Selection strategies can also focus on a single trait to favour the most specialized animals. Theoretically, if the environment provides enough resources, the selection strategy should not lead to changes in the interactions between life functions such as reproduction and survival. However, highly specialized farm animals can be required for breeding under conditions that differ largely from selection conditions. The consequence is a degraded ability of specialized animals to sustain reproduction, production and health, which leads to a reduced lifespan. This study was designed to address this issue using maternal rabbit lines. A highly specialized line with respect to numerical productivity at weaning (called V) and a generalist line that originated from females with a long reproductive life (called LP) were used to study the strategies that these lines develop to acquire and use the available resources when housed in different environments. In addition, two generations of line V, generations 16 and 36, were available simultaneously, which contributed to better understand how selection criteria applied in a specific environment changed the interplay between functions related to reproduction and survival. Results: We show that, under constrained conditions, line LP has a greater capacity for resource acquisition than line V, which prevents excessive mobilization of body reserves. However, 20 generations of selection for litter size at weaning did not lead to an increased capacity of nutrient (or resource) acquisition. For the two generations of line V, the partitioning of resources between milk production, body reserves preservation or repletion or foetal growth differed. Conclusions: Combining foundational and selection criteria with a specific selection environment resulted in female rabbits that had a different capacity to deal with environmental constraints. An increased robustness was considered as an emergent property of combining a multiple trait foundational criterion with a wide range of environmental conditions. Since such a strategy was successful to increase the robustness of female rabbits without impairing their productivity, there is no reason that it should not be applied in other livestock species.The authors thank Juan Carlos Moreno Pardo, Luis Rodenas Martinez and Eugenio Martinez Paredes for their technical support, and Doctors Manuel Baselga Izquierdo, Enrique Blas Ferrer and Concha Cervera Fras for their valuable comments in the first version of this work. We also thank the Spanish Ministry of Education and Science (Project AGL2011-30170-C02-01) for the economic support.Savietto, D.; Friggens, NC.; Pascual Amorós, JJ. (2015). Reproductive robustness differs between generalist and specialist maternal rabbit lines: the role of acquisition and allocation of resources. Genetics Selection Evolution. 47(2):1-11. https://doi.org/10.1186/s12711-014-0073-5S111472Knap, P. W. (2005). Breeding robust pigs. Australian Journal of Experimental Agriculture, 45(8), 763. doi:10.1071/ea05041Havenstein, G., Ferket, P., & Qureshi, M. (2003). Growth, livability, and feed conversion of 1957 versus 2001 broilers when fed representative 1957 and 2001 broiler diets. Poultry Science, 82(10), 1500-1508. doi:10.1093/ps/82.10.1500Havenstein, G., Ferket, P., & Qureshi, M. (2003). Carcass composition and yield of 1957 versus 2001 broilers when fed representative 1957 and 2001 broiler diets. Poultry Science, 82(10), 1509-1518. doi:10.1093/ps/82.10.1509Hansen, L. B. (2000). Consequences of Selection for Milk Yield from a Geneticist’s Viewpoint. Journal of Dairy Science, 83(5), 1145-1150. doi:10.3168/jds.s0022-0302(00)74980-0Poggenpoel, D. G., Ferreira, G. F., Hayes, J. P., & du Preez, J. J. (1996). Response to long‐term selection for egg production in laying hens. British Poultry Science, 37(4), 743-756. doi:10.1080/00071669608417904Estany, 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:10.1186/1297-9686-24-6-527Garcı́a, 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)00280-9Horan, B., Dillon, P., Faverdin, P., Delaby, L., Buckley, F., & Rath, M. (2005). The Interaction of Strain of Holstein-Friesian Cows and Pasture-Based Feed Systems on Milk Yield, Body Weight, and Body Condition Score. Journal of Dairy Science, 88(3), 1231-1243. doi:10.3168/jds.s0022-0302(05)72790-9Lucy, M. C. (2001). Reproductive Loss in High-Producing Dairy Cattle: Where Will It End? Journal of Dairy Science, 84(6), 1277-1293. doi:10.3168/jds.s0022-0302(01)70158-0Felver-Gant, J. N., Mack, L. A., Dennis, R. L., Eicher, S. D., & Cheng, H. W. (2012). Genetic variations alter physiological responses following heat stress in 2 strains of laying hens. Poultry Science, 91(7), 1542-1551. doi:10.3382/ps.2011-01988Vicente, 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.2011.07.019Lavara, R., Vicente, J. S., & Baselga, M. (2012). Estimation of genetic parameters for semen quality traits and growth rate in a paternal rabbit line. Theriogenology, 78(3), 567-575. doi:10.1016/j.theriogenology.2012.03.002Rauw, W. ., Kanis, E., Noordhuizen-Stassen, E. ., & Grommers, F. . (1998). Undesirable side effects of selection for high production efficiency in farm animals: a review. Livestock Production Science, 56(1), 15-33. doi:10.1016/s0301-6226(98)00147-xTheilgaard, 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:10.1186/1297-9686-39-2-207Sánchez, 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.2007-0217Van Noordwijk, A. J., & de Jong, G. (1986). Acquisition and Allocation of Resources: Their Influence on Variation in Life History Tactics. The American Naturalist, 128(1), 137-142. doi:10.1086/284547Reznick, D., Nunney, L., & Tessier, A. (2000). Big houses, big cars, superfleas and the costs of reproduction. Trends in Ecology & Evolution, 15(10), 421-425. doi:10.1016/s0169-5347(00)01941-8Theilgaard, 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/s1751731109003838Savietto, D., Cervera, C., Blas, E., Baselga, M., Larsen, T., Friggens, N. C., & Pascual, J. J. (2013). Environmental sensitivity differs between rabbit lines selected for reproductive intensity and longevity. animal, 7(12), 1969-1977. doi:10.1017/s175173111300178xEstany, 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)90021-3Vicente, J.-S., Viudes-de-Castro, M.-P., & García, M.-L. (1999). In vivo survival rate of rabbit morulae after vitrification in a medium without serum protein. Reproduction Nutrition Development, 39(5-6), 657-662. doi:10.1051/rnd:19990511Besenfelder, U., & Brem, G. (1993). Laparoscopic embryo transfer in rabbits. Reproduction, 99(1), 53-56. doi:10.1530/jrf.0.0990053Ferrian, S., Guerrero, I., Blas, E., García-Diego, F. J., Viana, D., Pascual, J. J., & Corpa, J. M. (2012). How selection for reproduction or foundation for longevity could have affected blood lymphocyte populations of rabbit does under conventional and heat stress conditions. Veterinary Immunology and Immunopathology, 150(1-2), 53-60. doi:10.1016/j.vetimm.2012.08.007Ferrian, 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.2013.01.008García-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.2011.938Savietto, 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.2012.1152Xiccato, G., & Trocino, A. (s. f.). Energy and protein metabolism and requirements. Nutrition of the rabbit, 83-118. doi:10.1079/9781845936693.0083Fortun-Lamothe, L., & Lebas, F. (1996). Effects of dietary energy level and source on foetal development and energy balance in concurrently pregnant and lactating primiparous rabbit does. Animal Science, 62(3), 615-620. doi:10.1017/s1357729800015174Cervera, C., & Carmona, J. F. (s. f.). Nutrition and the climatic environment. Nutrition of the rabbit, 267-284. doi:10.1079/9781845936693.0267Costa, C., Baselga, M., Lobera, J., Cervera, C., & Pascual, J. J. (2004). Evaluating response to selection and nutritional needs in a three-way cross of rabbits. Journal of Animal Breeding and Genetics, 121(3), 186-196. doi:10.1111/j.1439-0388.2004.00450.xQuevedo, 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/asc40850161Friggens, N. C., Ingvartsen, K. L., & Emmans, G. C. (2004). Prediction of Body Lipid Change in Pregnancy and Lactation. Journal of Dairy Science, 87(4), 988-1000. doi:10.3168/jds.s0022-0302(04)73244-0Friggens, 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)00111-8Turer, A. T., & Scherer, P. E. (2012). Adiponectin: mechanistic insights and clinical implications. Diabetologia, 55(9), 2319-2326. doi:10.1007/s00125-012-2598-xTheilgaard, 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.2006.01.007Sánchez, 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.2011-4065Coureaud, G., Schaal, B., Coudert, P., Rideaud, P., Fortun-Lamothe, L., Hudson, R., & Orgeur, P. (2000). Immediate postnatal sucking in the rabbit: Its influence on pup survival and growth. Reproduction Nutrition Development, 40(1), 19-32. doi:10.1051/rnd:2000117Rosell, 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.2008.08.003Fortun-Lamothe, L., Prunier, A., Bolet, G., & Lebas, F. (1999). Physiological mechanisms involved in the effects of concurrent pregnancy and lactation on foetal growth and mortality in the rabbit. Livestock Production Science, 60(2-3), 229-241. doi:10.1016/s0301-6226(99)00096-2Kirkwood, T. B. . (2002). Evolution of ageing. Mechanisms of Ageing and Development, 123(7), 737-745. doi:10.1016/s0047-6374(01)00419-5Kirkwood, T. B. L. (2005). Understanding the Odd Science of Aging. 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Levels of the available phosphorus and particle size of dicalcium phosphate in brown egg layer hens diet from 24 to 58 weeks of age

Um experimento foi conduzido para verificar o efeito de níveis de fósforo e do tamanho de partícula do fosfato bicálcico na dieta de poedeiras comerciais na fase de produção. Utilizou-se um delineamento experimental inteiramente casualizado, em esquema fatorial 2 × 3 com dois tamanhos de partícula do fosfato (fino e granulado) e três níveis de fósforo disponível (0,28; 0,38 e 0,48%), totalizando seis tratamentos, cada um com cinco repetições de oito aves. As dietas experimentais foram isoproteicas, isocalóricas e isocálcicas. O consumo de ração, a produção de ovos, a massa de ovos, a conversão alimentar, a porcentagem de casca, a gravidade específica e os teores de cinzas, cálcio, fósforo e magnésio nos ossos não foram afetados pelas dietas. Dietas contendo fosfato bicálcico (fino ou granulado) e 0,28% de fósforo disponível atendem às exigências de fósforo de galinhas poedeiras semipesadas de 24 a 58 semanas de idade.An experiment was carried out to verify the effect of levels of phosphorus and the particle size of dicalcium phosphate on diets for brown egg layer hens during production phase. A complete randomized experimental design as a 2 × 3 factorial arrangement, with two sizes of particles of phosphate (fine and granulate) and three levels of available phosphorus (0.28, 0.38 and 0.48%), totalizing six treatements with five replications of eight birds each, was used. The experimental diets were isoproteic, isocaloric, and isocalcium. Feed intake, egg production, egg mass, feed conversion, shell percentage, egg specific gravity, ash, calcium, phosphorus and magnesium levels in the bones were not affected by the diets. Diets with dicalcium phosphate (fine or granulated) and 0.28% available phosphorus level meet the phosphorus requirements in brown egg layer hens from 24 to 58 weeks of age

Consequences of rearing feeding programme on the performance of rabbit females from 1st to 2nd parturition

[EN] To evaluate how rearing programmes could affect resources allocation and reproductive performance of primiparous rabbit females, a total of 118 rabbit females were used to evaluate the effects of five rearing feeding programmes on their performance from 1st to 2nd parturition: CAL, fed ad libitum C diet (11.0 MJ digestible energy (DE), 114 g digestible protein (DP) and 358 g NDF/kg dry matter (DM) until 1st parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until 1st parturition; F, fed ad libitum with F diet (8.7 MJ DE, 88 g DP and 476 NDF/kg DM) until 1st parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until 1st parturition; FCF, fed with F diet ad libitum until 16 weeks of age, then C diet ad libitum until 20 weeks and then F diet ad libitum until 1st parturition. From 1st parturition, C diet was ad libitum offered to all the experimental groups until 2nd parturition. CAL females presented lower feed intake than females of F, FC and FCF groups in the 1st week of lactation (on av. ¿16.6%; P<0.05). During 1st lactation, the perirenal fat thickness change in CAL females was not different from 0 (+0.02 mm), while in the other four groups it increased (on av. +0.44 mm; P<0.05). Plasma of females fed with F diet during rearing (F, FC and FCF) had lower non-esterified fatty acids content than those exclusively fed with C diet (¿0.088 and ¿0.072 mmol/l compared to CAL and CR, respectively; P<0.05). FCF litters had higher weight than F litters at day 21 of lactation (+247 g; P<0.05), but FCF litter had significantly lower weight than FC litters at weaning (+170 g; P<0.05). CR females had the shortest average interval between the 1st and 2nd parturition (49 days) and FCF females the longest (+ 9 days compared to CR; P<0.05). At 2nd parturition, liveborn litters of F females were larger and heavier than litters of FCF females (+2.22 kits and +138 g; P<0.05), probably due to the lower mortality at birth of F litters (¿16.5 percentage points; P<0.05). In conclusion, rearing females on fibrous diets seems to increase the ability of primiparous rabbit females to obtain resources, especially at the onset of lactation.The authors thank the Spanish Ministry of Education and Science (Project AGL2006-07596) for the economic support to conduct this study.Martinez-Paredes, E.; Savietto, D.; Ródenas Martínez, L.; Cervera Fras, MC.; Blas Ferrer, E.; Brecchia, G.; Boiti, C.... (2019). Consequences of rearing feeding programme on the performance of rabbit females from 1st to 2nd parturition. Animal. 13(10):2173-2182. https://doi.org/10.1017/S175173111900051XS217321821310Verdelhan S , Bourdillon A , David JJ , Huirtaurd JJ , Lédan L , Renouf B , Roulleau X and Salaun JM 2005. 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Phosphates with different fluorine: phosphorus relations in the diet for broiler chicken

Um experimento foi conduzido com o objetivo de verificar os efeitos de diferentes relações flúor:fosforo na alimentação sobre o desempenho de frangos de corte. Foram utilizados 1.000 pintos de corte de 1 dia distribuídos em um delineamento inteiramente casualizado, com quatro tratamentos e cinco repetições de 50 aves por boxe. Os tratamentos consistiram de quatro fontes de fósforo com relações flúor:fósforo de 1:40, 1:60, 1:80 e 1:100. O experimento foi dividido em três fases experimentais: 1 a 21, 22 a 42 e 43 a 49 dias de idade. Em cada fase, avaliou-se o consumo de ração, o ganho de peso e a conversão alimentar. Ao final do experimento, foram abatidas duas aves de cada repetição para coleta da tíbia e de músculos do peito para análise das concentrações de flúor, cálcio, fósforo e magnésio desses tecidos. As relações flúor:fósforo avaliadas não afetaram o desempenho dos frangos de corte. A deposição óssea de flúor é proporcional à sua concentração na dieta, no entanto, a elevação dos níveis de flúor da dieta não influencia sua deposição nos músculos.An experiment was conducted to evaluate the effect of different fluorine:phosphorus ratios in the diet on performance of broiler chickens. One thousand broiler chickens with one day old were allotted to a completely randomized experimental design with four treatments with five replications of fifty broilers per experimental unit. The treatments was composed by four phosphorus sources with fluorine: phosphorus ratios of 1:40, 1:60,1:80, 1:100 and fed during three experimental phases: 1-21, 22-42 and 43-49 days. In each phase, feed intake, weight gain and feed conversion were evaluated. At the end of experiment, two birds per replication were slaughtered and their tibias and samples of muscle tissue from breast were collected for determination of fluorine, calcium, phosphorus and magnesium contents. The fluorine to phosphorus ratios did not affect the performance of broiler chickens. Bone deposition of fluorine is proportional to their concentration in diet. However, the increase of fluorine levels in diet does not influence their deposition in the muscle tissue