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

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

Effect of Dietary Level of Beet Pulp, with or without Molasses, on Health Status, Growth Performance, and Carcass and Digestive Tract Traits of Rabbits

[EN] Beet pulp is a raw material widely used in feed for growing rabbits, because it is a good source of soluble fiber, and its inclusion is frequently associated with a reduction in the incidence of digestive disorders. Beet pulp may or may not be accompanied by the molasses that is also obtained in the beet sugar extraction process, but no information is available on the effect of molasses presence on the response of the rabbits. This work evaluates the effect of the inclusion of beet pulp, with or without molasses, on the growth performance, carcass, digestive tract, and fermentative profile of the cecum in growing rabbits. The results of the present work have shown that beet pulp linearly reduced the growth performance and carcass yield of growing rabbits and, although the inclusion of beet pulp could contribute to reducing the risk of digestive disorders, when beet pulp included molasses, even higher incidence was observed. To evaluate the effect of dietary level of beet pulp, with or without molasses, on growth performance, a total of 470 28-day-old rabbits were used (614 +/- 6 g). Animals were randomly allocated into five dietary treatment groups: Control, without beet pulp; BP20, and BP40 with 20 and 40% of beet pulp without molasses, respectively; and BPM20 and BPM40, with 20 and 40% of beet pulp with molasses, respectively. Daily feed intake (DFI) and average daily gain (ADG) were controlled at 28, 49, and 59 days of age. Carcass and digestive tract traits were also determined at 59 days of age. Mortality and morbidity were controlled daily. Mortality during the growing period was higher in BPM than in BP groups (+9.2%; p < 0.05). The higher the inclusion of beet pulp, the lower the DFI and ADG of animals (5.5 and 4.6% for every 20% inclusion, respectively; p < 0.001), as well as the dressing out percentage, the liver proportion, and the dissectible fat percentage of their carcasses. However, the best feed efficiency during the last 10 days was obtained with the BPM40 group. The higher the inclusion of beet pulp, the higher the weight of the empty gastrointestinal tract and cecum (+2.4 and +3.0 percentage points for every 20% inclusion, respectively; p < 0.001). In fact, a higher inclusion of beet pulp decreased the pH and dry matter and decreased the total volatile fatty acids content of cecum richer in acetic acid but poorer in propionic, isobutiric, isovaleric, and valeric acids. Stomach weight was lower, and the capric acid content in the cecum was higher in the BPM than in the BP group. The inclusion of beet pulp in the feed reduced the growth performance and carcass yield of growing rabbits, and an even higher incidence of digestive disorders was observed when beet pulp included molasses.This research was funded by the Spanish Ministry of Education and Science (grant no. AGL2014-53405-C2-1-P).Arce, O.; Alagón, G.; Ródenas Martínez, L.; Martinez-Paredes, E.; Moya, V.; Cervera, C.; Pascual Amorós, JJ. (2022). Effect of Dietary Level of Beet Pulp, with or without Molasses, on Health Status, Growth Performance, and Carcass and Digestive Tract Traits of Rabbits. Animals. 12(23):1-12. https://doi.org/10.3390/ani12233441112122

Plasmatic Urea Nitrogen in Growing Rabbits with Different Combinations of Dietary Levels of Lysine, Sulphur Amino Acids and Threonine

[EN] Formulating diets to maximize nutrient harnessing has positive effects on performance and environment. In the case of growing rabbits, clues exist indicating that animals with high growth rate when consuming current diets show lower protein retention than expected, and it could be related to amino acid supply. The aim of this work is to find the amino acid combination (27 experimental diets: 3 levels of the 3 main limiting amino acids: lysine, sulphur amino acids, and threonine) that would minimize the nitrogen excretion in the bloodstream, a marker of the efficiency in the amino acid use This combination is a good candidate to be tested in order to improve performance and reduce pollution. A total of 27 experimental diets were formulated starting from the same basal mixture, with a moderate content of crude protein and digestible energy (155 g and 9.86 MJ/kg of digestible matter (DM), respectively, both estimated). The contents of lysine, sulphur amino acids and threonine were variable. The first one, close to the current recommendations (Medium, M; 8.1, 5.8 and 6.9 g/kg DM for lysine, sulphur amino acids and threonine, respectively), and two other levels were on average 15% higher (High, H; 9.4, 6.6 and 7.8 g/kg DM for lysine, sulphur amino acids and threonine, respectively) or lower (Low, L; 6.7, 4.9 and 5.7 g/kg DM for lysine, sulphur amino acids and threonine, respectively). Diets were named with three letters, indicating lysine, sulphur amino acids and threonine levels, respectively. In total, 918 weaned rabbits (28 days old) were used (34 per diet). At weaning, animals were fed ad libitum with a commercial diet until day 46, day 47 each collective cage was randomly switched to one experimental diet. At day 48, blood samples were collected at 08:00h then the animals were subjected to 10 h of fasting and a second blood sample was extracted at 21.00h. At 08:00h, Pasmatic urea nitrogen (PUN) was higher with the L level of lysine (p< 0.001), unaffected by the level of sulphur amino acids and increased with the level of threonine (p< 0.001). At 21:00h, minimum PUN was observed with the MHL diet (14.72 +/- 0.661 mg/dL). Taken into account the usual recommendations (established for a diet containing 11.3 MJ DE/kg DM, and then being 0.72, 0.51 and 0.61 g/MJ DE for lysine, sulphur amino acids and threonine, respectively), these results suggest that a diet containing more lysine and sulphur amino acids per energy unit (around 0.82 and 0.67 g/MJ DE) could better fit the growing rabbit requirements, although studies on the effects of such a diet on performance and protein retention are necessary.This study was supported by the Interministerial Commission for Science and Technology (CICYT) from the Spanish Government (AGL2017-85162-C2-1-R). The grant for Pablo Marin from the Ministry of Education, Culture and Sports (FPU-2014-01203) is also gratefully acknowledged.Marín-García, P.; López Luján, MDC.; Ródenas Martínez, L.; Martinez-Paredes, E.; Blas Ferrer, E.; Pascual Amorós, JJ. (2020). Plasmatic Urea Nitrogen in Growing Rabbits with Different Combinations of Dietary Levels of Lysine, Sulphur Amino Acids and Threonine. Animals. 10(6):1-8. https://doi.org/10.3390/ani10060946S18106Quevedo, 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/asc200688Pascual, M., Pla, M., & Blasco, A. (2008). Effect of selection for growth rate on relative growth in rabbits1,2. Journal of Animal Science, 86(12), 3409-3417. doi:10.2527/jas.2008-0976Pascual, M., & Pla, M. (2007). Changes in carcass composition and meat quality when selecting rabbits for growth rate. Meat Science, 77(4), 474-481. doi:10.1016/j.meatsci.2007.04.009Marín-García, P. J., Ródenas, L., Martínez-Paredes, E., Cambra-López, M., Blas, E., & Pascual, J. J. (2020). A moderate protein diet does not cover the requirements of growing rabbits with high growth rate. Animal Feed Science and Technology, 264, 114495. doi:10.1016/j.anifeedsci.2020.114495Carabaño R., Villamide M.J., García J., Nicodemus N., Llorente A., Chamorro S., & Menoyo D. (2010). New concepts and objectives for protein-amino acid nutrition in rabbits: a review. World Rabbit Science, 17(1). doi:10.4995/wrs.2009.664Taboada, E., Mendez, J., & de Blas, J. (1996). The response of highly productive rabbits to dietary sulphur amino acid content for reproduction and growth. Reproduction Nutrition Development, 36(2), 191-203. doi:10.1051/rnd:19960204Taboada, E., Mendez, J., Mateos, G. ., & De Blas, J. . (1994). The response of highly productive rabbits to dietary lysine content. Livestock Production Science, 40(3), 329-337. doi:10.1016/0301-6226(94)90099-xDe Blas, J. C., Taboada, E., Nicodemus, N., Campos, R., Piquer, J., & Méndez, J. (1998). Performance response of lactating and growing rabbits to dietary threonine content. Animal Feed Science and Technology, 70(1-2), 151-160. doi:10.1016/s0377-8401(97)00063-1Roth-Maier, D. A., Ott, H., Roth, F. X., & Paulicks, B. R. (2004). Effects of the level of dietary valine supply on amino acids and urea concentration in milk and blood plasma of lactating sows. Journal of Animal Physiology and Animal Nutrition, 88(1-2), 39-45. doi:10.1046/j.0931-2439.2003.00458.xDonsbough, A. L., Powell, S., Waguespack, A., Bidner, T. D., & Southern, L. L. (2010). Uric acid, urea, and ammonia concentrations in serum and uric acid concentration in excreta as indicators of amino acid utilization in diets for broilers. Poultry Science, 89(2), 287-294. doi:10.3382/ps.2009-00401Marín-García, P. J., López-Luján, M. del C., Ródenas, L., Martínez-Paredes, E. M., Blas, E., & Pascual, J. J. (2020). Plasma urea nitrogen as an indicator of amino acid imbalance in rabbit diets. World Rabbit Science, 28(2), 63. doi:10.4995/wrs.2020.12781Van Milgen, J., & Dourmad, J.-Y. (2015). Concept and application of ideal protein for pigs. Journal of Animal Science and Biotechnology, 6(1). doi:10.1186/s40104-015-0016-1Fernández-Carmona J., Blas E., Pascual J.J., Maertens L., Gidenne T., Xiccato G., & García. (2010). Recommendations and guidelines for applied nutrition experiments in rabbits. World Rabbit Science, 13(4). doi:10.4995/wrs.2005.516Real Decreto 53/2013, Por el Que se Establecen las Normas Básicas Aplicables Para la Protección de los Animales Utilizados en Experimentación y Otros Fines Científicos, Incluyendo la Docencia. BOE 34https://www.boe.es/diario_boe/txt.php?id=BOE-A-2013-1337Cifre, J., Baselga, M., García-Ximénez, F., & Vicente, J. S. (1998). Performance of a hyperprolific rabbit line I. Litter size traits. Journal of Animal Breeding and Genetics, 115(1-6), 131-138. doi:10.1111/j.1439-0388.1998.tb00336.xEstany, 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:10.1186/1297-9686-24-6-527Bosch, L., Alegría, A., & Farré, R. (2006). Application of the 6-aminoquinolyl-N-hydroxysccinimidyl carbamate (AQC) reagent to the RP-HPLC determination of amino acids in infant foods. Journal of Chromatography B, 831(1-2), 176-183. doi:10.1016/j.jchromb.2005.12.002Eggum, B. O. (1970). Blood urea measurement as a technique for assessing protein quality. British Journal of Nutrition, 24(4), 983-988. doi:10.1079/bjn19700101Nicodemus, N., Mateos, J., Blas, J. C. de, Carabaño, R., & Fraga, M. J. (1999). Effect of diet on amino acid composition of soft faeces and the contribution of soft faeces to total amino acid intake, through caecotrophy in lactating doe rabbits. Animal Science, 69(1), 167-170. doi:10.1017/s1357729800051201García, A. I., de Bias, J. C., & Carabaño, R. (2004). Effect of type of diet (casein-based or protein-free) and caecotrophy on ileal endogenous nitrogen and amino acid flow in rabbits. Animal Science, 79(2), 231-240. doi:10.1017/s1357729800090093Monteiro-Motta, A. C., Scapinello, C., Oliveira, A. F. G., Figueira, J. L., Catelan, F., Sato, J., & Stanquevis, C. E. (2013). Levels of lysine and methionine+cystine for growing New Zealand White rabbits. Revista Brasileira de Zootecnia, 42(12), 862-868. doi:10.1590/s1516-3598201300120000

Long-term implications of feed energy source in different genetic types of reproductive rabbit females: I. Resource acquisition and allocation

[EN] To achieve functional but also productive females, we hypothesised that it is possible to modulate acquisition and allocation of animals from different genetic types by varying the main energy source of the diet. To test this hypothesis, we used 203 rabbit females belonging to three genetic types: H (n=66), a maternal line characterised by hyper-prolificacy; LP (n=67), a maternal line characterised by functional hyper-longevity; R (n=79), a paternal line characterised by growth rate. Females were fed with two isoenergetic and isoprotein diets differing in energy source: animal fat (AF) enhancing milk yield; cereal starch (CS) promoting body reserves recovery. Feed intake, weight, perirenal fat thickness (PFT), milk yield and blood traits were controlled during five consecutive reproductive cycles (RCs). Females fed with CS presented higher PFT (+0.2 mm, P0.05), particularly for those fed with AF. Moreover, LP females fed with AF progressively increased PFT across the RC, whereas those fed with CS increased PFT during early lactation (+7.3%; P<0.05), but partially mobilised it during late lactation (-2.8%; P<0.05). Independently of the diet offered, LP females reached weaning with similar PFT. H females fed with either of the two diets followed a similar trajectory throughout the RC. For milk yield, the effect of energy source was almost constant during the whole experiment, except for the first RC of females from the maternal lines (H and LP). These females yielded +34.1% (P<0.05) when fed with CS during this period. Results from this work indicate that the resource acquisition capacity and allocation pattern of rabbit females is different for each genetic type. Moreover, it seems that by varying the main energy source of the diet it is possible to modulate acquisition and allocation of resources of the different genetic types. However, the response of each one depends on its priorities over time.The authors thank Juan Carlos Moreno for his technical support. The grant for Alberto Arnau from the Ministry of Economy and Finance (BES-2012-052345) is also gratefully acknowledged. This study was supported by the Interministerial Commission for Science and Technology (CICYT) of the Spanish Government (AGL2014-53405-C2-1-P).Arnau-Bonachera, A.; Cervera Fras, MC.; Blas Ferrer, E.; Larsen, T.; Martinez-Paredes, E.; Ródenas Martínez, L.; Pascual Amorós, JJ. (2018). Long-term implications of feed energy source in different genetic types of reproductive rabbit females: I. Resource acquisition and allocation. animal. 12(9):1867-1876. https://doi.org/10.1017/S1751731117003287S1867187612

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. Comparaison de deux programmes alimentaires pour la préparation des futures reproductrices. In Proceedings of the 11émes Journées de la Recherche Cunicole, 29–30 November 2005, Paris, France, pp. 119–122.Quevedo, 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., Savietto, D., Cervera, C., & Baselga, M. (2013). Resources allocation in reproductive rabbit does: a review of feeding and genetic strategies for suitable performance. World Rabbit Science, 21(3). doi:10.4995/wrs.2013.1236Pascual, J. J., Castella, F., Cervera, C., Blas, E., & Fernández-Carmona, J. (2000). The use of ultrasound measurement of perirenal fat thickness to estimate changes in body condition of young female rabbits. Animal Science, 70(3), 435-442. doi:10.1017/s135772980005178xMartínez-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/s1751731111002643Manal, A. F., Tony, M. A., & Ezzo, O. H. (2010). Feed restriction of pregnant nulliparous rabbit does: consequences on reproductive performance and maternal behaviour. Animal Reproduction Science, 120(1-4), 179-186. doi:10.1016/j.anireprosci.2010.03.010Littell, 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:10.2527/1998.7641216xFriggens, 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/s1751731111001820Blas, C. de, & Mateos, G. G. (s. f.). Feed formulation. Nutrition of the rabbit, 222-232. doi:10.1079/9781845936693.0222Rebollar, P. G., Pereda, N., Schwarz, B. F., Millán, P., Lorenzo, P. L., & Nicodemus, N. (2011). Effect of feed restriction or feeding high-fibre diet during the rearing period on body composition, serum parameters and productive performance of rabbit does. Animal Feed Science and Technology, 163(1), 67-76. doi:10.1016/j.anifeedsci.2010.10.005Statistical Analysis System (SAS) 2002. SAS/SAT user’s guide (release 9.1). SAS Institute Inc., Cary, NC, USA.Bonnano A , Mazza F , Di Grigoli A and Alicata ML 2004. Effects of restricted feeding during rearing, combined with a delayed first insemination, on reproductive activity of rabbit does. In Proceedings of the 8th World Rabbit Congress, 7–10 September 2004, Puebla, México, pp. 224–230.Arnau-Bonachera, A., Cervera, C., Blas, E., Larsen, T., Martínez-Paredes, E., Ródenas, L., & Pascual, J. J. (2017). Long-term implications of feed energy source in different genetic types of reproductive rabbit females: I. Resource acquisition and allocation. animal, 12(9), 1867-1876. doi:10.1017/s1751731117003287Daly, M. E., Vale, C., Walker, M., Alberti, K. G., & Mathers, J. C. (1997). Dietary carbohydrates and insulin sensitivity: a review of the evidence and clinical implications. The American Journal of Clinical Nutrition, 66(5), 1072-1085. doi:10.1093/ajcn/66.5.1072Federation Internationale de Lacterie 1993. Determination de la teneur en azote. FIL Standard: 20B. Secrétariat General Federation Internationale de Lacterie, Brussels, Belgium.Xiccato, 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:10.2527/1999.772416xViudes-de-Castro, P., Santacreu, M., & Vicente, J. (1991). Effet de la concentration énergétique de l’alimentation sur les pertes embryonnaires et fœtales chez la lapine. Reproduction Nutrition Development, 31(5), 529-534. doi:10.1051/rnd:19910505Pascual, J. J., Cervera, C., Blas, E., & Fernández-Carmona, J. (1999). Effect of high fat diets on the performance, milk yield and milk composition of multiparous rabbit does. Animal Science, 68(1), 151-162. doi:10.1017/s1357729800050177Brecchia, 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.2005.09.006Savietto, D., Cervera, C., Ródenas, L., Martínez-Paredes, E., Baselga, M., García-Diego, F. J., … Pascual, J. J. (2014). Different resource allocation strategies result from selection for litter size at weaning in rabbit does. Animal, 8(4), 618-628. doi:10.1017/s1751731113002437Martínez-Paredes, E., Ródenas, L., Pascual, J. J., & 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. doi:10.1017/s1751731118000162Rommers, J. M., Meijerhof, R., Noordhuizen, J. P. T. M., & Kemp, B. (2004). Effect of feeding program during rearing and age at first insemination on performances during subsequent reproduction in young rabbit does. Reproduction Nutrition Development, 44(4), 321-332. doi:10.1051/rnd:200403

Do Growing Rabbits with a High Growth Rate Require Diets with High Levels of Essential Amino Acids? A Choice-Feeding Trial

[EN] Two diets were designed to investigate the effect of the growth rate on amino acid requirements in growing rabbits: M diet (with medium levels of amino acids, following current nutritional recommendations for growing rabbits) and H diet (with high levels of lysine, sulphur amino acids and threonine compared with current nutritional recommendations). Performance, nutrient retention and digestibility (faecal and ileal) trials, as well as a choice-feeding test were conducted. We found no differences in animal performance, nutrient retention and digestibility parameters between diets, but the animals showed a preference for the M diet, expressed by a high intra-individual repeatability in preference. Our results provide useful information and nutrition tools to move towards precision protein nutrition in growing rabbits. As a consequence of the genetic selection process in growing rabbits, there are currently fast-growing animals exhibiting an average daily gain that may exceed 45 g/d. The protein requirements of these animals, namely amino acid requirements, may differ from animals with low growth rates. The objective of this work was to evaluate growth performance, the coefficient of total tract apparent digestibility (CTTAD), the apparent ileal digestibility (AID) of amino acids and nutrient retention of fast-growing rabbits when they had access to a diet with high levels of amino acids and/or a diet formulated with current nutritional recommendations in a choice-feeding trial. To this end, two diets were formulated: the M diet following current nutritional recommendations for growing rabbits (including 8.1, 5.8 and 6.9 g/kg dry matter (DM) of total lysine, sulphur amino acids and threonine, respectively) and the H diet with higher levels of total lysine, sulphur amino acids and threonine (9.4, 6.6 and 7.8 g/kg DM, respectively). A total of 220 weaned rabbits, from a paternal line selected for the growth rate, had free access to the M diet, the H diet or both (MH) diets from 28 to 63 days of age. The CTTAD of DM, crude protein and gross energy from 49 to 53 days of age as well as the AID of amino acids of the diets at 63 days of age were determined. Protein, amino acids and energy retained in the empty body from 28 to 63 days of age were also registered. No significant differences in growth performance, CTTAD, AID and nutrient retention between dietary treatments were observed. However, animals fed the H diet showed a higher AID of cysteine (p < 0.05) and higher threonine retention (p < 0.05) compared to the M diet. As regards the choice-feeding trial, MH animals showed a higher feed intake of the M diet compared to the H diet (+8.61%; p < 0.001), and furthermore, more than 50% of the animals preferred the M diet throughout the experimental period (p < 0.05). Our results suggest that animals with high growth rates do not show significantly higher productive traits when fed the H diet compared to the M diet. As regards choice feeding, MH animals were capable of choosing their preferred diet, showing high intra-individual repeatability in preference for the M diet. It would be interesting to continue studying this behaviour of choice based on amino acid levels.This research was funded by the Interministerial Commission for Science and Technology (CICYT; grant no. AGL2017-85162-C2-1-R).Marín-García, PJ.; López Luján, MDC.; Ródenas Martínez, L.; Martinez-Paredes, E.; Cambra López, M.; Blas Ferrer, E.; Pascual Amorós, JJ. (2021). Do Growing Rabbits with a High Growth Rate Require Diets with High Levels of Essential Amino Acids? A Choice-Feeding Trial. Animals. 11(3):1-13. https://doi.org/10.3390/ani11030824S11311

Nutritive value of distillers dried grains with solubles from barley, corn and wheat for growing rabbits

The authors acknowledge Juan Carlos Moreno for his technical support and the Spanish Ministry of Education and Science (Project AGL2014-53405-C2-1-P) for the economic support to conduct this study.Alagon, G.; Arce-Cabrera, ON.; Martinez-Paredes, E.; Ródenas Martínez, L.; Moya, V.; Blas Ferrer, E.; Cervera Fras, MC.... (2016). Nutritive value of distillers dried grains with solubles from barley, corn and wheat for growing rabbits. Animal Feed Science and Technology. 222:217-226. https://doi.org/10.1016/j.anifeedsci.2016.10.024S21722622

Blending learning: Una nueva forma de enfocar las sesiones prácticas

Las competencias son elementos muy apreciados por los empleadores, en especial las relacionadas con el pensamiento práctico. Esta realidad es más evidente en las sesiones prácticas de laboratorio, donde los alumnos deben aplicar conocimientos teóricos a casos prácticos. En el actual trabajo se pretende implantar la metodología docente “Blended learning” que combina docencia presencial con on line, con el fin de favorecer la adquisición de la competencia transversal “Aplicación y pensamiento práctico”, así como una mayor interiorización de los conceptos aprendidos. La metodología docente se implantó en alumnos de grado, en concreto en las sesiones de laboratorio de la asignatura: Fisiología Animal y Humana (11109) del segundo curso del Grado en Biotecnología de la Universitat Politècnica de València. Los resultados obtenidos mostraron que la implantación de la metodología docente permitió desarrollar el pensamiento práctico, ya que la nota media categórica fue de “A: Excelente”. Además, se observó una mejora en la calificación de la nota del examen teórico-práctico, lo que indica una mejor interiorización de los conceptos impartidos. Por tanto, se puede concluir que la metodología “Blended learning” ha sido una metodología eficaz para no sólo mejorar la adquisición de la competencia transversal, sino también para la calificación académica