Efecto del aumento de fibra digestible por sustitución de almidón y del nivel de grasa en el pienso de peridestete sobre el desarrollo del ciego y los principales parámetros de la actividad fermentativa en conejos

El presente trabajo aborda el estudio de los efectos del aumento del contenido en fibra digestible en sustitución de almidón y del nivel de grasa del pienso peridestete, sobre el desarrollo del ciego y sus parámetros fermentativos, entre los 28 y los 42 días de vida de los conejos.Ródenas Martínez, L. (2007). Efecto del aumento de fibra digestible por sustitución de almidón y del nivel de grasa en el pienso de peridestete sobre el desarrollo del ciego y los principales parámetros de la actividad fermentativa en conejos. http://hdl.handle.net/10251/12581Archivo delegad

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

Characterisation and In Vitro Evaluation of Fenugreek (Trigonella foenum-graecum) Seed Gum as a Potential Prebiotic in Growing Rabbit Nutrition

[EN] A fenugreek seed gum, extracted fromTrigonella foenum-graecumseeds and rich in galactomannan, was chemically and physically characterised and its prebiotic potential for young rabbits was evaluated in vitro, both as pure fenugreek seed gum and when included up to 20 g/kg in rabbit diets rich in soluble and insoluble fibre. Fenugreek seed gum was resistant to pepsin and pancreatin digestion but was totally fermented by rabbit caecal bacteria. Fenugreek seed gum linear inclusion up to 20 g/kg in diets rich in soluble fibre has led to a reduction in the solubility of some nutrients during in vitro enzymatic phase and an increase in the fermented fraction. Fenugreek seed gum satisfies two essential conditions of a prebiotic: resistance to enzymatic digestion and being totally fermented by caecal bacteria. Some components of soluble fibre appear to have prebiotic effects that can contribute to improving digestive health in post-weaning rabbits. In this work, a fenugreek seed gum (FGS), extracted fromTrigonella foenum-graecumseeds and rich in galactomannan, was characterised. Both the pure FSG and ten substrates obtained by the inclusion of 0, 5, 10, 15 and 20 g/kg of FSG in diets rich in soluble (SF) and insoluble (IF) fibre were evaluated in vitro to determine FSG prebiotic potential for rabbit diets. FSG was rich in total sugars (630 g/kg dry matter), consisting entirely of galactose and mannose in a 1:1 ratio, and a moderate protein content (223 g/kg dry matter). Pure FSG was affected very little by in vitro digestion, as only 145 g/kg of the FSG was dissolved during the enzymatic phase. However, the linear inclusion of FSG up to 20 g/kg in growing rabbit feeds has led to a reduction in the solubility of some nutrients during in vitro enzymatic phase, especially in SF diets. Pure FSG not digested during the enzymatic phase almost completely disappeared during the in vitro fermentation phase, 984 g/kg of this indigestible fraction. However, although linear inclusion of FSG up to 20 g/kg in SF diets increased the fermented fraction, no relevant changes in the fermentation profile were observed. In conclusion, FSG satisfies two essential conditions of the prebiotic effect, showing resistance to in vitro enzymatic digestion and being totally fermented in vitro by caecal bacteria, although in vivo studies will be necessary to determine its prebiotic potential.This study is supported by the Ministerio de Economia, Industria y Competitividad of the Spanish Government (AGL2017-85162-C2-1R), the Universitat Politecnica de Valencia (Project 20180290; Spain), and the Higher School of Agriculture of Mateur of the Carthage University (Tunisia Republic). The grant for Jihed Zemzmi from the Carthage University is also gratefully acknowledged.Zemzmi, J.; Ródenas Martínez, L.; Blas Ferrer, E.; Najar, T.; Pascual Amorós, JJ. (2020). Characterisation and In Vitro Evaluation of Fenugreek (Trigonella foenum-graecum) Seed Gum as a Potential Prebiotic in Growing Rabbit Nutrition. Animals. 10(6):1-15. https://doi.org/10.3390/ani10061041S115106Rosell J.M., de la Fuente L.F., Badiola J.I., Fernández de Luco D., Casal J., & Saco M. (2010). Study of urgent visits to commercial rabbit farms in Spain and Portugal during 1997-2007. World Rabbit Science, 17(3). doi:10.4995/wrs.2009.652Gidenne, T., Arveux, P., & Madec, O. (2001). The effect of the quality of dietary lignocellulose on digestion, zootechnical performance and health of the growing rabbit. Animal Science, 73(1), 97-104. doi:10.1017/s1357729800058094Carabaño R., Villamide M.J., García J., Nicodemus N., Llorente A., Chamorro S., & Menoyo D. (2010). 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Effect of mannan oligosaccharides on the performance, intestinal morphology and cecal fermentation of fattening rabbits. Animal Feed Science and Technology, 126(1-2), 107-120. doi:10.1016/j.anifeedsci.2005.06.009Jiang, J. X., Zhu, L. W., Zhang, W. M., & Sun, R. C. (2007). Characterization of Galactomannan Gum from Fenugreek (Trigonella foenum-graecum) Seeds and Its Rheological Properties. International Journal of Polymeric Materials, 56(12), 1145-1154. doi:10.1080/00914030701323745Van Nevel, C. J., Decuypere, J. A., Dierick, N. A., & Molly, K. (2005). Incorporation of galactomannans in the diet of newly weaned piglets: Effect on bacteriological and some morphological characteristics of the small intestine. Archives of Animal Nutrition, 59(2), 123-138. doi:10.1080/17450390512331387936Dakia, P. A., Blecker, C., Robert, C., Wathelet, B., & Paquot, M. (2008). Composition and physicochemical properties of locust bean gum extracted from whole seeds by acid or water dehulling pre-treatment. 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Journal of Dairy Science, 74(10), 3583-3597. doi:10.3168/jds.s0022-0302(91)78551-2Bosch, 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.2005.12.002McCleary, B. V. (1988). Carob and guar galactomannans. Biomass Part A: Cellulose and Hemicellulose, 523-527. doi:10.1016/0076-6879(88)60163-7Chaires-Martínez, L., Salazar-Montoya, J. A., & Ramos-Ramírez, E. G. (2008). Physicochemical and functional characterization of the galactomannan obtained from mesquite seeds (Prosopis pallida). European Food Research and Technology, 227(6), 1669-1676. doi:10.1007/s00217-008-0892-0Nour, A. A. M., & Magboul, B. I. (1986). Chemical and amino acid composition of fenugreek seeds grown in Sudan. 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Effects of feeding programme on the performance and energy balance of nulliparous rabbit does

A total of 190 rabbit females were used to evaluate five feeding programmes from 9 weeks of age to the first parturition: CAL, fed ad libitum with a control diet (C: 11.0 MJ digestible energy (DE) and 114 g digestible protein (DP)/kg dry matter (DM)) until first parturition; CR, fed ad libitum with C diet until 12 weeks of age and then C diet restricted (140 g/day) until first parturition; F, fed ad libitum with a low-energy, high-fibre diet (F: 8.7 MJ DE and 88 g DP/kg DM) until first parturition; FC, fed with F diet ad libitum until 16 weeks of age, and C diet ad libitum until first 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 first parturition. The rabbits were artificially inseminated at 18 weeks of age. CAL group had a higher mortality rate compared with the other groups between 9 and 12 weeks of age (34% v. 3%; P,0.05) and during the last 3 weeks of first pregnancy (14% v. 3%; P,0.05). The CAL and FC females presented higher BW and perirenal fat thickness (PFT) than CR females at 11 days of pregnancy (10.41 kg and 10.6 mm; P,0.05), with F females showing medium values. The type of feeding procedure did not affect the fertility rate of young females at first artificial insemination. Differences in BW disappeared at parturition, when only CAL females presented a greater PFT than CR and FC females (10.3mm; P,0.05). In comparison with FCF, CAL females had smaller and thinner live born litters (22.5 kits and 2139 g, respectively; P,0.05), with CR, F and FC females showing medium values. The low number of kits born alive for CAL females was because of their lesser total number of kits born (21.7 kits; P,0.05) and the greater mortality of their litters at birth (113.9%; P,0.05) compared with FCF females. Non-esterified fatty acid was higher in the blood of females fed C diet (CAL and CR) than in others at partum day (on average 10.15 mmol/l; P,0.05). In conclusion, the ad libitum use of diets for lactating rabbit does throughout the rearing period could lead young rabbit females to present a higher risk of early death and smaller litter size at first parturition. Feed restriction or earlier use of suitably fibrous diets led females to achieve the critical BW and fat mass at first mating to ensure reproduction.The authors thank the Spanish Ministry of Education and Science (Project AGL2006-07596) for the economic support to conduct this study.Martínez Paredes, EM.; Ródenas Martínez, L.; Martínez Vallespín, B.; Cervera Fras, MC.; Blas Ferrer, E.; Brecchia, G.; Boiti, C.... (2012). Effects of feeding programme on the performance and energy balance of nulliparous rabbit does. Animal. 6(7):1086-1095. https://doi.org/10.1017/S1751731111002643S1086109567Pascual, J. J., Castella, F., Cervera, C., Blas, E., & Fernández-Carmona, J. (2000). 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Selection for leanness in broilers using plasma lipoprotein concentration as selection criterion. Leanness in Domestic Birds, 41-57. doi:10.1016/b978-0-408-01036-8.50007-5Sørensen, M. T., Danielsen, V., & Busk, H. (1998). Different rearing intensities of gilts: Livestock Production Science, 54(2), 159-165. doi:10.1016/s0301-6226(97)00176-0Xiccato, G., & Trocino, A. (s. f.). Energy and protein metabolism and requirements. Nutrition of the rabbit, 83-118. doi:10.1079/9781845936693.0083Brecchia, 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.2005.09.006European Union 2003. Protection of animals used for experimental purposes. Directive 86/609/EEC of 24th November 1986, amended 16th September 2003.Martínez-Vallespín, B., Martínez-Paredes, E., Ródenas, L., Cervera, C., Pascual, J. J., & Blas, E. (2011). Combined feeding of rabbit female and young: Partial replacement of starch with acid detergent fibre or/and neutral detergent soluble fibre at two protein levels. Livestock Science, 141(2-3), 155-165. doi:10.1016/j.livsci.2011.05.014Marteniuk, J. V., & Herdt, T. H. (1988). Pregnancy Toxemia and Ketosis of Ewes and Does. Veterinary Clinics of North America: Food Animal Practice, 4(2), 307-315. doi:10.1016/s0749-0720(15)31050-1Barb, C. ., Barrett, J. ., Kraeling, R. ., & Rampacek, G. . (2001). Serum leptin concentrations, luteinizing hormone and growth hormone secretion during feed and metabolic fuel restriction in the prepuberal gilt. Domestic Animal Endocrinology, 20(1), 47-63. doi:10.1016/s0739-7240(00)00088-

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

Plasma urea nitrogen as an indicator of amino acid imbalance in rabbit diets

[EN] In recent decades, recommendations on dietary protein content have been considerably reduced, while fibre content has been increased. Under these conditions, an adequate dietary amino acid balance could be crucial to optimise feed efficiency. Plasma urea nitrogen (PUN) level could be a good indicator of an amino acid imbalance and its potential has already been studied in other species, but not yet in rabbits. The main objective of the present work was to detect the possible interest of PUN in pinpointing amino acid deficiencies in rabbits. Two experimental diets were formulated from the same basal mixture, following all the recommendations for growing rabbits, except lysine, whose content was variable, following current guidelines in diet P8.1 or lower from those in P4.4 (with 8.1 and 4.4 g/kg dry matter of lysine and with 757 and 411 mg of lysine per MJ of digestible energy). Three different trials were designed: one where the animals were fed ad libitum (AL) and two others in which fasting periods of 10 h were included; one where feeding was restored at 08:00 h (Fast8h) and the other at 18:00 h (Fast18h). A total of 72 three-way crossbred growing rabbits (24 animals for each trial in a split-plot trial) up to a total of 12 recordings were used. Blood samples were taken every 4 h in AL trial and every hour after refeeding up to a total of six controls, in trials Fast8h and Fast18h. The differences between balanced and unbalanced diets in lysine were highest (P&lt;0.001) between 04:00 h and 12:00 h in animals fed ad libitum, and at 3 h after refeeding (21:00 h) in Fast18h. These results suggest that PUN could be an adequate indicator to detect deficiencies in amino acids in growing rabbitdiets.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 Marín from the Ministry of Education, Culture and Sports (FPU2014-01203) is also gratefully acknowledged.Marín García, PJ.; López Luján, MDC.; Ródenas Martínez, L.; Martínez-Paredes, EM.; Blas Ferrer, E.; Pascual Amorós, JJ. (2020). Plasma urea nitrogen as an indicator of amino acid imbalance in rabbit diets. World Rabbit Science. 28(2):63-72. https://doi.org/10.4995/wrs.2020.12781OJS6372282AOAC. 2000. Official methods of analysis of the Association of Official Analytical Chemists, 18th ed. AOAC, Arlington, USA.Baselga M. 2004. Genetic improvement of meat rabbits. In Proc.: 8th World Rabbit Congress. September, 7-10, 2004, Puebla, México. 1: 1-13.Batey I.L. 1982. Starch analysis using thermostable alphaamylases. Starch, 34: 125-128. https://doi.org/10.1002/star.19820340407Bellier R., Gidenne T., Vernay M., Colin M. 1995. In vivo study of circadian variations of the cecal fermentation pattern in postweaned and adult rabbits. J. Anim. Sci. 73: 128-135. https://doi.org/10.2527/1995.731128xBlasco A. 1989. Genética y nutrición del conejo. In: de Blas C. (ed). Alimentación del conejo. Ediciones Mundi Prensa, Madrid, 1-15.Boletín Oficial del Estado. 2013. Real 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 34, 11370-11421.Bosch 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. J. Chromatogr., 831: 176-183. https://doi.org/10.1016/j.jchromb.2005.12.002Brown J.A., Cline T.R. 1974. Urea excretion in the pig: an indicator of protein quality and amino acid requirements. J. Nutr., 104: 542-545. https://doi.org/10.1093/jn/104.5.542Carabaño R., de Blas J.C., García A.I. 2000. Recent advances in nitrogen nutrition in rabbits. World Rabbit Sci. 8: 14-28.Carabaño R., Piquer J., Menoyo D., Badiola I. 2010. The digestive system of the rabbit. In: de Blas C., Wiseman J. (ed). Nutrition of the Rabbit. CABI Publishing. CAB International, Wallingford, Oxon, UK, 1-18. https://doi.org/10.1079/9781845936693.0001Carabaño R., Villamide M.J., García J., Nicodemus N., Llorente A., Chamorro S., Menoyo D., García-Rebollar P., García-Ruiz A.I., De Blas, J.C. 2009. New concepts and objectives for proteinamino acid nutrition in rabbits. A review. World Rabbit Sci., 17: 1-14. https://doi.org/10.4995/wrs.2009.664Cartuche L., Pascual M., Gómez E.A., Blasco A. 2014. Economic weights in rabbit meat production. World Rabbit Sci., 22: 165-177. https://doi.org/10.4995/wrs.2014.1747Coma J., Carrion D., Zimmerman D.R. 1995. Use of plasma urea nitrogen as a rapid response criterion to determine the lysine requirement of pigs. J. Anim. Sci., 73: 472-481. https://doi.org/10.2527/1995.732472xComa J., Zimmerman D.R., Carrion D. 1996. Lysine requirement of the lactating sow determined by using plasma urea nitrogen as a rapid response criterion. J. Anim. Sci., 74: 1056-1062. https://doi.org/10.2527/1996.7451056xde Blas J.C., Gonzalez-Mateos G. 2010. Feed Formulation. In: de Blas C., Wiseman J. (ed). Nutrition of the Rabbit. second ed. CABI International. Wallingford, 222-232. https://doi.org/10.1079/9781845936693.0222de Blas C., Taboada E., Nicodemus N., Campos R., Piquer J., Méndez J. 1998. Performance response of lactating and growing rabbits to dietary threonine content. Anim. Feed Sci. Technol., 70: 151-160. https://doi.org/10.1016/S0377-8401(97)00063-1Donsbough A.L., Powell S., Waguespack A., Bidner T.D., Southern 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. Poult. Sci. 89: 287-294. https://doi.org/10.3382/ps.2009-00401Eggum B.O. 1970. Blood urea measurement as a technique for assessing protein quality. Br. J. Nutr., 24: 983-988. https://doi.org/10.1079/BJN19700101Feki S., Baselga M., Blas E., Cervera C., Gomez E.A. 1996. Comparison of growth and feed efficiency among rabbit lines selected for different objectives. Livest. Prod. Sci., 45: 87-92. https://doi.org/10.1016/0301-6226(95)00081-XForbes J.M. 2007. Voluntary Food Intake and Diet Selection. In: Farm Animals. CAB International, Wallingford, U.K, 226-246. https://doi.org/10.1079/9781845932794.0000Gidenne T., Lebas F., Fortun-Lamothe L. 2010. Feeding behaviour of rabbits. In: de Blas C., Wiseman J. (ed). Nutrition of the Rabbit. CABI International, Wallingford, 233-252. https://doi.org/10.1079/9781845936693.0233Gidenne T., Garreau H., Drouilhet L., Aubert C., Maertens L. 2017. Improving feed efficiency in rabbit production, a review on nutritional, technico-economical, genetic and environmental aspects. Anim. Feed Sci. Technol., 225: 109-122. https://doi.org/10.1016/j.anifeedsci.2017.01.016Hirakawa H. 2001. Coprophagy in leporids and other mammalian herbivores. Mam. Rev., 31: 61-80. https://doi.org/10.1046/j.1365-2907.2001.00079.xMaertens L., Cavani C., Petracci, 2010. Nitrogen and phosphorus excretion on commercial rabbit farms: calculations based on the input-output balance. World Rabbit Sci., 13: 3-16. https://doi.org/10.4995/wrs.2005.533Maertens L. 2009. Possibilities to reduce the feed conversion in rabbit production. In Proc.: Giornate di Coniglicoltura. Associazione Scientifica Italiana di Coniglicoltura. Forli. Italy. 1: 1-10.Marín-García P.J., Ródenas L., Martínez-Paredes E.M., Cambra-López M., Blas E., Pascual J.J. 2019. A moderate protein diet does not cover the requirements of growing rabbits with high growth rate. Anim. Feed Sci. Technol., 264: 114495. https://doi.org/10.1016/j.anifeedsci.2020.114495Marín-García P.J., Blas E., Cervera C., Pascual J.J. 2016. A deficient protein supply could be affecting selection for growth rate in rabbits. In. Proc., 68th Book of Abstracts of Annual Meeting of the European Federation of Animal Science. Belfast, UK, 1: 489.Mertens D.R. 2002. Gravimetric determination of amylase-treated neutral detergent fibre in feeds with refluxing beakers or crucibles: collaborative study. J. AOAC Int., 85: 1217-1240.Nicodemus N., Mateos J., de Blas C., 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. Anim. Sci., 69: 167-170. https://doi.org/10.1017/S1357729800051201Prud'hon M., Chérubin M., Goussopoulos J., Carles Y. 1975. Évolution, au cours de la croissance, des caractéristiques de la consommation d'aliments solide et liquide du lapin domestique nourri ad libitum. Ann. Zootec., 24: 289-298. https://doi.org/10.1051/animres:19750212Romero C., Nicodemus N., García-Rebollar P., García-Ruiz A.I., Ibáñez M.A., de Blas J.C. 2009. Dietary level of fibre and age at weaning affect the proliferation of Clostridium perfringens in the caecum, the incidence of epizootic rabbit enteropathy and the performance of fattening rabbits. Anim. Feed Sci. Technol., 153: 131-140. https://doi.org/10.1016/j.anifeedsci.2009.05.005Roth-Maier D.A., Ott H., Roth F.X., Paulicks B.R. 2003. Effects of the level of dietary valine supply on amino acids and urea concentration in milk and blood plasma of lactating sows. J. Anim. Physiol. Anim. Nutr., 88: 39-45. https://doi.org/10.1046/j.0931-2439.2003.00458.xSAS. 2009. SAS/STAT ® 9.2 User's guide. SAS Inst. Inc., Cary NC, USA.Schneider J.D., Nelssen J.L., Tokach M.D., Dritz S.S., Goodband R.D., DeRouchey J.M. 2006. Determining the total sulfur amino acid to lysine requirement of the lactating sow. 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Technol. 182: 100-110. https://doi.org/10.1016/j.anifeedsci.2013.04.00

A moderate protein diet does not cover the requirements of growing rabbits with high growth rate

[EN] Genetic selection for feed efficiency has increased the growth rate and requirements of growing rabbits, while the protein content of commercial feeds has been adjusted to avoid digestive disorders. The aim of this work was to evaluate how a diet with moderate levels of protein content [146 g crude protein (CP)/kg] could be affecting protein and amino acids acquisition depending on the growth rate of the animals. From 189 weaned rabbits (28 days old), only 41 animals were selected at 42 days, in order to ensure the greatest variability for growth rate during fattening. To achieve this goal, animals came from three genetic lines: H and LP (maternal lines selected by litter size) and R (paternal line selected for growth rate), characterised by normal, moderate and high growth rate during the fattening period, respectively. Apparent faecal digestibility of dry matter (DM), CP and gross energy (GE) of the diet from 49-53 days of age, as well as the ileal apparent digestibility of DM, CP and amino acids at 63 days of age, was determined in all the selected animals. Protein, energy and amino acids retained in the empty body during the fattening period were also determined by slaughtering 15 weaning rabbits at 28 days, and the 41 selected animals at 63 days of age. Animals from the R line showed higher feed intake than those from maternal lines, as well as lower feed conversion ratio, even below that expected from their growth rate. Apparent faecal digestibility of GE and apparent ileal digestibility of DM, CP and cystine of the diet were higher in LP than in H rabbits (P < 0.05), showing intermediate values in R rabbits. However, apparent ileal digestibility of glutamic acid and glycine was significantly higher in R than in H rabbits (P < 0.05), showing intermediate values in LP rabbits. As expected, both daily protein and energy retained in the empty body increased as growth increased. However, R growing rabbits seem to have lower protein retained and higher energy retained in the empty body than that expected from their growth. In fact, protein to energy retained ratio was clearly lower for R growing rabbits. These results seem to show the possible existence of some limiting amino acid when current moderate protein diets are used in growing rabbits with high growth rates, recommending a review of the amino acid requirements for the growing rabbits from paternal lines.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.; Ródenas Martínez, L.; Martinez-Paredes, E.; Cambra López, M.; Blas Ferrer, E.; Pascual Amorós, JJ. (2020). A moderate protein diet does not cover the requirements of growing rabbits with high growth rate. Animal Feed Science and Technology. 264:1-11. https://doi.org/10.1016/j.anifeedsci.2020.114495S111264Alagón, G., Arce, O. N., Martínez-Paredes, E., Ródenas, L., Moya, V. J., Blas, E., … Pascual, J. J. (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. doi:10.1016/j.anifeedsci.2016.10.024Batey, I. L. (1982). Starch Analysis Using Thermostable alpha-Amylases. Starch - Stärke, 34(4), 125-128. doi:10.1002/star.19820340407Birolo, M., Trocino, A., Zuffellato, A., & Xiccato, G. (2016). Effect of feed restriction programs and slaughter age on digestive efficiency, growth performance and body composition of growing rabbits. Animal Feed Science and Technology, 222, 194-203. doi:10.1016/j.anifeedsci.2016.10.014Cartuche, L., Pascual, M., Gómez, E. A., & Blasco, A. (2014). Economic weights in rabbit meat production. World Rabbit Science, 22(3), 165. doi:10.4995/wrs.2014.1747Cifre, 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.xCosta, 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.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:10.1186/1297-9686-24-6-527García-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.2014.07.005Gidenne, T., & Perez, J.-M. (2000). Replacement of digestible fibre by starch in the diet of the growing rabbit. I. Effects on digestion, rate of passage and retention of nutrients. Annales de Zootechnie, 49(4), 357-368. doi:10.1051/animres:2000127Lv, J.-M., Chen, M., Qian, L.-C., Ying, H.-Z., & Liu, J.-X. (2009). Requirement of crude protein for maintenance in a new strain of laboratory rabbit. Animal Feed Science and Technology, 151(3-4), 261-267. doi:10.1016/j.anifeedsci.2009.01.001Mínguez, C., Sanchez, J. P., EL Nagar, A. G., Ragab, M., & Baselga, M. (2015). Growth traits of four maternal lines of rabbits founded on different criteria: comparisons at foundation and at last periods after selection. Journal of Animal Breeding and Genetics, 133(4), 303-315. doi:10.1111/jbg.12197Partridge, G. G., Garthwaite, P. H., & Findlay, M. (1989). Protein and energy retention by growing rabbits offered diets with increasing proportions of fibre. The Journal of Agricultural Science, 112(2), 171-178. doi:10.1017/s0021859600085063Pascual, 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.2007.04.009Pascual, 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.2008-0976Quevedo, 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/asc200688Sánchez, 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.2007-0217Savietto, 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.2012.1152Savietto, 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/s1751731113002437Trocino, A., García Alonso, J., Carabaño, R., & Xiccato, G. (2013). A meta-analysis on the role of soluble fibre in diets for growing rabbits. World Rabbit Science, 21(1). doi:10.4995/wrs.2013.1285Van Soest, P. J., Robertson, J. B., & Lewis, B. A. (1991). Methods for Dietary Fiber, Neutral Detergent Fiber, and Nonstarch Polysaccharides in Relation to Animal Nutrition. Journal of Dairy Science, 74(10), 3583-3597. doi:10.3168/jds.s0022-0302(91)78551-

Growth performance of three paternal rabbit lines with different potential for growth rate and resilience

[EN] This experiment aimed to compare the growth performance, digestive efficiency and health status of three paternal lines for growing rabbits. The R line was selected by growth rate during the growing period for 37 generations; the RF line was founded by selecting a population of elite R animals (average daily gain>60 g/d); and the RFLP line was founded by backcrossing males from the RF line with females from the LP maternal line. A total of 387 weaned rabbits were used to evaluate growing performance from weaning until 63 d of age in individual cages, in three batches. Additionally, 33 animals were used to determine nutrient digestive efficiency in a digestibility trial. Body weight and feed intake were controlled at weaning (28 d), 46 and 63 d of age. Mortality and morbidity were also monitored daily. During the digestibility trial, feed intake and faeces excretion were controlled daily. Results showed no significant effects of genetic type on body weight, daily feed intake and feed conversion ratio throughout the experiment. However, RF animals had a higher average daily gain from 28 to 46 d of age (+4.4%; P<0.05) compared with R animals, but lower from 46 to 63 d of age (–4.3%; P<0.05). Regarding digestive efficiency, RF and RFLP lines showed slightly higher faecal digestibility for dry matter and gross energy of the diet compared with the R line (+1.3 percentage points; P<0.05). Mortality was higher in animals from R and RF lines compared with RFLP (on av. 25.40 vs. 14.06%; P<0.05). Our results suggest that the RFLP genetic line could be a suitable alternative to the R line, as it shows a similar growth performance but a lower incidence of digestive disorders.This study was funded by the Ministry of Science, Innovation and Universities of the Government of Spain (AGL2017-85162-C2-1-R) and the General Direction of Science and Research of the Generalitat Valenciana (AICO/2012/256). The grantfor Catarina Peixoto Gonçalves is also gratefully acknowledged (GRISOLIAP/2019/149; from the General Direction of Science andResearch of the Generalitat Valenciana).Peixoto-Gonçalves, C.; Martínez-Paredes, E.; Ródenas, L.; Corpa, JM.; Blas, E.; Cambra-López, M.; Pascual, JJ. (2023). Growth performance of three paternal rabbit lines with different potential for growth rate and resilience. World Rabbit Science. 31(4):221-228. https://doi.org/10.4995/wrs.2023.1984122122831

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). 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