Effect of level of dietary soluble fibre and threonine on digestion and growth performance in post-weaning rabbits

The aim of this work was to study the effect of soluble fibre and threonine deficiency on digestion and performance after weaning in rabbits. Four diets in a 2 x 2 factorial arrangement were used with two level of soluble fibre (89 vs.119 g/kg) and two level of threonine (5 vs. 6.4 g/kg). Two experiments were conducted with rabbits weaned at 25 (35/diet) and 35 (32/diet) d of age to determine apparent ileal (at 35 and 46 d) and faecal digestibility, intestinal mucin concentration, mucosa morphology and growth traits. The increase of soluble fibre improved intestinal mucosa integrity and mucin secretion leading to a better health status of the rabbits when the sanitary conditions worsened. Mucosa barrier traits were not affected by dietary threonine level although in poor sanitary conditions a low threonine level impaired rabbit health suggesting a limiting status of this amino acid

Quantification of soluble fibre in feedstuffs for rabbits and evaluation of the interference between the determinations of soluble fibre and intestinal mucin.

This work compared the quantification of soluble fibre in feeds using different chemical and in vitro approaches, and studied the potential interference between soluble fibre and mucin determinations. Six ingredients: sugar beet pulp (SBP), SBP pectins, insoluble SBP, wheat straw, sunflower hulls and lignocellulose, and seven rabbit diets, differing in soluble fibre content, were evaluated. In experiment 1, ingredients and diets were analyzed for total dietary fibre (TDF), insoluble dietary fibre (IDF), soluble dietary fibre (SDF), aNDFom (corrected for protein, aNDFom-cp) and 2-step pepsin/pancreatin in vitro DM indigestibility (corrected for ash and protein, ivDMi2). Soluble fibre was estimated by difference using three procedures: TDF?IDF (SDFIDF), TDF?ivDMi2 (SDFivDMi2), and TDF?aNDFom-cp (SDFaNDFom-cp). Soluble fibre determined directly (SDF) or by difference as SDFivDMi2 were not different (109 g/kg DM, on average). However, when it was calculated as SDFaNDFom-cp the value was 40% higher (153 g/kg DM, P menor que 0.05), whereas SDFIDF (124 g/kg DM) did not differ from any of the other methods. The correlation between the four methods was high (r ? 0.96; P ? 0.001; n = 13), but it decreased or even disappeared when SBP pectins and SBP were excluded and a lower and more narrow range of variation of soluble fibre was used. In experiment 2, the ivDMi2 using crucibles (reference method) were compared to those made using individual or collective ankom bags in order to simplify the determination of SDFivDMi2. The ivDMi2 was not different when using crucibles or individual or collective ankom bags. In experiment 3, the potential interference between soluble fibre and intestinal mucin determinations was studied using rabbit intestinal raw mucus, digesta and SBP pectins, lignocelluloses and a rabbit diet. An interference was observed between the determinations of soluble fibre and crude mucin, as contents of TDF and apparent crude mucin were high in SBP pectins (994 and 709 g/kg DM) and rabbit intestinal raw mucus (571 and 739 g/kg DM). After a pectinase treatment, the coefficient of apparent mucin recovery of SBP pectins was close to zero, whereas that of rabbit mucus was not modified. An estimation of the crude mucin carbohydrates retained in digesta TDF is proposed to correct TDF and soluble fibre digestibility. In conclusion, the values of soluble fibre depend on the methodology used. The contamination of crude mucin with soluble fibre is avoided using pectinase

Effect of supplementation with β-glucan of Saccharomyces cerevisiae and chito-oligosaccharides on digestion and growth performance in weanling rabbits

The aim of this work was to study the effect of yeast β-glucans and chito-oligosaccharides supplementation on digestion and growth performance of growing rabbits. Five experimental diets were prepared. A control diet was formulated with 18.1% protein, 33.1% neutral detergent fibre and 13% soluble fibre (on DM basis). Another four diets were obtained by supplementing control diet with β-glucans (200 or 400 ppm. BG2 and BG4) and chito-oligosaccharides (200 or 400 ppm. OT2 and OT4). No antibiotic was used. In the first experiment, 56 rabbits / treatment weighing 510 ± 73.0g weaned at 28 d of age were used to record mortality, and in 42 rabbits / treatment growth traits were recorded. Rabbits fed control, BG4 and OT4 diets (42/treatment), were used to determine the body composition by bioelectrical impedance technique measured at 28, 38 and 63 d of age. Experimental diets were offered from weaning up to 38 d of age. At this moment all rabbits were fed the control diet up to 63 d of age. Another group of 24 rabbits / treatment received from 28 to 38 d of age the five diets containing mordanced ytterbium. They were slaughtered at 38 d of age and ileal digesta collected to quantify ileal digestibility and caecal pH recorded. Faecal digestibility was measured from 36 to 38 d of age (9rabbits/diet). In the second experiment, three hundred thirty-four rabbits were separated from their mothers at 19 d of age (329 ± 65g) and assigned to the control, BG4 and OT4 diets. Rabbits suckled every morning for 10 minutes until 28 d of age. After weaning at 28 d of age, two hundred thirty-one rabbits received the same experimental diets than in the first period (77 rabbits per diet) and were caged individually to determine growth performance. At 19 d of age, 10 rabbits from 10 different litters were slaughtered to determine the digestive parameters (relative weight of total digestive tract, stomach and caecum ).At 27 and 38 d of age 30 rabbits(3 rabbits/treatment and litter) from each of the same 10 litters which have been chosen before (at 19 d of age) were slaughtered to determine the same measurements. Diet supplementation with β-glucans and chito-oligosaccharides did not affect ileal and faecal DM digestibility and faecal digestibility of fat, protein and fibre. Similarly, no treatment effect was found on growth traits along fattening period in the two experiments. In the first experiment, the mortality increased in rabbits supplemented with 200 ppm β-glucans compared to 400 ppm β-glucans (P = 0.048).In the second experiment, the mortality rates were lower than in the first one, and there were no other effect of treatments. The type of diet did not modify the retention and efficiency of both nitrogen and energy in the whole animal or in the carcass. However, rabbits fed supplemented diets with chito-oligosacchharides showed a higher faecal excretion of nitrogen (P=0.034) and energy (P=0.076) between 28 and 38d of age. Treatments had no effect on the relative weight of digestive organs. In conclusion, in our condition the supplementation of β-glucans and chito-oligosaccharides does not provide any advantage to growing rabbits

Efecto de las fracciones soluble en insoluble de la fibra de la pulpa de manzana sobre la digestibilidadi ileal y fecal en conejos

El objetivo del presente trabajo fue estudiar el efecto de la fibra soluble e insoluble de pulpa de manzana sobre la digestibilidad ileal y fecal en conejos. Se formularon cuatro piensos con niveles similares de fibra insoluble (FND 32,4%) y proteína (18,6%, ambos sobre MS). El nivel de fibra soluble fue bajo en el pienso control (4,6%, su fibra procedió de cascarilla de avena y paja) y aumentó en los piensos con pulpa de manzana depectinizada (7,1%), pulpa de manzana (9,3%) y pectinas de manzana (10,5%). Se determinó la digestibilidad fecal en 23 gazapos/pienso entre los 55 y los 59 d de edad, y se sacrificaron 23 gazapos/pienso a los 60 d de edad para proteger la digesta ileal y determinar la digestibilidad ileal

Influence of inoculum type (ileal, caecal and faecal) on the in vitro fermentation of different sources of carbohydrates in rabbits

[EN] Two in vitro experiments were performed to analyse the fermentative potential of ileal content, caecal content, soft faeces and hard faeces from adult rabbits. Experiment 1 evaluated 3 doses (0.5, 1.0 and 2.0 g fresh digesta/g substrate dry matter [DM]) of ileal and caecal digesta as inoculum in 28 h-incubations. Two ileal and 2 caecal inocula were obtained, each by pooling the ileal or caecal digesta of 2 adult rabbits. Pectin from sugar beet pulp (SBP) and the insoluble residue obtained after a 2-step in vitro pre-digestion of SBP and wheat straw were used as substrates. The 0.5 dose produced the lowest (P0.05) between the 1.0 and 2.0 doses (44.9, 51.6 and 53.8 mL/g substrate DM, respectively; values averaged across inocula and substrates). Experiment 2 evaluated two doses of ileal inoculum (1 and 1.5 g fresh digesta/g substrate DM) and compared ileal digesta, caecal digesta, soft faeces and hard faeces as inoculum for determining in vitro gas production (144-h incubations) of the 3 substrates used in Experiment 1 and wheat starch. Three inocula of each type were obtained, each by pooling either digesta or faeces from 3 rabbits. There were no differences (P>0.05) between the 2 ileal doses tested in gas production parameters, and therefore the 1.0 dose was selected for further ileal fermentations. Starch and pectin showed similar (P>0.05) values of gas production rate and maximal gas production rate when they were fermented with caecal digesta (0.038 vs. 0.043%/h, and 13.7 vs. 15.2 mL/h, respectively), soft (0.022 vs. 0.031%/h, and 9.97 vs. 9.33 mL/h) and hard faeces (0.031 vs. 0.038%/h, and 13.6 vs. 10.8 mL/h), and values were higher than those for SBP and wheat straw; in contrast, values for starch and pectin differed with the ileal inoculum (0.046 vs. 0.024%/h, and 18.4 vs. 6.60 mL/h). Both ileal and caecal gas production parameters were well correlated with those for hard and soft faeces inocula, respectively (r≥0.77; P≤0.040). The ileal inoculum showed a relevant fermentative potential, but lower than that of caecal digesta and soft and hard faeces for all substrates except wheat starch.Funding from the Spanish Ministry of Economy and Competitiveness (Project AGL2011-22628) and the Comunidad Autónoma de Madrid (CAM; Project MEDGAN ABI-2913) is gratefully acknowledged.Abad-Guamán, R.; Larrea-Dávalos, JA.; Carabaño, R.; García, J.; Carro, MD. (2018). Influence of inoculum type (ileal, caecal and faecal) on the in vitro fermentation of different sources of carbohydrates in rabbits. World Rabbit Science. 26(3):227-240. https://doi.org/10.4995/wrs.2018.9726SWORD227240263Abad R., Ibañez M.A., Carabaño R., García J. 2013. Quantification of soluble fibre in feedstuffs for rabbits and evaluation of the interference between the determinations of soluble fibre and intestinal mucin. Anim. Feed Sci. Tech., 182: 61-70. https://doi.org/10.1016/j.anifeedsci.2013.04.001Abad-Guamán R., Carabaño R., Gómez-Conde M.S., García J. 2015. Effect of type of fiber, site of fermentation, and method of analysis on digestibility of soluble and insoluble fiber in rabbits. J. Anim. Sci., 93: 2860-2871. https://doi.org/10.2527/jas.2014-8767Association of Official Analytical Chemists International. 2000. Official Methods of Analysis 17th ed. AOAC International, Washington, DC.Bindelle J., Buldgen A., Lambotte D., Wavreille J., Leterme P. 2007. Effect of pig faecal donor and of pig diet composition on in vitro fermentation of sugar beet pulp. Anim. Feed Sci. Technol., 132: 212-226. https://doi.org/10.1016/j.anifeedsci.2006.03.010Boletín Oficial del Estado (BOE). 2013. Royal Decree 53/2013 of February 1st on the protection of animals used for experimentation or other scientific purposes. BOE nº 34, 11370-11421. https://www.boe.es/boe/dias/2013/02/08/pdfs/BOE-A-2013-1337.pdf Accessed January 2017. In Spanish.Bovera F., Calabro S., Cutrignelli M.I., Infascelli F., Piccolo G., Nizza S., Tudisco R., Nizza A. 2008. Prediction of rabbit caecal fermentation characteristics from faeces by in vitro gas production technique: roughages. J. Anim. Physiol. Anim. Nutr., 92: 260-271. https://doi.org/10.1111/j.1439-0396.2007.00748.xBovera F., D'Urso S., Di Meo C., Piccolo G., Calabro S., Nizza A. 2006. Comparison of rabbit caecal content and rabbit hard faeces as source of inoculum for the in vitro gas production technique. Asian Austral. J. Anim. Sci., 19: 1649-1657. https://doi.org/10.5713/ajas.2006.1649Bovera F., D'Urso S., Meo C.D., Tudisco R., Nizza A. 2009. A model to assess the use of caecal and faecal inocula to study fermentability of nutrients in rabbit. J. Anim. Physiol. Anim. Nutr., 93: 147-156. https://doi.org/10.1111/j.1439-0396.2007.00795.xCalabrò S., Nizza A., Pinna W., Cutrignelli M., Piccolo V. 1999. Estimation of digestibility of compound diets for rabbits using the in vitro gas production technique. World Rabbit Sci., 7: 197-201. https://doi.org/10.4995/wrs.1999.401Carabaño R., Fraga M.J., Santoma G., de Blas C. 1988. Effect of diet on composition of cecal contents and on excretion and composition of soft and hard feces of rabbits. J. Anim. Sci 66: 901-1000. https://doi.org/10.2527/jas1988.664901xCarabaño R., García J., de Blas J.C. 2001. Effect of fibre source on ileal apparent digestibility of non-starch polysaccharides in rabbits. Anim. Sci., 72: 343-350. https://doi.org/10.1017/S1357729800055843Falcão-e-Cunha L., Peres H., Freire J.P.B., Castro-Solla L. 2004. Effects of alfalfa, wheat bran or beet pulp, with or without sunflower oil, on caecal fermentation and on digestibility in the rabbit. Anim. Feed Sci. Technol., 117: 131-149. https://doi.org/10.1016/j.anifeedsci.2004.07.014García J., Carabaño R., de Blas J.C. 1999. Effect of fiber source on cell wall digestibility and rate of passage in rabbits. J. Anim. Sci., 77: 898-905. https://doi.org/10.2527/1999.774898xGarcía J., Carabaño R., Pérez-Alba L., de Blas J.C. 2000. Effect of fiber source on cecal fermentation and nitrogen recycled through cecotrophy in rabbits. J. Anim. Sci., 78: 638-646. https://doi.org/10.2527/2000.783638xGarcía J., Gidenne T., Falcão-e-Cunha L., de Blas C. 2002. Identification of the main factors that influence caecal fermentation traits in growing rabbits. Anim. Res. 51: 165-173. https://doi.org/10.1051/animres:2002011Gidenne T. 1992. Effect of fiber level, particle-size and adaptation period on digestibility and rate of passage as measured at the ileum and in the feces in the adult-rabbit. Brit. J. Nutr., 67: 133-146. https://doi.org/10.1079/BJN19920015Gidenne T. 1994. Effect of a reduction in fiber content on the rate of passage through the digestive-tract of the rabbit-comparison of models for the fecal kinetics of 2 markers. Reprod. Nutr. Dev., 34: 295-307. https://doi.org/10.1051/rnd:19940403Goering H.K., Van Soest P.J. 1970. Forage Fiber Analysis (Apparatus, Reagents, Procedures, and Some Applications). USDA Agricultural Research Service, Handbook, Washington, DC.Gouet P., Fonty G. 1979. Changes in the digestive microflora of holoxenic rabbits from birth until adulthood. Ann. Biol Anim. Bioch., 19: 553-566. https://doi.org/10.1051/rnd:19790501Littell R.C., Henry P.R., Ammerman C.B. 1998. Statistical analysis of repeated measures data using SAS procedures. J. Anim. Sci., 76: 1216-1231. https://doi.org/10.2527/1998.7641216xMarounek M., Vovk S.J., Skrivanova V. 1995. Distribution of activity of hydrolytic enzymes in the digestive-tract of rabbits. Brit. J. Nutr., 73: 463-469. https://doi.org/10.1079/BJN19950048Menke K.H., Raab L., Salewski A., Steingass H., Fritz D., Schneider W. 1979. The estimation of the digestibility and metabolizable energy of ruminant feedingstuff from the gas production when they are incubated with rumen liquor in vitro. J. Agr. Sci., 93: 217-222. https://doi.org/10.1017/S0021859600086305Mertens D.R., Allen M., Carmany J., Clegg J., Davidowicz A., Drouches M., Frank K., Gambin D., Garkie M., Gildemeister B., Jeffress D., Jeon C.S., Jones D., Kaplan D., Kim G.N., Kobata S., Main D., Moua X., Paul B., Robertson J., Taysom D., Thiex N., Williams J., Wolf M. 2002. Gravimetric determination of amylase-treated neutral detergent fiber in feeds with refluxing in beakers or crucibles: Collaborative study. J. AOAC Int., 85:1217-1240.Mould F.L., Kliem K.E., Morgan R., Mauricio R.M. 2005. In vitro microbial inoculum: A review of its function and properties. Anim. Feed Sci. Tech., 123: 31-50. https://doi.org/10.1016/j.anifeedsci.2005.04.028Murray S.M., Flickinger E.A., Patil A.R., Merchen N.R., Brent J.L., Fahey G.C. 2001. In vitro fermentation characteristics of native and processed cereal grains and potato starch using ileal chyme from dogs. J. Anim. Sci., 79: 435-444. https://doi.org/10.2527/2001.792435xOmed H.M., Lovett D.K., Axford R.F.E. 2000. Faeces as a source of microbial enzymes for estimating digestibility, In: Givens D., Owen E., Axford R., Omed H. (Eds.), Forage Evaluation in Ruminant Nutrition, CAB International, UK, pp. 135-154. https://doi.org/10.1079/9780851993447.0135Padilha M.T.S., Licois D., Gidenne T., Carre B., Fonty G. 1995. Relationships between microflora and caecal fermentation in rabbits before and after weaning. Reprod. Nutr. Dev., 35: 375-386. https://doi.org/10.1051/rnd:19950403Pascual J.J., Cervera C., Fernández-Carmona J. 2000. Comparison of different in vitro digestibility methods for nutritive evaluation of rabbit diets. World Rabbit Sci., 8: 93-97. https://doi.org/10.4995/wrs.2000.425Penney R.L., Folk G.E., Galask R.P., Petzold C.R. 1986. The microflora of the alimentary tract of rabbits in relation to pH, diet and cold. J. Appl. Rabbit Res., 9: 152-156.Piattoni F., Demeyer D., Maertens L., 1997. Fasting effects on in vitro fermentation pattern of rabbit caecal contents. World Rabbit Sci., 5: 23-26. https://doi.org/10.4995/wrs.1997.314Rodríguez-Romero N., Abecia L., Fondevila M., Balcells J. 2011. Effects of levels of insoluble and soluble fibre in diets for growing rabbits on faecal digestibility, nitrogen recycling and in vitro fermentation. World Rabbit Sci., 19: 85-94. https://doi.org/10.4995/wrs.2011.828SAS Institute Inc. 2011. Base SAS® 9.3 Procedures Guide. SAS Institute Inc. Cary, NC, USA.Schofield P., Pitt R.E., Pell A.N. 1994. Kinetics of fiber digestion from in-vitro gas-production. J. Anim. Sci., 72: 2980-2991. https://doi.org/10.2527/1994.72112980xTagliapietra F., Williams B.A., Awati A., Bonsembiante M., Schiavon S., Verstegen M.W.A. 2003. In vitro degradation kinetics of four carbohydrates using ileal and faecal inocula from suckling piglets. Ital. J. Anim. Sci., 2: 195-197.Trocino A., García J., Carabaño R., Xiccato, G. 2013. A meta-analysis on the role of soluble fibre in diets for growing rabbits. World Rabbit Sci., 21: 1-15. https://doi.org/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. J. Dairy Sci., 74: 3583-3597. https://doi.org/10.3168/jds.S0022-0302(91)78551-2Wang D., Williams B.A., Ferruzzi M.G., D'Arcy B.R. 2013. Different concentrations of grape seed extract affect in vitro starch fermentation by porcine small and large intestinal inocula. J. Sci. Food Agr., 93: 276-283. https://doi.org/10.1002/jsfa.5753Williams B.A., Bhatia S.K., Boer H., Tamminga S. 1995. A preliminary study using the cumulative gas production technique to compare the kinetics of different fermentations by use of standard substrates. Ann. Zootech., 44: 35. https://doi.org/10.1051/animres:19950505Williams B.A., Bosch M.W., Awati A., Konstantinov S.R., Smidt H., Akkermans A.D.L., Verstegen M.W.A., Tamminga S. 2005. In vitro assessment of gastrointestinal tract (GIT) fermentation in pigs: Fermentable substrates and microbial activity. Anim. Res., 54: 191-201. https://doi.org/10.1051/animres:2005011Williams B.A., Verstegen M.W., Tamminga S. 2001. Fermentation in the large intestine of single-stomached animals and its relationship to animal health. Nutr. Res. Rev., 14: 207-228. https://doi.org/10.1079/NRR20012

Efecto de la suplementación con arginina y glutamina sobre la digestiblidad ileal y fecal de gazapos tras el destete

Se estudió el efecto de la suplementación con arginina y glutamina así como su posible interacción sobre la digestibilidad ileal y fecal de los nutrientes en gazapos tras el destete. Para ello se formuló una dieta basal (C) y se fabricaron otros 3 piensos añadiendo un 0,4% de arginina (ARG), un 0,4% de glutamina (GLN) y una mezcla de un 0,4% de arginina y un 0,4% de glutamina (ARG+GLN) a la ración basal. Se observó una interacción ARG×GLN en la digestibilidad fecal de la EB y el N (P = 0,008 y P = 0,001 respectivamente). La suplementación con ARG o GLN mejoró la digestibilidad de estos componentes en comparación con el pienso control, si bien cuando el pienso estuvo suplementado con ambos aminoácidos ARG+GLN mostró valores intermedios entre el grupo control y los suplementados con ARG o GLN (P < 0,001). La digestibilidad fecal de la FND fue superior en los piensos suplementados con GLN (P < 0,001). Los tratamientos no modificaron la digestibilidad ileal de la MS ni del N (P ≥ 0,44). La suplementación con glutamina tendió a incrementar la digestibilidad ileal del ácido glutámico (P = 0,099) respecto a los gazapos no suplementados, mientras que no afectó a la digestibilidad ileal de los demás aminoácidos (P ≥ 0,13). La suplementación con arginina + glutamina aumentó o tendió a aumentar la digestibilidad ileal aparente de la mayor parte de los aminoácidos esenciales y no esenciales de los gazapos de 35 d de edad (P < 0,096) respecto a la suplementación con glutamina

Utilización de bolsas ANKOM® en la determinación de la digestibilidad de la materia seca in vitro en conejos.

La metodología de digestibilidad in vitro de la materia seca (DMSiv) desarrollada por Ramos et al. (1992) para predecir la digestibilidad de la materia seca y valor nutricional de diferentes alimentos comúnmente utilizados en la alimentación de conejos, ha sido estandarizada y validada por diferentes laboratorios (Villamide et al. 2008 y Carabaño et al. 2008), demostrándose su fiabilidad, reproducibilidad y repetibilidad. Uno de los puntos críticos de las metodologías gravimétricas es la filtración con crisol, ya que las propiedades físicas junto con la composición química de diversas materias primas dificultan este proceso y aumentan la variabilidad en los resultados (Mertens, 2002). Por otra parte la digestión individual de las muestras limita la capacidad de análisis. Con la finalidad de corregir estas limitaciones se propuso como alternativa el uso de bolsas ANKOM ® , ya utilizadas en el análisis secuencial de Van Soest (Kenneth et al., 1999), digeridas colectivamente en un mismo recipiente. Además de la utilización de bolsas, como novedad se incluyó al final de la digestibilidad un lavado adicional de las bolsas. El objetivo de este trabajo fue determinar la validez de esta modificación en la digestibilidad in vitro ileal (dos pasos) y fecal (tres pasos

Efecto del perfil de carbohidratos del pienso sobre los rendimientos de conejas reproductoras

El objetivo del presente trabajo fin de máster fue estudiar el desarrollo productivo de las conejas reproductoras frente a la administración de dos niveles de fibra soluble a través de la inclusión de pulpa de remolacha y de dos tipos de almidón en este caso el de trigo y guisante. Para lograr este objetivo se llevaron a cabo tres objetivos principales: i) Evaluación de los parámetros productivos de las conejas durante los tres primeros ciclos reproductivos. ii) Evaluación de la digestibilidad fecal de las conejas nulíparas y lactantes. iii) Estimación de la composición química corporal de las conejas mediante técnica de impedancia bioeléctrica para analizar el balance energético y nitrogenado en cada uno de los ciclos. Para ello se formularon cuatro piensos organizados factorialmente (2 x 2), con dos niveles de fibra soluble (FS) (bajo 6,4% y alto 10,6% MS, BFS y AFS, respectivamente), combinados con dos fuentes de almidón: trigo (con harina de colza; T) y guisante (G). Así, se obtuvieron 4 piensos: 1) bajo nivel de fibra soluble y trigo como fuente de almidón (BFS-T); 2) alto nivel de fibra soluble y trigo como fuente de almidón (AFS-T); 3) bajo nivel de fibra soluble y guisante como tipo almidón (BFS-G); y, 4) alto nivel de fibra soluble y guisante como fuente de almidón (AFS-G). Los piensos tuvieron similar concentración de proteína bruta (20,3% MS) y de energía bruta (18,9 MJ/kg MS), pero diferentes niveles de almidón, tanto para el trigo (BFS: 11,6% y AFS: 17,3% MS) como guisante (BFS: 12,8 % y AFS: 17,4 %). En este estudio se utilizaron 180 conejas inseminadas a los 123 días de edad, las cuales fueron asignadas al azar a los piensos experimentales después de confirmada la gestación. Después de cada parto se llevó a cabo la homogenización de las camadas dentro de los tratamientos y las conejas fueron inseminadas 11 días después. A lo largo de los tres primeros partos se midió la composición química y el contenido de energía de las conejas: en la inseminación artificial, preparto, parto y destete (mediante impedancia bioeléctrica); además, digestibilidad, sus rendimientos productivos, mortalidad, consumo de pienso y el crecimiento de las camadas. El periodo experimental finalizo el día de parto correspondiente a la tercera inseminación. La proporción total de bajas durante el experimento casi se duplicó en los grupos que consumieron los piensos con guisante respecto a los de trigo (29,7 vs. 15,3%, P=0,032). La digestibilidad fecal de la proteína también se redujo un 4,4% al incluir guisante en lugar de trigo (P=0,002), lo que redujo el contenido en proteína digestible del pienso (P=0,011), y también se redujo al aumentar el nivel de la fibra soluble (un 3,7%; P=0,010). Estos cambios modificaron el contenido en energía digestible del pienso en conejas nulíparas, que se redujo al incluir guisante (P< 0,001). La digestibilidad fecal del almidón empeoró un 1,5% al sustituir el trigo por el guisante (P=0,046), en especial cuando el guisante se combinó con un mayor nivel de fibra soluble, lo que dio lugar a una interacción fibra soluble x tipo de almidón (P=0,044). Así, en conejas lactantes no se observó efecto de los tratamientos sobre la ingestión de MS (que fue un 74% superior al de las conejas primíparas), y digestibilidad de la energía, aunque numéricamente los valores fueron similares a los de las primíparas. El consumo de pienso en el periodo del destete al parto aumentó un 13% al sustituir el trigo (más la harina de colza) por el guisante (P=0,004). Los niveles de fibra soluble y el tipo de almidón no afectaron al número total de nacidos por camada (11,6 gazapos/camada de media; P ≥ 0,24), y a los nacidos vivos (11,2 gazapos/camada de media; P ≥ 0,31), observándose una tendencia a reducirse el número de nacidos muertos cuando el trigo se combinó con baja fibra soluble y el guisante con alta fibra soluble (P=0,078). Los niveles de fibra soluble y el tipo de almidón no modificaron la composición química de ninguno de los estados fisiológicos de las conejas durante el ensayo. El periodo entre los 28 d de gestación y el parto fue de media de 2,75 d y tendió a reducirse en las conejas alimentadas con guisante (P=0,055. En este periodo, no se observaron diferencias debidas a los tratamientos ni en el consumo de pienso, de energía digestible ni en la movilización de grasa por parte de las conejas. En definitiva, el trigo sería preferible al guisante como fuente de almidón, mientras que el incremento de fibra soluble no mejora los rendimientos productivos de las conejas.<br /

Efecto del nivel de fibra soluble y de la relación omega6 y omega3 sobre los balances de nitrógeno y energía de conejos en cebo

La inclusión de pulpa de remolacha en sustitución de cebada reduce la eficacia de retención de la energía y el rendimiento de la canal, especialmente cuando su nivel de inclusión supera el 15% (De Blas y Carabaño, 1996). Aproximadamente, este es el nivel requerido para satisfacer las recientes recomendaciones de fibra soluble (Trocino et al., 2013). Por el contrario, cuando la pulpa de remolacha sustituye al heno de alfalfa no empeora la eficacia de retención de la energía (Carabaño et al., 1997)