Effects of the comminution rate and microbial contamination of particles in the rumen on accuracy of in situ estimates of digestion of protein and amino acids of dehydrated sugar beet pulp

[EN] Effects of the correction of microbial contamination (using N-15 techniques) and of considering the comminution rate (k (c)) of particles in the rumen on effective estimates of the ruminally undegraded (RU) fraction and its intestinal effective digestibility (IED) were examined in a sample of dehydrated sugar beet pulp (DBP) generating composite samples (from rumen-incubated residues) representative of the chemical composition of RU. Tested fractions were dry matter (DM), organic matter (OM, tested only for RU), crude protein (CP) and amino acids (AA). The study was performed on three rumen and duodenum cannulated wethers fed with a 2:1 (fresh weight basis) chopped oat hay-to-concentrate diet supplied at 40g DM/kg BW0 center dot 75 in six equal meals per day. The DBP showed sigmoid degradation kinetics: the fractional degradation rate increased by 5 center dot 8 times as time (h) increased from 0 to infinity. The k (c) rate (measured in the diet concentrate) represented 5 center dot 74% of the total rumen retention time of particles. As a result, the RU of DM was over-evaluated by 6 center dot 53% when k (c) was not considered. Microbial contamination of RU was high as in DM as in CP. Therefore, the overestimation of RU of DM was increased to 12 center dot 2% when this contamination was not corrected. The lack of this correction also led to large over-evaluations of RU and IED of CP and AA. As a result, the overestimation of the intestinal digested fraction was 40 center dot 9% for CP and 45 center dot 0% for total analysed AA. This overestimation varied largely among AA (from 18 center dot 9 to 88 center dot 7%). Corrected proportions of RU and IED were also variable among AA. Hypotheses on the causes of this variability are given. Resultant changes in the AA profile of the intestinal digested protein had some negative impact on the supply of essential AA and cysteine without affecting lysine. This problem is limited because the microbial protein synthesized from DBP fermentation in the rumen is largely predominant in the AA supply to the host.This work was supported by the CICYT-funded Project AGL 2006-08300. Analyses of 15N isotope ratios were performed at the Servicio Interdepartamental de Investigacion, Universidad Autonoma de Madrid. Spain.González, J.; Arroyo, JM.; Guevara González, JA.; Moubi, R.; Piquer Querol, O.; Moya, V. (2014). Effects of the comminution rate and microbial contamination of particles in the rumen on accuracy of in situ estimates of digestion of protein and amino acids of dehydrated sugar beet pulp. Journal of Agricultural Science. 1(152):166-174. doi:10.1017/S0021859613000233S1661741152Milgen, J. V., & Baumont, R. (1995). Models based on variable fractional digestion rates to describe ruminal in situ digestion. British Journal of Nutrition, 73(6), 793-807. doi:10.1079/bjn19950085Rodríguez, C. A., González, J., Alvir, M. R., Repetto, J. L., Centeno, C., & Lamrani, F. (2000). Composition of bacteria harvested from the liquid and solid fractions of the rumen of sheep as influenced by feed intake. British Journal of Nutrition, 84(3), 369-376. doi:10.1017/s0007114500001653Rodríguez, C. A., & González, J. (2006). In situ study of the relevance of bacterial adherence to feed particles for the contamination and accuracy of rumen degradability estimates for feeds of vegetable origin. British Journal of Nutrition, 96(2), 316-325. doi:10.1079/bjn20061830Pereira, J. C., & González, J. (2004). Rumen degradability of dehydrated beet pulp and dehydrated citrus pulp. Animal Research, 53(2), 99-110. doi:10.1051/animres:2004005Mahadevan, S., Erfle, J. D., & Sauer, F. D. (1980). Degradation of Soluble and Insoluble Proteins by Bacteroides Amylophilus Protease and by Rumen Microorganisms2. Journal of Animal Science, 50(4), 723-728. doi:10.2527/jas1980.504723xLi, X., Kieliszewski, M., & Lamport, D. T. A. (1990). A Chenopod Extensin Lacks Repetitive Tetrahydroxyproline Blocks. Plant Physiology, 92(2), 327-333. doi:10.1104/pp.92.2.327Grenet, E., & Barry, P. (1990). In vivo and in sacco digestibility and rumen microbial degradation of cell walls of soyabean and rape integuments and of dehydrated beet pulp in sheep, observed by scanning electron microscopy. The Journal of Agricultural Science, 115(3), 429-435. doi:10.1017/s0021859600075882González, J., Faría-Mármol, J., Arroyo, J. M., Centeno, C., & Martínez, A. (2010). Effects of ensiling onin situruminal degradability and intestinal digestibility of corn forage. Archives of Animal Nutrition, 64(3), 204-220. doi:10.1080/17450391003691450González, J., Ouarti, M., Rodríguez, C. A., & Alvir, M. R. (2006). Effects of considering the rate of comminution of particles and microbial contamination on accuracy of in situ studies of feed protein degradability in ruminants. Animal Feed Science and Technology, 125(1-2), 89-98. doi:10.1016/j.anifeedsci.2005.05.013Arroyo, J. M., & González, J. (2011). Effects of the ruminal comminution rate and microbial contamination of particles on accuracy ofin situestimates of ruminal degradability and intestinal digestibility of feedstuffs. Journal of Animal Physiology and Animal Nutrition, 97(1), 109-118. doi:10.1111/j.1439-0396.2011.01248.xAlcaide, E. M., Garcı́a, A. I. M., & Aguilera, J. . (2000). A comparative study of nutrient digestibility, kinetics of degradation and passage and rumen fermentation pattern in goats and sheep offered good quality diets. Livestock Production Science, 64(2-3), 215-223. doi:10.1016/s0301-6226(99)00149-9Udén, P., Colucci, P. E., & Van Soest, P. J. (1980). Investigation of chromium, cerium and cobalt as markers in digesta. Rate of passage studies. Journal of the Science of Food and Agriculture, 31(7), 625-632. doi:10.1002/jsfa.2740310702Barrie, A., Brookes, S. T., Prosser, S. J., & Debney, S. (1995). High productivity analysis of15N and13C in soil/plant research. Fertilizer Research, 42(1-3), 43-59. doi:10.1007/bf00750499Van 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)78551-2Dhanoa, M. S., Siddons, R. C., France, J., & Gale, D. L. (1985). A multicompartmental model to describe marker excretion patterns in ruminant faeces. British Journal of Nutrition, 53(3), 663-671. doi:10.1079/bjn19850076Showalter, A. M. (1993). Structure and function of plant cell wall proteins. The Plant Cell, 5(1), 9-23. doi:10.1105/tpc.5.1.9BERNARD, L., MARVALIN, O., YANG, W. Z., & PONCET, C. (1988). Colonisation bactérienne de différents types d’aliments incubés in sacco dans le rumen ; conséquences pour l’estimation de la dégradabilité de l’azote. Reproduction Nutrition Développement, 28(Suppl. 1), 105-106. doi:10.1051/rnd:19881127González, J., Ouarti, M., Rodríguez, C. A., & Centeno, C. (2009). A simplified management of thein situevaluation of feedstuffs in ruminants: Application to the study of the digestive availability of protein and amino acids corrected for the ruminal microbial contamination. Archives of Animal Nutrition, 63(4), 304-320. doi:10.1080/17450390903020463Van Milgen, J., Murphy, M. R., & Berger, L. L. (1991). A Compartmental Model to Analyze Ruminal Digestion. Journal of Dairy Science, 74(8), 2515-2529. doi:10.3168/jds.s0022-0302(91)78429-

Ensiled citrus pulp as a by-product feedstuff for finishing pigs: nutritional value and effects on intestinal microflora and carcass quality

[EN] Forty pigs of 76.8 +/- 4.2 kg body weight were fed four different diets varying in ensiled citrus pulp (ECP) inclusion level (0, 50, 100, and 150 g of ECP/kg of diet on dry matter base). The trial lasted 5 weeks. During the last week, faecal samples were obtained to calculate apparent nutrient digestibility; also volatile fatty acids (VFA) content in faeces was determined. The digestible energy and protein of ECP was estimated by regression analysis. During the trial faecal samples were collected to determine enterobacteria and lactobacilli counts. At slaughter, carcass characteristics were registered. The inclusion of ECP in the diets decreased energy digestibility but increased neutral and acid detergent fibre digestibility linearly (p3.0.co;2-cIvarsson, E., Liu, H. Y., Dicksved, J., Roos, S., & Lindberg, J. E. (2012). Impact of chicory inclusion in a cereal-based diet on digestibility, organ size and faecal microbiota in growing pigs. animal, 6(7), 1077-1085. doi:10.1017/s1751731111002709Jensen BB, Jørgensen H, 1994. Effect of dietary fiber on microbial activity and microbial gas production in various regions of the gastrointestinal tract of pigs. Appl Environ Microbiol 60: 1897–1904.Jørgensen, H., Zhao, X.-Q., & Eggum, B. O. (1996). The influence of dietary fibre and environmental temoperature on the development of the gastrointestinal tract, digestibility, degree of fermentation in the hind-gut and energy metabolism in pigs. British Journal of Nutrition, 75(3), 365-378. doi:10.1079/bjn19960140Jouany JP, 1982. Volatile fatty acid and alcohol determination in digestive contents, silage juices, bacterial cultures and anaerobic fermentor contents. Sci Aliment 2: 131-144.Kayouli C, Lee S, 1998. Supplementary feeding for dairy smallholders in Pacific Island Countries: Fiji, Samoa, Vanuatu, Cook Islands, Solomon Islands and Tonga. In: Manual of smallholder milk production in the South Pacific; Lee S, Kennard R, Kayouli C, eds. FAO Sub-Regional Office for the Pacific, Apia (Samoa). pp: 67-101.Kyriazakis, I., & Emmans, G. C. (1995). The voluntary feed intake of pigs given feeds based on wheat bran, dried citrus pulp and grass meal, in relation to measurements of feed bulk. British Journal of Nutrition, 73(2), 191-207. doi:10.1079/bjn19950023Leterme, P., Londoño, A. M., Estrada, F., Souffrant, W. B., & Buldgen, A. (2005). Chemical composition, nutritive value and voluntary intake of tropical tree foliage and cocoyam in pigs. Journal of the Science of Food and Agriculture, 85(10), 1725-1732. doi:10.1002/jsfa.2177Macfarlane, G. T., Gibson, G. R., Beatty, E., & Cummings, J. H. (1992). Estimation of short-chain fatty acid production from protein by human intestinal bacteria based on branched-chain fatty acid measurements. FEMS Microbiology Letters, 101(2), 81-88. doi:10.1111/j.1574-6968.1992.tb05764.xMárquez, M. C., & Ramos, P. (2007). Effect of the inclusion of food waste in pig diets on growth performance, carcass and meat quality. animal, 1(4), 595-599. doi:10.1017/s1751731107685000Pascual, J. M., & Carmona, J. F. (1980). Composition of citrus pulp. Animal Feed Science and Technology, 5(1), 1-10. doi:10.1016/0377-8401(80)90005-xMartínez-Vallespín B, Navarrete C, Martínez-Paredes E, Ródenas L, Cervera C, Blas E, 2011. Determinación de la fibra soluble en detergente neutro: modificaciones del método original. Proc XIV Jornadas sobre Producción Animal; Sanz A et al., eds. May, Monta-ana, Zaragoza. pp: 17-18.Montagne, L., Pluske, J. ., & Hampson, D. . (2003). A review of interactions between dietary fibre and the intestinal mucosa, and their consequences on digestive health in young non-ruminant animals. Animal Feed Science and Technology, 108(1-4), 95-117. doi:10.1016/s0377-8401(03)00163-9NRC, 2012. Nutrient requirements of swine. National Research Council, Nat Acad Press, Washington DC, USA.Noblet, J., & Le Goff, G. (2001). Effect of dietary fibre on the energy value of feeds for pigs. Animal Feed Science and Technology, 90(1-2), 35-52. doi:10.1016/s0377-8401(01)00195-xO’Fallon, J. V., Busboom, J. R., Nelson, M. L., & Gaskins, C. T. (2007). A direct method for fatty acid methyl ester synthesis: Application to wet meat tissues, oils, and feedstuffs. Journal of Animal Science, 85(6), 1511-1521. doi:10.2527/jas.2006-491Oluremi, O. I. A., Okafor, F. N., Adenkola, A. Y., & Orayaga, K. T. (2010). Effect of Fermentation of Sweet Orange (Citrus sinensis) Fruit Peel on its Phytonutrients and the Performance of Broiler Starter. International Journal of Poultry Science, 9(6), 546-549. doi:10.3923/ijps.2010.546.549O'Sullivan TC, Lynch PB, Morrisey PA, O'Grady JF, 2003. Evaluation of citrus pulp in diets for sows and growing pigs. Ir J Agr Food Res 42: 243-253.Rijnen MMJA, Verstegen MWA, Heetkamp MJW, Haaksma J, Schrama JW, 2001. Effect of dietary fermentable carbohydrates on energy metabolism in group-housed sows. J Anim Sci 79: 148-154.Ruiz, U. S., Tomaz, M. C., Pascoal, L. A. F., Watanabe, P. H., Amorim, A. B., Melo, G. M. P., & Daniel, E. (2012). Nutrient digestibility of degermed, dehulled corn, citrus pulp, and soy protein concentrate by barrows. Journal of Animal Science, 90(suppl_4), 170-172. doi:10.2527/jas.53863Stein, H. H., & Shurson, G. C. (2009). BOARD-INVITED REVIEW: The use and application of distillers dried grains with solubles in swine diets. Journal of Animal Science, 87(4), 1292-1303. doi:10.2527/jas.2008-1290Van Kleef, D. J., Deuring, K., & van Leeuwen, P. (1994). Anew method of faeces collection in the pig. Laboratory Animals, 28(1), 78-79. doi:10.1258/002367794781065942Van 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)78551-2Van Winsen, R. L., Urlings, B. A. P., Lipman, L. J. A., Snijders, J. M. A., Keuzenkamp, D., Verheijden, J. H. M., & van Knapen, F. (2001). Effect of Fermented Feed on the Microbial Population of the Gastrointestinal Tracts of Pigs. Applied and Environmental Microbiology, 67(7), 3071-3076. doi:10.1128/aem.67.7.3071-3076.2001Villamide, M. J., Garcı́a, J., Cervera, C., Blas, E., Maertens, L., & Perez, J. M. (2003). Comparison among methods of nutritional evaluation of dietary ingredients for rabbits. Animal Feed Science and Technology, 109(1-4), 195-207. doi:10.1016/s0377-8401(03)00177-9Watanabe, P. H., Thomaz, M. C., Ruiz, U. dos S., Santos, V. M. dos, Fraga, A. L., Pascoal, L. A. F., … Faria, H. G. de. (2010). Effect of inclusion of citrus pulp in the diet of finishing swines. Brazilian Archives of Biology and Technology, 53(3), 709-718. doi:10.1590/s1516-89132010000300028Watanabe, P. H., Thomaz, M. C., Ruiz, U. S., Santos, V. M., Masson, G. C. I., Fraga, A. L., … Silva, S. Z. (2010). Carcass characteristics and meat quality of heavy swine fed different citrus pulp levels. Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 62(4), 921-929. doi:10.1590/s0102-09352010000400023Williams, B. A., Verstegen, M. W. A., & Tamminga, S. (2001). Fermentation in the large intestine of single-stomached animals and its relationship to animal health. Nutrition Research Reviews, 14(02), 207. doi:10.1079/nrr200127Wood, J. D., & Enser, M. (1997). Factors influencing fatty acids in meat and the role of antioxidants in improving meat quality. British Journal of Nutrition, 78(1), S49-S60. doi:10.1079/bjn19970134Xandé, X., Régnier, C., Archimède, H., Bocage, B., Noblet, J., & Renaudeau, D. (2010). Nutritional values of sugarcane products in local Caribbean growing pigs. animal, 4(5), 745-754. doi:10.1017/s175173110999173xZacharias, B., Kerler, A., & Drochner, W. (2004). The influence of 5% and 10% dietary apple pectin on parameters of fermentation in faeces and caecal digesta of weaning pigs. Archives of Animal Nutrition, 58(2), 149-156. doi:10.1080/0003942041000166750

Composition of free and adherent ruminal bacteria: inaccuracyof the microbial nutrient supply estimates obtained using freebacteria as reference samples and 15N as the marker

Previous studies have indicated that 15N enrichment of solid-associated bacteria (SAB) may be predicted from the same value in liquid-associated bacteria (LAB). The aims of this study were to confirm this and to measure the error in the nutrient supply from SAB, when LAB are used as the reference sample. For this purpose, the chemical and amino acid (AA) compositions of both the bacterial populations were studied in four experiments carried out on different groups of three rumen cannulated wethers. Diets (one in Experiments 1 and 4 and three in Experiments 2 and 3) had forage-to-concentrate ratios (dry matter (DM) basis) between 2 : 1 and 40 : 60, and were consumed at intake levels between 40 and 75 g DM/kg (BW) 0.75. The bacteria samples were isolated after continuous infusion of ( 15NH 4) 2SO 4 (40, 18, 30 and 25 mg 15N/day, in Experiments 1 to 4, respectively) for at least 14 days. In all experiments, SAB had consistently higher concentrations of organic matter (826 v. 716 g/kg DM, as average) and total lipids (192 v. 95 g/kg DM, as average) than LAB. Similar CP concentrations of both populations were observed, except a higher concentration in SAB than in LAB in Experiment 3. A consistent (in Experiment 4 only as tendency) higher AA-N/total N ratio (on average 17.5%) was observed in SAB than in LAB. The 15N enrichment in SAB was systematically lower than in LAB. On the basis of the results of all studies a close relationship was found between the 15N enrichment in SAB and LAB, which was shown irrespective of experiments. This relationship was established from Experiments 1 and 2 and the above cited previous results (n = 20; P < 0.001; R 2 = 0.996), and then confirmed from the results of Experiments 3 and 4. These relationships between SAB and LAB demonstrate that CP supply from SAB is underevaluated by, on average, 21.2% when LAB are used as the reference. This underevaluation was higher for true protein and even higher for the lipid supply (32.5% and 59.6%, respectively, as an average of the four experiments). Large differences in AA profile were observed between SAB and LAB. The prediction equation obtained using 15N as the marker may be used to correct the errors associated with the traditional use of LAB as the reference sample, and therefore to obtain more accurate estimates of the microbial nutrient supply to the ruminants. © Copyright The Animal Consortium 2011.Financial support was provided by the CICYT funded Projects AGL 2001-3662, AGL 2005-01712 and AGL 2006-08300. Analyses of 15N isotope ratios were performed at the Servicio Interdepartamental de Investigacio´ n, Universidad Auto´ noma de Madrid, Spain.González, J.; Arroyo, J.; Ouarti, M.; Guevara-González, J.; Rodríguez, C.; Alvir, M.; Moya Salvador, VJ.... (2012). Composition of free and adherent ruminal bacteria: inaccuracyof the microbial nutrient supply estimates obtained using freebacteria as reference samples and 15N as the marker. Animal. 6(3):468-475. https://doi.org/10.1017/S17517311110018074684756

Determinación de producción de metano en caprinos alimentados con dietas con distintos cereales

Three primiparous 1.5 year old Murciano-Granadina female goats in maintenance were used. Their average body weight was 33.08 ± 2.1 kg. The objective was to determine methane production in two diets differing of the type of cereal grain (barley or corn). Two consecutive digestibility trials were conducted using diets differing in the cereal type (barley or maize grains). The adaptation period has a duration of 7 days and the digestibility period 5 days. Methane production (CH4 ) was determined by indirect calorimetry with an open circuit mask adapted to small ruminants. Methane production was determined on day four of digestibility trial, before feeding and three more measurements every 35 minutes during feeding. There were no significant differences neither in dry matter intake (758 g MS/goat and day on average) nor in dry matter digestibility coefficients (CDMS= 69.2% on average). Significant differences (p<0.05) were observed in the methane production during the feeding time with levels of 0.69 and 0.77 l/h for the barley and maize based diets, respectively. No significant differences between diets were observed when CH4 was expressed on gross energy intake basis, and the value obtained for the experimental mixed diets was 4.8.Se utilizaron tres cabras primíparas de raza Murciano-Granadina de un año y medio de edad y en estado de mantenimiento, con un peso medio de 33,08 ± 2,1 kg, con el objeto de determinar la producción de metano al administrarles dos dietas que difirieron únicamente en el tipo de cereal (grano de cebada o maíz). Se realizaron dos pruebas de digestibilidad consecutivas mediante la administración de las dos dietas. Tras un periodo de adaptación de 7 días se analizó la digestibilidad aparente durante 5 días. La producción de metano (CH4) se determinó por calorimetría indirecta mediante una máscara de circuito abierto adaptada a pequeños rumiantes. El CH4 se midió el día 4 de la prueba de digestibilidad, antes de administrar la ración diaria y se realizaron tres medidas más cada 35 minutos mientras comían. No se observaron diferencias significativas en el consumo de materia seca (con 758 g MS/cabra y día de media), ni entre los coeficientes de digestibilidad de materia seca de las dos dietas (CDMS= 69,2% de media). Durante la comida se observaron diferencias (p<0,05) en la producción de metano con valores de 0,69 l/h para la dieta que contenía grano de cebada frente a 0,77 l/h para la dieta con grano de maíz. Cuando se expresó la producción de CH4 sobre la ingestión de energía (Ym) no se observaron diferencias significativas entre dietas, y el valor medio para las dietas mixtas estudiadas fue de 4,8.López Luján, MDC.; Ródenas Martínez, L.; Piquer Querol, O.; Cerisuelo, A.; Cervera Fras, MC.; Fernández Martínez, CJ. (2011). Determinación de producción de metano en caprinos alimentados con dietas con distintos cereales. Archivos de Zootecnia : Revista Trimestral. 60(232):943-951. http://hdl.handle.net/10251/45850S9439516023

Efecto del tipo de curva de lactación sobre la condición corporal de la coneja

537 lactations from 134 does (until the fifth lactation) were fit to a beta-modified function in order to know the effect of the lactation curve shape on the performance and body condition of reproductive rabbit does. It was found a strong correlation between the lactation curve shape (equation parameters: K, a and b) with the body condition of the reproductive does and the main productive parameters: higher energy intake and live weight in each period (0-21 days and 21-28 days of lactation) leads to higher milk production in this same period.The moment (beginning or ending of lactation) at which does improves her body condition is correlated to milk production at this moment. Furthermore it could be interesting to achieve a management which leads to a high production at the begging of the lactation period (lower �a� and higher �b�) in order to avoid an excessive mobilisation of reserves at the end of lactation and the survival of the litter.Se estudió el efecto de la forma de la curva de lactación de 537 lactaciones pertenecientes a 134 conejas reproductoras (de la 1ª a la 5ª lactación) sobre la condición corporal de la coneja y los principales parámetros productivos ajustándolas a una función Beta-modificada. Se encontró una correlación importante entre los coeficientes de la ecuación (K, a y b) y los parámetros estudiados: a mayor ingestión de energía digestible y/o mayor peso vivo de la coneja en cada periodo de la lactación (0-21 y 21-28 días) mayor producción de leche en ese mismo periodo. El momento (principio o final de la lactación) en el que la coneja recupera reservas está también correlacionada con la mayor o menor producción de leche en ese momento. En conclusión, sería interesante conseguir sistemas de manejo que favorezcan una elevada producción de leche al inicio de la lactación (menor �a� y mayor �b�) que evita una excesiva movilización de reservas al final de la lactación y una mayor supervivencia de la camada

Determinación de producción de metano en caprinos alimentados con dietas con distintos cereales

Three primiparous 1.5 year old Murciano-Gra- nadina female goats in maintenance were used. Their average body weight was 33.08 ± 2.1 kg. The objective was to determine methane production in two diets differing of the type of cereal grain (barley or corn). Two consecutive digestibility trials were conducted using diets differing in the cereal type (barley or maize grains). The adaptation period has a duration of 7 days and the digestibility period 5 days. Methane production (CH 4 ) was determined by indirect calorimetry with an open circuit mask adapted to small ruminants. Methane production was determined on day four of digestibility trial, before feeding and three more measurements every 35 minutes during feeding. There were no significant differences neither in dry matter intake (758 g MS/goat and day on average) nor in dry matter digestibility coefficients (CDMS= 69.2% on average). Significant differences (p<0.05) were observed in the methane produc- tion during the feeding time with levels of 0.69 and 0.77 l/h for the barley and maize based diets, respectively. No significant differences between diets were observed when CH 4 was expressed on gross energy intake basis, and the value obtained for the experimental mixed diets was 4.8.Se utilizaron tres cabras primíparas de raza Murciano-Granadina de un año y medio de edad y en estado de mantenimiento, con un peso medio de 33,08 ± 2,1 kg, con el objeto de determinar la producción de metano al administrarles dos dietas que difirieron únicamente en el tipo de cereal (grano de cebada o maíz). Se realizaron dos pruebas de digestibilidad consecutivas mediante la administración de las dos dietas. Tras un perio- do de adaptación de 7 días se analizó la digestibi- lidad aparente durante 5 días. La producción de metano (CH 4 ) se determinó por calorimetría indi- recta mediante una máscara de circuito abierto adaptada a pequeños rumiantes. El CH 4 se midió el día 4 de la prueba de digestibilidad, antes de administrar la ración diaria y se realizaron tres medidas más cada 35 minutos mientras comían. No se observaron diferencias significativas en el consumo de materia seca (con 758 g MS/cabra y día de media), ni entre los coeficientes de diges- tibilidad de materia seca de las dos dietas (CDMS= 69,2% de media). Durante la comida se observa- ron diferencias (p<0,05) en la producción de metano con valores de 0,69 l/h para la dieta que contenía grano de cebada frente a 0,77 l/h para la dieta con grano de maíz. Cuando se expresó la producción de CH 4 sobre la ingestión de energía (Ym) no se observaron diferencias significativas entre dietas, y el valor medio para las dietas mixtas estudiadas fue de 4,8

Degree of Saturation and Free Fatty Acid Content of Fats Determine Dietary Preferences in Laying Hens

Behavioural and genetic evidence shows that the taste system is intimately related to the sensing of nutrients with consequences for poultry nutrition practices. A better understanding of how chickens may sense fat could provide the background for selecting feedstuffs used in poultry feeds. Acid oils have the potential to be economical and sustainable feedstuffs. These fat by-products from the edible oil refining industry possess a similar fatty acid composition to the crude oils but are richer in free fatty acids (FFA). An experiment was conducted to study the effect of FFA content and the unsaturated:saturated ratio (U:S) on dietary preferences in hens. Four fat sources were added to a basal diet at an inclusion rate of 6%, determining the experimental diets: soybean oil (SO; high U:S, 5% FFA); soybean acid oil (SA; high U:S, 50% FFA); palm oil (PO; low U:S, 5% FFA); and palm fatty acid distillate (PFAD; low U:S, 50% FFA). The experimental diets were offered in a series of double-choice tests to forty-eight Lohmann Brown laying hens housed individually in cages. Each hen was offered the ten potential binary combinations of the four diets including each diet compared to itself (referred to as four control double-choices). Feed intake was measured for two hours twice a day after one hour of fasting. Consumption was analysed as a standard preference index (% of test diet intake in comparison with the total intake). Preference values were compared to the random choice value of 50% using the Student's t-test. None of the four control comparisons differ significantly from 50% (p > 0.05), indicating that the changes in preference values observed in the other binary comparisons were related to the dietary changes associated to fat ingredients. Hens showed a feed preference for palm oil added diets over soybean oil diets (p < 0.05), with PO and PFAD being equally preferred (p < 0.05). However, in this trial the hens demonstrated a preference for SO (low %FFA) when offered in choice with SA (high %FFA) (p < 0.05). These results suggest that the degree of saturation plays an important role in dietary fat preferences: hens prefer predominantly saturated oils even when these are rich in FFA. Furthermore, when presented with a choice between predominantly unsaturated oils, hens prefer feed with a low %FFA. In conclusion, %FFA and the U:S ratio affected feed preferences in hens. The use of oils with greater preference values may give rise to greater feed palatability, enhancing feed intake at critical stages

INFLUENCE OF BETAINE ON GOAT MILK YIELD AND BLOOD METABOLITES

Betaine is a natural occurring compound with methyl donor properties which is increasingly being used in animal feeding. Betaine, an oxidative product of choline is able to replace methionine in some physiologically important body processes. The subject of this work was to study the effect of betaine added to the diet on milk production and blood metabolites on Murciano-Granadina dairy goats.  Sixty lactating goats were selected from a commercial Murciano-Granadina goat herd (EXCAMUR S.L.) located in Murcia Region (Spain). Goats were selected from a 250 goats herd, taken  into account the age, stage of lactation (2.5 as average), live weight (36 kg as average) and type of birth (2 kids). Two homogenous groups of 30 goats were made and fed with 1.5 kg of compound feed and 1 kg of alfalfa hay per day and goat. Goats were fed twice a day and water was provided ad libitum. Both groups received the same diet but for the second group the diet was supplemented with 4 g∙kg-1 betaine (betaine anhydrous, Danisco Animal Nutrition). The feeds, presented in pellets, were formulated in based on recommendations of INRA (2007). The experimental period was 6 months and the experimental diets were provided 15 days before parturition. The herd was machine milked once at day. Chemical composition, milk production and blood metabolites of each goat were recorded and analyzed at the end of the trial. Variance analysis and means comparison were carried out using the general lineal model procedure and Tukey test for mean comparison. Goats fed with betaine diet had higher milk fat than goats fed control diet (4.8 vs. 5.2 % for control and betaine respectively;