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-
