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Unprotected choline chloride alters microbial community composition in a dual-flow continuous culture system.

J. A. Arce-Cordero

Abstract:

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Unprotected choline chloride alters microbial community composition in a dual-flow continuous culture system.
J. A. Arce-Cordero*1, P. Fan1, H. F. Monteiro1, X. Dai1, B. Calvo2, R. Lobo1, K. Estes3, K. C. Jeong1, A. P. Faciola1. 1Department of Animal Sciences, University of Florida Gainesville, FL, 2Department of Animal Sciences, Maringa State University Maringa, Parana, Brazil, 3Balchem Corporation New Hampton, NY.

Choline (Cho) is usually fed as rumen-protected Cho to prevent Cho ruminal microbial degradation and assure Cho supply for absorption in the small intestine; however, some Cho is degraded in the rumen and its effects on ruminal microbial population are unknown. Therefore, our objective was to evaluate the effects of unprotected choline chloride on ruminal microbial community composition when fed to diets with different NDF concentration. We used 8 fermenters of a dual-flow continuous culture system in a 4x4 duplicated Latin-square with a 2x2 factorial arrangement; factors being: choline chloride supplementation (0 and 2.5 g/kg of DM) and dietary NDF% (30% and 40% of DM). Resulting treatments were: 1) 30% NDF + choline; 2) 30% NDF, without choline; 3) 40% NDF + choline, 4) 40% NDF, without choline. Basal diets were fed at 0800 and 2000, and choline chloride was provided 4 times/d. Each experimental period lasted 10 d. Bacterial samples were collected on d 8, 9, and 10 at 3, 6, and 9 h after morning feeding and a composite sample per time point was made for each fermenter. Particle associated bacteria (PAB) and liquid associated bacteria (LAB) were analyzed separately. Sequencing of V4 region of bacterial 16s rRNA was performed with Illumina MiSeq and data were analyzed with QIIME, R, and SAS. Main effects of choline supplementation (Cho), dietary NDF% (NDF), and their interaction (Cho � NDF) were tested. Cho supplementation impacted relative abundance (RA) of taxonomic orders by increasing Selenomonadales RA in PAB (P = 0.04) and decreasing Fibrobacterales RA in LAB (P = 0.05). At the genus level, Cho increased RA of Ruminococcaceae (P = 0.02), Megasphaera (P = 0.05) and Prevotella (P = 0.08) in PAB; while Succinivibrio RA in PAB was greater in response to Cho only when the 30% NDF diet was provided (Cho � NDF, P = 0.02). Our results indicate that unprotected choline chloride alters ruminal microbial populations associated with carbohydrate fermentation by increasing RA of bacteria associated with starch utilization and propionate synthesis.

Keywords: 16s rRNA, in vitro, methyl donor.

Biography: Jose got his MS in ruminant nutrition at Colorado State University in 2016, then started his PhD program at University of Florida where he is currently a PhD candidate whose main research focus has been the effects of micronutrient supplementation on ruminal fermentation