03189naa a2200277 a 450000100080000000500110000800800410001902200140006002400420007410000170011624501330013326000090026650004980027552017850077365300260255865300230258465300190260765300210262665300380264765300150268570000200270070000180272070000190273870000220275777301320277910643702023-11-15       2023    bl uuuu     u00u1 u    #d  a0377-84017 a10.1016/j.anifeedsci.2023.1158062DOI1 aBRUTTI, D.D.  aEffects of the use of tannins on the ruminal fermentation of cattlebA meta-analysis and meta-regression.h[electronic resource]  c2023  aArticle history: Received 22 January 2022; Received in revised form 11 October 2023; Accepted 21 October 2023; Available online 24 October 2023. -- Correspondence: Barcellos, J.O.J.; Departamento de Zootecnia, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves n. 7712, RS, Porto Alegre, Brazil; email:julio.barcellos@ufrgs.br -- FUNDING: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior [ Coordination for the Improvement of Higher Education Personnel] (CAPES). --  aABSTRACT.- This systematic review-meta-analysis (MA) estimates the impact of including tannins in beef and dairy cattle diets on short-chain fatty acids (SCFA), ammonia nitrogen (N-NH3), dry matter digestibility (DMD), and methane (CH4) production. The effects are described according to the sources (natural or extract), type of tannin (condensed, CT, or hydrolyzed HT or blend), total tannin concentration in the source, and doses. The bibliographic search was performed in five electronic databases: CAB-Abstracts, PubMed, Scopus, Science Direct, and Web of Science. Predefined protocols were used at all stages of the systematic review process. An MA for random effects was performed for each indicator separately with the mean difference between the control (without tannin) and treated (with tannin) groups. Twenty-seven articles were included for this study, of which 20 were for SCFA, 20 for N-NH3, 14 for DMD, and 10 for CH4. The inclusion of HT reduced the total SCFA concentration (p = 0.005). Within a dose range of 10-40 g/kg of a CT extract, the total SCFA concentration was reduced by 0.804 mM in the rumen fluid (p < 0.016). The effects of tannins on reducing the N-NH3 concentration are evident, either extracted or naturally in the plant, and regardless of the type of tannin (p < 0.05). DMD was reduced with the use of a tannin blend (p = 0.041) and the inclusion of tannins reduced CH4 production (p = 0.005), with moderate heterogeneity (I2 = 44.5 %). Through the 27 studies included, we concluded that tannins affect the concentration of N-NH3, SCFA, DMD, and CH4. Tannins associated with balanced protein-energy diets can reduce ruminal protein degradability and CH4 production, which can benefit animal metabolism and the environment. © 2023 Elsevier B.V.  aNatural feed additive  aPhenolic compounds  aPlant extracts  aProanthocyanidin  aSISTEMA GANADERO EXTENSIVO - INIA  aTanic acid1 aCANOZZI, M.E.A.1 aSARTORI, E.D.1 aCOLOMBATTO, D.1 aBARCELLOS, J.O.J.  tAnimal Feed Science and Technology, December 2023, Volume 306, article 115806. https://doi.org/10.1016/j.anifeedsci.2023.115806