02269nam a2200229 a 450000100080000000500110000800800410001910000170006024501820007726001710025930000160043052014130044665000230185965300190188270000200190170000190192170000200194070000170196070000190197770000220199670000210201820392232024-06-19       2015    bl uuuu     u00u1 u    #d1 aSILVA, M. G.  aIn vitro activity of different antimicrobials on amino acid deamination in ruminal fluid from dairy cows fed corn silage or corn silage/concentrate diets.h[electronic resource]  aIn: SIMPÓSIO NACIONAL DE BOVINOCULTURA LEITEIRA - SIMLEITE, 5.; SIMPÓSIO INTERNACIONAL DE BOVINOCULTURA LEITEIRA, 3., 2015, Viçosa, MG. Anais... Viçosa: UFVc2015  ap. 293-296.  aFor many decades, antimicrobials have been used in livestock diets as growth-promoting agents (Berchielli, 2011). Monensin, an ionophore antibiotic frequently fed to cattle herds, has shown activity against several ruminal gram-positive bacteria and usually inhibits amino-acid deamination in vitro (Lima et al., 2009). Virginiamycin, an antibiotic produced by Streptomyces virginae, is generally effective against lactic acid bacteria and helps to maintain ruminal pH in vivo in conditions of induced acidosis (Coe et al., 1999). Although these antibiotics show desirable effects on ruminal fermentation, the growing concern with public health and the impact of antibiotics fed to livestock in selecting resistant bacteria has attracted attention to the development of alternatives to antimicrobials used for growth promotion (Russell & Mantovani, 2002). In this scenario, antimicrobial peptides (bacteriocins), such as nisin and bovicin HC5, have shown effects on ruminal fermentation that are similar to the ionophore antibiotics. In this study, we compared the in vitro effects of these two bacteriocins on amino acid deamination with the activity of monensin and virginiamycin. Because we hypothesized that inhibitory activity could be affected by microbiota composition determined by the diet, two dairy cows fed corn silage or high concentrate-based diets were used as rumen-fluid donors in this study  aruminant nutrition  aLivestock diet1 aBENTO, C. B. P.1 aAZEVEDO, A. C.1 aLOPES, D. R. G.1 aSOUZA, S. M.1 aMOREIRA, E. A.1 aPEREIRA, L. G. R.1 aMANTOVANI, H. C.