Effect of Nigericin, Monensin, and Tetronasin on Biohydrogenation in Continuous Flow-Through Ruminal Fermenters

Abstract

Four ionophores differing in cation selectivity were compared for their effect on microbial fermentation and biohydrogenation by ruminal bacteria in continuous culture. Monensin and nigericin are monovalent antiporters with selective binding affinities for Na+ and K+, respectively. Tetronasin is a divalent antiporter that binds preferentially with Ca2+ or Mg2+. Valinomycin is a monovalent uniporter and does not exchange K+ for H+. Steady-state concentrations of 2 micrograms/ml of monensin, nigericin, tetronasin, or valinomycin were maintained by constant infusion into fermenters. Molar percentages of acetate were lower, and those of propionate were higher, in the presence of monensin, nigericin, and tetronasin; all three ionophores also decreased CH4 production. Concentrations of valinomycin as high as 8 micrograms/ml had no effect on volatile fatty acids or CH4 production. Monensin, nigericin, and tetronasin inhibited the rate of biohydrogenation of linoleic acid. Continuous infusion of C18:2n-6 at a steady-state concentration of 314 micrograms/ml into fermenters receiving monensin, nigericin, or tetronasin resulted in lower amounts of stearic acid and higher amounts of oleic acid. Ionophores increased total C18:2 conjugated acids mainly because of an increase in the cis-9, trans-11-C18:2 isomer. If reflected in milk fat, ionophore-induced changes in ruminal lipids could enhance the nutritional qualities of milk.

Effect of storage on fatty acid profile of butter from cows fed whole or ground flaxseed with or without monensin

“…Cows fed monensin had lower relative percentages of cis6-20:4 in butter fat than those fed the control diets. Monensin supplementation increased relative percentages of unidentified fatty acids probably as a result of a greater production of trans fatty acid in the rumen with monensin supplementation (Fellner et al, 1997). The n-6 to n-3 ratio in butter fat was significantly higher for cows supplemented with monensin but all ratios were below the 4:1 ratio recommended for reducing potential risk of coronary heart diseases (Sim, 1998).…”

“…Flaxseed processing increased concentration of polyunsaturated fatty acids in butter fat and higher percentage of unsaturated FA has been positively correlated with better spreadability of butter (Enjalbert et al, 1997). Spreadability is improved with a reduction in milk fat globule size (Goudédranche et al, 2000) as a result of enhanced water retention by the milk fat globule membrane, which, in turn, induces a reduction in butter dry matter content (Michalski et al, 2002).…”

“…Monensin is known to decrease in vitro ruminal biohydrogenation of PUFA (Van Nevel & Demeyer, 1995) and to increase total CLA concentration in vitro (Fellner et al, 1997) and in milk of dairy cows (da Silva et al, 2007). Moreover, feeding ground compared with whole flaxseed increased concentrations of conjugated linoleic acid and cis3-18:3 in milk fat (da Silva et al, 2007).…”

Targets and procedures for altering ruminant meat and milk lipids

“…The trans-11 isomer represented at least 80 % of the total trans-18 : 1 acids (Fellner et al 1995). Trans-18 : 1 and conjugated octadecadienoic acids or CLA constituted 13 and 0·5 % of the total FA respectively, whereas the conjugated diene isomers were shown to contain 33 % of the cis-9, trans-11 isomer (Fellner et al 1997). Biohydrogenation only occurs with free FA, but the system is easily overloaded, especially in vitro, with inhibition of the process by the free acids and accumulation of trans-18 : 1 and CLA.…”

Fontes de lipídio e monensina sódica na fermentação, cinética e degradabilidade ruminal de bovinos

“…Foi relatado que alguns microrganismos gramnegativos mudam suas propriedades em presença de monensina, o que explica a redução da lipólise. De acordo com Fellner et al (1997) e Jenkins et al (2003), a monensina reduziu a taxa de bio-hidrogenação por inibição da lipólise. Esse efeito na microbiota pode ser responsável pela alteração na degradação da MS e PB, neste estudo.…”