In Vitro Lactic Acid Inhibition and Alterations in Volatile Fatty Acid Production by Antimicrobial Feed Additives

Abstract

Batch culture fermentations were used to determine the effects of avoparcin, lasalocid, monensin, narasin, salinomycin, thiopeptin, tylosin, virginiamycin, monensin + tylosin combination, and two new ionophore compounds (RO22-6924/004 and RO21-6447/009) on lactic acid and volatile fatty acid (VFA) production. Ruminal fluid from cattle fed a high alfalfa hay diet was incubated with glucose for 12 h in a buffered medium to determine the effect of antimicrobial compounds on lactic acid concentration. Fermentations treated with antimicrobial compounds had higher final pH and lower L(+) lactic acid concentration. Narasin and salinomycin were more inhibitory than other ionophore compounds. Monensin and tylosin in combination was more effective than monensin alone. Among the nonionophore compounds, avoparcin was the least effective and thiopeptin, tylosin and virginiamycin were extremely effective in reducing lactic acid concentration. Ruminal fluid from cattle fed a diet of alfalfa hay and grain (50:50) was incubated with a mixture of sugars, casein and urea for 12 h in a buffered medium to determine the effect of antimicrobial compounds on VFA production. Generally, total VFA concentration was not affected by antimicrobial compounds except RO22-6924/004, tylosin and virginiamycin, which caused a reduction at high concentrations. Tylosin, monensin and tylosin mixture, thiopeptin and virginiamycin at high concentrations (greater than 6.0 micrograms/ml) increased the acetate proportion. All compounds increased the molar proportion of propionate. Tylosin and virginiamycin at high concentrations (greater than 6.0 micrograms/ml) decreased the proportion of propionate. Monensin and tylosin in combination had no effect on propionate proportion. Among the compounds tested, narasin and salinomycin were the most effective in enhancing propionate proportion. Ionophore compounds were more inhibitory to butyrate production than the nonionophore compounds. Batch culture fermentations may be used to quantitate the relative efficacy of antimicrobial compounds to alter ruminal fermentation characteristics.

Effects of high concentrate:forage ratio diets containing monensin on the management of ruminal acidosis in Gezhel lambs

“…These findings are consistent with previous researches, which showed monensin caused a significant decrease in ammonia production, probably as a result of reduced proteolysis, degradation of peptides and deamination of amino acids in the rumen (Yang and Russell, 1993;Nagaraja et al, 1997). Importantly, monensin has been found to reduce the risk of acidosis in vitro (Nagaraja et al, 1987) and prevent clinical acidosis in cattle experimentally induced to exhibit acidosis with rumen pH increasing in treated animals (Horn et al, 1981;Nagaraja et al, 1981). Monensin acts by inhibiting the growth of Streptococcus bovis, as well as other major lactate-producing rumen bacteria such as Lactobacillus, Butyrivibrio and Lachnospira in vitro (Dennis et al, 1981).…”

Effect of virginiamycin and monensin supplementation on performance of multiparous Holstein cows

“…Some studies have indicated a growth promoting effect of virginiamycin in ruminants through improved weight gain and feed efficiency and decreased incidence of liver abscesses and acidosis in grain fed cattle (Hedde, 1984;Rogers et al, 1995). The effect of virginiamycin on gram-positive bacteria is similar to that of monensin, although the modes of action differ (Nagaraja et al, 1987). Virginiamycin supplementation, therefore, could potentially result in the same benefits for dairy cows as described above for monensin.…”

Effects of monensin and virginiamycin supplementation in finishing diets with distiller dried grains plus solubles on growth performance and digestive function of steers

“…The basis for improved growth performance is not certain. Virginiamycin inhibits growth of ruminal lactic acid-producing bacteria, limiting ruminal lactate accumulation (Hedde et al 1980;Nagaraja et al 1987;Hynes et al 1997;Clayton et al 1999;Coe et al 1999). Thus, virginiamycin might reduce risk of lactic acidosis and associated digestive dysfunctions following ruminal overload of rapidly fermentable carbohydrate (Owens et al 1998).…”