Feed Additive Monensin Research Articles

Staphylococcus aureus mutants resistant to the feed-additive monensin show increased virulence and altered purine metabolism.

Ionophores are antibacterial compounds that affect bacterial growth by changing intracellular concentrations of the essential cations, sodium and potassium. They are extensively used in animal husbandry to increase productivity and reduce infectious diseases, but our understanding of the potential for and effects of resistance development to ionophores is poorly known. Thus, given their widespread global usage, it is important to determine the potential negative consequences of ionophore use on human and animal health. In this study, we demonstrate that exposure to the ionophore monensin can select for resistant mutants in the human and animal pathogen Staphylococcus aureus, with a majority of the resistant mutants showing increased growth rates in vitro and/or in mice. Whole-genome sequencing and proteomic analysis of the resistant mutants show that the resistance phenotype is associated with de-repression of de novo purine synthesis, which could be achieved through mutations in different transcriptional regulators including mutations in the gene purR, the repressor of the purine de novo synthesis pathway. This study shows that mutants with reduced susceptibility to the ionophore monensin can be readily selected and highlights an unexplored link between ionophore resistance, purine metabolism, and fitness in pathogenic bacteria.IMPORTANCEThis study demonstrates a novel link between ionophore resistance, purine metabolism, and virulence/fitness in the key human and animal pathogen Staphylococcus aureus. The results show that mutants with reduced susceptibility to the commonly used ionophore monensin can be readily selected and that the reduced susceptibility observed is associated with an increased expression of the de novo purine synthesis pathway. This study increases our understanding of the impact of the use of animal feed additives on both human and veterinary medicine.

Metabolic processes in the rumen and productive effect in the case of ionophore influence

Cycle functions of tricarboxylic acids and cyclic process of the synthesis in fatty acids are possible under conditions of normal carbohydrate metabolism. That is why it is important to know the nature of normal condition of metabolism in the rumen and reasons of its disturbances and also be skillful enough to influence exogenous factors. Among the latter metabolic engineering is of special importance, which with the help of constructing the scales and speed of the cascade of main reactions in transformations of appropriate combinations of substrates and other effectors makes it possible to get the highest and productive effect. The article presents experimental data concerning the influence of antibiotic feed additive of monensin on metabolic processes in the rumen of calves and its productive effect. Obtained results of metabolism investigations in carbohydrates by means of mixed populations in the rumen of ruminants under the influence of ionophore additive widen information as to its role in the digestion of nutrients of the ration and also add some information concerning the influence on intermediate exchange and productive effect of exogenous factors of substrate – ergotropic complex which allows to construct a significant acceleration of anabolic processes and achieve high production levels. Research showed that ionophore additives have a high influence on the rumen intermediate metabolism of the growing calves especially when fed plants. Antibiotic feed additive monensin when given in the doze 0,5 gr/kg of living mass a day influences greatly the metabolic processes in the rumen, especially during the period of accustoming of animals to plant feeds and next periods. This influence is revealed first of all in the change of molar proportion of VFA ratio (increase of molar part of propionate because of acetate decrease), and also in average daily gains by 10,4% (compared with 1037 g and 939 g).

МЕТАБОЛІЧНІ ПРОЦЕСИ В РУБЦІ ТА ПРОДУКТИВНИЙ ЕФЕКТ У ТЕЛЯТ ЗА ДІЇ ЙОНОФОРУ

Functions tricarboxylic acid and a cyclic fatty acid synthesis process is only possible under normal carbohydrate metabolism. It is therefore important to know the nature of the normal state of metabolism in the rumen and the reasons for its violations, and have the knowledge and skill in time to influence exogenous factors. Among the latter is particularly important metabolic engineering that by constructing the scale and speed of the cascade of reactions major transformations appropriate combinations of substrates and other effectors, yields on high–quality animals and productive effect.The article presents experimental data on the effect of antibiotic feed additive monensin on metabolic processes in the rumen of calves and its productive effect. The results of carbohydrate metabolism studies with mixed populations of microorganisms rumen of ruminant animals of the additive ionophore expand the existing information about its role in the assimilation of nutritious diet substances, as well as complementary data on the features of influence on of intermediate exchange and productive effect of exogenous factors substrate–ergotropic complex that, in ultimately, it allows the construction of a significant acceleration of anabolic and achieve high levels of performance.Research evidence that growing calves, especially when switching to vegetarian diet, supplements ionophore significant effect on scar of intermediate metabolism.Feeding calves antibiotic feed additive monensin at a dose of 0.5 g/kg body weight per day, showing a measurable impact on the metabolic processes in the rumen, especially during the habituation of animals to the vegetation and in subsequent periods of feeding. This effect is primarily a change in the molar ratio of VFA (increase the molar proportion of propionate at the expense of acetate), and the average daily gain in growth by 10.4% (1037 against 939 g).

Bovicin HC5 inhibits wasteful amino acid degradation by mixed ruminal bacteriain vitro

Streptococcus bovis HC5 produces a broad spectrum lantibiotic (bovicin HC5) that inhibits pure cultures of hyper ammonia-producing bacteria (HAB). Experiments were preformed to see if: (1) S. bovis HC5 cells could inhibit the deamination of amino acids by mixed ruminal bacteria taken directly from a cow, (2) semi-purified bovicin was as effective as S. bovis HC5 cells, and 3) semi-purified and the feed additive monensin were affecting the same types of ammonia-producing ruminal bacteria. Because purified and semi-purified bovicin HC5 was as effective as S. bovis HC5 cells, it appeared that bovicin HC5 was penetrating the cell membranes of HAB before it could be degraded by peptidases and proteinases. Mixed ruminal bacteria that were successively transferred and enriched nine times with trypticase did not become significantly more resistant to either bovicin HC5 (50 AU mL(-1)) or monensin (5 microM), and amplified rDNA restriction analysis indicated that bovicin HC5 and monensin appeared to be selecting against the same types of bacteria.

Effect of monensin feeding and withdrawal on populations of individual bacterial species in the rumen of lactating dairy cows fed high-starch rations

Real-time polymerase chain reaction (PCR) was used to quantify 16 procaryotic taxa in the rumina of two lactating dairy cows following supply and subsequent withdrawal of the feed additive monensin (13.9 mg/kg of diet dry matter) in a high-starch, silage-based ration. PCR was conducted on DNA from rumen samples collected 6 h post feeding on two successive days before monensin supplementation, after 30 days of monensin supplementation, and at six weekly intervals after monensin withdrawal. Mean values of relative population size (RPS, the percent of bacterial 16S rRNA copy number) for genus Prevotella increased (P < 0.05) from 41.8% without monensin to 49.2% with monensin and declined to 42.5% after monensin withdrawal. Mean RPS values for two biohydrogenating species (Megasphaera elsdenii and Butyrivibrio fibrisolvens) were low (<0.4%) and declined several-fold in response to monensin. Mean RPS values for the biohydrogenating species Eubacterium ruminantium, four cellulolytic species, four starch- or dextrin-fermenting species, and Domain Archaea were not altered (P > 0.10) upon monensin feeding or withdrawal. The data suggest that monensin in high-starch diets does not suppress populations of classical ruminal Gram-positive bacteria or the availability of H2, though it may affect bacteria involved in biohydrogenation of lipids that regulate bovine mammary lipogenesis.

Effects of Feed Additives and Mixed Eimeria Species Infection on Intestinal Microbial Ecology of Broilers

Evaluation of digestive microbial ecology is necessary to understand effects of growth-promoting feed. In the current study, the dynamics of intestinal microbial communities (MC) were examined in broilers fed diets supplemented with a combination of antibiotic (bacitracin methylene disalicylate) and ionophore (Coban 60), and diets containing 1 of 2 essential oil (EO) blends, Crina Poultry (CP) and Crina Alternate (CA). Five treatments were analyzed: 1) unmedicated uninfected control; 2) unmedicated infected control; 3) feed additives monensin (bacitracin methylene disalicylate) + monensin (Coban 60; AI); 4) EO blend CP; and 5) EO blend CA. Additives were mixed into a basal feed mixture, and EO were adjusted to 100 ppm. Chicks were infected by oral gavage at 19 d of age with Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Duodenal, ileal, and cecal samples were taken from 12 birds per treatment just before and 7 d after challenge; 2 samples each were pooled to give a final number of 6 samples total; and all pooled samples were frozen until used for DNA extraction. Denaturing gradient gel electrophoresis was used to examine PCR-amplified fragments of the bacterial 16S ribosomal DNA variable region. Results are presented as percentages of similarity coefficients (SC). Dendrograms of PCR amplicon or band patterns indicated MC differences due to intestinal location, feed additives, and cocci challenge. Essential oil blends CP and CA affected MC in all gut sections. Each EO had different effects over MC, and they differed in most instances from the AI group. The cocci challenge caused drastic MC population shifts in duodenal, ileal, and cecal sections (36.7, 55.4, and 36.2% SC, respectively). Diets supplemented with CP supported higher SC between pre- and postchallenge MC (89.9, 83.3, and 76.4%) than AI (81.8., 57.4, and 60.0%). We concluded that mixed coccidia challenge caused drastic shifts in MC. These EO blends modulated MC better than AI, avoiding drastic shifts after a mixed challenge.

Mitigation Options for Enteric Methane Emissions from Dairy Animals: An Evaluation for Potential CDM Projects in India

Enteric fermentation in livestock is an important source of anthropogenic methane emission. India, with its large livestock population, is estimated to contribute 10.8 Tg of methane annually from this source. An evaluation of various methane mitigation options indicate that some of the available technologies like, diet supplementation with feed additive and molasses urea product are highly cost effective in reducing enteric methane emissions. The gross cost of methane abatement from use of feed additive monensin premix ranges from €0.6 to €1.8/ton CO2 equivalent, for buffaloes and indigenous cows, respectively. The gross cost of enteric methane mitigation from supplementing molasses urea products and dietary manipulation through increased concentrate feeding is much higher. But, as the monetary value of the increased milk production on application of these technologies was higher than the annual cost of reduction strategy for buffaloes and crossbred cows, the net costs of the former mitigation option was negative for buffaloes (€-28.1/ton CO2) and of the latter for crossbred cows (€-7.0/ton CO2,). The availability of cost-effective technologies suggest that the methane mitigation projects under CDM, can be planned in the Indian dairy sector to the mutual benefit of countries with emission targets and India. The vast dairy animal population of India and resulting methane emissions provide good opportunity these countries to buy reasonable quantum of emission credits from projects in India. Such projects will work to the benefit to India by providing a tool for technology transfer to increase animal productivity and attract capital that assists in more prosperous and environmental friendly milk production in the country.

Variations in the ability of ruminal gram-negative Prevotella species to resist monensin.

Gram-negative, ruminal Prevotella strains (n = 15) differed greatly in their sensitivity to the feed additive monensin. Strains that were repeatedly transferred with sublethal doses tolerated more monensin than those that were unadapted, but growth experiments indicated that the sensitivity range was as great as 2000-fold. Prevotella bryantii B(1)4 grew with monensin concentrations as high as 20 microM, but P. ruminicola H15a, D31d, 20-63, E40a, and D42f never initiated growth if monensin was greater than 0.01 microM. Washed cell preparations that were energized with glucose lost intracellular potassium when monensin was added, and potassium depletion could also be used as an index of monensin sensitivity. Adapted cells of P. bryantii B(1)4 had a half-maximal potassium depletion constant (K(d)) of 3.2 microM, but the K(d) values of P. ruminicola strains H15a, D31d, 20-63, E40a, and D42f were less than 0.04 microM. Maximal potassium depletion (K(max)) values range from 90% to 40%, and monensin-adapted cells always had lower K(max) values than unadapted cells. A linear regression of log K(d)/K(max) versus percentage decrease in optical density divided by monensin concentration had an r(2) of 0.75, and this regression indicated that potassium depletion from washed cells closely correlated with growth inhibition. P. bryantii B(1)4 had a K(d)/K(max) ratio that was sevenfold greater than other Prevotella strains, and this result indicated that P. bryantii may be unusual in its ability to grow with very high concentrations of monensin.

An rRNA approach for assessing the role of obligate amino acid-fermenting bacteria in ruminal amino acid deamination.

Ruminal amino acid degradation is a nutritionally wasteful process that produces excess ruminal ammonia. Monensin inhibited the growth of monensin-sensitive, obligate amino acid-fermenting bacteria and decreased the ruminal ammonia concentrations of cattle. 16S rRNA probes indicated that monensin inhibited the growth of Peptostreptococcus anaerobius and Clostridium sticklandii in the rumen. Clostridium aminophilum was monensin sensitive in vitro, but C. aminophilum persisted in the rumen after monensin was added to the diet. An in vitro culture system was developed to assess the competition of C. aminophilum, P. anaerobius, and C. sticklandii with predominant ruminal bacteria (PRB). PRB were isolated from a 10(8) dilution of ruminal fluid and maintained as a mixed population with a mixture of carbohydrates. PRB did not hybridize with the probes to C. aminophilum, P. anaerobius, or C. sticklandii. PRB deaminated Trypticase in continuous culture, but the addition of C. aminophilum, P. anaerobius, and C. sticklandii caused a more-than-twofold increase in the steady-state concentration of ammonia. C. aminophilum, P. anaerobius, and C. sticklandii accounted for less than 5% of the total 16S rRNA and microbial protein. Monensin eliminated P. anaerobius and C. sticklandii from continuous cultures, but it could not inhibit C. aminophilum. The monensin resistance of C. aminophilum was a growth rate-dependent, inoculum size-independent phenomenon that could not be maintained in batch culture. On the basis of these results, we concluded that the feed additive monensin cannot entirely counteract the wasteful amino acid deamination of obligate amino acid-fermenting ruminal bacteria.

Monensin and Avoparcin as Feed Additives to Grazing Ruminants

Abstract Flachowsky, G. and Richter, G.H. 1995. Monensin and avoparcin as feed additives to grazing ruminants. J. Appl. Anim. Res., 8: 137–144. Four series of experiments consisting of 15 experiments with a total of 1353 growing cattle and sheep were carried out. The feed additives monensin (series I to III) and avoparcin (series IV) were included in diets in different forms. Monensin was given in concentrate mixtures with minerals (series I and II) or as monensin device (series III), avoparcin was added to salts lick (series IV). All animals grazed the whole day. Monensin supplementation increased the daily weight gain by 102 (series I), 74 (cattle) and 10 (sheep, series II) and 8 g per day (series III), avoparcin improved it by 55 g (series IV) daily. Monensin and avoparcin improved weight gain of grazing ruminants under temperate conditions and monensin also improved weight gain under tropical conditions.

A comparison of unwilted and wilted grass silages offered to beef cattle without and with monensin sodium

AbstractA randomized block experiment was conducted to compare unwilted and wilted grass silages and the effects of the feed additive monensin sodium on the silage intake and performance of finishing beef cattle. Two regrowths from a predominantly perennial ryegrass (cv. S24) sward were ensiled either without wilting or after field wilting for 3 d (dry matter (DM) concentrations 161 and 266 g kg−1 respectively). Both silages were treated with formic acid (2·6 and 30 litre t−1 respectively) and were well preserved. The silages were offered ad libitum to forty‐eight Charolais‐cross cattle (thirty‐two steers and sixteen heifers, mean initial live weight 351 kg) for 145 d. All animals received 2·2 kg concentrates per head daily and half of those on each silage treatment received in addition 200 mg monensin sodium per head daily. Silage DM intake was 5.04, 504. 5·48, 5·63 ± 0.134 kg d−l; fasted liveweight gain was 0·69, 0·77. 0·64 and 0·73 ± 0.033 kg d−l and carcass gain was 0·47, 0·50, 0·40 and 0·45 ± 0·020 kg d−1 for the unwilted silage without and with monensin and the wilted silage without and with monensin respectively. It is concluded that wilting grass of low DM concentration for 3 d prior to ensiling reduced the performance of finishing beef cattle below that obtained from well‐preserved unwilted silage in spite of a higher DM intake being achieved with the wilted silage. The inclusion of monensin sodium in a silage‐based diet increased performance without significantly affecting feed intake.

Response of growing steers to monensin sodium supplementation and implantation with trenbolone acetate and hexoestrol

Current means of improving the efficiency of beef production in the United Kingdom include the use of hormonal anabolic compounds and the feed additive monensin sodium (monensin, ‘Romensin’, Elanco). Results from studies conducted mainly in the United States have shown that monensin may improve food conversion efficiency (e.g. Broome, 1980) which occurs as a result of variable reductions in food intake with or without increases in growth rate. These effects have been associated with alterations in the production of volatile fatty acids and methane in the rumen. Other studies have suggested that protein metabolism may also be affected (e.g. Pendlum, Boling &amp; Bradley, 1980).