monensin and laidlomycin

The objective of this research was to use data from multiple studies to comprehensively quantify the effects of feeding 1) laidlomycin propionate (LP), alone and/or in combination with chlortetracycline, compared with 2) monensin sodium (MS), alone and/or in combination with tylosin, at commercially approved dosages, on ADG, DMI, feed efficiency (FE), mortality, and carcass characteristics (HCW and liver abscesses). A secondary objective was to explore potential sources of heterogeneity among the comparative effectiveness studies. A systematic review of peer-reviewed literature and industry reports was used to identify studies that included direct comparisons of these treatments in finishing steers in North America. Random-effects meta-analysis models of performance, carcass, and health-related outcomes were fitted with extracted data, consisting of a total of 17 data sets comprising a total of 135 pens and 13,603 steers. Results showed that pens of steers fed LP had increased ADG (live and carcass adjusted), DMI, and HCW compared with those fed monensin ( < 0.05). However, liver abscesses were more common in LP-fed cattle than in MS-fed cattle ( < 0.05), presumably because of differences in the concurrently fed antimicrobials. No significant effects ( > 0.05) were identified for FE or for health-related outcomes (overall and cause-specific mortality). There was a substantial amount of heterogeneity in outcomes among studies, and when pen size and type of production setting were included in mixed-effects meta-regression models, they accounted for only a small proportion of the between-study heterogeneity found in the meta-analysis models. Therefore, caution should be exercised when interpreting summary estimates in the presence of substantial heterogeneity. However, these results provide comprehensive information on the comparative effects of different ionophores across multiple studies and multiple years, states, and production settings. These unique results can enable quantitative and informed decisions by potential end users of these feed additives that are widely used in the U.S. beef industry for reducing the costs of beef production through enhanced cattle performance.

Topics: Animals; Anti-Bacterial Agents; Body Composition; Cattle; Chlortetracycline; Liver Abscess; Male; Monensin; North America; Proton Ionophores; Tylosin

One hundred ninety-two steers (BW = 354 ± 23.5 kg) were used in a randomized block design to evaluate the effects of ionophore and ractopamine hydrochloride (RH) supplementation strategies on performance and carcass characteristics. Twelve pens of 4 steers were assigned to each of the following treatments: unsupplemented control (CON), laidlomycin propionate (12.1 mg/kg DM) with or without RH (LPRH and LP, respectively), and monensin sodium (36.4 mg/kg DM) with RH (MSRH). Steers were fed for 151 d, of which respective treatments received RH (Actogain; Zoetis, Florham Park, NJ) at a rate of 300 mg/(animal · d) for the final 32 d. Laidlomycin was removed from the LPRH treatment during this period, as no combination feeding has been approved. Upon harvest, carcass data were collected by trained personnel, and subsequent analysis of the LM was conducted to estimate tenderness using Warner-Bratzler shear force (WBSF). Prior to RH supplementation, both LP and LPRH had greater ADG ( ≤ 0.02) and G:F ( < 0.01) than CON, whereas MSRH was intermediate. During the final 32 d, MSRH improved G:F ( ≤ 0.02) compared to all other treatments and tended to increase ADG over unsupplemented controls ( = 0.05). Cattle receiving LP without RH had significantly greater BW at d 151 than CON ( = 0.02), whereas both RH treatments tended to improve final BW ( ≤ 0.09). Ionophores improved ADG ( ≤ 0.03) and G:F ( < 0.01) for the entire feeding period, and although LP-supplemented cattle had greater DMI for the final 32 d than both RH treatments ( ≤ 0.01), intakes for the 151-d trial were similar among treatments. Carcass weights were greater ( = 0.04) in cattle fed LP with no RH than CON, where cattle yielded an average of 12 kg more HCW. Ractopamine increased LM area in MSRH-supplemented cattle ( = 0.03) and tended to increase LM area for steers receiving LPRH ( = 0.07). Longissimus steaks of MSRH-supplemented cattle had greater WBSF values than CON ( = 0.04) after 7 d of postmortem aging and greater WBSF values than LPRH steaks after 28 d ( = 0.03). All other carcass and WBSF measurements were similar among treatments. The results of this study indicate that LP supplementation without RH may yield a performance similar to and carcass responses associated with the administration of a β-agonist. These results also suggest that performance and carcass characteristics for cattle fed LP are similar to those of cattle fed monensin throughout the feeding period.

Topics: Adrenergic beta-Agonists; Animal Feed; Animal Nutritional Physiological Phenomena; Animals; Body Composition; Cattle; Diet; Dietary Supplements; Ionophores; Male; Monensin; Phenethylamines; Trimethylsilyl Compounds

Three trials were conducted to evaluate the efficacy of laidlomycin propionate (LP) to reduce the incidence and severity of ruminal acidosis in cattle fed high-grain finishing diets. In each trial, LP was fed at 0, 6, or 12 mg/kg of diet DM. In two acidosis-challenge trials, ruminally fistulated steers were fed (DM basis) a 50% concentrate diet and then fed a 95% concentrate diet at a specific intake (2.75% BW) or steers were dosed intraruminally with a 100% concentrate diet. Laidlomycin propionate did not alter ruminal pH or total acid concentrations, but in Trial 1 the 6 mg/kg level altered (P < .10) the molar proportions of the acids, increasing total ruminal VFA and decreasing ruminal lactate. In Trial 3, a finishing trial, LP reduced (P < .10) intake day-to-day variation of individually fed steers during a 13-d adaptation period from a 65 to a 100% concentrate diet, suggesting reduced incidence of subacute acidosis. Feed intake was lower (P < .05) during the first 13 d of the trial due to LP but was not affected over the entire trial. Laidlomycin propionate improved feed efficiency (gain/feed) when calculated on a live weight basis (linear, P = .05) or carcass weight basis (linear, P = .20). Laidlomycin propionate does not prevent ruminal acidosis, but it may reduce the severity of ruminal acidosis during adaptation to a 100% concentrate diet.

Topics: Acidosis; Animal Feed; Animals; Body Composition; Body Weight; Cattle; Cattle Diseases; Diet; Hydrogen-Ion Concentration; Ionophores; Male; Monensin; Rumen; Severity of Illness Index

The synthesis of laidlomycin is described. With an established stereocontrolled synthetic route to the aldehyde 5, the known β-keto phosphonate 4 was coupled with 5 and the resulting enone was subjected to a sequential hydrogenolysis/hydrogenation and equilibration process to effect the correct spiroketalization for the natural product. The stereogenic carbons were elaborated by desymmetrization for C12, allylation for C13, vanadyl-induced epoxidation for C16, Zn(BH4)2 reduction for C17, a chiral building block for C18 and C24, Shi epoxidation for C20 and C21, Myers' alkylation for C22, and thermodynamic control for C25.

Topics: Monensin; Stereoisomerism

Polyether antibiotics such as monensin and salinomycin have been primarily used as coccidiostat and growth promoter. Since residues of these antibiotic in food may pose a health risk for sensitive individuals, their use should be carefully monitored. An immunochemical method was developed for the determination of polyether antibiotic using monoclonal antibody (Mab) produced by immunized mice. Conjugates of monensin, salinomycin and laidlomycin were prepared with bovine serum albumin (BSA), keyhole limpet haemocyanine (KLH) and ovalbumin (OVA) by mixed anhydride method and then used as immunogene to produce Mab. Eight hybridoma cell lines were isolated that produced Mabs that competed with polyether antibiotic-protein conjugates in BALB/c-SP2/0 fusion system. Two hybridoma with higher sensitivity, designated as 4G11F and 1C8F1F, were cultured for mass production and then purified from ascites fluid. Antibiotic-protein conjugates were quantitavely analyzed by using the purified Mabs through a competitive enzyme-linked immunosorbent assay (ELISA).

Topics: Animals; Anti-Bacterial Agents; Antibodies, Monoclonal; Antibody Specificity; Cell Line; Enzyme-Linked Immunosorbent Assay; Ethers; Female; Hemocyanins; Hybridomas; Immunization; Methicillin-Resistant Staphylococcus aureus; Mice; Mice, Inbred BALB C; Monensin; Ovalbumin; Pyrans; Serum Albumin, Bovine

Culture broth of a streptomycete isolate, Streptomyces sp. CS684 showed antibacterial activity on methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE). Among purified substances from the organism, CSU-1, which is active against MRSA and VRE, is a C37H62O12Na (M+, 721.3875), and identified as laidlomycin. The anti-MRSA and anti-VRE activity of CSU-1 was stronger than oxacillin and vancomycin. Phylogenetic analysis showed that strain CS684 is very similar to Streptomyces ardus NRRL 2817T, whereas the ability of Streptomyces sp. CS684 to produce laidlomycin was shown to be unique.

Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Korea; Methicillin Resistance; Monensin; Phylogeny; Soil Microbiology; Staphylococcus aureus; Streptomyces; Vancomycin Resistance

To examine the effects of ionophores on Salmonella and Escherichia coli O157:H7 in pure and mixed ruminal fluid cultures.. Four Salmonella serotypes (Dublin, Derby, Typhimurium, and Enteriditis) and two strains of E. coli O157:H7 (ATCC 43895 and FDIU 6058) were cultured in the presence of varying concentrations of ionophores (monensin, lasalocid, laidlomycin propionate, and bambermycin) in pure and mixed ruminal fluid cultures. Bacterial growth rates in pure culture were not affected (P > 0.10) by ionophores at concentrations up to 10 times the approximate rumen ionophore concentration under normal feeding regimens. Likewise, ionophores had no effect (P > 0.10) on Salmonella or E. coli CFU plated from 24-h ruminal fluid incubations. Ionophore treatment decreased (P < 0.01) the acetate : propionate ratio in ruminal fluid cultures as expected.. Ionophores had no effect on the foodborne pathogens Salmonella and E. coli O157:H7 in vitro.. The results suggest that ionophore feeding would have little or no effect on Salmonella or E. coli populations in the ruminant.

Topics: Animals; Bambermycins; Cattle; Culture Media; Escherichia coli; Food Microbiology; Ionophores; Lasalocid; Monensin; Salmonella

Escherichia coli O157:H7 and Salmonella are widely recognized as important agents of foodborne disease with worldwide distribution. The use of ionophores in feeding growing ruminants is widespread in the United States and has attracted recent interest due to the apparent temporal relationship between initial ionophore use and the increase in human E. coli O157:H7 cases. Two experiments were conducted to evaluate the effects of short-term feeding of ionophores on fecal shedding, intestinal concentrations, and antimicrobial susceptibility of E. coli O157:H7 and S. typhimurium in growing lambs. Sixteen lambs were used in each experiment, four lambs per treatment group: monensin, laidlomycin propionate, bambermycin, and a control treatment. Lambs were fed a grain and hay (50:50) diet with their respective ionophore for 12 d before experimental inoculation with E. coli O157:H7 or S. typhimurium. Animals were maintained on their respective diets an additional 12 d, and fecal shedding of inoculated pathogens was monitored daily. Lambs were killed and tissues and contents were sampled from the rumen, cecum, and rectum. No differences (P > 0.05) in fecal shedding of Salmonella or E. coli O157:H7 were observed due to treatment. Occurrence of Salmonella or E. coli in luminal contents and tissue samples from the rumen, cecum, and rectum did not differ (P > 0.05) among treatments. Feeding monensin decreased (P < 0.05) the incidence of scours in sheep infected with Salmonella compared with the other treatments. No differences in antimicrobial susceptibility were found in any of Salmonella or E. coli O157:H7 isolates. Results from these studies indicate that short-term ionophore feeding had very limited effects on E. coli and Salmonella shedding or on antimicrobial susceptibility in experimentally infected lambs.

Topics: Animals; Anti-Bacterial Agents; Bambermycins; Carrier State; Colony Count, Microbial; Diarrhea; Drug Resistance, Bacterial; Escherichia coli Infections; Escherichia coli O157; Feces; Female; Food Microbiology; Ionophores; Male; Monensin; Random Allocation; Salmonella Infections, Animal; Salmonella typhimurium; Sheep; Sheep Diseases

Two experiments, Trial 1 (in vitro) and Trial 2 (in vivo), were conducted to examine the effects of ionophores, monensin, laidlomycin, and laidlomycin propionate on whole-animal O2 consumption, organ weights, jejunal glucose absorption, and O2 utilization, as well as growth, feed and water consumption, and feed efficiency. In Trial 1, 30 male Swiss-Webster mice, 8 wk old, were used to measure the in vitro effects of each of the ionophores at concentrations of 1.62 or 16.2 mM. Six combinations of three ionophores at two concentrations resulted in a total of eight treatments. All eight treatments were exposed to jejunal rings from a single mouse for a total of 30 observations per treatment. Jejunal rings were exposed to each ionophore treatment for 15 min. Laidlomycin propionate (16.2 mM) decreased (P < 0.02) glucose absorption, as estimated by H3-3-O-methyl glucose uptake compared with all other treatments, whereas laidlomycin propionate (1.62 mM) increased (P = 0.032) jejunal DM content compared with 16.2 mM laidlomycin propionate. In Trial 2, 40 5-wk-old mice were allotted into four treatments--control and 16.2 mM each of monensin, laidlomycin, and laidlomycin propionate--for a total of 10 observations per treatment. Ionophores were administered via the drinking water for 14 d. No ionophore treatment had any effect on whole-mouse O2 consumption. Monensin increased (P = 0.004) stomach size and decreased (P = 0.049) the efficiency of BW gain compared with controls. Laidlomycin propionate decreased (P = 0.032) the percentage of whole jejunum oxygen consumption due to oubain-sensitive respiration compared with control. The efficiency of intestinal glucose absorption was not changed due to treatment in either trial. Under the conditions of these studies, monensin, laidlomycin, and laidlomycin propionate had minimal and inconsistent effects on jejunal function and energy utilization in mice. This investigation suggests that changes in the energetic requirements of animals treated with ionophores are not an issue in animal production.

Topics: Animals; Biological Transport; Dose-Response Relationship, Drug; Energy Metabolism; Glucose; In Vitro Techniques; Intestinal Absorption; Ionophores; Jejunum; Male; Mice; Monensin; Organ Size; Oxygen Consumption; Random Allocation

Tarentaise heifers fitted with a rumen cannula (539 +/- 7.5 and 487 +/- 15.7 kg avg initial BW in Exp. 1 and 2, respectively) were used in two Latin square metabolism experiments having 2 x 2 factorial treatment arrangements to determine the effects of supplementation with Aspergillus oryzae fermentation extract (AO) or laidlomycin propionate (LP) on intake, digestion, and digestive characteristics of Neotyphodium coenophialum-infected (IF) or uninfected (FF) tall fescue (Festuca arundinacea) hay diets consumed ad libitum. Heifers were housed in individual stanchions in a metabolism facility with ambient temperatures controlled to range between 26.7 and 32.2 degrees C daily. Total feces and urine were collected for 5 d following a 21-d dietary adaptation period. In situ DM and NDF disappearance and ruminal fermentation characteristics were also determined. In Exp. 1, DMI was 24% greater (P < 0.01) by heifers offered FF than by those offered IF (6.7 vs 5.4 kg/d). Heifers fed 2 g/d AO tended (P = 0.09) to consume 4% more DM than those fed a diet without AO. Degradable DM and NDF fractions of IF were greater (P < 0.01) than those of FF, but AO supplementation did not affect situ disappearance (P > or = 0.42). In Exp. 2, DMI was 18.9% greater (P < 0.01) by heifers offered FF than by those offered IF (6.6 vs 5.5 kg/d). Heifers fed LP (50 mg/d) consumed 10.6% less (P < 0.05) DM than those not fed LP (5.7 vs 6/5 kg/d). Digestibility of NDF tended to be greater (P = 0.08) and digestibility of ADF was greater (P < 0.05) from FF than from IF. Conversely, apparent N absorption (%) was greater (P < 0.05) from IF than from FF. Heifers fed LP had lower (P < 0.05) ADF digestibility than those not fed LP. In situ degradable DM and NDF fractions were greater (P < 0.01) from IF than from FF. Diets supplemented with LP had higher (P < 0.01) indigestible DM and NDF fractions than those without LP. Propionic acid and total VFA concentrations were greater (P < 0.05) from heifers offered FF than from those offered IF and from heifers fed LP than from those not fed LP. Therefore, it appears the major effect of N. coenophialum was a reduction in forage intake and total-tract fiber digestibility in certain situations. Response to the feed additives was similar whether heifers were offered IF or FF and no evidence was apparent that either additive would improve performance substantially by animals consuming low-quality fescue hay diets.

Topics: Animal Feed; Animals; Aspergillus oryzae; Cattle; Dietary Fiber; Dietary Supplements; Digestion; Drinking; Eating; Fatty Acids, Volatile; Female; Fermentation; Hypocreales; Monensin; Poaceae; Rumen

We conducted two experiments to evaluate the effect of the ionophore laidlomycin propionate (LP) on steer performance and ruminal N metabolism. Experiment 1 was a 91-d growth study evaluating the growth and ruminal characteristics of steer calves consuming supplemental LP. Steers (n = 96; 255 +/- 3 kg; four steers/pen; six pens/treatment) were used in a randomized complete block design with a 2 x 2 factorial arrangement of treatments consisting of two levels of dietary CP (formulated to be 10.5 and 12.5% of DM) with and without LP (11 mg/kg diet DM). Ruminal fluid was collected via stomach tube on d 91 from one steer randomly selected from each pen. No CP x LP interactions were observed with performance data (P > .64). Final weight and total gain were greater (P < .07) for 12.5% CP and LP compared with 10.5% CP and control steers, respectively. Also, DMI was increased (P = .08) with 12.5% CP but not with LP supplementation (P = .36). In addition, ADG and gain:feed ratio were greater (P < .03) for both 12.5% CP and supplemental LP. Ruminal NH3 N concentration was greater (P < .09) with 12.5% CP and LP. Total VFA concentration and molar proportion of acetate were not affected by treatment (P > .11). However, propionate concentration was increased (P < .09) with 12.5% CP and LP, and acetate:propionate was lower (P = .02) with LP supplementation. In Exp. 2, six steers were used in a replicated 3 x 3 Latin square design to compare ruminal fermentation and protein degradation in steers without ionophore feeding or adapted to LP or monensin. In vitro deamination of amino acids by adapted ruminal microbes was also assessed. Ionophore supplementation decreased (P = .07) ruminal NH3 N concentration compared with control steers, and LP increased (P = .02) ruminal NH3 N compared with monensin. Molar proportion of acetate was decreased (P = .02) and propionate increased (P = .01) with ionophore treatment. Consequently, ionophore supplementation depressed the acetate:propionate ratio (P = .01). In situ degradation rate of soybean meal (SBM) CP was greater (P = .09) with ionophore treatment, but estimates of SBM undegradable intake protein were not altered by treatment (P > .25). Microbial specific activity of net NH3 N release and alpha-amino N degradation were decreased (P < .04) with ionophores. Based on this study, LP and monensin did not affect the extent of ruminal degradation of SBM CP but decreased amino acid deamination.

Topics: Animal Feed; Animals; Cattle; Dietary Proteins; Male; Monensin; Nitrogen; Rumen; Weight Gain

Two isonitrogenous diets (12.5% CP) containing 20 (20% NPN) or 40% (40% NPN) of the N as nonprotein N were evaluated with 0 or 10 mg laidlomycin propionate (LP)/kg in a 2 x 2 factorial arrangement. Changes in dietary NPN:N ratio were developed by partial substitution of urea N for fish meal N. In Trial 1, four Holstein steers (349 kg) with cannulas in the rumen and proximal duodenum were used to evaluate treatment effects on digestive function. Total tract OM digestion was slightly greater (1.2%, P < .10) for diets containing 20% of N as NPN, due to greater (3.4%, P < .05) postruminal OM digestion. Supplemental LP decreased passage of microbial N to the small intestine (7.4%, P < .10) and ruminal degradation of dietary CP (DIP, 8.1%, P < .10). Decreasing the NPN:N ratio decreased microbial N flow to the small intestine (7.5%, P < .10) and DIP (15%, P < .01) and increased (6%; P < .05) the flow of indispensable amino acids to the small intestine. Supplemental LP increased (P < .10) ruminal pH. There were no treatment effects (P > .10) on ruminal molar proportions of acetate or propionate. In Trial 2, 120 Holstein steers (122 kg) were used to evaluate treatment effects on growth performance. Decreasing the NPN:N ratio increased ADG (P < .01) by 36, 40, and 16%, respectively, for the initial three 56-d periods of the trial. Overall, ADG was 17% greater (P < .01) for cattle consuming diets containing 20 vs 40% NPN. Decreasing the NPN:N ratio increased (P < .01) gain efficiency by 17 and 14%, respectively, for the initial two 56-d periods. Overall, gain efficiency was 6% greater (P < .01) for diets containing 20% NPN. Dietary NPN:N ratio did not influence (P > .10) the NE value of diets. Supplemental LP did not affect DMI (P > .10) but increased ADG (6%, P < .01) and gain efficiency (5%, P < .05) and decreased (11%, P < .05) the maintenance energy requirements. Protein nutrition limited growth performance of calves receiving the 20% NPN diets during the initial 112 d of the trial. With the 40% NPN diets, protein nutrition limited growth performance throughout most of the trial (d 1 to d 224). We conclude that LP will enhance daily weight gain and gain efficiency of calf-fed Holstein steers. Conventional urea-based diets will not diminish response to LP, although they may not meet the metabolizable amino acid requirements of calf-fed Holsteins during the first three-quarters of the feeding period.

Topics: Amino Acids; Animal Nutritional Physiological Phenomena; Animals; Cattle; Dietary Proteins; Dietary Supplements; Digestion; Intestine, Small; Male; Meat; Monensin; Rumen

Topics: Anti-HIV Agents; Gene Expression; HIV-1; Monensin; RNA, Messenger; Viral Envelope Proteins; Virus Replication

The objective of this study was to compare the effects of laidlomycin propionate and monensin on the in vitro fermentation of ground corn, Trypticase, or alfalfa hay by mixed ruminal microorganisms. Ruminal fluid was collected from two steers fed 9.27 kg DM of a high-concentrate (62.2% ground corn and 17.4% cottonseed hulls) diet per day and composited. In the first study, no ionophore was included in the diet; the diet in the second study contained 11.1 g of laidlomycin propionate per ton of feed. The animals were allowed an adjustment period of 14 d for each dietary treatment before samples were collected. When ruminal fluid from unadapted animals was used, both monensin and laidlomycin propionate decreased (P<.05) CH4 concentration and the acetate:propionate ratio with ground corn and alfalfa hay. Monensin reduced (P<.05) in vitro dry matter disappearance of alfalfa and increased (P<.05) final pH in the ground corn and alfalfa hay fermentations. Both laidlomycin propionate and monensin decreased (P<.05) concentrations of acetate, propionate, isobutyrate, isovalerate, CH4, and NH3 in Trypticase fermentations. When ruminal fluid from adapted animals was used, both ionophores still reduced the concentrations of most fermentation products. However, there was generally less inhibition compared with fermentations inoculated with unadapted mixed ruminal microorganisms. In the presence of 5 mM maltose, mixed ruminal bacteria produced high concentrations (10 to 11 mM) of lactate, and addition of both ionophores to these fermentations was effective in reducing (P<.05) lactate production. In conclusion, laidlomycin propionate alters the mixed ruminal microorganism fermentation in a manner similar to monensin, but, at the concentrations used in this study, monensin seemed to be a more potent inhibitor.

Topics: Animal Feed; Animals; Anti-Bacterial Agents; Cattle; Fermentation; Gram-Positive Bacteria; Ionophores; Male; Medicago sativa; Monensin; Peptides; Rumen; Zea mays

We used 216 Holstein steers (151 kg) in a 262-d trial to evaluate the influence of dietary magnesium level (.19, .25, and .32%) and laidlomycin propionate (LP; 0 vs 11 ppm, air-dry basis) on growth performance and NE value of the diet. During the initial 112 d of the trial, LP increased (P < .01) ADG (6.3%) and feed efficiency (4.2%). From d 112 until slaughter, LP increased (P < .05) ADG (9.7%) and feed efficiency (4.5%). Across the 262-d feeding period, LP supplementation enhanced (P < .01) ADG (8.9%) and feed efficiency (6.3%). There was an interaction (P < .05) between dietary Mg and LP on NE value of the diet. The enhancement in NE value of the diets owing to LP with .19, .25, and .32% dietary Mg were .5, 3.0, and 5.9%, respectively. Six Holstein steers (302 kg) were used in a 6 x 6 Latin square experiment to evaluate treatment effects on characteristics of ruminal and total tract digestion. There were no treatment interactions (P > .10) on site and extent of digestion of OM, starch, and N. Supplemental Mg increased (quadratic effect, P < .10) ruminal OM digestion. Neither LP nor dietary Mg level affected (P > .10) ruminal digestion of starch and feed N. Supplemental LP decreased (15%, P < .05) ruminal microbial efficiency. Total tract digestion of OM and N increased (linear effect, P < .01) with increasing dietary Mg level. There were interactions between LP and dietary Mg level on ruminal soluble-Mg concentration (linear effect, P < .01) and Mg absorption (quadratic effect, P < .05). Apparent total tract Mg digestion increased owing to LP (P < .01) and dietary Mg level (linear effect, P < .01). There were no treatment effects (P > .10) on ruminal pH. Dietary Mg level did not influence (P > .10) ruminal VFA concentrations or molar proportions. Supplemental LP increased (14%; P < .10) total ruminal VFA concentration but did not affect (P > .10) VFA molar proportions. We conclude that LP will increase daily weight gain and feed efficiency of calf-fed Holstein steers and that this response may be enhanced by increasing dietary Mg level.

Topics: Adipose Tissue; Animal Feed; Animals; Cattle; Cattle Diseases; Diet; Dietary Supplements; Digestion; Eating; Liver Abscess; Magnesium; Male; Meat; Monensin; Rumen; Weight Gain

The objective of this study was to compare the effects of laidlomycin propionate and monensin on cell growth, glucose fermentation, and glucose uptake in Streptococcus bovis strain JB1 and Selenomonas ruminantium strain HD4. Experiments were also conducted to compare the effects of both ionophores on sodium-dependent serine transport and cell yield in S. bovis. Batch cultures (500 mL) of each bacterium were grown on 3.6 g/L D-glucose in semidefined medium and treated with either 5 ppm monensin or 2 ppm laidlomycin propionate (n=2). Cell growth was monitored by measuring optical density at 600 nm (OD600). Glucose and L-lactate concentrations were measured using coupled enzyme assays. In S. bovis, both monensin and laidlomycin propionate decreased OD600, glucose utilization, and L-lactate production. Neither ionophore had any effect on glucose utilization by S. ruminantium. [14C]Glucose uptake between 5 and 30 min by both bacteria was not altered by either ionophore. Sodium-dependent [14C]serine uptake by S. bovis was inhibited by monensin but not laidlomycin propionate. When S. bovis was grown in glucose-limited continuous culture (dilution rate=.10 h(-1)) at extracellular pH 6.7, increasing concentrations of both ionophores decreased bacterial yield, and both ionophores were more potent at an extracellular pH of 5.7. However, monensin was a more potent inhibitor than laidlomycin propionate at pH 6.7 and 5.7. Collectively, these results suggest that the ionophore laidlomycin propionate inhibits the Gram-positive bacterium S. bovis in a manner similar to that of monensin, but, at the concentrations used in this study, laidlomycin propionate seems to be less potent than monensin in inhibiting serine uptake and cell yield.

Topics: Animals; Biological Transport; Fermentation; Glucose; Hydrogen-Ion Concentration; Ionophores; Monensin; Rumen; Selenomonas; Serine; Streptococcus bovis

A metabolism trial and a growth-performance trial were conducted to evaluate the interaction of dietary magnesium level (.18 vs .32%) and laidlomycin propionate (LP) (0 vs 11 ppm, airdry basis) on utilization of a high-energy finishing diet by feedlot steers. There were no treatment effects (P > .10) on ruminal and total tract digestion of OM and ADF. However, there was an interaction (P < .05) between magnesium level and LP on ruminal starch digestion. With LP, magnesium level had no effect on ruminal starch digestion. Without LP, increasing dietary magnesium decreased ruminal starch digestion. Laidlomycin propionate decreased (P < .10) ruminal degradation of feed N (13.9%) and microbial efficiency (8.9%) and increased (P < .10) total tract N digestibility. There were no treatment interactions (P > .10) on site and extent of magnesium digestion. Magnesium absorption decreased with increased dietary magnesium (11.6%, P < .05) and LP (16.9%, P < .01). There was an interaction (P < .10) of treatments on postabomasal calcium absorption. With the low magnesium level LP increased calcium absorption, whereas with the higher magnesium level LP decreased calcium absorption. There was an interaction between magnesium level and LP on ruminal pH at .5 h (P < .05) and 8 h (P < .10) after feeding. In general, ruminal pH increased with LP supplementation at the lower magnesium level and decreased with LP supplementation at the higher magnesium level. There were interactions (P < .05) between magnesium level and LP on ruminal VFA molar proportions and estimated methane production. At the lower magnesium level, the effects of LP on VFA molar proportions were small. At the higher magnesium level, however, LP decreased (13.2%) molar proportions of acetate and increased (26.5%) molar proportions of propionate. There was an interaction (P < .05) between magnesium level and LP on feed intake. At the lower magnesium level, LP increased (3.9%) feed intake; at the higher magnesium level LP decreased (4.4%) intake. Increasing dietary magnesium enhanced ADG (6%, P < .10). Both magnesium and LP enhanced (2.8%, P < .10) diet NE, and this effect was strictly additive. There were no effects (P > .10) of magnesium level or LP on plasma magnesium concentrations. Plasma calcium concentrations were decreased by supplemental magnesium (15.2%, P < .05) and increased by LP (16.0%, P < .01). We conclude that dietary magnesium levels modulate the metabolic and performance responses of feedlot

Topics: Absorption; Animals; Body Composition; Calcium; Cattle; Diet; Digestion; Dose-Response Relationship, Drug; Drug Interactions; Food, Fortified; Hydrogen-Ion Concentration; Magnesium; Male; Monensin; Rumen

Two hundred eighty-eight beef steers (British x Continental x Brahman) were fed a 90% concentrate diet containing either no ionophore (control), laidlomycin propionate at either 6 or 12 mg/kg of dietary DM, or monensin plus tylosin (31 and 12 mg/kg of DM, respectively). Neither of the two levels of laidlomycin propionate nor monensin plus tylosin affected (P greater than .10) ADG or feed:gain ratio. Monensin plus tylosin reduced (P less than .01) daily DMI for the 161-d trial period compared with the other three treatments. Laidlomycin propionate at 6 mg/kg increased (P less than .05) DMI relative to the control, laidlomycin propionate at 12 mg/kg, and monensin plus tylosin diets during the 2nd wk of the trial and from d 57 to 84. Treatments did not affect carcass measurements. In a second experiment, 12 ruminally cannulated steers were fed diets containing no ionophore or laidlomycin propionate at either 6 or 12 mg/kg of DM. Samples were obtained for two consecutive days while the dietary concentrate level was 75%, after which the diet was switched abruptly to 90% concentrate, and samples were collected on several days during a 21-d period. The rate at which steers consumed their daily allotment of feed was not altered markedly by laidlomycin propionate. Likewise, laidlomycin propionate did not affect total ruminal VFA concentrations or proportions. Ruminal concentrations of D-lactate were reduced (P less than .10) by 6 but not by 12 mg/kg of laidlomycin propionate.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Ammonia; Animal Feed; Animals; Body Weight; Cattle; Eating; Fatty Acids, Volatile; Fermentation; Hydrogen-Ion Concentration; Male; Monensin; Rumen; Tylosin

3H-26-deoxylaidlomycin (I) was fed to growing cultures of Streptoverticillium olivoreticuli IMET 43782 producing both I and laidlomycin (II). The incorporation of labelled I into laidlomycin II was neglible showing a role of I as precursor of II to be at variance. Otherwise, a measurable conversion was achieved by the use of sonicated 48 hrs mycelium suggesting that final oxidation of I to II could be mediated by a compartmentized oxidoreductase.

Topics: Fermentation; Monensin; Oxidation-Reduction; Streptomycetaceae

One thousand twenty steers and heifers were used in six feeding trials to examine the influence of laidlomycin propionate on feedlot performance and to determine the most efficacious dietary concentrations of that ionophore. Cattle were fed diets ranging in energy content from 1.08 to 1.49 Mcal NEg/kg of DM. Laidlomycin propionate improved rate of gain and feed conversion in both steers and heifers. Improvements in performance were not evident when laidlomycin propionate was fed at only 3 mg/kg. However, both average daily gain and feed conversion were improved by laidlomycin propionate within the range of 6 to 12 mg/kg of DM (P less than .001). Feed consumption was not substantially affected by inclusion of laidlomycin propionate in the diet. Improvements in ADG and feed conversion were greater on lower-energy diets than on higher-energy diets, but both these performance characteristics were improved regardless of the type of diet fed. Average daily gain was maximized with laidlomycin propionate at 6 mg/kg, whereas improvements in feed conversion were sustained through 12 mg/kg. Carcasses of cattle fed diets containing 6 to 12 mg/kg of laidlomycin propionate weighed 7.3 kg more (P less than .001) than carcasses of cattle fed the control diets. Yield grade and quality grade were not affected by laidlomycin propionate (P greater than .05).

Topics: Animal Feed; Animals; Cattle; Digestion; Dose-Response Relationship, Drug; Eating; Energy Intake; Female; Male; Monensin; Weight Gain

The capacity of laidlomycin (I) and the new 26-deoxylaidlomycin (II) to facilitate passive fluxes of cations through a layer of organic solvent (CHCl3/n-heptane) was estimated in comparison to monensin A (III). While II displayed a 10fold higher transport rate for sodium as compared to calcium, laidlomycin (I) was distinguishable by mediating approx. 100 times lower conveyance of the divalent cations.

Topics: Anti-Bacterial Agents; Biological Transport; Calcium; Molecular Structure; Monensin; Sodium

We have studied the effect of two carboxylic ionophores, monensin and laidlomycin, on the replication of measles virus in KB cells. The yield of infectious virus was markedly depressed at the concentrations of the ionophores which had no effect on overall viral protein synthesis. The ionophores selectively blocked the migration of hemagglutinin (H) glycoprotein from Golgi apparatus to the cell surface. As a result, H glycoprotein is prevented from being converted from incompletely glycosylated form to the mature form. The inhibitory effect on the transport and glycosylation of H was reversed, although gradually, upon the removal of the ionophores.

Topics: Anti-Bacterial Agents; Cell Transformation, Viral; DNA Replication; Fluorescent Antibody Technique; Furans; Hemagglutinins, Viral; Humans; KB Cells; Kinetics; Measles virus; Monensin; Virus Replication

Topics: Animals; Anti-Bacterial Agents; Chickens; Coccidiostats; Monensin; Phenylcarbamates; Propionates

The polyether ionophore, laidlomycin, and several acyl derivatives were tested for their ability to favorably alter fermentation in two types of in vitro rumen fluid incubations. Dose response data were used to estimate the concentration (microgram/ml) of each ionophore required for either 50% maximal enhancement of propionic acid production (EC50) or 50% maximal inhibition of lactic acid production (IC50). Acylation of laidlomycin with straight-chain acyl groups from two to 12 carbon atoms tended to improve the potency of laidlomycin, especially for inhibiting lactic acid production. Comparative incubations using laidlomycin butyrate, laidlomycin and monensin indicated that both laidlomycin butyrate (EC50 = .3) and monensin (EC50 = .7) were more potent enhancers of propionic acid production than laidlomycin (EC50 = 2.0; P less than .05). Laidlomycin butyrate (IC50 = .3) was a more potent inhibitor of lactic acid production than either laidlomycin (IC50 = 1.8) or monensin (IC50 = 1.3; P less than .05). In a continuous culture experiment, three chemostats each received laidlomycin butyrate or monensin at the rate of .5 micrograms/ml of effluent/d while two flasks remained as control. Propionic acid production was increased (P less than .01) from 22.9 mmol/d in control flasks to 30.5 and 33.7 mmol/d in flasks treated with monensin and laidlomycin butyrate, respectively. Concomitant decreases in production rates of acetic, butyric and isovaleric acids also were observed (P less than .01). Thirty-six steers were used in a 56-d trial to evaluate effects of laidlomycin butyrate and monensin, at 33 mg/kg of diet, on feedlot performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Anti-Bacterial Agents; Body Weight; Cattle; Chemical Phenomena; Chemistry; Fatty Acids, Volatile; Female; Fermentation; Furans; Lactates; Lactic Acid; Male; Models, Biological; Monensin; Rumen

Topics: Acylation; Animals; Anti-Bacterial Agents; Chemical Phenomena; Chemistry; Chickens; Coccidiosis; Esters; Furans; Magnetic Resonance Spectroscopy; Monensin; Structure-Activity Relationship

Topics: Anti-Bacterial Agents; Bacteria; Chemical Phenomena; Chemistry, Physical; Ethers; Monensin; Mycoplasma; Streptomyces