Levels Of Monensin Research Articles

Evaluation of increasing levels of condensed tannin extracted from Acacia mearnsii on performance, carcass traits, meat quality, methane emission, and health of finishing Nellore bulls

The objective of this study was to evaluate the impact of increasing levels of condensed tannin extracted from Acacia mearnsii on the performance, carcass traits, meat quality, methane (CH4) emissions, and health of finishing Nellore bulls in a feedlot system. Eighty 20-month-old Nellore bulls (426.7 ± 24.46 kg of body weight (BW)) were individually housed with ad libitum access to feed and water. The study followed a completely randomized design with five treatments, each consisting of sixteen animals. Treatments included a negative control (no additives), 3 levels of tannin (0.8, 1.6, and 3.2 g of tannin/kg DM; Tanfeed®, Tanac Company), and a positive control (28 mg/kg DM monensin; Elanco®). Animals underwent a 21-day adaptation period with three step-up adaptation diets before entering the 89-day finishing phase. The adaptation dietary program consisted of ad libitum feeding with 3 adaptation diets over 21 days, in which the finishing phase lasted 89 days. The adaptation dietary program consisted of ad libitum feeding of 3 step-up adaptation diets for 3 weeks (21 d). The concentrate level of the diet (DM basis) increased from 40 % to 50 % in week 1, 50–56 % in week 2, and 56–75 % in week 3 (finishing diet). The experimental period (adaptation + finishing phases) lasted 110 d. The diet was formulated to meet the requirements while considering an average daily gain (ADG) of 1.6 kg/d. Enteric CH4 emissions were estimated using the sulfur hexafluoride (SF6) tracer gas technique. Performance and carcass traits, except for shear force and ash in meat, were not affected by increasing levels of dietary tannin or monensin (P>0.10). Regression analysis indicated a quadratic effect on shear force, with the lowest value observed at 1.6 g/kg DM of dietary tannin inclusion (P=0.05). Ash in meat increased quadratically with tannin inclusion, peaking at 1.6 g/kg DM of tannin addition, differing from monensin-treated bulls (P=0.05). However, CH4 emission as g/d decreased quadratically with increasing tannin levels (P<0.01), reaching the lowest emission at 0.8 g/kg DM of tannin inclusion, differing from monensin treatment (P<0.01). Also, CH4 emission intensity (g/kg DMI at CH4 sampling period) tended to decrease quadratically with tannin inclusion (P=0.09), with the lowest intensity observed at 0.8 g/kg DM of tannin inclusion, but not differing from monensin-treated bulls. Liver abscess and rumen scores were not impacted by tannin level in the diet (P = 0.26 and 0.19, respectively); however, the odds of having a liver (0 to A+ scale) and ruminitis score (0-10 scale) of 0 was 0.178 less for monensin-treated bulls compared to control and 0.224 less for monensin than tannin-treated bulls at 3.2 g/kg DM of inclusion, respectively. Overall, condensed tannin effectively reduced meat shear force and CH4 emissionin finishing Nellore bulls in a dose-dependent manner, without detrimental effects on performance.

Diet and monensin influence the temporal dynamics of the rumen microbiome in stocker and finishing cattle

BackgroundStocker cattle diet and management influence beef cattle performance during the finishing stage, but knowledge of the dynamics of the rumen microbiome associated with the host are lacking. A longitudinal study was conducted to determine how the feeding strategy from the stocker to the finishing stages of production affects the temporal dynamics of rumen microbiota. During the stocker phase, either dry hay or wheat pasture were provided, and three levels of monensin were administrated. All calves were then transported to a feedlot and received similar finishing diets with or without monensin. Rumen microbial samples were collected on d 0, 28, 85 during the stocker stage (S0, S28 and S85) and d 0, 14, 28, 56, 30 d before slaughter and the end of the trial during the finishing stage (F0, F14, F28, F56, Pre-Ba, and Final). The V4 region of the bacterial 16S rRNA gene of 263 rumen samples was sequenced.ResultsHigher alpha diversity, including the number of observed bacterial features and the Shannon index, was observed in the stocker phase compared to the finishing phase. The bacterial amplicon sequence variants (ASVs) differentiating different sampling time points were identified. Dietary treatments during the stocker stage temporally impact the dynamics of rumen microbiota. For example, shared bacteria, including Bacteroidales (ASV19) and Streptococcus infantarius (ASV94), were significantly higher in hay rumen on S28, S85, and F0, while Bacteroidaceae (ASV11) and Limivicinus (ASV15) were more abundant in wheat. Monensin affected rumen microbial composition at a specific time. Transportation to feedlot significantly influenced microbiome structure and diversity in hay-fed calves. Bacterial taxa associated with body weight were classified, and core microbiotas interacted with each other during the trial.ConclusionsIn summary, the temporal dynamics of the rumen microbiome in cattle at the stocker and finishing stage are influenced by multiple factors of the feeding strategy. Diet at the stocker phase may temporarily affect the microbial composition during this stage. Modulating the rumen microbiome in the steers at the stocker stage affects the microbial interactions and performance in the finishing stage.

Effect of monensin on milk production efficiency and milk composition in lactating dairy cows fed modern diets

Since the US Food and Drug Administration's approval of monensin in 2004, significant nutritional advances have been made to increase feed efficiency and milk fat production. Recent evidence suggests monensin's adverse effect on milk fat percentage may be absent when diets are formulated to address known diet-induced milk fat depression risk factors. Thus, study objectives were to evaluate effects of monensin level on dry matter intake (DMI), milk production and composition, and efficiency of high-producing cows fed diets formulated to optimize milk fat. Ninety-six lactating Holstein cows (36 primiparous, 60 multiparous; 106 ± 17 d in milk [DIM]) were balanced by parity, DIM, and milk production and were randomly assigned to 1 of 12 pens with 8 cows per pen. All cows received 11 g/t monensin for 5 wk after which pens received 1 of 4 dietary treatments (n = 3) formulated to provide 0 (CON), 11 (R11), 14.5 (R14.5), or 18 (R18) g/t monensin for 9 wk. The basal diet was 54% forage, 27% NDF, 29% starch, and 2.3% rumen unsaturated fatty acid load. Pen was the experimental unit and data were analyzed using the Fit Model Procedure of JMP. Effects of treatment, time, and treatment × time interaction were included as fixed effects and pen as a random effect. Least squares means were determined and linear and quadratic contrasts were tested. Dry matter intake tended to decrease linearly with increasing monensin dose. Milk yield, fat percentage, and protein percentage and yield were unaffected by treatment while fat yield was quadratically increased. Milk de novo and mixed fatty acid (FA) yields (g/d) increased quadratically with monensin whereas preformed FA linearly decreased during the experimental period. Energy-corrected milk (ECM) was quadratically increased by monensin. Milk urea nitrogen concentrations increased linearly with increasing monensin dose. Monensin linearly increased feed efficiency (ECM/DMI, 3.5% fat-corrected milk/DMI, and solids-corrected milk/DMI). Body weight gain did not differ between treatments. Estimated dietary energy tended to increase linearly with increasing monensin level. These data suggest monensin improves component-corrected milk production efficiency, estimated dietary energy, and does not negatively affect milk fat percentage or FA profile.

A newly developed bacteriocin like substance to replace monensin in diets of lactating ewes.

The aim of the present experiment was to evaluate the effect of feeding a newly produced bacteriocin-like substance (BLS) as a replacement formonensin in the diets of lactating ewes. In Experiment 1, the effects of BLS or monensin at 0.5, 1, 1.5, and 2g/kg diet on in vitro ruminal fermentation were compared. In Experiment 2, 30 multiparous Barki ewes were divided into three treatments in a complete randomized design for 90 days. The ewes were fed a basal diet without supplementation or supplemented with monensin or BLS at 0.5g/kg DM diet. In Experiment 1, the highest levels of BLS and monensin decreased gas production, while all levels of additives linearly decreased methane production. In Experiment 2, BLS increased nutrient digestibility. Additives increased ruminal total and individual volatile fatty acids and decreased ruminal ammonia-N. The BLS increased serum albumin and decreased the concentrations of serum liver enzymes, while both additives increased serum glucose and decreased urea-N. Additives increased daily production of milk, while the BLS treatment increased the feed efficiency. It is concluded that dietary inclusion of BLS at 0.5g/kg DM for lactating ewes is recommended to replace monensin.

Tetracyclines in pasteurized milk commercialized in São Paulo, Brazil: occurrence and dietary risk assessment based on single and combined exposure with polyether ionophores

ABSTRACT Tetracyclines and polyether ionophores are veterinary drugs frequently used in animals reared for food production. Despite the benefits, residues can be harmful for human health if levels are higher than those considered safe. The aim of this study was to evaluate, by LC-MS/MS, tetracyclines residues in pasteurised milk samples marketed in São Paulo state, Brazil and estimate the exposure of the adult/adolescent/children population. Within the eight antibiotics monitored two were detected, tetracycline and 4-epitetracycline, found in 22.5% and 12.5% of the samples, respectively. Since the same samples had been previously tested for polyether ionophore residues, risk assessment based on dietary exposure to tetracyclines when considered individually and in combination with the ionophores was performed. The daily intakes were below the acceptable daily intake (ADI) for tetracycline. Considering the levels of monensin reported in a previous study, the combined exposure with tetracycline and 4-epi-tetracycline also indicated low potential health concerns.

Monensin and concentrate supplementation level affect forage ruminal measurements and forage in situ disappearance of bermudagrass fed to beef cattle

The objective of this study was to evaluate the effects of monensin and concentrate supplementation levels on bermudagrass (Cynodon dactylon) in situ disappearance and ruminal measurements. The experiment was conducted in Ona, Florida, and treatments were the factorial arrangement of 2 supplementation levels [0.4 (low) or 4 kg/d (high)] and 2 monensin levels (0 or 20 mg/kg of the DMI) distributed in a Latin square design. The supplement was 17.1% CP and 79.1% TDN. Steers receiving the higher supplementation level had greater (P = 0.01) total DMI (1.4 vs. 1.0 ± 0.1% BW), but there was no difference in forage DMI (P = 0.72, mean = 1.0 ± 0.1% BW). Monensin did not affect total DMI or forage DMI (P ≤ 0.74). There was a monensin × supplementation level interaction on ruminal propionate concentration. The interaction occurred because there was no effect (P = 0.64) of monensin with low supplementation (mean = 12 ± 1.2 mol/100 mol); however, monensin increased (P = 0.01) propionate on the high supplementation level (19 vs. 15 ± 1.5 mol/100 mol). There was no effect (P > 0.05) of monensin on potential DM, CP, and NDF disappearance; however, greater supplementation level increased (P < 0.03) potential DM and NDF disappearance. Monensin did not change forage disappearance measurements but increased ruminal propionate concentrations in steers receiving higher supplementation level. Higher supplementation level was effective to increase total DMI and forage DM and NDF disappearance.

Encapsulated nitrate replacing soybean meal in diets with and without monensin on in vitro ruminal fermentation

This study assessed the association between encapsulated nitrate product (ENP) and monensin (MON) to mitigate enteric methane (CH4) in vitro and possible effects on ruminal degradability, enteric fermentation characteristics, and microbial populations. Six treatments were used in randomized complete design in a 2×3 factorial arrangement with two levels of MON (0 and 2.08 mg/mL of buffered rumen fluid) and three levels of ENP (0, 1.5 and 3.0%). The substrate consisted of 50% Tifton-85 hay and 50% concentrate mixture (ground corn and soybean meal). ENP replaced soybean meal to achieve isonitrogenous diets (15% CP). No ENP×MON interaction was observed for any measured variable (P > 0.05) except for the relative abundance of F. succinogenes (P = 0.02) that linearly increased in diets with MON when ENP was added. The ENP addition decreased CH4 production (P < 0.01) without affecting (P > 0.05) truly degraded organic matter nor the relative abundance of methanogens. Hydrogen production was reduced with MON (P = 0.04) and linearly decreased with ENP inclusion (P = 0.02). We concluded that use of nitrate is a viable strategy for CH4 reduction, however, no additive effect of ENP and MON was observed for mitigating CH4 production.

Effects of a blend of cinnamaldehyde-eugenol and capsicum (Xtract® Ruminant 7065) and ionophore on performance of finishing Holstein steers and on characteristics of ruminal and total tract digestion

ABSTRACT Our objective was to evaluate the interaction of supplemental essential oils (EO) and monensin (MON) on performance and digestion. Two levels of EO (0 vs 0.011% Xtract®) and two levels of MON (0 vs 33 mg/kg) were evaluated in a 2 × 2 factorial arrangement. Treatment effects on 216-d growth performance were evaluated in 96 Holstein steers. Supplemental MON enhanced (P ≤ 0.05) ADG, DMI and gain efficiency. Without EO, MON improved (P < 0.05) gain efficiency and dietary NE. However, in diets with both EO and MON, gain efficiency and dietary NE were not different from non-supplemented diets (interaction, P < 0.10). Treatment effects on characteristics of digestion were evaluated using four cannulated steers. Ruminal digestion of OM and N were greater for MON alone. Ruminal digestion of OM and N were similar for EO-alone vs MON-alone, but not by the combination of the two (interaction P ≤ 0.02). Supplemental MON enhanced (P ≤ 0.02) total tract digestion of OM and N. We conclude that supplemental EO-alone or MON-alone may enhance gain efficiency and NE value of the diet. However, effects are negated when fed in combination. Treatment effects on performance are consistent with digestion measures.

Effect of level of monensin on rumen fermentation characteristics in Awassi lambs

The current study was conducted in the Animal field of the Department of Animal Production – College of Agriculture - Al-Qasim Green University for the period from 10/10/2019 to 19/1/2020 to investigate the effect of addition of monensin at levels of 15, 30 and 45 mg/kg concentrate on growth performance of Awassi lambs. First treatment in which lambs were fed concentrate diet without addition of monensin was considered the control treatment. Sixteen male Awassi lambs were used with an average weight of 24.85 and 4-6 months of age. The lambs were randomly distributed to the experimental treatments, four lambs per each using the individual feeding in the cages. The concentrate diet was offered at a level of 2.75% of the body weight at 2 meals, morning and evening meals, while the ground wheat straw was offered at free choice. Results revealed no significant effect of level of monensin on pH values, whereas ruminal ammonia concentrations were significantly decreased (P˂0.05) from 7.54 in the control treatment to 6.08 and 6.45 mg/100 ml due to addition of monensin at levels of 30 and 45 mg/kg. Moreover, addition of monensin at a level of 30 mg/kg concentrate diet significantly increased (P˂0.05) ruminal concentration of total volatile fatty acids to 13.76 as compared with 10.99 mM/100 ml for control treatment. Concentrations of all rumen fermentation characteristics were significantly affected (P˂0.01) by time of ensiling.

Effect of level of monensin on rumen fermentation characteristics in Awassi lambs

The current study was conducted in the Animal field of the Department of Animal Production – College of Agriculture - Al-Qasim Green University for the period from 10/10/2019 to 19/1/2020 to investigate the effect of addition of monensin at levels of 15, 30 and 45 mg/kg concentrate on growth performance of Awassi lambs. First treatment in which lambs were fed concentrate diet without addition of monensin was considered the control treatment. Sixteen male Awassi lambs were used with an average weight of 24.85 and 4-6 months of age. The lambs were randomly distributed to the experimental treatments, four lambs per each using the individual feeding in the cages. The concentrate diet was offered at a level of 2.75% of the body weight at 2 meals, morning and evening meals, while the ground wheat straw was offered at free choice. Results revealed no significant effect of level of monensin on pH values, whereas ruminal ammonia concentrations were significantly decreased (P˂0.05) from 7.54 in the control treatment to 6.08 and 6.45 mg/100 ml due to addition of monensin at levels of 30 and 45 mg/kg. Moreover, addition of monensin at a level of 30 mg/kg concentrate diet significantly increased (P˂0.05) ruminal concentration of total volatile fatty acids to 13.76 as compared with 10.99 mM/100 ml for control treatment. Concentrations of all rumen fermentation characteristics were significantly affected (P˂0.01) by time of ensiling.

Intoxicación con monensina en un feedlot de búfalos de Argentina

&lt;p&gt;El objetivo de este trabajo fue describir un envenenamiento accidental por monensina en búfalos domésticos (Bubalus bubalis) pertenecientes a un feedlot ubicado en la región nordeste de Argentina. Los signos clínicos incluyeron ansiedad, posición ortopneica con rechinamiento&lt;br /&gt;de dientes, diarrea, debilidad muscular, depresión y recumbencia. En los animales expuestos&lt;br /&gt;a monensina se observaron aumentos significativos de creatin fosfoquinasa y aspartato aminotransferasa. A la necropsia, los búfalos presentaron áreas pálidas de distribución irregular, hidrotórax, congestión y edema pulmonar. Al examen histológico se observó degeneración y necrosis de músculos cardíaco y esquelético. El análisis del alimento reveló niveles tóxicos de monensina, por lo cual se diagnosticó una toxicosis por ionóforos. A pesar de los efectos positivos de la monensina como fuente de alimento de los animales, se debe requerir un mayor nivel de precaución al alimentar búfalos con ionóforos.&lt;/p&gt;

Polyether ionophores residues in pasteurized milk marketed in the state of São Paulo, Brazil: Occurrence and exposure assessment

This paper aimed to survey the occurrence of six polyether ionophores (lasalocid, maduramycin, monensin, narasin, salinomycin and semduramycin) in pasteurized milk using a validated method by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). For that, 40 samples of pasteurized milk, from seven brands, collected in six locations (supermarkets, grocery stores and greengrocers) in the metropolitan region of São Paulo and Campinas, São Paulo State, Brazil, were evaluated. Sampling included whole (18), skimmed (8) and semi-skimmed (10) milk as well as lactose-free (4) products. Only monensin antibiotic residues were found in the analyzed samples. This ionophore was confirmed in 45% of the samples and quantified in 32.5% at concentrations ranging from 0.1 to 0.27 μg kg−1. The positive samples were whole or semi-skimmed milk. Considering the levels of monensin reported in the present study and data on milk consumption in Brazil, an exposure assessment indicated that the intake of this antibiotic does not represent a risk to health.

Monensin occurrence in surface water and its impact on aquatic biota in a stream of the southeast Pampas, Argentina.

Monensin is an ionophore antibiotic used as a feed additive and growth promoter in cattle production worldwide. The occurrence of monensin in aquatic surficial ecosystems is of concern due to its possible detrimental effects on human health and native biota. Argentina is one of the most important cattle beef producers worldwide; however, there is little knowledge on the environmental occurrence of monensin and the associated risks to aquatic biota. In this study, we developed a method for the extraction and quantification of monensin in surface water; then, we evaluated the occurrence of monensin in a stream impacted by different animal husbandry's operations, and then, we analyzed the ecological implications of monensin residues on aquatic organisms using the risk quotient (RQ) method. Sampling was carried out on August 2017 from the headwaters to the floodplain of the El Pantanoso stream, Buenos Aires province, Argentina. Monensin detection frequency was 75% (n = 20). The median level was 0.40 μg/L and the maximum concentration was 4.70 μg/L. The main input of monensin was from a cattle slaughterhouse, an activity that has not been considered before in the literature as a source of emission of veterinary pharmaceuticals into the environment. The RQ assessment showed that monensin levels could have potential negative effects on aquatic biota in the sampling site closest to the cattle slaughterhouse. The data obtained in this study shows that monensin was present in El Pantanoso surface waters at levels of high ecotoxicological risk to aquatic biota.

Influence of Cinnamon Essential Oil and Monensin on Ruminal Biogas Kinetics of Waste Pomegranate Seeds as a Biofriendly Agriculture Environment

The objective of present experiment was to compare the effect of cinnamon essential oil with monensin on the environmental biogas production kinetics of pomegranate seeds. Experimental treatments were: pomegranate seeds (control), pomegranate seeds with 12 mg monensin/kg dry matter, pomegranate seeds with 24 mg monensin/kg dry matter, pomegranate seeds with 150 mg cinnamon essential oil/kg dry matter and pomegranate seeds with 250 mg cinnamon essential oil/kg dry matter. The biogas produced by treatments incubation was recorded at 4, 6, 8, 12, 16, 24, 36, 48, 72, 96 and 120 h after incubation. The results showed that biogas production decreased numerically at 120 h after incubation in the treatment containing monensin (at 24 mg/kg dry matter) and cinnamon essential oil (at 150 and 250 mg/kg dry matter) compared to the control treatment. The addition of monensin and cinnamon essential oil had a significant effect (P < 0.05) on increasing partitioning factor and fermentation efficiency compared to control treatment. Concentration of ammonia nitrogen at 120 h of incubation was reduced (P < 0.05) by adding different levels of cinnamon essential oil and monensin at the level of 24 mg, and total volatile fatty acids were significantly reduced in treatments containing cinnamon essential oil. Concentrations of ammonia nitrogen and total volatile fatty acids showed an incremental effect (P < 0.05) with the addition of 12 mg of monensin. In conclusion, cinnamon essential oil and monensin can be used in an environmentally conducive and acceptable way to diminish biogas emissions from ruminants; therewith ameliorate environmental conditions. However, the cinnamon essential oil can be easily used in livestock diets to improve fermentation and reduce biogas production.

PSVII-11 Monensin and supplementation level effects on ruminal parameters and in-situ disappearance of steers receiving bermudagrass

Abstract The objective of this study was to evaluate the effects of monensin and supplementation level on bermudagrass (Cynodon dactylon) in situ disappearance and ruminal parameters. The experiment was conducted in Ona, FL. Treatments were the factorial arrangement of 2 supplementation levels [0.4 (low) or 4 kg/d (high)] and 2 monensin levels (20 mg/kg of the DM intake or no monensin) distributed in a latin square design. Four rumen-cannulated steers were used with 10-d adaptation and 3-d incubation and collection periods. Samples were incubated in the rumen with nylon bags and analyzed for DM, CP, and NDF disappearance. Rumen fluid was collected for 3 d during the incubation period and analyzed for pH, ammonia, propionate, lactate, and butyrate. There was no effect (P &amp;gt; 0.05) of monensin on potential DM, CP, and NDF disappearance; however, greater supplementation level increased (P &amp;lt; 0.03) potential DM disappearance (64 vs. 61%) and NDF disappearance (60 vs. 57%). Steers receiving greater supplementation level had greater (P = 0.01) total DMI (1.4 vs. 1.0% BW) but there was no difference in forage DMI (P = 0.72, mean = 1.0 ± 0.1% BW). There was a monensin × supplementation level interaction on ruminal propionate concentration. The interaction occurred because there was no effect (P = 0.64) of monensin with low supplementation (mean = 12 ± 1.2 mol/100 mol); however, monensin increased propionate on high supplementation from 15 to 19 mol/100 mol. There was an increase (P &amp;lt; 0.05) in ruminal ammonia (from 1.9 to 4.4 mg/100 ml) and lactate (from 60 to 64 mol/100 mol) from low to high supplementation. Rumen pH and butyrate were not affected by monensin or supplementation (P &amp;gt; 0.12). Monensin did not change forage disappearance parameters but increased ruminal propionate production in steers receiving greater amount of concentrate.

408 Effect of monensin intake during a stocker phase and subsequent finishing phase on rumen bacterial diversity of beef steers

Abstract Three monensin levels during a stocker phase (0, 800, 1600 g/ton fed in a free choice mineral) and two levels during finishing [0 (U) or 37.5 mg/kg diet DM (M)] were used to determine the effects of monensin supplementation during a stocker and subsequent finishing phase on rumen bacterial communities of beef steers. Thirty calves were fed pearl millet (Pennisetum glaucum) hay with soybean hull and corn gluten feed supplement (0.5% BW daily, AF basis) or grazed fall wheat pasture (Triticum aestivum) during a stocker phase and then transported 1,067 km to Canyon, TX, for finishing. Rumen fluid was collected on d 0, 28, and the end of the stocker phase (d 85). Samples were also obtained at feedlot d 0, 14, 28, 56, and immediately prior to a diet change to include a beta-adrenergic agonist and before shipping for harvest. Rumen microbiota were characterized by next generation sequencing the 16S v4 hypervariable region with the Illumina MiSeq platform. During the stocker phase, Prevotella and Bacteroidetes were the most dominant genus regardless of diet or treatment. Monensin decreased (P ≤ 0.01) alpha diversity (Shannon Index) for cattle consuming hay on d 28 of the stocker phase. In the feedlot, Prevotella, Lachnospiraceae, and Bacteroidetes were the most abundant genus. Steers that were previously on the 0 and 1600 treatments during the stocker phase and were fed monensin at the feedlot had decreased alpha diversity (P = 0.04) on feedlot d 14 compared to those that did not. Monensin at the feedlot tended to increase alpha diversity on d 28 for cattle previously on the 1600 treatment (P = 0.06), and on d 56 for cattle previously on the 0 treatment (P = 0.06). This experiment provides a better understanding of the effect of monensin on rumen bacterial communities throughout production.

184 Effect of monensin intake during a stocker phase and subsequent finishing phase on performance and carcass characteristics of feedlot steers

Abstract Three experiments were conducted to determine the effects of monensin supplementation during the stocker and finishing phase on feedlot performance and carcass characteristics of beef steers. In Exp. 1 and 2, steers (n = 61, BW = 345 ± 20 kg and n = 70, BW = 298 ± 26 kg) were fed hay and supplement or grazed wheat pasture (Exp. 1) or bermudagrass (Exp. 2) and then were transported 1,068 km to Canyon, TX, for finishing. For Exp. 3 steers (n = 59, BW = 322 ± 31 kg) grazed wheat pasture and then transported 636 km to Stillwater, OK, for finishing. Treatments were arranged as a 3 × 2 factorial with three monensin levels during the stocker phase (0, 800, 1600 g/ton fed in a free choice mineral) and two levels during finishing [0 (UN) or 37.5 mg/kg diet DM (RUM). There were no location × treatment interactions (P ≥ 0.19) for performance or carcass measurements, therefore data were pooled across locations. Stocker × feedlot treatment interactions were not observed for performance data (P ≥ 0.50), but were observed for carcass characteristics. Cattle consuming RUM in the feedlot had decreased (P &lt; 0.01) DMI and increased (P &lt; 0.01) G:F compared with UN. Cattle on 1600UN treatment had the greatest LM area whereas 0U had the least (103.4 vs 96.3 cm2). Steers on the 800UN and 1600UN treatments had decreased YG and 800RUM had the greatest (2.31 and 2.22 vs 2.75). Cattle consuming RUM during finishing had increased (P = 0.03) fat thickness compared to UN. Supplementation of monensin to stocker cattle may have minimal impact on subsequent feedlot performance. Providing monensin in feedlot diets still decreases DMI and improves feed efficiency of feedlot cattle.

Insights into the Populations of Proteolytic and Amino Acid-Fermenting Bacteria from Microbiota Analysis Using In Vitro Enrichment Cultures.

This study evaluated the effects of nitrogen source composition and monensin on the populations of proteolytic and amino acid-fermenting bacteria using in vitro enrichment culture. The experiment was designed with a 2 × 2 factorial arrangement: two nitrogen sources, casein (Cas) and tryptone (Try), and two levels of monensin, 0 (C) and 5µmol/L (M), resulting in four treatments: Cas-C, Cas-M, Try-C, and Try-M. Ruminal fluid collected from three cannulated Holstein dairy cows was used as the inoculum. Each treatment culture was consecutively transferred six times after 24h of incubation. The results showed that ammonia concentration was lower in Cas than in Try, and it was reduced by monensin addition. In the 6th transfer enrichment cultures, the 16S rRNA gene copy numbers of total bacteria were reduced by monensin but was unaffected by nitrogen sources. Principal component analysis showed that the bacterial communities differed among the treatments. At the genus level, Peptostreptococcus accounted for as much as 41% of the total bacteria in Try-C, but it made up less than 0.02% in the other three treatments. A Pearson correlation analysis showed that the relative abundance of Peptostreptococcus was positively correlated with ammonia concentration. Overall, the results suggest that nitrogen source composition and monensin can affect ruminal ammonia production by modulating the ruminal proteolytic bacterial communities, and some hyper-ammonia-producing bacteria of the genus Peptostreptococcus may be among the main culprits contributing to the high ammonia concentration in the rumen.

65 Effect of Monensin Level on Mineral Intake and Performance of Grazing Steers.

65 Effect of Monensin Level on Mineral Intake and Performance of Grazing Steers.

Comparative effects of Moringa oleifera root bark and monensin supplementations on ruminal fermentation, nutrient digestibility and growth performance of growing lambs

Two comparative in vitro and in vivo experiments were accomplished to assess the effects of Moringa oleifera root bark (MRB) and ionophore antibiotic monensin as dietary feed additives for ruminants' diets. In the in vitro experiment, the effects of graded levels of MRB (0, 25 and 50g/kg DM) and monensin (40mg/kg DM) on ruminal fermentation and degradability parameters were evaluated using the semi-automatic gas production (GP) system. Results were subjected to regression analysis (dose-response analysis) and ANOVA to select the MRB effective dose. In the in vivo experiment, eighteen Barki lambs (BW; 25±3.1kg) were randomly allotted into three dietary treatments (n=6/treatment) as: control (basal diet without additive), monensin (40mg/kg DM) and MRB (25g/kg DM). The experiment lasted for 70 days to collect ruminal samples and evaluate lamb performance, while the subsequent 7 days were assigned for the nutrient digestibility and nitrogen balance trial. The GC–MS analysis of MRB showed that the most abundant phytochemicals were organosilicons, alkaloids and benzoic acid ester. Results of the in vitro assay showed that both MRB doses inhibited (P<0.01) CH4 production (ml/g DM) without adverse effects on GP and degradability compared to control. Diet supplemented with 25gMRB/kg DM resulted in the highest increase (P=0.03) of propionate compared to control. Ammonia concentration was decreased (P<0.01) by monensin, while protozoal counts were not affected by all experimental diets. The in vivo effects of MRB on ruminal fermentation profile were different from those of in vitro assay. MRB enhanced (P<0.05) the total short chain fatty acids, acetate production and nutrients digestibility, while monensin enhanced propionate (P<0.01) compared to other diets. Both monensin and MRB exhibited similar reductions (P<0.01) in protozoal counts, urine N excretions and estimated CH4 produced per unit of body weight gain while enhanced (P<0.05) the body N retention, average daily gain, and feed efficiency compared to control. These results suggested that, although MRB was less effective than monensin, it favourably modified the ruminal fermentation process and nutrients digestibility, thus it could be used as a novel dietary feed additive for ruminant diets.