Monensin, virginiamycin, and flavomycin in a no-roughage finishing diet fed to zebu cattle

Effects of different additives on cattle feed intake and performance - a systematic review and meta-analysis

In the last few years, there has been a growing interest in the use of natural feed additives in animal feed. These can be used as replacements for antibiotics, to alter rumen fermentation and increase feed efficiency in ruminants. Therefore, the objective of this study is to evaluate the effects of adding different feed additives in the diet of beef and dairy cattle on their performance, dry matter intake (DMI) and feed efficiency, through a systematic review followed by meta-analysis. The systematic review suggested 43 peer-reviewed publications, according to the pre-established criteria. In beef cattle, the ionophore antibiotics reduced the DMI, improved the feed efficiency without interfering in the average daily gain (ADG). Non-ionophore antibiotics and propolis extract increased the ADG. In dairy cattle, the ionophores, yeast-based additives, and enzyme additives increased the feed efficiency, DMI, and daily milk production (MY), respectively. Essential oil supplementation in beef and dairy cattle had no effect on the feed intake and animal performance. The systematic review and meta-analysis allowed us to conclude that different feed additives have different effects on cattle performance, however, our results suggest that there are a few gaps regarding their effects on animal performance.

Impact of combined management strategies of monensin and virginiamycin in high energy diets on ruminal fermentation and nutrients utilization

Feed additives such as monensin (MON) and virginiamycin (VM) are commonly utilized in feedlot diets to enhance rumen fermentation. Nevertheless, the precise effects of combining MON and VM during specific feedlot periods and the advantages of this combination remain unclear. This study was designed to investigate the effects of withdrawal of MON when associated with VM during the adaptation and finishing periods on ruminal metabolism, feeding behavior, and nutrient digestibility in Nellore cattle. The experimental design was a 5 × 5 Latin square, where each period lasted 28 days. Five rumen-cannulated Nellore yearling bulls were used (414,86 ± 21,71 kg of body weight), which were assigned to five treatments: (1) MON during the entire feeding period; (2) VM during the entire feeding period; (3) MON + VM during the adaptation period and only VM during the finishing period 1 and 2; (4) MON + VM during the entire feeding period; (5) MON + VM during the adaptation and finishing period 1 and only VM during the finishing period 2. For the finishing period 1, animals fed T3 had improved potential degradability of dry matter (p = 0.02). Cattle fed T3 and T5 had the highest crude protein degradability when compared to animals receiving T2 (p = 0.01). Animals fed T2 and T3 had reduced the time (p < 0.01) and area under pH 6.2 (p = 0.02). Moreover, animals fed T4 had greater population of protozoa from the genus Diplodinium (p = 0.04) when compared to those from animals fed T2, T3 and T5. For the finishing period 2, animals fed T3 had greater starch degradability when compared to animals receiving T4 and T5 (p = 0.04). Animals fed T3, T4 and T5 had increased the duration of time in which pH was below 5.6 (p = 0.03). The area under the curve for ruminal pH 5.2 and pH 5.6 was higher for the animals fed T3 (p = 0.01), and the area under pH 6.2 was higher for the animals fed T3 and T5 (p < 0.01) when compared to animals receiving T2. There is no substantial improvement on the rumen fermentation parameters by the concurrent utilization of MON and VM molecules, where the higher starch and protein degradability did not improve the rumen fermentation.

The influence of virginiamycin on digestion and ruminal parameters under feedlot conditions

This experiment aimed to assess the impact of virginiamycin on in vitro gas production dynamics, rumen kinetics, and nutrient digestibility in beef steers fed a grain-based diet. Nine ruminally cannulated British-crossbred steers (596 ± 49 kg) were assigned to this experiment. Animals were housed in three pens (n = 3/pen) equipped with a Calan gate feed system and water troughs. Pens were enrolled in a 3 × 3 Latin square design containing three periods of 16 d, and a 5-d washout interval between periods. Dietary treatments consisted of virginiamycin (VM) administration at 0 (VM0), 180 (VM180), or 240 mg/d (VM240). During days 15 and 16 of each period, about 600 mL of rumen fluid and urine samples were collected before (0 h), and at 4, 8, 12, and 16 h after the morning feed (0730 hours), rumen inoculum was used to take pH and redox potential measurements immediately after collection using a portable pH and redox meter, and subsamples were taken for volatile fatty acids (VFA) and NH3-N analyses, and urine samples were composited daily and analyzed for creatinine and purine derivatives (PD) content to estimate microbial crude protein flow. During the 4-h post-morning feed rumen collection, rumen inoculum was utilized to perform in vitro gas production measurements. Fecal samples were collected on day 16 of each period to estimate nutrient digestibility using acid detergent insoluble ash as an internal marker. Animals were considered the experimental unit for the statistical analyses, and periods and squares were included as random variables. The total and rate of gas production were similar among treatments (P ≥ 0.17). The second-pool (i.e., fiber) gas production increased linearly as VM inclusion increased (P = 0.01), with VM240 being greater compared to VM180 and VM0 (7.84, 6.94, and 6.89 mL, respectively). Ruminal pH linearly increased as VM increased, with VM240 being greater than VM0 and VM180 intermediate (5.90, 5.82, and 5.86, respectively; P = 0.03). The VFA concentrations did not differ (P ≥ 0.13), but the acetate-to-propionate ratio was the highest in VM240 (P = 0.005). Branched-chain VFA increased (P ≤ 0.03) while lactate concentrations decreased (P = 0.005) linearly with VM. The ruminal NH3-N concentration was the lowest in the VM0 (P = 0.006). The estimated absorbed PD, purine derivative to creatinine index, and microbial N flow increased linearly with VM (P ≤ 0.07). The provision of VM influenced rumen dynamics in a dose-dependent manner.

Ruminal responses, digestibility, and blood parameters of beef cattle fed diets without forage with different hybrids and processing of the corn

The objective of this study was to evaluate the effects of corn hybrid and processing methods on intake and digestibility of nutrients, rumen fermentation and blood metabolites of steers fed no-forage finishing diets. Four ruminally fistulated Nellore castrated steers (502 ± 15 kg initial body weight) were distributed in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement consisting of two corn hybrids (semi-dent and flint) and two processing methods (dry milled and high moisture grain). Interactions of hybrid and processing methods were observed on intake of dry matter (DM), organic matter (OM) and crude protein (CP), as well as on digestibility of DM and CP, rumen pH and ammonia nitrogen (N-NH₃ ). There was no interaction between hybrid and processing for the volatile fatty acids (VFA) total, acetate (C2), propionate (C3), isobutyric (iC4) and valeric (nC5) concentrations. VFA total concentration shown an average of 103.4 mmol/L. The C2 and C3 concentrations had no effect of the hybrid or processing with averages of 58.7 mmol/L for C2, and 31.3 mmol/l for C3. There was an effect of the processing method on starch consumption and fecal pH, the highest values were observed in grains with high moisture content. Starch digestibility was 0.89 g/g in dry milled and 0.96 g/g in high moisture corn. The greatest digestibility of starch in high moisture corn, irrespective of the corn hybrid, provided evidence of an increase in the energy supply, which may improve the feed efficiency and growth performance of cattle fed no-roughage finishing diets.

Withdrawal of sodium monensin when associated with virginiamycin during adaptation and finishing periods on feedlot performance, feeding behavior, carcass, rumen, and cecum morphometrics characteristics of Nellore cattle

Feed additives such as monensin (MON) and virginiamycin (VM) are widely used in feedlots diets to maximize rumen fermentation. However, the knowledge about the effects of MON and VM combinations in specifics feedlot periods and the benefits of this association are still unclear. This study aimed to evaluate the effects of withdrawal of MON when associated with VM during the adaptation and finishing periods on feedlot performance of Nellore cattle. The experiment was designed as a completely randomized block replicated six times (four animals/pen) in which 120 Nellore bulls (378.4 ± 24.4 kg) were allocated in 30 pens and fed for 112 days according to the following treatments: (T1) MON during the entire feeding period; (T2) VM during the entire feeding period; (T3) MON+VM during the adaptation period and only VM during the finishing period 1 and 2; (T4) MON+VM during the entire feeding period; (T5) MON+VM during the adaptation and finishing period 1 and only VM during the finishing period 2. After 112 days on feed, no treatment effect was observed for DMI (P ≥ 0.12). However, bulls fed T5 had greater (P = 0.05) final BW and ADG when compared to T1, T2, and T4. Cattle from T3 and T5 groups presented heavier HCW (P = 0.05) than that fed T1, T2, and T4. Nellore bulls fed T1 and T5 had lower (P < 0.01) DMI variation than those receiving T2. The withdrawal of MON when associated with VM during the final third of the feedlot period improved overall final BW, ADG, and HCW when compared to bulls fed either MON or VM, but did not positively impact feedlot performance when compared to cattle that had MON withdrawn at the end of the adaptation period.

Influence of supplemental flavomycin on growth performance, carcass characteristics, and nutrient digestibility in calf-fed Holstein steers

The objective of this study was to evaluate the influence of supplemental flavomycin on cattle growth performance, carcass characteristics, diet digestibility, and ruminal fermentation characteristics of calf-fed Holstein steers. One hundred Holstein steers (123 ± 7 kg) were balanced by weight and assigned to 20 pens. Dietary treatments consisted of a steam flaked corn-based diet supplemented with (dry matter basis): 1) control, no feed additive; 2) 6.6 mg/kg flavomycin; 3) 13.2 mg/kg flavomycin, and 4) 30 mg/kg monensin (MON). There were no treatment effects (P ≥ 0.17) on live weight, average daily gain (ADG), and gain efficiency. Flavomycin did not affect dry matter intake (DMI; P ≥ 0.24). Flavomycin supplementation did not affect (P ≥ 0.37) the ratio of observed vs. expected DMI. However, MON decreased (P = 0.02) observed vs. expected DMI by 3.7%. There were no treatment effects (P ≥ 0.44) on ruminal pH or temperature. Flavomycin did not affect (P ≥ 0.13) carcass characteristics and liver abscess among steers. Four Holstein steers (463 ± 20 kg) with ruminal cannulas were used in 4 × 4 Latin square experiment to study treatment effects on site and extent of digestion, ruminal pH, and volatile fatty acid (VFA) molar proportions. Dietary treatments were the same as experiment 1. Flavomycin tended to increase (linear effect, P = 0.07) ruminal organic matter (OM) digestion, associated with increased (linear effect, P < 0.01) ruminal starch digestion. Supplementing flavomycin at 13.2 mg/kg decreased net microbial N synthesis (quadratic effect, P = 0.03). Compared with control, MON tended to increase (P = 0.10) ruminal neutral detergent fiber (NDF) digestion and increased (P < 0.01) ruminal starch digestion. Monensin did not affect (P = 0.39) net microbial N synthesis, but decreased (P = 0.01) ruminal degradation of feed nitrogen (N). There were no treatment effects (P > 0.10) on total tract apparent digestion of DM, OM, NDF, and starch. Flavomycin decreased ruminal pH (quadratic effect, P < 0.01) measured 4 h postprandial. Compared with control, MON increased ruminal pH (P = 0.03). Flavomycin increased (linear effect, P = 0.03) ruminal propionate molar proportion and decreased (linear effect, P ≤ 0.04) ruminal molar proportions of acetate and butyrate, and decreased (linear effect, P = 0.02) acetate:propionate molar ratio and estimated methane production. We conclude that supplementing flavomycin at 6.6 or 13.2 mg/kg had no major effects on cattle growth performance, carcass characteristics, diet digestibility, and ruminal fermentation characteristics.

Combined use of monensin and virginiamycin to improve rumen and liver health and performance of feedlot-finished steers

Monensin and virginiamycin are included in beef cattle finishing diets as prophylaxis to minimize the incidence of ruminal acidosis and liver abscesses. Due to different and probably complementary modes of action, this study aimed to determine the effects of a combination of monensin and virginiamycin, both included in the diet at recommended doses, on ruminal health, the occurrence of liver abscesses, and growth performance of feedlot-finished cattle. One hundred and forty-four steers (6 animals/pen) were fed 1 of 3 corn-based finishing diets containing 30 mg of monensin (MN), 25 mg of virginiamycin (VM), or 30 and 25 mg of monensin and virginiamycin (MN + VM), respectively, per kilogram of dry matter. Ruminal pH probes were inserted into two animals per pen and set to record pH every 10 min. On d 100, animals were slaughtered, and rumens and livers were recovered, on which occurrence and degree of ruminal damage, prevalence and number of liver abscesses, and liver scores (A-: livers with no more than two small abscesses; A+: livers with at least one large abscess or more than four medium abscesses; A: any other abscessed liver) were determined. Simultaneous inclusion of monensin and virginiamycin resulted in a 4.3% decrease (P < 0.04) in dry matter intake (DMI; 8.8, 9.2, and 9.2 ± 0.19 kg/d for MN + VM, MN, and VM-fed animals, respectively) and similar (P > 0.13) average daily body weight gain (ADG; 1.49 ± 0.021 kg/d) and hot carcass weight (HCW; 269 ± 1.7 kg), compared with feeding diets containing one additive or the other. Therefore, in terms of ADG, a 9.4% improvement (P < 0.01) in feed efficiency was observed in MN + VM-fed animals. Backfat thickness (5.6 ± 0.08 mm) and ribeye area (69.9 ± 0.53 cm²) remained unaffected (P ≥ 0.74), as well as the minimum (4.98 ± 0.047), mean (6.11 ± 0.037), and maximum ruminal pH (7.23 ± 0.033) values and the time (125 ± 22.3 min/d), area (57.67 ± 12.383 pH × h), and episodes (22 ± 3.8 bouts) of pH below 5.6 (P ≥ 0.12). Overall, prevalence (24 ± 3.4%) and the number of liver abscesses (1.6 ± 0.14 abscesses/abscessed liver), liver scores (20 ± 3.1% of A- and 4 ± 1.8% of A livers), and prevalence (67 ± 3.5%) and degree of damage to the ruminal epithelium (2.5 ± 0.22% affected surface) were similar (P ≥ 0.18) across treatments; however, the occurrence of ruminal lesions tended (P ≤ 0.07) to be associated with that of liver abscesses and reduced ADG when feeding monensin alone.

Association of virginiamycin and multiple supplement for cattle fed a high-quality tropical forage

The aim of this study was to evaluate the effect of adding virginiamycin to either mineral mixture or multiple supplement on intake, digestion, ruminal fermentation profile, rumen microbial production, blood metabolites, and liver metabolism of zebu heifers fed a high-quality tropical forage. Eight Brahman heifers were assigned to a replicated 4 × 4 Latin Square design. The treatments were: mineral mixture, mineral mixture with virginiamycin, multiple supplement, and multiple supplement with virginiamycin. The basal diet consisted of a high-quality Tifton 85 hay (Cynodom sp.) chopped at 10-cm particle size and fed twice daily. The mineral mixture was provided daily at 120 g/animal. The multiple supplement was formulated to provide 300 g of crude protein (CP)/kg as fed, contained mineral mixture, corn grain, and urea: ammonium sulfate, and was daily provided at 200 g/animal. The mineral mixture and multiple supplement provided the same daily amount of minerals. The amount of supplemental virginiamycin was based on a maximum theoretical response on animal performance (50 mg/100 kg body weight) and daily mixed to the supplements types. The treatments were compared according to a 2 × 2 factorial arrangement (mineral mixture and multiple supplement, with or without virginiamycin). The virginiamycin supplementation did not alter either voluntary intake or digestibility (P≥0.44). Using the multiple supplement decreased forage (P&lt;0.05) and digested organic matter (DOM, P&lt;0.10) intake, but increased dietary CP : DOM ratio (P&lt;0.01). The multiple supplement increased the ruminal ammonia concentration (P&lt;0.04) and the acetate-to-propionate ratio (P&lt;0.06). Virginiamycin increased urinary nitrogen (N) when provided along with multiple supplement (P&lt;0.05). Fecal N was decreased by multiple supplement (P&lt;0.06). Despite these effects, no effect was verified on either body N accretion (P≥0.48) or microbial N production in the rumen (P≥0.27). Virginiamycin decreased the blood IGF-1 (P&lt;0.07). The hepatic gene expression for propionyl-CoA carboxylase was increased by virginiamycin (P&lt;0.01). Virginiamycin increased the hepatic gene expression of both citrate synthase and pyrivate carboxylase when mineral mixture was provided (P&lt;0.01), but decreased it when animals were fed multiple supplement (P&lt;0.04). Using a low-intake multiple supplement with a high CP content for cattle fed high-quality forage causes a substitutive effect on forage intake, but keeps nitrogen accretion unchanged. That pattern indicates an improvement in feed efficiency. On the other hand, virginiamycin supplementation seems to cause some post-prandial influences, which may vary according to the type of supplement. Those influences apparently improve animal efficiency.

Comparing Blend of Essential Oils Plus 25-Hydroxy-Vit-D3 Versus Monensin Plus Virginiamycin Combination in Finishing Feedlot Cattle: Growth Performance, Dietary Energetics, and Carcass Traits

Ninety crossbreed bulls (349.5 ± 8.25 kg initial weight) were used in an 87day trial to compare the effects of a blend of essential oils plus 25-hydroxy-Vit-D3 (EO + HyD) versus the combination of monensin with virginiamycin (MON + VM) on feedlot growth performance and carcass characteristics. Dietary treatments (nine replicates/treatment) were supplemented with 40 mg/kg diet dry matter of MON + VM (equal parts) or with 120.12 mg/kg diet dry matter of a combination of standardized mixture of essential oils (120 mg) plus 0.12 mg of 25-hydroxy-vitamin-D3 (EO + HyD). There were no treatment effects on dry matter intake (DMI, p = 0.63). However, the coefficient of variation in day-to-day DMI was greater for EO + HyD than for MON + VM (11.4% vs. 3.88%, p = 0.04). There were no treatment effects (p ≥ 0.17) on daily weight gain, gain-to-feed ratio, and estimated dietary net energy. Cattle supplemented with EO + HyD had greater Longissimus muscle area (7.9%, p < 0.01) and estimated retail yield (1.6%, p = 0.03), and tended to have heavier (1.7%, p = 0.10) carcass weight. Differences among treatments in dressing percentage, fat thickness, kidney−pelvic−heart fat, and marbling score were not appreciable (p > 0.10). It is concluded that growth performance response and dietary energetic are similar for finishing cattle supplemented with EO + HyD vs. MON + VM. However, compared with MON + VM, supplementation with EO + HyD during the finishing phase may improve carcass Longissimus area and carcass yield.

Avaliação da eficácia, inocuidade e depleção residual da flavomicina em novilhos confinados

Resumo A flavomicina é um aditivo que pertence à classe dos não ionóforos, contudo, com poucos estudos realizados com bovinos confinados em fase de terminação. Diante disso, o objetivo do presente estudo foi avaliar a eficácia da flavomicina sobre o desempenho produtivo, comportamento ingestivo, características de carcaça e os parâmetros bioquímicos de novilhos terminados em confinamento. Foram avaliados 32 novilhos inteiros, ½ sangue Angus ½ sangue Nelore, provenientes do mesmo rebanho, com idade média de 11 meses ± 1,5 meses e peso corporal inicial de 337 kg ± 6 kg. O delineamento experimental foi o de blocos casualizados, composto por dois tratamentos e oito repetições, sendo: Dieta sem flavomicina (controle) e Dieta com flavomicina (0,5 g animal dia-1 do produto FLAVIMPEX®80). Não ocorrendo diferença entre os tratamentos, o consumo de matéria seca médio dos animais foi de 10,03 kg dia-1, eficiência alimentar de 0,158 kg, ganho médio diário de 1,593 kg dia-1, digestibilidade aparente da dieta de 61,69%. O uso da flavomicina não foi eficaz no desempenho animal, assim como não trouxe alterações no comportamento ingestivo e melhorias nas características de carcaça dos animais. A Proteína Plasmática Total, Aspartato amino-transferase e creatinina foram inferiores para os animais suplementados com flavomicina em relação ao grupo controle. Em relação ao período experimental houve redução nos índices de Proteína Plasmática Total, aumento na albumina, Gama-Glutamil Transferase e ureia dos bovinos, mas todos se mantiveram dentro dos valores de referência para a espécie.

On the efficacy, innocuity and residual depletion of flavomycin in confined steers

Abstract Flavomycin is a non-ionophore additive little studied in finishing confined cattle. Therefore, this study aimed to evaluate the effectiveness of flavomycin on productive performance, ingestive behavior, carcass traits and biochemical parameters of steers finished in confinement. 32 whole steers, ½ Angus e ½ Nellore blood, from the same herd, with a mean age of 11 ± 1.5 months and initial body weight of 337 ± 6 kg were evaluated. The experiment was a randomized block design, consisting of two treatments and eight replications, as follows: Diet without flavomycin (control) and Diet with flavomycin (0.5 g FLAVIMPEX®80 animal day-1). There was no difference between treatments, the average dry matter intake of the animals was 10.03 kg day-1, feed efficiency was 0.158 kg, average daily gain was 1.593 kg day-1, apparent diet digestibility was 61.69%. The use of flavomycin was not effective in animal performance, and caused no changes in ingestive behavior and carcass traits of the animals. Total Plasma Protein, Aspartate amino-transferase and creatinine were lower for animals supplemented with flavomycin compared to the control group. In relation to the experimental period, there was a reduction in the levels of Total Plasma Protein, an increase in albumin, Gamma-Glutamyl Transferase and urea in cattle, but all remained within the reference range for the species.

Feed intake, nutrient digestibility, and selected rumen parameters in feedlot bulls fed diets with different feed additives

An experiment was conducted to evaluate the feed intake, nutrient digestibility and selected rumen parameters in feedlot bulls fed diets containing different feed additives. Six rumen-cannulated Nellore bulls (age = 8 ± 1.0 months; initial BW = 225 ± 13.2 kg) were distributed in a 6 × 6 Latin square design. Six experimental diets based on 30% corn silage and 70% concentrate on a dry matter (DM) basis were evaluated. Diets differed in feed additive on a DM basis, as follows: 1.4% bicarbonate and magnesium oxide in 3:1 ratio (BOX); 36 ppm lasalocid sodium (LAS); 30 ppm monensin sodium (MON); 25 ppm virginiamycin (VIR); 30 ppm monensin sodium plus 25 ppm virginiamycin (MV); and 3.15% commercial mineral supplement containing D-limonene and exogenous α-amylase (EOA). The experiment lasted 144 d, with six periods of 24 d. Each period consisted of 14 d for dietary adaptation, 3 d for feces and urine collection, and 7 d for omasal and ruminal digesta collection. Bulls fed the BOX diet showed greater (P < 0.05) intake of DM, organic matter (OM), neutral detergent fiber (apNDF), crude protein (CP), and starch compared to the other diets. Diets with LAS, MON, VIR, MV, or EOA did not influence (P > 0.05) the DM, OM, apNDF, CP, or starch intake of feedlot bulls. Bulls fed the EOA diet showed greater (trend; P = 0.09) ruminal digestibility of starch compared to the other diets. The feed additives did not affect (P > 0.05) the intestinal or total tract digestibility of starch, rumen pH, microbial efficiency, total rumen fluid, dilution rate, rate of intake, rate of degradation, or passage rate of the DM, OM, apNDF, and starch. In conclusion, LAS, MON, VIR, MV, and EOA diets reduced nutrient intake compared to BOX. Although all feed additives presented similar effects on rumen pH, temperature, and kinetics the presence of exogenous α-amylase in the EOA diet may increase ruminal starch digestibility and apparent total tract digestibility of DM and OM.

Effects of grain adaptation programs and antimicrobial feed additives on performance and nutrient digestibility of Bos indicus cattle fed whole shelled corn

Two experiments were conducted to evaluate the effects of feed additives [monensin (MON); 30 mg/kg of dry matter (DM), and virginiamycin (VM); 25 mg/kg DM] and grain adaptation programs [adding roughage (ROU; sugarcane bagasse) or not (NO-ROU) during the 20-d adaptation period] on performance, carcass characteristics, and nutrient digestibility of Bos indicus cattle fed finishing diets containing 85% whole shelled corn and 15% of a pelleted protein-mineral-vitamin supplement. In Exp.1, 105 Nellore bulls [initial body weight (BW) = 368 ± 25 kg] were used in a complete randomized block design with a 2 × 2 factorial arrangement of treatments, consisting of two feed additives (MON and VM) associated with two adaptation programs (ROU or NO-ROU during the 20-d adaptation period). Effects of feed additives × adaptation programs were not detected (P ≥ 0.13). Feed additives did not affect dry matter intake (DMI), average daily gain (ADG), and feed efficiency (G:F) during the 20-d adaptation period (P ≥ 0.35). During the total feeding period (105 d), feeding MON decreased DMI (P ≤ 0.03) compared to VM. Adding sugarcane bagasse to finishing diets during the 20-d adaptation period (ROU) increased ADG (P = 0.05) and G:F (P = 0.03), and tended to increase BW (P = 0.09) compared to NO-ROU. In Exp. 2, 10 ruminally cannulated Nellore steers (BW = 268 ± 38 kg) were used in a completely randomized design to evaluate the effects of the two feed additives used in the Exp. 1 (MON and VM; 5 steers/treatment) on DMI, total apparent digestibility of nutrients, and ruminal fermentation characteristics. No differences in DMI, total tract apparent digestibility of nutrients, and ruminal fermentation characteristics were observed between MON and VM (P ≥ 0.32). An effect of sampling day (P < 0.001) was observed for ruminal pH, which was greater on day 0 compared to day 7, 14, and 21 of the experimental period (P ≤ 0.05). In summary, supplementing monensin and virginiamycin for finishing Nellore bulls fed whole shelled corn diets, resulted in similar growth performance and carcass characteristics. Including sugarcane bagasse to adapt finishing bulls to no-roughage diets containing whole shelled corn is an alternative to increase growth performance.

Monensin associated or not with virginiamycin or functional oil for feedlot beef cattle

The objective of this study was to evaluate diets containing monensin (MON) associated or not with virginiamycin (VM) or functional oil based on cashew nut shell and castor beans (FO_cc) for beef cattle in feedlots on nutritional (intake and digestibility) and productive parameters. A total of 1410 non-castrated Nellore cattle were selected, with an average age of 18 months and with an initial mean body weight (BW) of 305 ± 41.52 kg. The diet showed a roughage to concentrate ratio of 23:77, with the supply of corn silage as a source of roughage. The following additive inclusions in the diet were evaluated: (1) MON: 27 mg MON/kg dry matter (DM); (2) MON + VM: 22 mg MON/kg DM + 19 mg VM/kg DM; and (3) MON + FO_cc: 22 mg MON/kg DM + 500 mg FO_cc/kg DM. Statistical analyses were obtained through a linear model using initial BW and days of feedlot as covariables and comparisons between treatments using mutually orthogonal linear contrasts with a 5% significance level. The association or not of MON with VM or FO_cc does not affect any of the nutritional and productive parameters evaluated. Animals that receive diets with MON + VM have higher average daily gain and feed efficiency (FE) than those that receive MON + FO_cc without showing differences in nutritional parameters. The supply of MON associated with VM or FO_cc does not increase intake and productive performance and, consequently, efficiency of feedlot beef cattle. However, in the case of use associated with MON, the VM provides greater performance than FO_cc without changing food intake.

Effects of supplementation with narasin, salinomycin, or flavomycin on performance and ruminal fermentation characteristics of Bos indicus Nellore cattle fed with forage-based diets

The aim of the present study was to evaluate the inclusion of narasin, salinomycin, or flavomycin for 140 d on ruminal fermentation parameters, apparent nutrient digestibility, and performance of Nellore cattle offered a forage-based diet. In experiment 1, 32 rumen-cannulated Bos indicus Nellore steers [initial body weight (BW) = 220 ± 12.6 kg] were assigned to individual pens in a randomized complete block design according to their initial shrunk BW. Within block, animals were randomly assigned to 1 of 4 treatments: (1) forage-based diet without feed additives (CON; n = 8), (2) CON diet plus 13 ppm of narasin (NAR; n = 8), (3) CON diet plus 20 ppm of salinomycin (SAL; n = 8), or (4) CON diet plus 3 ppm of flavomycin (FLA; n = 8). The experimental period lasted 140 d and was divided into 5 periods of 28 d each. The inclusion of feed additives did not impact (P ≥ 0.17) dry matter intake (DMI), nutrient intake, and apparent total tract digestibility of nutrients. Nonetheless, steers fed NAR had lower (P < 0.01) molar proportion of acetate compared with CON, SAL, and FLA steers, whereas ruminal acetate tended to be greater (P < 0.09) for SAL vs. CON and FLA, but did not differ (P = 0.68) between CON vs. FLA steers. Ruminal propionate was the highest (P < 0.01) for steers fed NAR and did not differ (P > 0.20) between CON, SAL, and FLA. Consequently, NAR steers had the lowest (P < 0.01) Ac:Pr ratio, whereas Ac:Pr did not differ (P > 0.18) among CON, SAL, and FLA. Total volatile fatty acids were greater (P < 0.04) for NAR and CON vs. SAL and FLA, but did not differ (P > 0.67) among NAR vs. CON and SAL vs. FLA. In experiment 2, 164 Nellore bulls (initial shrunk BW = 299 ± 2.5 kg) were assigned to feedlot pens for 140 d in a randomized complete block design. Within block (n = 10), animals were randomly assigned to the same treatments used in experiment 1. Average daily gain was greater (P < 0.01) in NAR vs. CON, SAL, and FLA bulls, and did not differ (P > 0.12) between CON, SAL, and FLA bulls. Bulls fed NAR had greater (P < 0.02) DMI (as kg/d or % BW) and final shrunk BW compared with CON, SAL, and FLA bulls, whereas DMI and final shrunk BW did not differ (P > 0.26) between CON, SAL, and FLA bulls. Feed efficiency, however, was not impacted (P = 0.51) by any feed additives used herein. Collectively, narasin was the only feed additive that benefited performance and ruminal fermentation of Nellore animals fed a forage-based diet.

Effects of monensin source on in vitro rumen fermentation characteristics and performance of Bos indicus beef bulls offered a high-concentrate diet

In Exp. 1, Brachiaria ruziziensis (11.1 % CP) was inoculated or not with two sources of monensin, resulting in three treatments: 1) no monensin inoculation (CONT), 2) 20 mg of monensin sodium-A/kg of DM (Elanco Animal Health; MON-A), and 3) 20 mg of monensin sodium-B/kg of DM (Shandong Qilu King-Phar Pharmaceutical Co. Ltd.; MON-B). Three rumen-fistulated Jersey steers were offered a cool-season forage-based diet and were used as the rumen inoculum donors. Volatile fatty acids concentrations were evaluated at 0, 6, 12, 24, 30, and 48 h after treatment inoculation. Overall, acetate and butyrate concentrations were reduced in MON-A vs. CONT (P ≤ 0.02), whereas both monensin products reduced Ac:Pr ratio vs. CONT (P ≤ 0.01); however, MON-A also (P = 0.05) reduced the Ac:Pr ratio vs. MON-B. A treatment × hour interaction was detected for rumen propionate concentration (P = 0.01), primarily because MON-A resulted in greater propionate than CONT and MON-B at 24 and 48 h (P ≤ 0.03), but no differences were observed between CONT vs. MON-B (P ≥ 0.27). In Exp. 2, 240 Nellore bulls (initial BW = 363.2 ± 40.9 kg) were ranked and blocked according to initial BW, and within blocks animals were allotted into pens (n = 10 pens/treatment). Pens were randomly assigned into one of three treatments: 1) corn-based diet with no monensin (CONT), 2) CONT plus 28 mg of MON-A/kg of DM, and 3) CONT plus 28 mg of MON-B/kg of DM. The CONT diet was composed of sugarcane bagasse, ground corn, DDGS, urea, and a mineral-vitamin mix. The experimental period lasted 106 d and was divided into a 21-d adaptation period and an 85-d finishing phase. During the adaptation phase, both monensin sources increased (P ≤ 0.01) BW change, ADG, and F:G, as well as reduced DMI variation (P = 0.02). When the entire experimental period was evaluated, no treatment effects were detected for final BW, DMI, and ADG (P ≥ 0.26). Nonetheless, DMI variation was reduced as monensin was included (P = 0.01) and only MON-A improved the efficiency by reducing F:G vs. CONT (P = 0.05) and biological efficiency vs. MON-B (P = 0.05). Additionally, carcass ADG tended (P = 0.10) to be greater for MON-A vs. MON-B, whereas no other differences in the carcass characteristics were observed (P ≥ 0.53). In summary, the source of monensin inoculated in vitro and offered to Nellore bulls during the feedlot phase significantly affected the energetic efficiency and the performance of the animals.

Effect of bambermycin and dietary distillers grains concentration on growth performance and carcass characteristics of finishing steers1

An experiment was conducted comparing medicated feed additives (MFA) bambermycin or monensin sodium and tylosin phosphate in feedlot diets containing modified distillers grains (mDGS). Crossbred steers (n = 256; initial full BW 418 ± 28.5 kg) were allocated into three weight blocks in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. The factors were: MFA (bambermycin at 20 mg/steer daily or monensin + tylosin at 380 and 90 mg/steer daily, respectively) and mDGS inclusion (15% and 30% of diet DM). Twenty-four pens were utilized, resulting in six replications per treatment. Steers were fed a diet consisting of a 1:1 combination of dry-rolled and high-moisture corn with the roughage portion of the diet consisting of corn silage and corn stover. Steers in the heaviest two blocks were marketed after 104 d and steers in the lightest block were marketed after 126 d. Overall average daily gain (ADG) tended (P = 0.08) to be greater for bambermycin vs. monensin and tylosin, and was not affected (P = 0.17) by mDGS level. Dry matter intake was lower (P ≤ 0.05) with 30% mDGS with monensin and tylosin than with any other treatment. Feed efficiency was not affected by mDGS, MFA, or their interaction (P ≥ 0.30). Marbling scores were greater (P = 0.01) greater for bambermycin vs. monensin and tylosin, and tended (P = 0.08) to be greater with 15% mDGS than with 30% mDGS. Carcasses from steers fed bambermycin had a greater percentage of USDA choice than those fed with monensin and tylosin (P = 0.01). Liver abscess occurrence was not affected (P ≥ 0.17) by MFA, mDGS, or their interaction. Results from this experiment indicate that including bambermycin in feedlot diets containing 30% mDGS results in increased DMI when compared with including monensin and tylosin in 30% mDGS diet without the risk for increases in liver abscess occurrence.

Different combinations of sodium monensin and virginiamycin during feedlot finishing of Nellore cattle

Context The use of two feed additives, to maximise rumen fermentation, in finishing diets offered to feedlot cattle may positively impact performance. Aims This study, conducted at the São Paulo State University feedlot, Botucatu campus, Brazil, was designed to evaluate the effects of the combined use of monensin (MON; 30 mg/kg of dry matter; (DM)) and virginiamycin (VM; 25 mg/kg of DM) in high-concentrate diets during the adaptation and finishing periods on feedlot performance, carcass traits, feeding behaviour, blood gas profile, rumen morphometrics and apparent total tract digestibility of nutrients of Nellore cattle. Methods The experiment was designed as a completely randomised block, replicated six times (3 bulls/pen), in which 72 20 months of age yearling Nellore bulls (388.0 ± 31.1 kg) were fed in 24 pens for 90 days according to the treatments: (1) MON during the entire feeding period (T1), (2) MON + VM during adaptation and only VM during the finishing period (T2), (3) MON + VM during the entire feeding period (T3), and (4) VM during the adaptation and MON + VM during the finishing period (T4). The adaptation program consisted of ad libitum feeding of three diets over the adaptation period of 19 days with concentrate level increasing from 69% to 84% of diet DM. Key results Overall, bulls fed on T2 had a greater DM intake (P &lt; 0.01), final bodyweight (P = 0.04), average daily gain (P = 0.03), hot carcass weight (P &lt; 0.01), final Longissimus muscle area (P = 0.05), Longissimus muscle area daily gain (P = 0.01), improved carcass G:F (P &lt; 0.01) and increased dressing percentage (P &lt; 0.01). Similarly, bulls fed on T2 were faster to consume 1 kg of either DM (P &lt; 0.01) or neutral detergent fibre (P &lt; 0.01) after 60 days on feed. Furthermore, bulls fed on T2 presented a greater (P = 0.05) cell proliferation index in the rumen papillae. Conclusions According to the results, Nellore yearling bulls should be fed high-concentrate diets containing MON and VM during adaptation, and only VM during the finishing period to improve overall feedlot performance. Implications The use of both MON and VM proved to be helpful only during the adaptation period.

Nitroethanol in Comparison with Monensin Exhibits Greater Feed Efficiency Through Inhibiting Rumen Methanogenesis More Efficiently and Persistently in Feedlotting Lambs

This study was conducted to determine the dietary supplemental effects of nitroethanol (NEOH) in comparison with monensin on growth performance and estimated methane (CH4) production in feedlotting lambs. Sixty male, small-tailed Chinese Han lambs were arranged at random into three dietary treatment groups: (1) a basal control diet (CTR), (2) the basal diet added with 40 mg/kg monensin (MON), (3) the basal diet added with 277 mg/kg nitroethanol (NEOH). During the 32-day lamb feeding, monensin and nitroethanol were added in period 1 (day 0-16) and then withdrawn in the subsequent period 2 (day 17-32) to determine their withdrawal effects. The average daily gain (ADG) and feed conversion rate in the whole period ranked: NEOH > MON > CTR (p < 0.01), suggesting that the dietary addition of NEOH in comparison with monensin presented a more lasting beneficial effect on feed efficiency. Methane emission was estimated with rumen VFA production and gross energy intake. Both monensin and NEOH addition in comparison with the control remarkably decreased CH4 emission estimate (24.0% vs. 26.4% decrease; p < 0.01) as well as CH4 emission per kg ADG (8.7% vs. 14.0% decrease; p < 0.01), but the NEOH group presented obvious lasting methanogenesis inhibition when they were withdrawn in period 2. Moreover, the in vitro methanogenic activity of rumen fluids was also decreased with monensin or NEOH addition (12.7% vs. 30.5% decrease; p < 0.01). In summary, the dietary addition of NEOH in comparison with monensin presented a greater promoting effect on growth performance in feedlotting lambs by inhibiting rumen methanogenesis more efficiently and persistently.

An assessment of the effectiveness of virginiamycin on liver abscess incidence and growth performance in feedlot cattle: a comprehensive statistical analysis

The judicious use of commercial products in livestock operations can be part of a sustainable and environmentally friendly production scenario. This study was designed to gather published data of virginiamycin (VM) used in feedlot conditions of the United States and analyze its effectiveness and optimum dosage in reducing the liver abscess incidence (LAI). The dataset contained 26 studies that evaluated more than 7,156 animals of diverse breeds fed in several regions in the United States under different management. Statistical analyses included contingency tables to assess the nonparametric independence of the LAI, meta regression analysis to remove study effects and to evaluate LAI and animal performance, broken-line analysis to determine thresholds of VM dosage on LAI, and residual-based shading mosaic plots to illustrate the contingency analysis. There were 1,391 of 5,430 animals with LAI scores 1, 2, or 3 (LAI1-3) and 651 of 4,690 animals with LAI A+ (score 3). Our analyses suggested that there was a significant dependency (χ2P-value < 0.001) and significant asymmetry (McNemar's test P-value < 0.001) between LAI and VM treatment for both LAI1-3 and LAI A+. For the LAI1-3 group, only 22.5% of the treated animals had liver abscesses compared with 31.7% of the control animals. The metaregression analysis indicated that LAI1-3 was linearly reduced (P < 0.001) by about 0.42% per mg/kg of DM of VM. The lower 95% confidence interval of the intercept for LAI1-3 and LAI A+ obtained with a generalized nonlinear mixed regression was 18.7 and 20.3 mg/kg of DM, respectively. The broken-line regression analysis identified 2 thresholds for LAI (23.9 and 12.3 mg/kg of DM) at which the reduction in total LAI1-3 and LAI A+, respectively, would decrease faster as VM dosage increases (from 2.14% to 6% and from 1.91% to 4.33% per mg of VM per kg of DM, respectively). Additionally, our analyses indicated that after accounting for the study effects, VM significantly increased ADG at 2.08 g BW/d per mg/kg DM compared with 0.92 g BW/d per mg/kg DM for monensin (P < 0.001), suggesting that VM was about 2.3 times more effective in increasing ADG for the same dosage and feeding period length. All analyses yielded consistent results that led us to conclude that VM is effective in reducing LAI when fed between approximately 12 and 24 mg/kg of DM, and the maximum reduction might occur at approximately 24 mg/kg of DM or higher.

Dynamics of methanogenesis, ruminal fermentation, and alfalfa degradation during adaptation to monensin supplementation in goats

This study aimed to examine the temporal (hourly within a day and daily over the long term) effects of monensin on CH₄ emissions, ruminal fermentation, and in situ alfalfa degradation in dairy goats during dietary monensin supplementation by controlling the confounding effects of feed intake and ambient temperature. Six ruminally cannulated dairy goats were used, and they were housed in environmental chambers and fed a restricted amount of ration throughout the experiment. The experiment included a baseline period of 20 d followed by a treatment period of 55 d with 32 mg of monensin/d. During the whole experiment, CH₄ production was measured every 5 d, whereas fermentation characteristics and in situ alfalfa degradation were analyzed every 10 d. The CH₄-depressing effect of monensin was time dependent on the duration of treatment, highly effective at d 5 but thereafter decreased gradually until d 55 even though CH₄-suppressing effect still remained significant. The decreasing effects of monensin on ruminal acetate proportion and acetate to propionate ratio also faded over days of treatment, and the acetate proportion returned up to the pre-supplementation level on d 50. Monensin supplementation elevated ruminal propionate proportion and decreased the effective ruminal degradability of alfalfa NDF, but both measurements tended to recover over time. The postprandial increase rate of hourly CH₄ emissions was reduced, whereas that of propionate proportion was enhanced by monensin supplementation. However, the postprandial responses to monensin in CH₄ emission rates, ruminal VFA profiles, and in situ degradation kinetics declined with both hours after feeding and days of treatment. Our results suggest that the CH₄-suppressing effect of monensin supplementation in goats was attributed to reductions in both ruminal feed degradation and acetate to propionate ratio, but those reductions faded with time, hours after feeding, and days of treatment.

Effect of increasing monensin sodium levels in diets with virginiamycin on the finishing of Nellore cattle

This study evaluated the effect of increasing levels of monensin sodium (MON) in diets with virginiamycin (VM) on the finishing of feedlot cattle. Two hundred and eighty intact male Nellore cattle (348 ± 32 kg body weight, 22 months) received one of the following five diets: control diet (without additives); diet containing VM (25 mg per kg dry matter) combined with 0 (MON0), 10 (MON10), 20 (MON20) or 30 (MON30) mg MON per kg dry matter. During adaptation (28 days), the MON0 diet increased dietary net energy for maintenance and gain compared to the control diet (P = 0.04). The combination of additives linearly reduced dry matter intake, body weight and average daily gain (P < 0.01). Considering the total study period (110 days), there was a trend of greater net energy intake for maintenance (P = 0.09) and hot carcass weight (P = 0.06) for animals fed MON0 compared to the control diet. The combination of additives linearly reduced dry matter intake (P = 0.04) and linearly increased gain : feed and dietary net energy for maintenance and gain (P < 0.01). The combination of VM with MON at a dose of 30 mg/kg dry matter is recommended for Nellore feedlot cattle because it improves the efficiency of energy utilization.

A fluorescence switch sensor for detection of virginiamycin based on graphene oxide-supported carbon quantum dots and molecularly imprinted polymer

A fluorescence switch sensor was developed for the detection of virginiamycin, which was based on graphene oxide-supported carbon quantum dots (GO/C-dots) as the signal indicator and molecularly imprinted polymer (MIP) as the recognition template.