bulletChemical Structure
bulletChemical Formula
bulletMolecular Weight:
bulletCas No.:
2-[2-Ethyloctahydro-3'-methyl-5'-[tetrahydro-6-hydroxy-6-(hydroxymethyl)-3,5-dimethyl-2H-pyran-2-yl][2,2'-bifuran-5-yl]]-9-hydroxy-ß-methoxy-a,?,2,8-t, 63714, A-3823A, monensic acid, Monensin, Romensin

MONENSIN is the polyether ionophore antibiotic, which is produced by fermentation of Streptomyces cinnamonensis. It is active against certain gram-positive microorganisms primarily against coccidia, such as Eimeria acervulina, E. mivat, E. brunetti, E. maxima, E. necatrix, E. tenella in broiler chickens.

MONENSIN acts on the trophozoite in the first cycle of schizogony. The mechanism by which MONENSIN acts is based on its ability to form complexes with sodium and potassium ions and to prevent penetration across the cell membrane of coccidia. MONENSIN prevents sodium transport while potassium is accumulated in the cell of the parasite thereby inhibiting mitochondrial functions of the parasite, oxidation and hydrolysis of adenosine triphosphate.

In ruminants with developed forestomachs MONENSIN increases the rate of weight gain and enhances feed efficiency.


1. Prevention of coccidiosis caused by Eimeria acervulina, E. mivati, E. brunetti, E. maxima, E. necatrix, E. tenella in broiler chickens.  2. For enchanced feed efficiency and increased rate of weight gain in young cattle and lambs with developed forestomachs.
Pure, 10% and 20% Premix (Insoluble oral powder). For10% Premix, each 100g of insoluble powder contains 10 g of monensin (in the form of sodium salt) and an insoluble carrier.
Stable under normal storage conditions. Unstable in contact with acidic and alkaline substances. It maintains its stability very well for two years when stored under ambient temperature.
bulletDosage & Administration
MONENSIN is intended for use only in ruminants with fully developed forestomachs. Detailed dosage and administration guide is as follows:
Animal species 10% premix 20% premix Pure Substance
Broiler chickens 900 - 1100 g/t 450 - 550 g/t 90 - 110 g/t
Turkeys up to
10 weeks of age
540 - 900 g/t 270 - 450 g/t 54 - 90 g/t
Fattening beef cattle 50 -300 g/t 25 - 125 g/t 5 -30 g/t
Fattening lambs 100g 50g 10g/t
Breeding heifers and bulls, body weight over 200 kg 50-300 g/t 25-125 g/t 5 - 30 g/t

Young pasture cattle, body weight over 200 kg

0.5 -2 g per head per day

0.25 -1 g per head per day

0.05 -0.2 g per head per day

Remarks: The total daily amount of Monensin 10% premix given to cattle should not be less than 0.5 kg and not more than 3.5 kg per head per day.


Important: must be thoroughly mixed in feeds before use.
Thoroughly mix 500 g (0.50 kg) of MONENSIN PREMIX in one metric tonne (1000 kg) of feed to provide monensin at 99 g monensin activity per metric tonne of feed.
It is recommended that MONENSIN PREMIX be mixed with a small quantity of the finishing feed before it is incorporated in to the bulk of the feed being prepared.
Broiler chickens - feed the medicated feed continuously as the sole ration

1. Do not use this medicated feed for treatment of outbreaks of coccidiosis.
2. Do not allow canines, horses or other equines, or guinea fowl access to formulations containing monensin. Ingestion of monensin by these species has been fatal.
3. Poultry consuming monensin should not be treated with products containing tiamulin. Severe growth depression may occur.
4. May be used in feeds containing the pellet binding agents bentonite (2%), Attapulgite (2%), Kaolin (2.5%), Lignin Sulfonate (4%), Carboxy Methylcellulose (0.1%) or Agri-Colloid.
5. Do not exceed recommended levels as reduced average daily gains may result
1. Do not feed to replacement and laying chickens. Do not use MONENSIN in lactating dairy cows.
2. When mixing and handling MONENSIN PREMIX, use protective clothing, impervious gloves and a dusk mask. Operators should wash thoroughly with soap and water after handling.
3. Do not supplement monensin from other sources (eg. other feedstuffs containing monensin or other slow release devices containing monensin).


LD50 = 200 mg/kg LW.

1.5 to 2 times the usual dose for 3 weeks = loss of weight.

3 to 6 times the usual dose = reduction of the daily weight gain, feed consumption, mortality.

Decrease of water consumption.

In warm circumstances : reduction of feed consumption. 


Authorised for growing breeder hens. 


Residue in the eggs. 


At 100 ppm reduction of fertility (Jones – 1990). 


LD50 = 335 mg/kg LW for the young ones.

200 – 300 ppm at 7-8 weeks : decrease of weight and of the feed consumption from 13 to 24% (Potter & al –1986)

For the full grown : <100 ppm continuously = mortality (Halvorsen & al – 1982) 


No negative results at 2 times of the usual broiler dose (Perlstein –1984), paralysis at 158 ppm for the Pékin duck(Reece – 1988). 


Paralysis, mortality at the usual broiler dose  (Reece – 1988). 


No negative results at the usual dose (Jurkovic – 1982). 


No negative results at the  usual dose.


No negative results at the  usual dose.


Toxic at 100 ppm. LD50 = 40 mg/kg LW. 


DLD50 = 2 mg/kg LW (it means 10 kg of a broiler feed for a 500 kg horse).

External signs : ataxia, paralysis, salivation, cardiac myopathy , mortality.




From 40 to 100 ppm : anorexia, decrease of growth.

Very high toxic at 6-10 the dose recommended for cattle.

LD50 = 25 mg/kg LW. 


LD0* = 4 mg/kg LW.

During 3 month : 22 ppm without negative results.

At 66 ppm : 10% of cardiac injury.

At 110 ppm : 10% of mortality. 


LD50 = 16 – 50 mg/kg LW. 

*LD0= Minimum fatal dose at single administration.

 25 Kg Bag  in one compound paper bag with plastic liner inside. Or in 25 Kg fiber drums.
Store in a cool and dry place
bulletShelf Life
2 years.
In need of further information, please kindly us at: or or call our direct phone: 0086 133 5582 2008

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