Rumensin Premix & Millmix Feeding Recommendations

Rumensin in its Premix/Millmix form is one of the most versatile forms of Rumensin. It can be purchased as a standard or customized ingredient within commercially available compound dairy, calf and cattle feeds. It can be blended into bulk feeds such as PKE, either at feedmill or farm level, and it can be added directly to silages and supplements on farm.


Two Formulations

Two forms of Rumensin are available for in-feed use.

Rumensin 10% Premix contains Rumensin active at 10% concentration. Target dose rate for dairy cattle is 3 grams per head per day. Each 25kg bag contains 8333 cow doses. The 10% Premix product is designed for on-farm or small feed-mill use.

Rumensin 20% Millmix contains Rumensin active at 20% concentration. Target dose rate for dairy cattle is 1.5 grams per head per day. Each 25kg bag contains 16,666 cow doses. The 20% Millmix product is for feed-mill use only.

Rumensin Premix is extremely cost effective, but as with any micro-ingredient, it does need to be well mixed and managed to get the right daily dose to every animal. The following tips will help you achieve this.

The Ideal Dose

Because supplements are fed at different rates, there can be variation in the amount of Rumensin that a particular cow will consume in the feed. The label dose
rate for Rumensin 10% Premix is 3 grams per head per day. This is the optimal rate to target.

Good results will still be achieved with intakes of 2 grams of Rumensin 10% Premix concentrate per day, and with intakes up to 5 grams per day.

As you move to progressively higher rates, cows may show loss of appetite and diarrhoea and they will lose any Rumensin advantage.


Contrary to some competitor comments, Rumensin has a wide margin of safety.

The LD50 for monensin (the lethal dose that will lead to death in 50% of the animals), is equivalent to feeding 40x the label dose rate for a 500kg dairy cow.

At a more practical level, cows that are fed at 5x the label dose rate have no mortality risk but will develop scouring and reduced appetite. When normal dose rates are resumed, they will fully recover health and productivity within days.


Feeding Methods

The optimal way to minimise intake variation with supplements is with an in-shed feeding system.

Ad-lib feeding systems are less expensive and easier to manage, but some cows can gorge, while other less competitive cows may miss out.

The addition of micro-ingredient additives to ad-lib fed supplements needs to consider this aspect.

Are you starting on a new feed supplement?

Cows, or more specifically their rumens, need time to adjust to any new diet, whether it be silages, concentrates, crops or Rumensin. An introductory period is recommended during which time the volume of any new feed offered is slowly stepped up. This helps prevent rumen disorders.

Once the cow has adjusted to the feed, best results are obtained by maintaining consistent daily supplement levels over the supplementary feeding period. Frequent stopping and starting is not a good feeding strategy. 

Contact Us

VetEnt has a Rumensin feed option available or we can customize a feed for your requirements.

Alternatively, you may be able to use Rumensin Premix directly on farm.

For more information on using Rumensin in-feed, please contact us.

Make an Appointment

For emergencies or urgent appointments within the next 24 hours, please phone the clinic directly.