Improve silage quality with molasses

Produced on over 85% of livestock farms in Ireland, grass silage is a vitally important constituent of diets on both dairy and beef enterprises. Depending on production systems, grass silage can account for 20-25% of dairy cow diets and up to 30% of suckler cow diets. Costing between €120 – €140 per tonne of dry matter (DM) to produce, good quality grass silage is far more cost-efficient than purchasing concentrates at €250 – €300 per tonne of (DM). Producing high quality grass silage is dependent on a number of different factors, good attention to detail and having a well laid out plan will all help in achieving the desired quality silage on farm.

Plan a good silage strategy:

Due to the diverse nature of stock carried on farms over the winter period, nutritional demands can vary quite considerably. Dry cows, of good body condition score (BCS) for instance, require a far lower plain of nutrition for maintenance and foetal growth to that of a milking cow or a growing or fattening animal. Therefore, targeting stock groups with silage of appropriate dry matter digestibility (DMD) can lead to significant cost savings through both reduced intakes and compound feed bills. Implementing a comprehensive silage strategy, that clearly outlines the farms nutritional requirements can consequently be of huge benefit. Examples of the basics of a silage plan are detailed below:

  • Define the highest quality of silage required on farm.
  • Estimate of the quantity of silage that will be needed.
  • Pre-plan crop harvesting date.
  • Examine silage pit and bale storage facilities prior to harvesting.


Effect of cutting date on quality:

Assessment of silage quality and quantity requirements are key to identifying crop harvesting date. Farmers should aim to maximise forage yield while also achieving the target silage (DMD) value for their stock. Grass heading date, which generally occurs from the 20th of May onwards, has one of the largest impacts on grass silage quality prior to it entering the clamp. Once the seed head emerges, silage (DMD) falls quite rapidly at a rate of 0.5 units per day. Depending on requirements, farmers, should aim to mow just as the seed head appears, delaying this by 5-6 days can be the difference between producing good and average quality silage.

When to use Molasses:

The basic process of silage production is best described as the conversion of plant sugars to fermentation acids through the rapid achievement of an anaerobic environment. Crop chop length, speed of clamp filling, consolidation and sealing all play key roles for this process to be effective.  However, the crops overall sugar content entering the clamp also plays a vital role in the quality of the fermentation. Targeting a crop sugar content of 3% or greater pre-harvest should be a prerequisite.

Reaching this sugar content target is not always achievable however, and can be influenced by many different factors. Sward type, state of lodging and weather conditions can all influence a standing crops sugar content. Where plant sugars are below 3%, adding a sugar-based additive in the form of molasses as a fermentation stimulant can be very effective. Sugar levels dependant, application rates can vary from 9 to 18 litres per tonne of fresh herbage. Application at these rates will allow for increased preservation acid production while also reducing ammonia N content and silage pH levels. Additionally, molasses will also help bind the clamp together, reduce air availability while also aiding in increasing the overall storage capacity of the clamp. Its flexibility allows molasses to be applied to the sward via a sward applicator or directly to the forage clamp via a hydraulic pump.