Guide to maximising fibre potential in grass silage

Formulating diets to get the most out of forage, rather than bought-in compound feeds, has long been accepted as a way for dairy producers to be more profitable.

However, nutritionist Roy Eastlake says many growers are not maximising the potential of forage, and particularly grass silage. This could be having an impact on profit and cow performance.

Below, he explains why maximising fibre potential in grass silage is so important and the practical ways farmers can do this.

See also: Forage analysis and how to interpret results on-farm

The value of forage and fibre

Fibre is essential for energy and rumen function in ruminant diets. Unlike maize silage, which provides fibre and starch, grass silage is all about fibre, says Mr Eastlake.

With fuel prices and the cost of fertiliser up and purchased feed costs rising, maximising fibre utilisation is critical, he adds. “Production from forage offers exceptional value in comparison with compound feed sources.”

As well as feeding more grass silage, growers should also focus on improving the quality of that silage. Doing so can bring potentially large cumulative savings and cost benefits compared to bought-in feed, he says (see “The value of maximising fibre”).

Kingshay’s Dairy Costings Focus 2021 report shows a 4.36p/litre difference in margin over purchased feed (MOPF) a litre when ranking herds according to the proportion of milk produced from forage.

The MOPF for the bottom 25% was 18.21p/litre, while for the top 10%, it was 22.57p/litre.

This illustrates the breadth of impact forage can have on profitability, adds Mr Eastlake.

How to improve forage quality and fibre utilisation

Rumen efficiency is at the core of better utilisation. Mr Eastlake says it is important to look holistically and consider all the factors that are likely to influence this.

He adds that improvements can be made by targeting three main areas: forage quality and management; environment and management; and diet balancing and feeding (see “Key ways to maximise rumen efficiency for improved cow production, health, fertility and welfare”, below).

Focusing specifically on forage, making more consistent, higher-quality silage is essential, says Mr Eastlake. “You need quality fibre to maximise the rumen function in a dairy cow and improve digestion.”

He advocates an “opti-cut” system. This involves three key elements:

• Pre-cut testing to ensure grass is at the right stage for cutting (based on when it is most digestible)
• Optimum management before and during the silage-making process
• Using an inoculant to maintain and maximise the nutritional value of the silage.

Forage planning should involve multiple parties – including the agronomist, nutritionist, consultant and contractor, for example – to discuss all aspects of silage-making, from the fertiliser strategy to which fields will be cut and when.

Mr Eastlake says growers should be aiming for a first cut in April, depending on the outcome of the pre-cut test.

“We know the first cut is critical and, in the UK, I believe April is the new May [in the South]. You have got to be cutting mid-April to get the most from forage.

“If you miss that window, as we saw a lot of farmers do last year, you end up with clamps full of average silage that cows do not like as it is not as digestible. The best systems are cutting every four to five weeks.”

Though earlier cuts may cause concern over elevated moisture levels, Mr Eastlake says that while drier silages of 30% dry matter (DM) are preferred, it is still possible to get good performance from wetter silage.

This is provided it is cut at the right stage, ensiled with a high level of management, and treated with a crop-specific proven inoculant.

Choice of inoculant will depend on whether farmers want to help fermentation or aerobic stability.

It is also important to reduce wastage. The Smart Silage project, led by the Institute of Biology at Aberystwyth University, concluded that average DM losses during silage making are 25%.

Mr Eastlake says these losses can arise in the field, during fermentation, in the clamp, and at feed out, so careful management is required.

Underpinning all of this is monitoring and measuring all aspects of silage-making and forage production to ensure the steps taken to improve forage quality and fibre utilisation are working, he concludes.

Roy Eastlake was speaking at a recent event hosted by Lallemand Animal Nutrition to launch its Forward with Fibre guide.

Opti-cut in practice: Shropshire dairy farm case study

The benefits of improving the quality of grass silage have been observed at a dairy farm in Shropshire where nutritionist Roy Eastlake gives advice.

The herd averages 13,500 litres/year, is housed year-round and produces more than 1,000kg milk solids a cow a year. Cows are fed a total mixed ration (TMR) of maize and grass silage.

Mr Eastlake started working with the farm in 2019. Grass silage quality has improved since adopting an opti-cut system (see “Grass silage analysis at one Shropshire dairy farm”).

“The farm is averaging production levels of 45 litres a cow a day, which is only possible with really good-quality feed,” he says.