How to make the most of high protein silage

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Dr Robin Hawkey

This year’s grass silage is very high in protein, meaning producers could save money by using lower protein concentrates over the winter. But it is also extremely variable, so it will be essential to analyse it and balance diets carefully, says Robin Hawkey, senior nutritionist at Mole Valley Feed Solutions.

“On average, protein contents are at 15% compared to 13.8% last year,” he explains. “That’s a big jump.” The highest samples are at 27.8% against 21% last year – and the extremes continue in other areas, too. Although the average neutral detergent fibre (NDF) is 46.4% compared to 47.4% last year, the lowest analyses are at 32.4% versus 38.6%. “The averages hide a really big range.”

Dry matter contents are similar, year-on-year, at 36.3%, with metabolisable energy (ME) averaging 10.9MJ/kg and sugars 1.9% – but ranging from 0.2% to 9.5%. And the lactic acid is a lot higher at 77.3g/kg versus 74.5g/kg last year – within a range from two to 166.9g/kg. If high acid combines with a lower NDF, it will upset the rumen bugs, and will need to be buffered, warns Robin.

Feed efficiency

In order to meet these varied needs, Mole Valley has launched a new range of lower protein concentrates, which will also help farmers to comply with processors’ demands for improved feed efficiency and carbon footprints.

“Traditionally, cake is formulated at 18% protein,” notes Robin. The new SilageMax range is 16% protein and comes with two options: Low Acid (LA) Boost and High Acid (HA) Balance.

SilageMax LA Boost should be fed with restricted fermentation (low lactic acid) silage, to provide energy to the rumen bugs, boosting fermentation and so producing more propionate from the rumen, which is important for energy supply. The feed contains wheat, beans, maize gluten, sunflower and rumen-protein rapeseed. “As rumen function could be restricted, it contains higher levels of rumen-fermentable protein and energy to drive microbial activity and microbial protein production,” explains Robin.

In contrast, SilageMax HA Balance provides a counter to ‘fast and fizzy’ silage which is likely to lower rumen pH and pass straight through the cow. It contains soya hulls to boost fibre, palm kernel, maize grain as a form of bypass starch, and soya and rumen-protected rapeseed as bypass protein, alongside and an acid buffer; Acid Buf. In addition, it has X1 live yeast to promote fibre-digesting bacteria that are particularly sensitive to pH.

Wide spectrum

“The aim is to keep the high protein silage in the cow and utilise it,” says Robin. “We have a whole range of cakes for mid-range silage – but where it’s testing at either end of the spectrum, these options will really help you get the most from your forage.”

Producers who are feeding last year’s maize silage may find it has higher lactic acid and lower pH than when it was first analysed, he warns. “It could be very different – silage that tested at 64% lactic acid in November is now at 68%, so it may benefit from adding HA Balance.”

Both cakes also contain biotin which is beneficial for hoof strength, longevity and liver function, adds Robin. “It helps the liver enzymes to produce glucose. The liver is responsible for making use of the nutrients available, so we want to make sure it’s functioning as effectively as possible.”