Dairy farmers warned not to get hung up on high-sugar grasses

Dairy farmers getting hung up on “high-sugar” grass varieties and failing to make re-seeding decisions based on a complete evaluation of the mix could be making a costly error.

It’s an error that’s contributing to a shortfall in efficient grass use in the UK, which means £1bn worth of milk and meat is being directly produced from supplementary feed when it could be produced from grass.

That’s the stark message from seed house DLF Trifolium, which is urging grassland farmers to choose varieties for their re-seeding mixtures that provide the correct balance of sugars – fast and slow-acting – and protein.

“High-sugar grasses may be suitable for some systems such as low-cost grazing, but they aren’t so suitable for farmers relying on conserved forage to produce milk where the role of grass silage is usually to provide protein to counterbalance high energy forages,” said DLF Trifolium’s agricultural sales director, Tim Kerridge.

“We have a grass variety with the second highest sugar content on the NIAB Recommended List – but we don’t promote it in isolation because we believe farmers should be assessing a range of a variety’s characteristics before making a decision.”

DLF Trifolium, which is owned by a Danish-based company, says its latest trial work has tended to show that grass varieties promoted as providing high sugar can be low in protein.

“There’s a lot more to grass than sugar. When we breed grass, we look at yield, dry matter and energy. These are critical but farmers must also look at disease resistance – there’s no point in having grass with a higher-quality profile if it’s going to be at risk of disease.

“The building blocks of grass quality are the protein content and the water soluble carbohydrate. In our trial work, we’ve focused on neutral detergent fibre and cell wall digestibility – that’s what determines how much feed value the cow can get from the grass.

“In Denmark, cell wall digestibility is the cornerstone of grass breeding and it’s the water-soluble carbohydrate contained in the cell wall that makes the sugar immediately available to the cow,” said Mr Kerridge.

He urged dairy farmers to be wary of tetraploids that are marketed as high-sugar grasses because of the fluctuations in their sugar content during the course of a day and during the season.

“They are an unstable source of sugar but this characteristic isn’t shown on the NIAB list because it’s a costly exercise to evaluate. Cell wall digestibility is the characteristic our breeders are aiming for so that slowly digestible fibre is available to the cow – a bit like providing pasta for a marathon runner rather than a sprinter taking a sugar drink for a kick-start to the race.”

Johnny Bax, of Biotal/L’Allemand Animal Nutrition, added that cell wall digestibility was the “all encompassing measure” of what’s happening to the forage inside the rumen.

“If we want to get cows to eat more, we have to increase the rate of passage of forage through the rumen. But if we can improve cell wall digestibility of the grass in the forage there will be real benefits because we can extract more of the nutrient in the limited time it’s in the rumen.”

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