Average 2017 first cut grass silage quality is better than at the first stage of last year, reports Trouw Nutrition GB. It appears farmers are heeding advice to cut grass earlier to ensure a better nutritive value.

The company has now analysed over 1,000 first cut samples at its Ashbourne laboratory, the UK’s largest such facility. “Our initial results show that, on average, grass silage quality has improved, principally as a result of cutting dates being brought forward,” says Trouw’s ruminant nutrition specialist Tom Goatman. “Grass growth was also slower this spring, meaning crops were less mature at harvest which is reflected in the analyses seen so far.

“All the traditional measures of quality have improved compared to 2016.  Dry matter content is higher at 33.7% while crude protein has risen from 14.5% to 15.2%.  D value is 70.1%, up from 67.6% last year, helping ME to rise from 10.8MJ to 11.2MJ.  Intake potential has also risen to 105.5, suggesting cows can be expected to eat reasonable quantities.

“A cow consuming 10kg DM of this year’s average silage could be expected to give M+7.4 litres per day, up from 6.6 litres/day last year.  Over a 200 day winter this would be an extra 160 litres from forage per cow.”

Trouw has adopted the NutriOpt Dairy nutrient measurement system that takes account of the effect of rumen digestion on the silage and its break down into metabolisable end products. Dynamic Energy (DyNE) is the new term used to describe energy – as the sum of the end products of digestion, it gives a more accurate assessment of the energy actually used by the cow.

“Rationing using DyNE, a cow eating 10kgDM will be expected to produce 7.7 litres per day from silage which is more than expected using ME,” advised Mr Goatman. “Rationing on ME actually undervalues the potential of this year’s higher quality forage and could result in unnecessarily higher production costs.”

At the same time, the new analysis parameters can help ensure an improved rumen balance and better rumen health.  The 2017 silages have less NDF, which is reflected in a lower level of slowly fermentable carbohydrate, although the level of rapidly fermentable carbohydrate has increased.

At the same time, the levels of rumen fermentable proteins – both rapidly and slowly fermented – are higher, he continues. “For optimum digestive efficiency, the supply of carbohydrate and protein in the rumen needs to be in balance, so it will pay to feed more slowly fermentable carbohydrate sources this winter. Feeds like soya hulls or sugar beet will provide the required digestible fibre.”

Mr Goatman adds that the high acid load and low fibre index suggest that rumen health may be an issue next winter, and is a reflection of the higher levels of rapidly fermentable carbohydrate and lower level of digestible fibre.  Again sugar beet or soya hulls will help to supply digestible fibre to support rumen health and the protein energy balance.

“Overall, the average grass silage will feed well, allow an increase in production from forage this winter and act as the foundation for more cost-effective diets,” Mr Goatman concludes. “As usual, there is a tremendous range around the average so the start point must be to get clamps analysed regularly to ensure diet formulations are based on the forage actually being fed.”

 First cut grass silage analyses 2017 and 2016

2016 first cut 2017 first cut
Dry matter (%) 31.2 33.7
Crude protein (%) 14.5 15.2
D value (%) 67.6 70.1
ME (MJ/kgDM) 10.8 11.2
pH 4.1 4.3
Sugar (%) 2.7 2.9
NDF (%) 50.0 44.2
Intake potential (g/kgML) 98.5 105.5

NutriOpt analysis parameters- first cut 2017

2017 First Cut Average
Dynamic energy (MJ/kgDM) 6.1
Rapidly fermentable carbohydrate (g/kg) 200.3
Total fermentable carbohydrate (g/kg) 440.0
Rapidly fermentable protein (g/kg) 96.5
Total fermentable protein (g/kg) 111.1
Acid Load 50.5
Fibre Index 178.8

Source: Trouw Nutrition GB