Initial results from the UK’s largest forage analysis laboratory indicate the potential for increased production from grass silage this year, while new analytical terms will help farmers exploit the opportunity to drive more from forage.
Discussing the results from over 1000 grass silage samples analysed so far at the company’s laboratory in Ashbourne, Trouw Nutrition GB ruminant nutritionist Tom Goatman believes many dairy farmers have reaped the benefits of following advice to cut earlier to improve quality.
“Our initial results show that, on average, grass silage quality has improved, principally as a result of cutting dates being brought forward. 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.”
Mr Goatman explains that while traditional terms such as dry matter and crude protein may describe the silage in the clamp well, they do not describe how it will behave once the cow has eaten it and it has been broken down into the end products of digestion. Using new parameters produced as part of the NutriOpt Dairy system, farmers can now ensure their cows get the most from their grass silage.
Dynamic Energy (DyNE), is the new term used to describe energy, and is the sum of the end products of digestion giving the most 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. Rationing on ME actually under-values the potential of this year’s higher quality forage and could result in unnecessarily higher production costs.”
Mr Goatman says the new analysis parameters will help ensure improved rumen balance and better rumen health. He explains that this year’s silages have less NDF which is reflected in a lower level of slowly fermentable carbohydrate, although the level of rapidly fermentable carbohydrate has increased.
“Fermentable proteins have altered with increased rapidly and less slowly fermented protein. This change mirroring the carbohydrate content is good news because 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 also points out that the high acid load and low fibre index suggest that rumen health may be an issue 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 supporting rumen health and the protein energy balance.
“Overall, the average grass silage will feed well and give a chance to increase production from forage this winter and act as the foundation for more cost-effective diets. As usual, there is a tremendous range around the average so the start point must be to get clamps analysed regularly to ensure diets are formulated based on the forage actually being fed.”
Comparison of initial first cut analysis 2016 and 2017
|2016 first cut average||2017 first cut average|
|Dry matter (%)||31.2||33.7|
|Crude protein (%)||14.5||15.2|
|D value (%)||67.6||70.1|
|Intake potential (g/kgML)||98.5||105.5|
NutriOpt analysis parameters
|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|