Early silage analysis shows encouraging results for dairy farmers

Initial silage analysis shows that energy levels could mean cows are able to produce a litre more from forage over maintenance than last year.

Results gathered from more than 700 first-cut grass silage samples analysed by Trouw Nutrition GB are encouraging for dairy farmers, but experts warn that forage will need careful balancing.

Feed value and milk from forage

Ruminant technical development manager Dr Liz Homer says: “Following the cold winter and spring we would expect to see higher D value forages with better energy content, and this is what the analyses show.”

See also: How to ‘home test’ grass to know when to cut for silage

Dry matter is slightly lower although still within the target range, while overall feed value is better with improved crude protein content and similar ME content. Characteristics also show well-fermented crops.

Looking at the NutriOpt Dairy model developed by Trouw to determine feeding strategies, the “dynamic energy” suggests more milk from forage will be achievable.

“Dynamic energy, which is a more accurate measure of the energy actually available to the cow, is very high this year at 6.7MJ/kgDM,” Dr Homer says.

“This means a cow eating 10kgDM of the average silage could produce M+9.4 litres from forage, almost a litre more than from the same period last year. However, to achieve this the diet will have to be carefully balanced.

“Our analysis shows there are high levels of both rapid and slow fermentable carbohydrates in the silage and care will need to be taken to avoid tipping cows over the edge and increasing the risk of acidosis. This problem will be made worse due to the low fibre index.”

Fibre and acid watch needed

Dr Homer’s advice to farmers is:

• Monitor acid load and fibre index closely.
• Take care if adding rapidly fermentable energy sources such as cereals.
• A well-balanced diet may require the addition of structural fibre such as fermented wholecrop or less digestible later grass cuts.
• After maximising energy and microbial protein from the rumen, feeds high in bypass starch and protein can be added to complement high fermentable sources in the forage to meet desired production.

NDF and clamp slippage

NDF levels are similar to 2017, but with a lower lignin content. Pre-cut levels in grass showed generally higher NDF and fewer silages have low NDF content this year, which should help with clamp stability.

“Last year low NDF and structural fibre was one of the factors blamed for clamp slippage, so hopefully we will see more stable clamps this year as a result which will make for easier feeding out,” said Dr Homer.