Regular analysis advised as drought hits silage quality

Dairy farmers will need to carefully balance rations this year as drought has significantly influenced the quality of grass silage.

This is according to Liz Homer of Trouw Nutrition GB, who was commenting on analysis of 3,283 samples of first-cut and 619 samples of second-cut silage.

“Our early first cuts, which would usually be the best crops, showed lower energy content, reduced digestibility and higher NDF [neutral detergent fibre] content compared with typical early first cuts,” said Dr Homer.

See also: 3 ways a farmer is optimising silage management to cut costs

“As more first-cut crops have been analysed, as anticipated we have seen crude protein and metabolisable energy (ME) content continue to decline. Our average of first cuts is now 30.5% dry matter (DM), 11.2MJ ME, 48.6% NDF and 14.2 % crude protein.”

While grass silages this year have the potential to feed well, quality is very variable, and many are low in rapidly fermentable carbohydrates. Therefore, farmers should be conducting analysis regularly to check the ration is balanced, she added.

Protein and carbohydrate balance

High NDF and lignin values will impact digestibility.

“The key to unlocking the energy in grass silages and getting cows milking will be to get the rumen functioning and correctly balanced, looking closely at both the sources and fermentability of carbohydrates and protein,” said Dr Homer.

While the high fibre index of this year’s silage reduces acidosis risk, it could compromise rumen throughput, so attention to maximising DM intakes will be needed to maintain milk yield.

“Positively, this high fibre index can support some cereal supplementations, which may be required in the rumen to get it firing, and to balance with the fermentable proteins to digest that fibre,” she explained.

Low crude protein

While early first cuts analysed at 15.3% DM crude protein, the first-cut average was 14.2%, and that fell to 13.3% in second cuts.

Dr Homer said she thought this was likely to be partly down to reduced fertiliser use.

She said care must be taken with lower protein silages, particularly if fed alongside a lower-protein maize or wholecrop silage.

Although protein supplementation might appear expensive, it could be very cost-effective in terms of nutrients supplied to the animal.

Top tips for feeding this year’s forage

• Understand availability – do an inventory of forage stocks and bought-up feeds, know the quality of forage and the formulation of other feed
• Get silage analysed regularly – this should be fortnightly for a herd of more than 200 cows and at least monthly for smaller herds
• Do a least-cost formulation for the total ration. This may mean using a higher cost compound at a lower feed rate – remain flexible
• Balance the rumen – maximise intakes of the less digestible forages through appropriate supplementary ingredients, as well as practical measures such as pushing up
• Remember heifers, dry cows and transition cows – ensure their requirements are still met
• Ease pressure on stocks – cull cows that are not performing
• Manage silage and grazing fields into winter – if growth picks up, topping or grazing may be needed to prevent lignified crops next spring
• Be mindful of starchy products from the food industry – get details of their fermentability

A snapshot of regional variation

• NutriOpt fermentable energy and protein balance gives the balance of rumen-degradable protein and rumen-degradable carbohydrate. A positive figure means there is more fermentable protein in the diet and carbohydrate supplementation will be required, and a negative represents the opposite.