Silage - managing the risk

Published 8 May 15

Grass silage is potentially the most valuable silage you will produce but managing the risks associated with it, both weather related and management related, is crucial, says Piers Badnell, AHDB Dairy Technical Extension Officer. There are three areas where losses can occur with silage, field loses (5 – 10%), clamp losses (5 – 20%) and feed out losses (5 – 10%), and attention to detail can help reduce the risk at each stage.

Field losses

Pre-test grass to asses D, sugars and nitrate levels and make sure you cut early, before the ear emerges in order to maximise D value. At heading date (when 50% of the tillers have started to head), D value is at about 70 (ME 11.2), just seven days later it will have dropped to a D value of 67 (ME 10.7).

A quality wilt is crucial for good silage. If your mower spreads to full width make sure it’s working, otherwise you need to get the tedder up right behind it to spread the grass fully. When it rains the moisture will pass right through the grass like this, if it is sitting in clumps in a row they act as a sponge and will hang onto moisture and heat up.

Clamp losses

Attention to detail in clamp management really pays off. The pit is the most important place in the silage-making process. Either be there yourself, or have someone there who knows what you want, to make sure things are done the way you expect them to.

Recently, I met with a farmer who calculated the cost of his losses from around the pit, and came up with the figure of £24,000. This figure doesn’t surprise me. You don’t see the losses but it is the equivalent of someone turning up and taking two loads away a day.

The list below isn’t new but it’s worth highlighting again:

  • Make sure the clamp is clean and the sides are sheeted
  • Consolidate grass in thin layers (20 – 25cm)
  • Consolidate grass evenly
  • Sheet the clamp overnight and don’t be tempted to roll the next morning
  • Seal the clamp properly
  • Weigh the top of the clamp and protect the silage sheet.

If the cut grass is arriving too quickly at the clamp for adequate and even consolidation to take place, you need to talk to your contractor. As they need to know what you expect and it is worth any extra money spent on many hours for the reduced loss to silage.

Concentrate on consolidating at the sides of the clamp, the centre receives plenty of consolidation as it is travelled across.

Feed out losses

Once you’ve produced high-quality forage, don’t waste it. Provide enough space for all cows to get to the feed and you’re not making losses through heating, dry matter loss or rejection. Make sure you are challenging the cows to eat it and not substituting with expensive bought-in feed.

Getting 16kg DM/day into your cows is a realistic objective and you can do this by reducing the risks from both weather and poor management, through a good relationship with your contractor and attention to detail.

Practical examples

The two examples below show how farmers in very different systems, manage those risk to produce consistently high-quality silage.

One farmer I visited recently, with a herd averaging 7,500 litres/cow yield, is aiming to get 16kg DM into his cows, every day of the year, either via grass or quality silage and he targets an ME of 11.5 for ensiled grass and 12+ ME for grazing. He produces such high quality by cutting early, before seed heads appear. This farmer has been having an ongoing conversation with his contractor since early March and because he cuts so early he can pick exactly the right weather window.

Table 1 below demonstrates the benefits to quality of cutting early and, although yields did suffer, second cut yields more than made up for the shortfall.

Table 1: Cutting date, silage energy content and yield

 Silage table

Source: Thomas, Bax and Osman (1998) More Milk from Grass

In the second example, a farmer with a herd averaging a yield of 11,000 litres/cow installed robotic milking machines and had to drop feeding concentrate in the trough, but instead introduced it in the robots, as a way of getting the cows to come in for milking. He then found himself in the position of being able to offer the cows more high-quality forage in place of the reduced concentrate. He, too, aims to get 16kg DM into his cows every day and has raised high milk from forage by 2,000 litres to 4,000 litres/cow/year.

This farmer produces such high-quality grass silage as a result of a good relationship with his contractor, who is kept fully informed about silage plans and given exact instructions on how the farmer wants things done.

Luppo Diepenbroek, independent farm consultant, wrote a piece last year for Forage for Knowledge about how to improve silage intake potential, for some more out-of-the box thinking on this topic.