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Silage Analysis and Ration Composition

Silage Analysis and Ration Composition

Keith Fahy, B&T Drystock Adviser, Teagasc Galway/Clare tells us that with weather deteriorating, grass growth reducing and in some cases poaching some farmers are starting to house their cattle. This is a great opportunity to take silage samples and indeed soil samples.

With the soaring costs of inputs such as feed and fertiliser farmers need to know exactly how much meal they need to substitute silage this winter. With soil samples being charged at approx. €25 per sample and silage at €35 a sample is an inexpensive activity to ascertain key information.

Why should I analyse my silage?

Knowing the quality of your feed is of vital importance to ensure animals are receiving enough energy, protein and minerals. With concentrates trading from anywhere from €420 to €480 per tonne depending on protein and specification it will be a costly activity substituting poor quality silage this winter. If a farmer had 50 weanlings to feed over a 120 day winter period and had a 66% DMD silage versus a 75% DMD silage it could cost up to an extra €4000 euro to substitute the poorer quality silage to ensure a 0.6kg average daily gain over the 120 days. That’s a significant cost to incur to correct poor management during the silage preservation period. This is calculated as the 66% DMD silage would have to be supplemented with concentrates at a rate of 1.8 kg per day versus 0.4 kg per day for a 75 DMD to gain 0.6kg/day. This is an increased rate of 1.4 kg/day and keeping 50 weanlings over a 120 day winter period would calculate to an extra 8.4 tonne of meal, at €465/tonne for a better quality ration this would amount to €3906 extra. This equates to a massive cost of €80 extra per weanling fed over the winter.

Table 1. Guideline daily feeding rates based on silage quality (DMD)

Animal typeTarget ADG66 DMD68 DMD70 DMD72 DMD74 DMD76 DMD
Weanling 0.6 kg/day 1.8 kg 1.5 kg 1.2 kg 0.9 kg 0.6 kg 0.4 kg
Finishing steer 1 kg/day 7.0 kg 6.0 kg 5.5 kg 5.0 kg 4.0 kg 4.0 kg
Finishing heifer 0.9 kg/day 7.0 kg 6.0 kg 5.5 kg 5.0 kg 4.0 kg 4.0 kg

What to look at when assessing the silage analysis report?

When looking at the different units of measure in the silage sample it is important that farmers understand the meaning behind each result. Dry matter digestibility, pH, UFL, Crude protein are some of the key parameters. Table 2 below explains each measure while showing farmers the targets of what their silages should be:

Table 2. Key information provided from silage analysis

Unit of measureMeaningLowHighTarget
Dry matter (%) Feedstuff less water content 13-17 40-55 28-32
pH Measure of acidity 3.4-3.7 4.5-5.5 3.8-4.5
Ammonia (%N) Indicator of grass N content at cutting 4-7 15-25 <10
NDF (%DM) Measure of forage fibre and initial potential 42-47 55-65 <44
DMD (%) Measure of quality 55-65 76-80 >72
ME (MJ/kg DM) Energy content (linked to DMD value) 8-9 11-12 >11
UFV/UFL (unit/kg DM) Energy content (linked to DMD value) 0.6-0.7 0.89-0.96 >0.89
Crude protein (% DM) Measures N as indicator of true protein content 7-9 15+ >13.5
Ash (% DM) indicator of soil contamination 5-6 12-15 <8.6

Forms of Concentrates available:

There are a range of different ways in which concentrates can be processed or fed.

  1. Pelleting or Cubing: this is common practice especially where feeding dairy cows or where rodents can be an issue as they allow for rapid intake by the animal. Pelleted or nuts also reduce the amount of dust that can be encountered when feeding coarse, flaked or grinded meal. Molasses is usually added in the process of pelleting to bind the different ingredients together.
  2. Grinding/Milling: is where ingredients are ground. Flour or maize would be a good example. This makes it easier for maize to be mixed into rations for pelleting. Ground maize meal is also fed to finishing cattle as it helps to develop a good cover of fat on the animal as it is high in energy.
  3. Flaking: This process can involve soaking in water over night, toasting and then rolling into flakes whilst at a reasonably hot temperature. Maize is often flaked as this can help to assist in the breakdown of starch which will subsequently help the rumen/stomach to break down this constituent.
  4. Coarse: Here we see concentrates fed as coarse or rougher type composition. Usually consisting of rougher raw materials like rolled barley for example. Putting minerals through this type of feed can be a little more difficult than pelleted feed.

What ingredients do I want to see at high inclusion rates in my concentrates?

When reading the ingredients on your concentrate label it is vital to know that the composition in terms of percentage in the feed are in descending order meaning the first ingredient you read will be at the highest inclusion rate. For that reason it is vital that the first 3 to 4 ingredients should have a high energy, UFL and protein rate. You don’t want to see lower quality feeds or poorer type by products at the beginning of the ration as this will indicate an inferior type ration.

  • Barley
  • Maize Meal

Barley is probably the most common feed ingredient in rations in Ireland and indeed around the world as it is high in energy and is the basis of the French Feed evaluation system the (UFL/UFV).

Maize meal is usually in high inclusion rates where animals are being finished for slaughter. Feeding Maize meal whole can be an issue as it is not very palatable, ideally it should be mixed through the ration or pellet.

  • Oats
  • Fodder Beet

Oats are an easy to grow crop and can survive better in acidic soils when compared to barley or wheat. Oats are a very safe feed and can be put in growing or finishing diets, it can be lower in energy when compared to other crops such as barley or maize.

Fodder beet is a high energy, high UFL feed but has a high moisture content. Ideally fodder beet should be cleaned or washed to prevent any stones or soil entering the animal’s digestive system. Fodder beet is quite palatable and is high in both sugars and digestible fibres but is quite low in protein at about 7 to 8% crude protein.

  • Soya Bean Meal

Soya bean meal is a fantastic source of protein, it is a by-product of soya bean oil production, consisting of a protein rate of 48%. It is an expensive form of protein as it is imported into Ireland. Brewers’ grain is also used to increase the protein in concentrates and is a by-product of the brewing industry.