Ration calculation

Feeding cows starts with the ration: what are you going to feed, and how much? The computer calculates this on the basis of the criteria and values you enter. The available forage is the starting point for this. Next are your production targets and your feeding method. Feed costs and expected production are key in the computer calculation.

Standard nutrient requirements

In a ration calculation, based on the feeds you have available you put together a daily ration that meets the animals’ energy, protein, fi bre and minerals/trace element requirements.

You will fi nd the standard nutrient requirements in documents such as the Table Book for Livestock Nutrient

Requirements (Tabellenboek Veevoeding) published by the Dutch Central Bureau for Livestock Feeding (CVB). The requirements depend on your production targets, i.e. the kilograms (lbs) of milk the cow must produce and how many kilograms (lbs) young cattle must put on in weight. You also need to bear in mind the maintenance requirements that depend on body weight. Then you can add in the expected growth of the foetus carried by the pregnant cow and the growth of the cow in the fi rst and second lactation.

Choosing feedstuffs

A ration consists of various products, or feedstuffs. Always start with the forage that you have in inventory. You know exactly how much there is and what its nutritional value is. Sometimes you can change the proportions fed to a limited extent. The nutritional value is the amount of energy, protein, fi bre and minerals it contains. Then comes the feed you buy in. You choose this on the basis of nutritional value and price. You also need to know to what extent and how quickly the feed ferments in the rumen. A degradable product ferments in the rumen, while a completely undegradable product passes through it unchanged.

Putting together a ration is a process of well-prepared trial and error. You have to make certain estimates and choices in your calculation. The cows will tell you within 48 hours (dung), one week (milk) and one month (BCS) whether you were right.

Steps for calculating rations

Rations are calculated on the computer, usually with special software. This will look for the cheapest possible ration that meets all the requirements entered, based on the feedstuffs and nutritional values you have entered.

1. Choose the right nutrient standards

2. Use the right figures

3. Include cow signals

4. Optimise in order of contents

5. If you give cows additional individual concentrate: do step 4 for 3 scenarios

For each group, specify the average cow and then the appropriate nutrient standards.

• Correct figures from feed analyses

• Actual, measured feed intake

E.g. if rumen fill is low, do not increase fermentation rate

1. Right energy content

2. Right protein content

3. Right fibre content

4. Right mineral content

1. Without additional concentrate

2. With average additional concentrate

3. With maximum additional concentrate

Rumen fermentation, energy and protein

The ration must make the right quantity of protein and energy available in the rumen in the right proportions. If the cow eats the same ration all day long, these proportions will rarely change. When estimating the fermentation rate, you need to look at the total ration. Depending on this, you can adjust it to create a slow or fast product. With fast products you can feed a cow more nutrients per day because they disappear from the rumen quickly, making room for new feed. But too rapid fermentation can cause rumen acidosis and can result in feed passing through too quickly, so utilisation of the feed drops and the cow may get sick.

Fermentation rate

Carbohydrates

Molasses

CCM

Milled wheat

Milled barley

Rolled wheat

Rolled barley

Caustic treated wheat

Include feed and cow signals

Crude protein

Urea

First assess silos and feed storage, feeding, feed in the manger, animals and manure. Is heating taking place or is there loss of taste? Are you feeding-out, loading, feeding and pushing up correctly? Are the animals producing what their genetics say they can? Can each animal eat from the ration without restriction for at least 22 hours per day? Is there plenty of fresh water available? What are the body condition scores (BCS) of the lactation groups?

Potatoes

Beet pulp, dry

Maize meal

Maize gluten

Maize silage

Beet pulp, wet

Lucerne

Grass silage

Palm kernel meal

Barley straw

Wheat straw

Rape straw

Distillers syrup

Field mustard meal (Prairie meal)

DDGS (Dried Distillers Grains)

Grass silage, wet (30% dm)

Sun ower seed meal

Maize gluten

Soya meal

Grass silage, dry (60% dm)

Brewer’s grains

The ‘fermentation rate’ is the speed at which the feed ferments in the rumen. Very fast products are associated with a high risk of rumen acidosis (carbohydrates) or rumen alkalosis (proteins) if the cow eats too much at once.