Buying feed at the right price

Introduction

The factor that most limits livestock performance during the grip of a drought is energy intake. Dry stock can be maintained on diets that have protein levels as low as 6%, provided the energy level of the feed is adequate.

The best feed to use is the feed that gives the best value for money. To determine this we must calculate the cost of the feed per unit of nutrient provided. When full hand feeding for maintenance, we need to calculate the cost per unit of metabolisable energy (ME).

What does ‘cheap’ really mean?

When purchasing stock feed, the most obvious information affecting the decision to buy is ‘dollars per tonne’. In actual fact this figure is often misleading. To make sense of the price per tonne, we must take account of the moisture content of the feed and also its ME and protein concentration. The amount of moisture is accounted for by determining the dry matter percentage (DM%) of the feed, and ME concentration is expressed as megajoules per kilogram of dry matter (MJ/kg DM).

ME concentration is inversely proportional to the fibre content of the feed; for instance, a fibrous feed such as poor quality hay has an ME value around 6.5 MJ/kg DM, whereas wheat, being low in fibre and high in starch, has an ME of approximately 13 MJ/kg DM.

Beware the so-called ‘cheap alternative’!

We can use information on DM% and ME concentration to calculate unit of cost of energy and hence determine the true dollar value of a stock feed.

The following calculations show how to compare the cost effectiveness of two typical feeds (in this case feed wheat and lucerne hay) as drought fodder:

At these prices lucerne hay is more than twice as expensive to feed as wheat, even though the cost per tonne is only 50% dearer than wheat.

Many other feeds become available during drought, including many types of low quality roughages such as crop stubbles. For example, sorghum stubble is typically found as round bales weighing 250 kg and priced from $70 per bale. With an energy value of only 7 MJ/kg, this fodder is costing around 4.4c/MJ and, although appearing to be good value, is in actual fact more expensive than lucerne hay.

An additional concern with some of these ‘cheap’ alternatives is that they are often so low in energy and protein that stock simply cannot eat enough to maintain their body weight. For example soybean stubble provides only 5.5 MJ/kg DM and could not provide a maintenance diet by itself. The sorghum stubble mentioned above, while being just adequate in provision of energy, is typically only around 3% crude protein and so would also be inadequate as a complete feed.

While it is always best to calculate the energy cost of feed on the actual nutritive value of the feed sample for sale, this is not always possible. Table 1 in Full hand feeding management of sheep (Agnote DAI-169) provides an alternative, where cost equivalence per tonne at different ME concentrations can be read simply from the table.

Buying feeds on a ‘protein value’ basis

Early in a drought, when there is ample quantity of dry pasture available, a suitable feeding strategy may involve the feeding of a protein source to balance the animals’ diet and improve intake levels. This strategy is only suitable for dry stock and will not be adequate for stock with higher demands (pregnancy, lactation or growth). To choose feeds in these circumstances first determine the cost per kilogram of crude protein (CP) provided.

To determine protein costs we first need to determine the cost per kilogram of dry matter as before, and then divide that value by the crude protein percentage (CP%) and multiply by 100. The following example shows the calculation for the cost of lupin protein—lupins are a popular choice as a protein-rich supplement.

Another alternative often used to supplement crude protein is urea lick blocks. These supply a non-protein nitrogen source. A typical commercial 10% urea block with some additional monoammonium phosphate (MAP) will supply the equivalent of around 40% CP.

These calculations show that lupins are far cheaper than urea lick block in providing crude protein. Lupins also contain energy which blocks do not provide.

There are many other possible alternatives to providing protein to stock. This method will determine the most cost-effective alternative.

Feed cost calculator

• Feed cost calculator is an interactive program that can be used to compare the values of feeds on an energy and crude protein basis.
• For instructions on its use, see Feed cost calculator—instructions.