Only recently a farmer asked me what good grain is. An interesting and very basic question, but then I realised that there are many livestock farmers who have little or no concept of what good grain is or should be. Perhaps it is the recent discovery of poor quality barley being imported that triggered the question.

Quality, like beauty, is very much in the eye of the beholder. For example, within the malting sector, distillers want lower protein, while brewers want moderate to high grain protein. Makers of flour have different requirements for milling wheat. But all grain users predominantly need starch and this also applies to feed producers.

For a grain to supply starch, it needs to have the skin or husk bulging, which means it is loaded with starch. In general, protein level in a sample depends on the level of nitrogen and starch.

Very well-filled grains tend to dilute the protein level to result in a low percentage protein, while less well-filled grains will tend to have higher protein content, but less starch. Grain content will always be compromised by the environment in which they grow.

Nowadays, native grain production involves a relatively standard management plan which is primarily targeted at starch production, which is energy for the feed user. Husbandry involves variety choice, fertiliser rates, growth regulation and plant protection. These have all been developed and refined over recent decades.

Quality grain needs to be well filled, showing predominantly plump grains which contain the starch to provide the energy for livestock. As well as physical testing, grain must also be ‘sweet and sound’ and these characteristics are measured by nose and eye respectively. Good grain should not contain lots of weed or other seeds and neither should it contain other organic sources, such as rodent faeces or ergot.

Sweet and sound is a basic and perhaps unquantifiable requirement. If a sample is allowed to remain high in moisture, or is allowed to re-wet, then it is possible that moulds can grow. These can leave a musty smell and unpalatable taste.

Quality measurement

Grain quality is measured in different ways using different tools. Standard tests ascertain the moisture content (there is no feeding value in water) of the grain, its specific weight and screenings level.

For the feed sector, energy is the main requirement and this characteristic tends to be evaluated by specific weight, as expressed in kilogrammes per hectolitre and measured using a chondrometer, and also screenings level.

For energy grains, such as feed wheat and barley, the width of the grain provides some measure of the level of starch or energy. Plump grains tend to be loaded with starch and this can easily be seen when such grains are rolled.

The screenings test measures grain width or plumpness, or lack of it, and narrow poorly filled grains fall through the different sieves used in the test. So it is the grains that do not have good grain fill that are measured as they have relatively little starch content.

The screenings test uses a number of screens with different-sized slits which allow grains of different size to pass through. While different screen sizes are used, it is generally the proportion that passes through a 2.2mm screen which provides the percentage screenings.

It is not difficult to understand how grains that are less than 2.2mm in width would have relatively little starch content. Some small grains are inevitable in any sample, but this will generally be below 2% when the grain is good, while values of 6% and over indicate lots of grains that have low starch levels.

Specific weight

The other main physical test for feed grains is specific weight. This is the weight of a given volume of grain. It is most easily seen as the weighbridge weight of a trailer of wheat versus oats or a trailer load of barley one year versus another. Specific weight dictates the weight that can be fitted into a given volume, more so than its feeding value.

For example, a field of spring barley produces 2.8t/ac at 20% moisture and it has a specific weight of 63KPH as harvested. When dried to 15%, this yield will drop to 2.635 t/ac.

If half of this field is put through a standard continuous flow dryer to dry the grain and the other half is put through a recycling batch dryer, they are likely to end up with very different specific weight levels when dried.

The dry barley from the continuous flow dryer is likely to increase to about 64 KPH, or possibly better, while the dry grain from the batch dryer is likely to be closer to 66 KPH, or even higher.

This is the simplest way of saying that specific weight is not a direct measure of feed value, but if the initial sample was 53 rather than 63 KPH, then this specific weight makes a definite statement.

So specific weight can be useful when dealing with grain at the lower end range of the norm. Specific weight is most commonly referred to by farmers as bushel weight. This is because bushel was an old imperial measure and the original test was named after it.

A bushel is an eight-gallon measure made like the butt of a wooden barrel. Bushel weight is the weight of this measure filled to water level (filled above water level with the surplus wiped off to water level). The weight differs most between crop species, but it also differs within a species. Depending on the specific cereal, bushel weights could vary from 40 pounds per bushel to over 60.

The bushel weight is also known as the test weight. When we moved from the imperial to the metric system, the test volume and weights were changed and we then measured in kilogrammes per hectolitre (KPH).

Even though the original bushel could be filled and handled manually, it was replaced by a test which weighted a sample in a specific container size following a well-prescribed filling methodology. This test was later altered for metrification and, since then, we are measuring KPH on a calibrated scale.

For your information, a hectolitre is a 100-litre container which could weigh up to 80kg. This is obviously not a weight that one can easily lift from the top of a trailer and so the test is done on a sample, as was the case with the bushel test.

The sample size is around one litre, or less, and the specifics around filling and weighing remain critical for test accuracy.

The challenge of bushel

While bushel is taken as a measure of quality, it is of limited value in this regard. The ability of any sample to fit into a specific volume is affected by many factors, such as the natural shape of the grain, the aggressiveness of previous handling, single or mixed species, etc.

The reason specific weights are higher out of a batch dryer is a result of the polishing the grain receives during continuous recirculation by auger.

Some wheat varieties in particular have irregular grain shape that does not allow them to pack well into a given volume. For this reason, a grain sample with a specific weight of 70KPH (min 72 KPH regarded as acceptable) could still be loaded with starch and have a very high energy value. Alternatively, a smaller grained variety (small grains tend to pack much better) with a specific weight of 75 KPH could well be a poorly filled sample.

Feeders who are very conscious of this chronic limitation of specific weight tend to use a fibre test to provide an additional indication of feed energy value. And varieties that tend to have small grains and naturally higher KPH levels have more grains and so more fibre per volume.

These simple facts challenge the usefulness of specific weight as an indicator of feeding value. However, it could prove to be a very useful measure for specific varieties providing the performance base levels are established.

Are feeders being short-changed by poor quality imports?

Given the variables that can influence test results, it is possible to polish grains to create a better specific weight. But when a test weight of 62 KPH for dry barley is accompanied by a screenings test of 10% or more, then it is obvious that the specific weight is unreliable for that sample.

It is still amazing how important the eye is in assessing the true feeding value of any sample of wheat or barley. This begs the question for end-users about the quality, or lack of it, in the recent shipments that were intercepted by the IFA.

The grain quality was visibly poor in the samples I saw and this should be the primary measurement by any end-user. As a buyer of feed, farmers need to take more interest in the ingredients that make up their rations, because the end product can be tweaked a bit either way to show the desired chemical feed analysis.

But the feeding value from a barley sample with over 10% screenings must be lower than from a sample with only 1% screenings.

There are other issues from the farming community’s point of view also. It was obvious from the ships intercepted by the IFA that the barley contained lots of undesirable entities.

I am not sure what many of these seeds were, but I am sure that they could pass freely through a grain roller, leaving them intact to cause a nasty problem on land somewhere in the future. Our feed imports should not be allowed to threaten the future of our farming sector in this way.