November 2015: Sprouting suspicions

Recently I took a few days’ holiday to help some friends during harvest with their mobile seed processing business. What has this to do with the intricacies of pig nutrition, that I’m normally involved with, you may wonder. My day-to-day work involves formulating diets for home mill-and-mix and wet feeding customers. Sometimes, I take samples for analysis – either home produced or bought-in materials. It’s interesting to look at these samples and visually compare them with the samples I’ve seen while operating seed processing machines.

For those unfamiliar with the process, we extract small light grain, chaff and weed seed to allow farmers to replant for the following season. It’s very easy to pick out specific issues in grain, such as sprouting.
This summer, while specific/hectolitre weights appeared average to good, there seemed to be a lot of sprouted grain in samples.

Sprouting grain affects the quality of both milling and feed wheat, and those using their own grain, along with all feed mills, should analyse the grain. This would typically be a standard MOPF (moisture, oil, protein and fibre) carried out by NIR.

However, when we’re looking at the effects of sprouting grains, we’re not so interested in a typical feed wheat test, but one normally reserved for milling wheat – the Hagberg falling number. This is a measure of alpha-amylase activity in wheat. As the grain starts to grow, the alpha-amylase breaks down the more complex starch into simpler sugars for the growing seed to utilise. In bread making, this causes dough to lose its elasticity.

Research has shown that relatively low levels of sprouting at about 10%, which can be difficult to detect with the naked eye if handling the material in bulk, can cause reductions in the energy value of wheat for pigs of about 8%. As the amount of sprouted grain increases above this level, the drop in energy values can be much greater.

There’s also the perceived issue with sprouting grains and mycotoxins, but in fact there’s no specific link. The main reason we assume a level of mycotoxin in sprouted grain is that the conditions allowing grain to sprout are similar to those that encourage mycotoxins-producing mould – damp, humid warm environments.

So, for home mixers and wet feeder systems, if the grain is heavily sprouted it’s worth having it tested for additional parameters this season, such as energy. And it may be wise to use a mycotoxin binder in the feed. While sprouted grain isn’t always contaminated, it can be cheaper to use a mycotoxin binder than it would be to have samples tested for mycotoxins, depending on the volume of grain being used and the number of samples analysed.

Compound feeders should discuss the quality of grain with their supplier and find out what tests are being carried out and if their testing strategy/test profile alters in a season such as this.

With the risk of large volumes of sprouted grain not making the cut for milling and being downgraded into the feed market, I’ll certainly be digging a little deeper into the quality of raw materials used in this year’s diets and I would urge others to do the same.

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