Distillers dried grains with solubles made from wheat (wDDGS) offer potential to reduce reliance on imported feed ingredients without compromising the performance or health of UK pigs and poultry, according to the results of a four-year project which were presented last week. This important co-product from the bioethanol industry could make a significant impact in improving the sustainability of these sectors by reducing greenhouse gas emissions. Senior editor of ThePoultrySite, Jackie Linden, reports.
Making pig production more sustainable is all about the front end, according to Nigel Penlington [pictured above], Environment and Buildings Manager for the British Pig Executive (BPEX).
Introducing the event, ‘The Future of Feed’ on new advances in co-products for pigs and poultry at Stoneleigh last week, he explained that feed has the biggest impact on sustainability.
Like many countries, the UK relies heavily on imported feed ingredients for livestock and so in 2010, a consortium of leading pig processors, manufacturers of distillers dried grains with solubles (DDGS), feed and nutrition companies and researchers began working on the Environmental and Nutritional Benefits of Bioethanol Coproducts (ENNBIO) project.
Funded by the LINK programme from the Defra, the members of the consortium contributed to the project, which explored the feasibility of using DDGS derived from wheat (wDDGS) as a replacement for imported proteins such as soybean meal. WDDGS is a co-product from the production of the renewable fuel, bioethanol.
Results of Feeding Trials
The studies into the feeding of wDDGS to pigs and poultry were presented to the meeting by Professor Julian Wiseman of the University of Nottingham.
Trials with broilers
The project started with broilers and in the first trial, performance was not significantly affected when the birds were fed zero or five per cent wDDGS in the starter and up to 18 per cent in the grower.
However, there was a tendency for growth rate and feed conversion to be adversely affected by the wDDGS.
When Dr Wiseman looked at the digestibility of the amino acids, it appeared that the published values that had been used for formulate the w-DDGS diets may have been too high.
Results of the second trial with broilers confirmed that the published values of amino acid digestibility were indeed higher than the material being tested, particularly for the key amino acid, lysine. Lysine digestibility was down at around 30 per cent in the test wDDGS.
Heating during the production of wDDGS was the key variable, Dr Wiseman explained.
A third trial was conducted with a commercial broiler company, Hook-2 Sisters, using diets containing 10 per cent wDDGS. There was no difference in liveweight between the two groups of birds and those fed the wDDGS diet actually had a better feed conversion.
In terms of costs, the wDDGS diet was more expensive than the usual diet because of the need to include some synthetic amino acids. However, the cost per kilo liveweight worked out lower with the wDDGS diet and the Production Efficiency Factor was actually better than the control diet.
Concerns over litter problems with the wDDGS diet were not realised – this group had fewer hock and foot pad problems than the controls.
Trials with laying hens
Turning to laying hens, it was thought the fermentable fibre in wDDGS could reduce egg production or lead to more dirty (or tarry) eggs but a small-scale trial at Nottingham showed these concerns were unfounded.
Based on this encouraging result, a commercial trial was carried out at Noble Foods, comparing a test diet with 7.5 per cent wDDGS with the usual diet.
No differences were found between the diets in terms of egg production or dirty eggs.
However, while the inclusion was wDDGS could be safely used in layer diets in partial substitution for imported soya, there were some concerns over physical characteristics of the material. It had been supplied non-pelleted, and the low bulk density made it more expensive to transport and more difficult to handle at the feed mill.
It was thought that pelleting the wDDGS would overcome these negative issues.
Commercial Feed Formulation with wDDGS
A key aspect in the incorporation of any raw material into a diet is to understand fully the nutrients it provides, said Dr Steven Jagger of AB Agri by way of introduction to his presentation to the meeting.
He explained that during the ethanol production process, the wheat is ground and cooked, water is added and then enzymes and yeast are added for the fermentation stage. Finally, it is distilled to drive off the ethanol, which is collected as the main product.
What remains after separation are the wet distillers grains and the syrup. These are dried together in order to obtain the co-product, wDDGS.
This is the crucial stage for its value as a feed ingredient: if the wet material is overheated, the amino acids can react with any residual sugars in what is called the Maillard reaction, the result of which is a reduction in digestibility, particularly of lysine, Dr Jagger said.
He then presented data from several sources, showing the reduction in digestibility of lysine in wDDGS.
He went on to explain a number of ways in which lysine digestibility can be predicted from the levels of crude protein or acid detergent fibre - both of which can be determined quite easily by chemical methods.
Finally, as with maize DDGS, the colour (luminance) of the product can give a rough indication of lysine digestibility.
Dr Jagger showed some examples of different cost scenarios and how they would affect the inclusion level of wDDGS in commercial pig diets.
Up to 30 per cent wDDGS can be included in grower and finisher diets for pigs, Dr Jagger concluded. He stressed that it is important to know accurate digestibility values for the product, and that the ability to predict these values is key.
He identified stage of production, relative raw material prices and amino acid digestibility as the main factors that affect the financial value of wDDGS in pig feeds.
Future of the Bioethanol Industry in the UK
£750 million was invested by private sources in the UK following the legislation set for biofuels in 2009 under the Renewable Energy Directive, and this included the establishment of three biorefineries in country, producing bioethanol and animal feed, according to Mark Chesworth, managing director of one of those companies, Vivergo Fuels.
As well as providing many thousands of jobs, directly and indirectly, and offering a new demand stream for arable farmers, EU ethanol production displaced 26.5 million barrels of oil in 2013, which may only be around two per cent of the total requirement but it does contribute to energy security and the balance of payments.
Vivergo is based on Humberside, explained Mr Chesworth. His company produces 420 million litres of bioethanol a year and 400,000 tonnes of animal feed, which is enough protein to feed around 20 per cent of the UK dairy herd – the main market for this co-product until now.
Looking to the future, he said, his company aims to have a measurable positive impact on the future sustainability of UK food and farming by offering a cost-effective replacement for imported proteins.