Eliminating nutritional variability is key to utilising co-products

Friday 19 June 2009

CO-PRODUCTS from the biofuel industry have the potential to be important feed sources for the pig and poultry industries.

And new technologies promise to add value to this feed material in the future.

That was the good news presented to delegates at this year’s British Society of Animal Science annual conference by ABN’s Steve Jagger and the SAC’s Tom Acamovic.

“In certain areas, obtaining further knowledge of how to improve the production process, rapidly measure the nutrient availability and use new technology to improve the nutrient value would increase utilisation and add value to the co-product produced,” said Dr Jagger, adding that variability in nutrient value was a particularly pressing issue.

“Old ethanol producing plants didn’t take a lot of notice of the nutritional value of the distillers’ grains they produced. But the new generation of plants are producing a more consistent co-product, have better drying facilities and are more interested in the nutritional value of the product,” added Dr Acamovic.

That said, there are three different processes to produce ethanol from wheat, for example, and the resulting end co-product analyses are also very different.

“Distillers’ grains are not all the same - I can’t stress that enough. There is still a lot of variability and the processing plants need to get a handle on that,” said Dr Acamovic.

Of the 37 samples he analysed, there was huge nutritional variation: “And from a nutritional point of view this is not good and certainly not conducive to the precise ration formulation required by poultry producers.

“If we could solve this variability problem then co-products could make up to 20% of broiler rations.”

Dr Jagger agreed that the main concern with the use of dried distillers’ grains with solubles (DDGS) in pig feeds was the degree of variation in composition and digestibility of nutrients. “This variation arises from differences in nutrient analysis of the incoming raw material, the amount of condensed distillers’ solubles added to the dried distillers’ grains, the quantity of starch converted to ethanol by the fermentation process and the temperature and duration of the drying process,” he explained.

The heating process reduced the availability of amino acids and this will reduced growth rates unless the inclusion level of DDGS is reduced or the amino acid availability is accurately assessed and accounted for,” he added.

Maize DDGS has been used successfully at levels of up to 15% in finishing pig diets: “But soft carcase fat may be an issue due to the level of polyunsaturated fatty acids in the diet,” said Dr Jagger.

Wheat DDGS has been used up to a level of 10% in finishing pigs diets, but reduced feed intake has been seen above this level.

“The use of enzymes may offer a means of increasing the utilisation of DDGS, but further investigation appears to be necessary to determine the type and level of enzyme required.

“To fully exploit the economic and nutritional value of DDGS in diets for pigs, either a rapid method of accurately assessing the nutrient availability is required or processes, which minimise heat damage, should be adopted to ensure the production of a consistent material,” concluded Dr Jagger.