Brewing new feeds with beer waste

(04.05.09) Beer production annually produces 30 million tonnes of brewer's spent grain (BSG) worldwide, which constitutes approximately 25% crude protein, 10% lipids, 50% crude fibre, and some ash. In the best case, BSG is sold in fresh form (75% water) as feed for cattle; in the worst case, its valuable nutrients are wasted as landfill. Given the constant search for alternative feeds and the new trends in poultry nutrition, what is the potential of dry BSG in monogastric diets?

APC post-doc Vegard Denstadli raised that question at a recent conference held in Norwich UK, Total Food 2009 ? Sustainability of the Agri-Food Chain, where he presented a study on BSG in broiler diets.

In short, BGS was more positive on bird performance than xylanase treatment.  Data revealed that BSG coarseness stimulated the gizzard: "In this way we allow the [chicken] 'stomach muscle" do the grinding, instead of wasting energy grinding it at the feed plant," says Denstadli. The data support earlier trials at UMB, where inclusion of oat hulls activated the stomach of poultry, and thus improved the capacity of the GI tract.

The concentration of arabinoxylan  (a polysaccharide) is high in BSG, and the trial investigated adding xylanase and xylanase pre-treatment . Based on the xylanase treatments, ileal and cecal concentrations of arabinose and xylose sugars revealed no differences in the ileum. However, birds fed pre-treated xylanase BSG showed significantly higher concentrations of soluble arabinose and xylose in the ceca. Denstadli's collaborators at Nofima Food are now examining whether xylanase treatment or BSG coarseness may have affected the microbiota composition.

In a second study, a follow up dose-response with dry BSG (up to 40% inclusion) showed a linear relationship between BSG inclusion and gizzard weights. At 30% inclusion level there was a significant drop in FCR and nutrient/energy digestibility. However, if corrected for the increase in insoluble fibre ? from 10% at control (no BGS) to 30% fibre at 40% BSG inclusion ? BSG-fed poultry performed just as well if not better than the control.

Looking towards the future, lessons learned are being applied to fish diets. "BSG is preferable for omnivorous fish, such as tilapia," says Vegard.  "For carnivorous fish we are investigating the effect of extracted, isolated (low molecular weight) barley beta-glucans." Experimental designs are now in progress. That effort alone is worth buying Vegard a pint.