PSA meeting: Cracks in mannan hypothesis under soybean meal based poultry diets
The global poultry industry is utilizing dietary β-mannanase enzyme supplementation for poultry diets
The global poultry industry is increasingly utilizing dietary β-mannanase enzyme supplementation for poultry diets as a valuable option to enhance production. But are the purported benefits supported by the latest science?
New research results, unveiled at the 2016 Poultry Science Association (PSA) annual meeting, July 11-13 in New Orleans, call into question the value of single activity β-mannanase source formulations, particularly when used with soybean meal based diets representing the vast majority of global production.
The fresh knowledge presented at PSA centres around a newly completed study led by Dr. Anna Rogiewicz of the University of Manitoba – an institution recognized among the global leaders in novel feed ingredient and feed enzyme research. Program collaborators include the University of Warmia and Mazury in Olsztyn, Poland, and Canadian Bio-Systems Inc.
“We’re learning that the story around mannans and mannanase is more complex,” says Rogiewicz. “There are questions that need more validation in the context of a soybean meal based diet, including the theory that β-mannans in the feed trigger an energy-draining feed induced immune response that would be minimized by β-mannanase supplementation.”
The multi-component study included analysis of β-mannan content in soybean meal based diets, along with in vitro experiments to evaluate the affinity of several leading β-mannanase source formulations, specifically with soybean meal based β-mannans.
The study also involved an in vivo broiler chicken trial to further evaluate impacts with the β-mannanase source formulations added to soybean meal based diets. This component was designed to evaluate the immune trigger theory.
The results confirmed that the β-mannan content within soybean meal based diets is very low and that – as opposed to the high amounts of β-mannans present in guar, copra or palm kernel meals – this small amount in soybean meal is not likely to contribute to any increased intestinal viscosity in poultry fed corn/soybean meal based diets.
The in vitro experiments showed substantial breakdown of β-mannans due to β-mannanase activity. However, results with the in vivo study showed “no effect” in terms of growth performance. There was also no evidence shown to indicate that the level of soybean meal based β-mannans triggered a feed induced immune response. This was evaluated by analysis of the weight of immune organs and the level of immunoglobulins in serum and the intestine.
“The theory has been that because β-mannans have a molecular pattern similar to some pathogens, this triggers a feed induced immunity response, thereby consuming energy that would be preferably directed to growth and performance,” says Rogiewicz. “However, the results of this study would indicate no feed induced immunity response triggered by β-mannans in soybean meal based diets. This may be due to the very low level of β-mannans in soybean meal based diets, as opposed to the much higher levels in, for example, copra or palm kernel meal based diets.”
Broader research and analysis by the University of Manitoba program suggests the best pathway to address β-mannans, along with a full range of target substrates in poultry feed, is through a multi-carbohydrase enzyme approach that utilizes synergies between enzyme sources and activities to maximize feed nutrition capture.