In vitro rumen fermentation characteristics of bakery by-products containing high starch and sugar

The objectives of this study were to evaluate the nutritional characteristics of bakery by-products (castella, pancake, baumkuchen) and their effect on rumen fermentation in vitro as compared with steam-flaked corn and barley as human-edible grains. The fermentation pattern of sugar and starch as pure components was also investigated. Additionally, rumen pH was evaluated using a low-capacity buffer. Bakery by-products contained high sugar (212–590 g/kg DM) and starch (262–545 g/kg DM). Castella exhibited the highest sugar content, whereas pancake and baumkuchen were rich in starch and ether extract within bakery by-products, respectively. The gas production rate at the early phase of incubation was higher in bakery by-products than in grains, and the highest in castella among all feeds. Bakery by-products produced higher total organic acids and propionate than grains. Bakery by-products also exhibited a lower rumen pH than grains during twenty-four hours of incubation with a low-capacity buffer. As pure components, sucrose showed a higher gas production rate and lower pH than starch. Overall, compared with grains, bakery by-products have the potential not only to supply more energy to ruminants but also decrease rumen pH because sugar and starch in bakery by-products ferment rapidly and produce higher organic acids in the rumen.