Is there a synergic effect when corn distillers dried grains with solubles (DDGS) or wheat middlings (WM) are steeped with combination of carbohydrase and protease?

An in vitro study was conducted to determine effects of steeping two co-products, DDGS or WM, with carbohydrase or protease alone, and in combination. The four treatments were; 1) coproduct steeped with water excluding enzymes (CON), 2) CON with carbohydrase (FDE) 3) CON with protease (PRO) 4) CON with carbohydrase and protease (FDEPRO). Co-product (50 g), 500 mL water and respective treatment was steeped for 72h at 37℃ in incubator shaker. At 0, 12, 24, 48, and 72h; pH was measured, and samples of supernatant submitted for mono-sugars and organic acid and of solids for fiber disappearance. Mono-sugar increased at 12-24h followed by a decrease at 48-72h in both co-products. Steeping DDGS with FDE and FDEPRO showed greater concentration of arabinose and glucose for than PRO at 12 h whereas xylose concentration was greater for FDEPRO than other treatments. At 12h, WM steeped with PRO had lower concentration of arabinose and xylose compared with FDE and FDEPRO, however, only FDE had a greater glucose concentration than PRO. In both co-products, pH decreased while lactic and acetic acid increased overtime. At 72h, both co-products showed lower pH and greater lactic acid concentration in FDE and FDEPRO than PRO. Greater disappearance of NDF and ADF was seen at 48-72h of steeping. At 72h, fiber disappearance was greater for FDE and FDEPRO than CON and PRO for DDGS but not for WM. In conclusion, enzyme application showed differences in the two co-products, however, combination of carbohydrase and protease seemed not necessary to improve mono-sugar release and fiber breakdown in these co-products. 

Key words: carbohydrase, corn DDGS, protease, steeping, wheat middlings.

Published in the proceedings of the Animal Nutrition Conference of Canada 2020. For information on the event, past and future editions, check out https://animalnutritionconference.ca/.