Using exogenous enzymes to increase the rumen degradability of wheat dried distillers grains with solubles.
Wheat dried distillers grains with solubles (DDGS) is widely used as a partial replacement for forages or concentrates in ruminant diets. We hypothesised that using exogenous enzymes (ENZ) would increase neutral detergent fibre (NDF) degradability of DDGS. The aims of the study were to (i) evaluate the effects of ENZ and their doses on in vitro gas production (GP) and degradability of wheat DDGS; and (ii) explore possible relationships between the major added enzymic activities and degradation, especially NDF degradation. Three commercially produced ENZ products that provided a range of xylanase, endoglucanase, exoglucanase and protease activities were used. Enzyme activities were assayed under normal rumen conditions with pH 6.0 and temperature 39°C. All three ENZ had a xylanase:endoglucanase ratio of 5:1 to 4:1, but ENZ3 had lower activity per millilitre. ENZ2 had relatively higher exoglucanase activity compared with the other products, with a ratio of xylanase:exoglucanase of 4:1 for ENZ2 compared with 23:1 for ENZ1 and 9:1 for ENZ3. Variable effects of the three ENZ products were observed on GP variables. Degradabilities of dry matter (DM), NDF, acid detergent fibre (ADF) and crude protein (CP) linearly (p < 0.05) increased with increasing ENZ doses, but ENZ1 and ENZ2 exhibited greater (p < 0.05) effects on degradabilities of DM, NDF and ADF compared to the ENZ3. There were positive correlations between added enzymatic activities and degradabilities of DM, NDF and ADF, except for degradability of CP. A multiple regression model analysis showed that xylanase was the main enzymic activity associated with increased degradation of NDF. The results demonstrated the potential of enzyme addition to improve ruminal degradability of wheat DDGS, with xylanase being the main enzymic activity associated with NDF degradability.
a Lethbridge Research Centre, Agriculture and Agri-Food Canada , Lethbridge , AB , Canada.
Zhixiong
Z
He
Shuai
S
Ding
Long
L
Xu
Karen Anne
KA
Beauchemin
Wenzhu
W
Yang
D000818:Animals; D044602:Cellulases / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism*; D005285:Fermentation; D010447:Peptide Hydrolases / Q000378:metabolism; D012417:Rumen / Q000502:physiology*; D014908:Triticum / Q000737:chemistry / Q000378:metabolism*
D004798:Enzymes; D044602:Cellulases; D043364:Endo-1,4-beta Xylanases; D010447:Peptide Hydrolases