PC fractions. For total truly digestible nutrient, amide II height
has a positive correlation (p ¼ 0.02) with TDN1x with R ¼ 0.74.
For in situ rumen protein and intestinal protein digestion,
protein amide II height has a negative correlation with
(p ¼ 0.009) in situ rumen CP digestibility (R_DCP) with
R¼0.67, and a positive correlation with (p ¼ 0.023) intestinal
CP digestibility (I_DCP) with R ¼ 0.60, and a positive correlation
with (p ¼ 0.030) total tract available protein (T_ACP) with
R ¼ 0.58. A positive correlation between protein amide I
height and amide II height ratio and in situ rumen DM digestibility
(R_DDM) with R ¼ 0.66 (p ¼ 0.010). Alpha-helix and
beta-sheet ratio has a positive correlation with (p ¼ 0.008)
R_DDM with R ¼ 0.67. The result in our study indicated that
higher protein structure amide I and amide II ratios (but peak
height and area) are associated with higher in situ rumen DM
digestibility in the co-products (corn DDGS and barley DDGS).
There are no publications available from other research labs
that could be used for comparisons with the results in this
study.
3.7. Protein secondary structure in relation to nutrient
profiles
The correlation between protein secondary structure and
protein chemical profiles, protein subfractions, truly