In this study, the objectives were to (i) identify the magnitude of differences between dry heating, moisture heating, microwave irradiation, and no-heated treatments on chemical profiles, energy values, the Cornell Net Carbohydrate and Protein System fractions, rumen degradation, and intestinal digestion of newly developed oat (Avena sativa) varieties; (ii) investigate heating induced changes in the molecular structure of the grains with the use of vibrational attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy; and (iii) predict rumen degradability of the nutrients based on the molecular spectral profile obtained from ATR-FTIR. Duration and temperature for each processing treatment were established based on previous studies. Results showed that heat processing treatments altered CHO fractions with undegradable CHO fraction (CC) increased by moisture heating. The ATR-FTIR spectroscopy was successful in detecting the processing induced CHO molecular structure changes in oat grain. The CHO molecular profiles were correlated to chemical profile and in situ rumen degradation characteristics. Lastly, multiple regressions with best model variable selection for prediction of nutritional value were obtained. In conclusion, heat processing methods tended to affect both energy values and rumen degradation features. The CHO molecular structure spectral profiles could be used as potential predictors for heated oat grain degradation.