RESUMO
Different feed processing techniques affect barley digestibility and nutrient utilization in ruminants. To our knowledge, there are few studies on the interactive relationship between carbohydrate molecular structure profiles of cool-season-adapted barley grain and nutritional characteristics for ruminants. The objectives of this study were: (1) to investigate the effect of different technological processing methods on carbohydrate chemical profiles, Cornell Net Carbohydrate and Protein System-carbohydrate subfractions, ruminal and intestinal carbohydrate digestion of barley grain in dairy cows; (2) to study the effect of heat processing on carbohydrate molecular structure of barley grain using advanced molecular spectroscopy; and (3) to associate processing-induced changes in carbohydrate molecular structure with changes in carbohydrate metabolic profiles in dairy cows. Barley grain samples collected from Crop Research Field in Western Canada underwent four different processing treatments: control, dry heating (120°C for 60 min in an air-ventilated oven), moist heating (120°C for 60 min in an autoclave), and microwave irradiation (900 W and 2450 MHz for 5 min in a microwave). The heating conditions used in the current study induced some changes in rumen-degradable and -undegradable digestible fibre (CB3) fraction. Intestinally digestible CB3 was decreased after moist heating. Moist heating decreased starch digestibility compared to the other three treatments. The processing-induced carbohydrate molecular structure changes, which was revealed by advanced vibrational molecular spectroscopic technique (attenuated total reflectance-Fourier transform infrared), could be used to predict carbohydrate nutritional value.