The inter-relationship between processing-induced molecular structure features and metabolic and digestive characteristics in hulled and hulless barley (Hordeum vulgare) grains with altered carbohydrate traits.

Abstract

The present study aimed to determine the microwave irradiation (MIR)-induced changes in protein molecular structures in barley (Hordeum vulgare) grains in relation to the truly absorbable protein nutrient supply to ruminant livestock systems. Samples from hulled and hulless cultivars of barley, harvested in consecutive years from four replicate plots, were evaluated. The samples were either kept raw or were irradiated with microwaves for 3 min (MIR3) or 5 min (MIR5). The truly absorbable protein nutrient supply to ruminant livestock systems was evaluated using the DVE/OEB system (DVE, truly absorbed protein in the small intestine; OEB, degraded protein balance). Molecular structure changes as a result of processing were revealed by vibrational molecular spectroscopy in the mid-infrared electromagnetic radiation region. Compared to the raw samples, MIR processing decreased (P < 0.05) the truly absorbable microbial crude protein and increased (P < 0.05) the truly absorbable rumen undegraded protein and endogenous protein supply without affecting the total truly absorbed protein supply to the small intestine (DVE) and degraded protein balance (OEB) in ruminant livestock systems. Changes in protein molecular structure (spectral intensities) were highly correlated with the changes in the truly absorbed protein nutrient supply to ruminant livestock systems. The results of the present study show that the changes in protein molecular structure as a result of MIR feed processing were associated with the truly absorbed protein supply to ruminant livestock systems. © 2016 Society of Chemical Industry.