Nutrient content, in-vitro digestibility, and starch and protein molecular appearance of intact and ammoniated steamed-flaked and/or steamed-infrared heated-flaked barley grain.

Background: The impact of different physical and/or chemical treatments in cereal grains on starch morphology and ruminal digestibility has been evaluated.

Aims: The effect of chemical and/or physical treatments on starch and protein molecular appearance and the ex-vivo digestibility of barley grain was studied.

Methods: Treatments were: steam-flaked barley grain (SFB), SFB treated with ammonium bicarbonate (A), urea (U), and malic acid (M) (SFB_AUM), SFB treated with A, U, and lactic acid (L) (SFB_AUL), steam-infrared heated-flaked barley grain (SIFB), SIFB treated with A, U, and M (SIFB_AUM), and SIFB treated with A, U, and L (SIFB_AUL). Chemicals including A, U, M, and L were used as 56, 8, 10, and 10 g/kg dry matter (DM), respectively. Chemical composition and molecular morphology were determined using scanning electron microscopy and Fourier-transform infrared spectroscopy (FTIR). In situ mobile bag technique and in vitro batch culture procedure were used to estimate ruminal and post-ruminal digestibility.

Results: Crude protein (CP) and starch concentrations in SFB_AUL were higher than the others (P<0.05). Starch granule morphology and protein structure were altered in the chemically treated samples. The potentially digestible fraction of DM was the highest in the SFB_AUM (P<0.05). Ruminal disappearance of DM, CP, and starch was improved in SFB_AUL and SIFB_AUL compared with other groups (P<0.05). The highest post-ruminal digestibility of starch and CP was observed in SIFB_AUL and SIFB (P<0.05).

Conclusion: Present results indicate that chemical processing with L and applied steam-infrared heated-flaked in barley grain may improve in vitro digestibility of starch and CP and increase granule sizes.