Dry matter disappearance and gelatinization of grains as influenced by processing and conditioning

Abstract

Four ruminally cannulated steers (average body weight 430 kg) were used in a 4 × 4 split plot. Latin square design, in situ experiment to evaluate grain processing methods and effects of grain conditioner on dry matter (DM) disappearance (DMI) and degree of gelatinization of four grains. Effects of grinding or steam flaking, with and without the addition of a commercial grain conditioner, on DMD of corn ( Zea mays), barley ( Hordeum vulgare), wheat ( Triticum vulgare) and sorghum ( Sorghum vulgare) were measured at incubation times of 0, 6, 12, 24, 36 and 48 h. Degree of gelatinization of grains was determined by polarized light microscopy as loss of birefringence. Ground grams had greater DMD than flaked grains at 0 h (sorghum, P < 0.05), 24 h (wheat, P < 0.01), 24 h (barley, P < 0.05) and 36 h (wheat, P < 0.01); however, steam flaking increased DMD at 36 h (corn, sorghum, P < 0.01) and 48 h (sorghum, P < 0.01) compared with grinding. In situ DMD was greater ( P < 0.05) for ground, ground + conditioned and steam-flaked barley than for steam-flaked + conditioned barley at 24 h. Ground wheat had the greatest ( P < 0.10) DMD among ground grains at 12 and 24 h; likewise, ground + conditioned wheat had the greatest ( P < 0.10) DMD among ground + conditioned grains. A trend for increased DMD of wheat was observed across time, and among processing and conditioning methods, compared with other grains. Degree of gelatinization was greater for steam-flaked than for ground grains. Corn, wheat and barley reached gelatinization at lower temperatures than sorghum. These data suggest that effects of processing and conditioning varied among grains and within grains across time. Use of a commercial grain conditioner did not consistently alter DMD of grains.