exploding, and roasting—may improve sorghum nutritive value as much as steam processing and rolling (Beeson and Perry, 1982). Starch digestibility was enhanced as much by micronizing and popping as it was by steam processing and rolling (Riggs et al., 1970; Hinman and Johnson, 1974; Croka and Wagner, 1975). Again, dry-heat treatments may not be as effective as steam processing to promote intake.
In intermediate- and high-roughage diets, dry-rolled sorghum is better utilized than in low-roughage diets (Keating et al., 1965). Thus, provided the whole grain is rolled, this process is likely to have a much smaller influence in these types of diets compared to those containing less roughage.
Although cattle ate more feed when they were given diets containing whole, as opposed to rolled barley, efficiency of utilization was greater for the rolled barley diets (Mathison et al., 1991b). Yaramecio et al. (1991) reported NEg values of 1.15 and 1.80 Mcal/kg for diets containing whole or rolled barley and most of this difference appeared to be due to improved digestibility. There is greater controversy about the value of steam-processed and rolled barley compared to dry-rolled barley. Zinn (1993) found steam-processed barley contained 2.24 Mcal/kg NEm and 1.56 Mcal/kg NEg, respectively, vs 2.14 and 1.47 for the dry-rolled grain. In the same experiment, benefits of a thin flake (0.19 kg/L) as opposed to a thick flake (0.39 kg/L) were evident. By contrast, steam processing of barley failed to improve the feeding value of a barley diet in two Canadian studies (Mathison et al., 1991a; Engstrom et al., 1992). Parrot et al. (1969) reported that steam processing and rolling did not improve digestibility of barley compared to dry rolling except when the initial DE value of the barley was low. Steam processing prior to rolling may be useful to maximize intake of barley diets, particularly in dry areas where dry-rolled or ground barley becomes too dusty. When barley is rolled or ground, fines should also be avoided to minimize digestive disturbances such as bloat (Hironaka et al., 1979). High-moisture barley has a feeding value equal to dry barley (Kennelly et al., 1988) and is superior in the rolled as opposed to whole form (Rode et al., 1986).
In medium- to high-roughage diets, dry-rolled barley was equivalent to the ammoniated high-moisture whole grain (Mandell et al., 1988) and steam-rolled dry barley was superior to the whole dry grain (Morgan et al., 1991).
Starch digestibility of a high-grain whole oat diet was 0.61 which contrasts to 0.69 when the oats were dry-rolled (Orskov et al., 1980). In mixed diets, whole oat grains seem to be well digested by cattle and there is little benefit in further processing (Campling, 1991).
Starch digestibility of a high-grain whole wheat diet was 0.83 and this was increased to 0.99 when the wheat wheat was rolled (Orskov et al., 1980). In contrast to oats, digestibility of starch in mixed diets containing whole wheat was only 0.60, as opposed to 0.86 for the same diet when the wheat was rolled and crushed (Toland, 1978). Steam-processed and rolled wheat, with a thick flake, has the same value as coarse ground or dry-rolled wheat (Brethour, 1970). Finely ground wheat should be avoided in beef cattle diets to maximize intake and prevent acidosis.
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