**6. Sprouted, frosted and drought-damaged wheat**

The differences in kernel hardness are the result of differences in affinity of starch and protein within endosperm, higher affinity decreases both the rate and extent of starch digestion in the rumen [36]. Although the endosperm within different wheat types differs in hardness, all wheat types are digested rapidly in the rumen. As a result, the information on the rate and extent to which hardness influences the site and extent of starch digestion in wheat is scarce. Soft wheat generally exhibits a faster rate of digestion than hard wheat in the rumen [3, 19]. However, this relationship is also dependent on the processing method used or the degree of wheat processing [31]. The hard wheat kernel may be more susceptible to shattering and generating the fine particles that are readily fermentable in the rumen [37]. Swan et al. [22] reported that starch granules from soft wheat appeared even more resistant to rumen digestion than the starch granules from hard wheat because of greater damage to the surface of starch granules in hard wheat after cracking using a mill. Recently, we conducted a study using rumen cannulated beef heifers fed either soft or hard wheat-based rations [3], there were no differences in the rumen pH and rumen acid concentrations between beef heifers fed soft or hard wheat. The lack of differences between soft and hard wheats can be explained by the fact that wheat grain was processed coarsely (i.e., processing index >80%) to avoid digestive upsets. Similarly, a feedlot study using beef steers that were fed soft or hard wheat with the similar wheat processing as did in the study by Yang et al. [3], did not show the differences in feed intake (averaged 11.3 kg dry matter/day), daily weight gain (1.79 kg), feed efficiency (160 g weight gain/kg dry matter intake), and net energy for growth [38]. It concluded that soft and hard wheat exhibited the similar feed value for feeding feedlot beef cattle if the ration is formulated with the same

energy level and wheat is processed at the same degree of processing.

Deoxynivalenol, commonly referred to as vomitoxin, is a mycotoxin that may be produced in wheat and barley grain infected by Fusarium head blight or scab [39]. The fusarium head blight may infect grain heads when wet weather occurs during the flowering and grain filling stages of plant development. Although the occurrence of fusarium head blight is not necessary to mean that deoxynivalenol is present, a high level of scabby kernels in the harvested grain means deoxynivalenol will likely be present. Levels of deoxynivalenol do not necessarily correlate with levels of physical damage in grain. The impact of deoxynivalenol in feed grains on animal performance and health vary with type of livestock animals. The evident production losses were observed in non-ruminant animals, in particularly swine when vomitoxininfested grains were fed [40, 41]. Research conducted with vomitoxin-infested barley indicates no apparent problems when fed to growing and finishing cattle or gestating or lactating beef cows [42]. It appears that cattle can tolerate high levels of vomitoxin (21 mg deoxynivalenol/ kg wheat) without impacts on performance or health of the cattle [43]. However, exercise caution with wheat or any grain that has gone out of condition or has mold damage. The possibility exists that molds and toxins will impact feeding value through reduced feed acceptance, intake and performance, as well as higher incidence of morbidity, the possibility of abortion in pregnant cattle and, in some cases, even death. Young calves, gestating cows and animals

**5. Deoxynivalenol content in wheat**

126 Global Wheat Production

under nutritional stress are most vulnerable [43].

Wheat can be priced competitively with other feed grains because of damage from disease, drought, or sprouting. Wet conditions during fall harvesting can cause widespread sprout damage to the grain crop. Physical and chemical characteristics could be different between sprouted grains and non-sprouted grains such as lower text weight and starch content but higher crude protein due to the concentration effect that occurs when starch is expended during the germination process. However, it has been reported that animal performance is similar when consuming sprout-damaged grain versus non-sprouted wheat grain. Rule et al. [45] reported no differences in growth performance or carcass characteristics when comparing sprouted wheat with non-sprouted wheat in finishing rations containing 77% wheat-based concentrate. Reed et al. [46] concluded that sprouted wheat is palatable, digestible sources of nutrients that can be used in beef cattle diets. These authors further indicated that the sprouted wheat should be processed similar to non-sprouted wheat for optimal utilization by the animal. Growth performance and feed efficiency were improved for steers fed diets containing rolled sprouted wheat compared with whole sprouted wheat [46].

Little data is available regarding the feeding value of frosted wheat. However, research conducted in Western Canada with frosted wheat indicates no difference in feeding value of frosted grain, compared with non-frosted grain when it was fed in feedlot rations. Droughtdamaged wheat generally has smaller kernels and is lower in starch content than wheat grown without drought stress. Nitrate toxicity should not be a concern with wheat grain. Wheat does not transfer nitrate into the seed during drought stress.
