**4.5. Level of wheat in the diet**

hard wheat varieties. These authors suggested that the micronization altered the properties of the endosperm in soft wheat that may be more closely resembles that of the harder wheat. The micronization may also change wheat starch that may be related to the nature of the endosperm with alterations of proteins within the fibrillin complex [30]. The reduction of rate and extent of wheat starch digestion using micronization method may provide an effective processing technique to modulate the rate of acid production during the fermentation of

**Figure 3.** Effects of processing and incubation time on in vitro rumen dry matter and protein digestibility. For dry matter digestibility, SEM = 1.1%, processing (*P* < 0.01), incubation time (*P* < 0.01) and process x incubation time (*P* < 0.68). For

crude protein digestibility, SEM = 2.3%, processing (*P* < 0.01), wheat (*P* < 0.01) and process x wheat (*P* < 0.79).

Recently, a series of experiments using beef cattle were conducted in our laboratory at the Lethbridge Research and Development Centre to determine the maximum level of wheat grain that could be included in finishing cattle rations, the effects of degree of grain processing on wheat utilization and comparison the feeding value between hard versus soft wheat. A study was conducted to compare inclusion of 90% wheat grain processed to processing index of either 75 or 85% on the growth performance of finishing beef cattle [31]. Compared to steers fed dry-rolled wheat with a processing index of 75%, steers fed wheat with a processing index of 85% ate 0.4 kg per day more feed. However, this difference in feed intake did not alter the daily gain or final live weight of steers. As a result, the feed efficiency, expressed as daily per unit of feed consumption, of steers fed wheat with a processing index of 85% was lower than for steers fed wheat with a processing index of 75%. Carcass traits had a trend to be different with higher back fat thickness but lower rib eye area and lower quality grade (% Canada AAA) for steers fed wheat with a processing index of 85% than with a processing index of 75%. The steers fed wheat with a processing index of 85% also had more numbers of liver abscesses. Therefore, a high processing index (85%, i.e., coarsely processed) increased feed consumption but reduced feed efficiency and adversely impacted carcass quality, including saleable meat

wheat in the rumen, thus reduce the severity of rumen acidosis.

124 Global Wheat Production

**4.4. Impact of degree of processing on the feed value of wheat**

Wheat grain is generally recommended to be fed to ruminants in combination with more fibrous or slowly fermented feed grains and limited to 40 or 50% of the diet (dry matter basis) because of its rapidly fermentable starch in the rumen. A study using rumen cannulated beef heifers was conducted to compare inclusion level of wheat relative to barley grain in finishing beef cattle rations on measuring rumen pH and fermentation, and digestibility if nutrients in the total digestive tract [33]. In this study wheat was substituted for barley grain at 0, 30, 60, or 90% of the diet dry matter with the remainder of the diet composed of 6% barley silage and 4% vitamin and mineral supplement. All grains were dry-rolled to a processing index of 80%. Increasing wheat level from 30, 60 to 90% in the diet linearly increased the duration of time that rumen pH was under 5.8, but ruminal pH below 5.5 and 5.2 were not affected. These results indicated that subclinical rumen acidosis was not exacerbated with increase of wheat grain up to 90%. Rumen acidosis includes acute acidosis and subacute acidosis (also called subclinical rumen acidosis). The acute acidosis is characterized by sustained low pH (<5.2) without recovery unless intervention is used [12]. The subacute rumen acidosis occurs in repeated bouts where pH is <5.6 for >3 h per day [34], but unlike the situation for acute acidosis, the pH recovers between bouts. The subacute rumen acidosis is a common metabolic disorder in animals fed high-grain diet with rapid fermentation of feed in the rumen and subsequent accumulation of volatile fatty acids (acetate, propionate, butyrate), whereas acute acidosis is caused by accumulation of lactic acid in the rumen and much less happen. Feed intake, animal performance and feed efficiency are adversely impacted when animals suffer from subacute rumen acidosis [12]. However, there was no effect of feeding increasing levels of wheat on rumen fermentation and nutrient digestibility, which suggest that the levels of wheat included in finishing diets of beef cattle could be higher than typically used in the feedlot industry if proper bunk management and processing are employed.

#### **4.6. Impact of wheat type on feed value**

Grain hardness is a trait that has been used for decades by the wheat industry to differentiate quality and market classes, and it is characterized as the resistance of the kernel to fracture [35]. 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.

The deoxynivalenol can be measured using several laboratory procedures. The most common method used by the Federal Grain Inspection Service and most grain handling and processing facilities is the immunological-antibody method called Enzyme Linked-Immunosorbent Assay (ELISA) because it is relatively fast and cheap. The gas chromatography-electron cap-

Quality Assessment of Feed Wheat in Ruminant Diets http://dx.doi.org/10.5772/intechopen.75588 127

The inability to feed wheat with high levels of deoxynivalenol to be fed to swine and poultry contributes to the lower price of wheat, but the impacts of deoxynivalenol on the feed value of wheat for beef cattle are largely unknown. According to [5], the level of deoxynivalenol in North American wheat ranges from 0.3 to 1.0 mg/kg, however the level of deoxynivalenol measured in specific lots can reach levels of up to 20 mg/kg. The highest deoxynivalenol levels are also usually associated with soft rather than hard wheat [5]. The maximum tolerated deoxynivalenol level by Canadian Food Inspection Agent in diets for swine, young calves, and lactating dairy animals is 1 mg/kg, and 5 mg/kg in diets for cattle and poultry. Ruminants are considered quite resistant to Fusarium toxins such as deoxynivalenol because of the detoxifying potential of rumen microbes. Previous studies have shown that the epoxide group-bearing parent toxin deoxynivalenol is metabolized to de-epoxy-deoxynivalenol [44]. However, little is known about the effects of Fusarium toxins (i.e., deoxynivalenol, fumonisins, trichothecenes, zearalenone) or their metabolites on the activity of rumen microbes and

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].

Wheat does not transfer nitrate into the seed during drought stress.

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.

ture (GC-EC) analytical method is quantitative and used to calibrate ELISA test kits.

the consequent effect on feed efficiency in ruminant animals.

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