**4. Processing wheat**

Processing of cereal grains either by grinding, rolling, tempering (i.e., addition of water prior to rolling), steam-rolling (i.e., exposure to steam prior to rolling) or steam flaking (i.e., longer duration of exposure and higher grain temperature) breaks down barriers such as the hull, pericarp and protein matrix and allows microbes access to the starch harbored within endosperm. Furthermore, these processes reduce the particle size of the grain, increasing the surface area available for microbial attachment that these actions increase the rate and extent of starch digestion [25]. Although wheat has the most rapid rate of starch digestion in the rumen, whole wheat kernels are poorly digested in the rumen, and thus need to be properly processed prior to being fed to animals. In fact, excessive processing of wheat results in fine particle sizes that can cause digestive upsets (rumen acidosis, bloat) that in themselves reduce the profitability of animal production. Conversely, under processing of wheat can result in whole kernels in the diet which are not digested by rumen microorganisms contributing to a loss of valuable starch in the manure.

method on dry matter and protein digestibility. Eight wheat samples collected from various sources were either ground through 2-mm sieve or dry-rolled to have processing index of 80%, and incubated for 24 h in batch culture. Dry matter digestibility ranged from 60 to 68% and from 28 to 38%, respectively, for ground and rolled wheat (**Figure 2**). The digestibility of protein varied from 52 to 62% or from 25 to 48%, respectively, for ground and rolled wheat. There was no interaction between wheat source and degree of processing. As expected, the digestibility of dry matter and protein was greater (*P* < 0.01) for ground wheat (64 and 56%) than for rolled wheat (34 and 38%) after 24 h of incubation. In vitro digestibility of dry matter and protein linearly (*P* < 0.01) increased with increasing incubation time and consistently higher (*P* < 0.01) with ground than rolled wheat, whereas no interaction between processing and incubation time was noticed (**Figure 3**). These results showed evident impact of processing method on the extent of wheat digestion in the rumen. The study also demonstrated the variation in the digestive value of commercially available wheat grain and emphasized the

Quality Assessment of Feed Wheat in Ruminant Diets http://dx.doi.org/10.5772/intechopen.75588 123

need to have an accurate and rapid means of quality assessment at the point of sale.

Micronization is a dry-heat process that generates infrared electromagnetic short waves to heat the feedstuff to approximately 110–115°C. It has been used to process grains to increase their utilization [27]. Rapid internal heating is accompanied by a rise in water vapor pressure that the feedstuff is cooked from the inside out and the kernel expands to the point of eversion. This process has been widely used to process grains for livestock consumption [28]. Wang et al. [29] reported that the micronization reduced the in situ dry matter digestibility of both full-fat canola seed and flaxseed. McAllister and Sultana [19] compared three different wheats varying with kernel hardness (i.e., soft, hard and durum) and found that in situ digestibility of dry matter, crude protein and starch were reduced by micronization processing in all three types of wheat. However, the reductions were greater with soft than

**Figure 2.** Effects of processing and wheat source on in vitro rumen dry matter and protein digestibility. For dry matter digestibility, SEM = 2.9%, processing (*P* < 0.01), wheat (*P* < 0.20) and process x wheat (*P* < 0.45). For crude protein

digestibility, SEM = 4.7%, processing (*P* < 0.01), wheat (*P* < 0.01) and process x wheat (*P* < 0.19).

**4.3. Micronization processing**
