**6. Feeding distiller grain for dairy cows**

Growing beef cattle require protein in the form of amino acids to maximize growth rate. One of the most effective and practical methods of improving feed efficiency, growth performance and reducing nitrogen excretion in beef cattle operations is to optimize protein formulation in the diet of growing cattle. Previous works show the necessity of protein supplements to maintain optimum growth rate in growing cattle diets, when these diets are based on barley or corn grain. Wheat distiller grain has not only the similar content of energy for cattle growth because of highly digestible fibre and relative high fat, but also has high protein content either in total or in the form of rumen by-pass. We previously conducted a growing study using beef steers to compare protein source with canola meal, wheat distiller grain, corn distiller grain or fractionated corn distiller grain, and found an improvement of averaged daily gain and feed efficiency over the control group (no protein supplement) [23]. However, steers fed corn distiller grain performed slightly better than that of steers fed wheat distiller grain, likely because of higher fat in corn than wheat distiller grain. McKinnon and Walker [21] reported that growing steers fed wheat distiller grain at 25 or 50% of dietary dry matter gained faster and were more efficient than steers fed a barley grain diet. In contrast, no benefit was reported when wheat distiller grain was fed at level of 17% [24] or at levels up to 40% [14] in growing diets. It appeared that when the level of wheat distiller grain is too high, dietary protein level can be exceeded to the protein requirement by animal. For example, in the study by Gibb et al. [14], including 40% of wheat distiller grain resulted in a dietary crude protein concentration up to 26%, which considerably exceeded the protein requirement of 12–14% for growing cattle. Although protein can be utilised for energy, the transamination, deamination and excretion of excess nitrogen is physiologically costly to the animals and results in an overall

Following growing period, beef cattle then go into the finishing phase. Rations for finishing beef cattle are high energy rations designed to put gain on as rapidly and efficiently as possible, to lay down adequate marbling, and to maximize carcass yield within a limited time frame. Thus, the finishing diets usually consist of high grain such as barley, corn or wheat at ranging 85–95%, and 5–15% of roughage. The role of roughage in finishing diets primarily serves as fibre source to stimulate chewing activity and to maintain rumen health. Number of studies were attempted to determine the optimum inclusion rate of wheat distiller grain as energy source in finishing diets. In barley grain-based finishing diets, no protein supplement is necessary since the protein requirement is met (12%). Feed consumption was either linearly increased [14, 25], linearly decreased [26] or did not differ [13] with increasing the inclusion rate of wheat distiller grain from 10, 20, 40 to 60%; however, growth performance and feed efficiency were overall not affected with increasing the replacement of grain with wheat distiller grain. These results indicated that wheat distiller grain can be successfully incorporated to substitute a portion of grain within finishing diets with minimal or no adverse impact on

The low starch content, but high fibre content of wheat distiller grain is suggested that feeding wheat distiller grain may help reduce the ruminal acidosis and maintain rumen health. It is speculated that a possible reduction in ruminal acidosis by feeding wheat distiller grain

loss of net energy.

**5.3. Distiller grain for finishing cattle**

300 Wheat Improvement, Management and Utilization

cattle growth performance.

The co-products from brewing or wet milling corn processing that are similar to the distiller grain from ethanol plant, has been historically fed to dairy cattle as protein supplement, especially as ruminal undegradable protein source. However, with expansion of ethanol production and consequently increasing distiller grain availability, feeding wheat distiller grain to dairy cattle has been spread recently not only as protein source but also as energy or fibre sources [31]. In fact, high-producing dairy cows are often at risk of subacute rumen acidosis, a common digestive disorder usually caused by feeding a diet containing highly fermentable carbohydrates with insufficient effective fibre to maintain rumen health [32]. Because the distiller grain contain low starch which is highly fermentable in the rumen, and high digestible fibre as well as relative high fat, it was suggested that feeding distiller grain in dairy cow diets could be potentially reduce the incidence of rumen acidosis while maintain milk production. Numbers of studies have been conducted to assess wheat distiller grain as a fibre and energy source to partly replace grain, or roughage or both. Penner et al. [33] evaluated wheat distiller grain to include 10% of wheat distiller grain in the ration showed that feeding wheat distiller grain as a forage substitute increased milk yield by 7% and milk protein content by 9%, whereas milk fat content decreased from 3.36 to 3.04% even though milk fat yield was not affected. Zhang et al. [34] reported that feeding wheat distiller grain in partial replacement of barley grain had no negative effect on dairy cow production. Feeding wheat distiller grain as a partial replacement of barley silage can improve dairy cow production, but, it may decrease chewing time, ruminal pH and milk fat concentration [35]. Overall, substitution of wheat distiller grain for part of concentrate or roughage in dairy cow diets improves milk production as a result of increase of feed consumption without negatively impacting milk fat. In contrast, feeding wheat distiller grain to partly replace roughage may reduce milk fat content due to reduction of chewing activity and rumen pH. Thus, dairy producers and nutritionists formulate dairy rations to ensure cow chewing time is sufficient to maintain rumen pH which is linked to maintaining milk fat concentrations [34].

#### **7. Feeding distiller grain for small ruminants**

Abundant distiller grain from ethanol production can be used as alternatives to feed grains and other premium ingredients in sheep feeding to reduce feeding costs for sheep farmers. However, most of the studies with feeding wheat distiller grain are with cattle or pigs. With our best knowledge, only one study was conducted using growing lambs fed diets containing wheat distiller grain. O'Hara et al. [36] reported that wheat distiller grain could replace a mixture of barley grain and rapeseed meal at 20% dietary dry matter without negatively affecting feed intake, daily gain and carcass traits of growing lambs. Replacing part of barley grain with 20% of wheat distiller grain in finishing lambs also maintained a healthy rumen function, growth performance and carcass characteristics [36]. McKeown et al. [37] also found that triticale-based distiller grain could replace up to 60% barley grain without adversely affecting on growth performance or carcass traits of lambs. Inclusion of wheat distiller grain in growing or finishing lamb diets is likely a viable feeding management since wheat distiller grain can entirely replace protein supplement to meet protein requirement of growing lambs, and simultaneously used as energy and fibre source because of its high contents of protein, energy and fibre.
