Maize bran and hominy feed are primarily used as sources of energy for ruminants. They are less expensive than maize grain and, depending on their chemical composition, their nutritional value may allow a performance slightly lower, equal to, or even better than the whole grain.
Digestibility and energy content
The cell wall content of maize bran varies widely, which affects digestibility and energy content, despite the fairly good digestibility of maize cell walls. The digestibility of maize bran (76% TDN in NRC, 2001; 70% OM digestibility in the INRA-AFZ Tables, Sauvant et al., 2004) is generally considered to be about 89% that of corn gluten feed and 80% that of maize grain. The ME content of maize bran is approximately 90 and 80% of the ME of corn gluten feed and grain, respectively. Hominy feed containing 5-8% fat and 20% starch was found to have 87% of the energy value of maize grain in steers (Larson et al., 1993).
In wethers fed at maintenance, the NE for gain of wet corn bran was estimated at 6.7 MJ/kg DM (Fiems et al., 1996), a value consistent with the EN value for growth of 6.5 MJ/kg DM proposed by the INRA-AFZ tables (Sauvant et al., 2004). In growing bulls, ensiled maize bran had a positive effect on energy efficiency when it replaced 40% of maize silage (DM basis), and it was concluded that its in vivo OM digestibility was underestimated (Fiems et al., 1996). In finishing steers, maize bran from ethanol production (a mixture of bran and solubles) was found to have 100-108% of the energy value of maize, which could be explained by negative digestive interactions induced by dry-rolled maize in the control diet (Bremer et al., 2005). However, substituting dry-rolled maize and steam-flaked maize with regular maize bran decreased the gain:feed ratio by 5.2 and 13.8%, respectively (Macken et al., 2004).
Maize bran, like many maize by-products, has a rather low effective protein degradability (43%, Sauvant et al., 2004), and can be considered as a medium provider of metabolizable protein (7.7 in NRC, 2001 and 10.3 % DM in the INRA-AFZ tables (Sauvant et al., 2004)). However, it is likely that protein degradability of maize and hominy feed actually depends on the process undergone by the grain during wet or dry milling.
Maize bran can be used to fully replace maize in the concentrate fed to cows of medium level of production without affecting milk quality (Cardenas et al., 2002; Tahir et al., 2002). However, maize bran has to be combined with a protein supplement. In Tanzania, sunflower meal mixed with maize bran was effective in increasing milk yield during the dry season (Mlay et al., 2005). One advantage of maize bran is that it provides energy without causing negative digestive interactions with other ingredients. In Kenya, supplementation of elephant grass (Pennisetum purpureum) with 1 kg DM of maize bran did not significantly reduce the rumen degradation of the forage. It also increased the molar proportions of propionate, which may have increased the efficiency of utilization of ME and, therefore, milk production (Muinga et al., 1995). In the USA, the inclusion of 10 to 25% maize bran in the diet had a positive influence on energy intake and milk production (Janicek et al., 2007). When maize bran replaced dried ground maize grain in the concentrate portion of high-forage and low-forage diets, total replacement reduced OM intake, milk yield, milk energy, and milk protein. A strategy in which maize bran only partially replaces ground maize and part of the forage may be preferable (Arndt et al., 2014). Hominy feed with a composition close to that of maize grain could be used as an energy source alone or in combination with maize in dairy cows fed sorghum and ryegrass silages (Boyd et al., 2008). Likewise, hominy feed containing 47% starch (DM) could be used as the main energy supplement (28-35% diet DM) offered to mid-lactation cows fed maize and ryegrass silages, resulting in similar performance as that obtained with ground maize or steamed-flaked maize (Cooke et al., 2009). In Australia, pellets including 60% hominy feed and 34% wheat pollard were an effective replacement for sorghum grain in dairy cows fed tropical grass pasture in autumn. As they were highly palatable, they increased milk production and profit margins (Ehrlich et al., 1992).
In the USA, maize bran from wet milling fed to cattle at 15 or 30% (diet DM), either alone or in combination with steep liquor, increased DM intake and average daily gain, compared with a predominately dry-rolled maize diet. Maize bran also reduced acidosis, but there was a tendency for it to reduce digestibility and dietary energy (Scott et al., 1997). In finishing steers, maize bran from ethanol production (a mixture of bran and solubles) included at up to 45% of DM improved final weight, average daily gain, DM intake and feed:gain ratio compared to a blend of high-moisture and dry-rolled maize (Bremer et al., 2005). The same type of maize bran replaced maize in beef growing and finishing diets at up to 40% inclusion levels with no loss of performance (Buckner et al., 2007; Larson et al., 2007). A combination of maize bran and steep liquor fully replacing dry-rolled maize did not alter feed efficiency in growing cattle, and, as in the study of Scott et al., 1997, slightly decreased OM digestibility and increased the rumen pH (Sayer et al., 2013). Maize bran from ethanol production fed to finishing steers up to 45% of the diet resulted in a similar performance to that obtained with the same amount of DDGS (Bremer et al., 2005). Hominy feed containing 5-8% fat and 20% starch was substituted for up to 45% of the maize grain in cattle finishing diets without compromising performance (Larson et al., 1993).
Sheep and goats
Farmers in developing countries often use maize bran as a supplementary feed for small ruminants, at inclusion rates ranging from 10 to 25% of the total diet (Katongole et al., 2009). Maize bran is particularly valuable when used with poor forages. In Kenya, goats fed a diet of Rhodes grass (Chloris gayana) hay had better performance and nutrient digestibility when the diet was supplemented with Gliricidia sepium and maize bran, the maize bran allowing a better utilization of gliricidia (Ondiek et al., 1999). Likewise, in Tanzania, goats grazing star grass (Cynodon nlemfuensis) benefitted from leucaena supplementation when maize bran was included in the diet (Mjema-Mweta et al., 1995). In Nigeria, feeding maize stover plus urea and 150 g/d of maize bran provided adequate and profitable live-weight gain in goat kids during the dry season (Yahaya et al., 2013).