Depending on their composition, maize germ meal and maize germs are used in ruminant feeding either as a source of energy (as substitute for cereal grain, notably maize), protein or fat.
Maize germ meal
Maize germ meal is highly palatable to ruminants. The maximum inclusion rate recommended for dairy and beef cattle is 25% of the diet. Lower rates are recommended for calves (20%), lambs (15%) and ewes (20%) (Ewing, 1997).
Digestibility and degradability
Maize germ meal is very digestible to ruminants (OM digestibility 80-85%, Sauvant et al., 2004). Effective DM and protein degradability of maize germ meal (protein 10%, fat 8% DM) were found to be relatively high (75 and 74%, respectively) (Marcondes et al., 2009).
Dairy cattle
In the USA, dairy rations were successfully formulated with 15% maize germ meal (protein 17%, fat 18% DM) from dry milling ethanol production, substituting forage and concentrate feeds. Dry matter intake, yields of milk and milk components were maintained, with no major differences in rumen fermentation or digestibility (Kelzer et al., 2009). In Venezuela, supplementation of dual purpose cows fed maize stubble, pasture and fruit with maize germ meal (protein 22%, fat 11% as fed) increased milk yield, duration of lactation and reproductive performance (Miranda et al., 2002).
Growing cattle and sheep
In the USA, a series of experiments evaluated solvent-extracted germ meal in the diets of steer calves, finishing yearling steers and finishing lambs, as an individual feed ingredient, or when combined with steep liquor containing distillers solubles, or with maize bran and steep liquor containing distillers solubles to simulate wet maize gluten feed. Maize by-products replaced dry-rolled maize. In lambs, solvent-extracted germ meal lowered DM intake, digestibility and feed efficiency relative to maize. In finishing yearling steers, solvent-extracted germ meal promoted higher gains than the maize-based control diet when comprising less than 50% of the dietary DM. In calves, enhanced feed efficiency was observed when solvent-extracted germ meal was blended with steep liquor containing distillers solubles. As a component of wet maize gluten feed, solvent-extracted germ meal promoted greater gain:feed ratio than maize bran. In calf diets based on 55% concentrates, replacing 50% of maize bran with solvent-extracted germ meal (7% in the diet) improved feed efficiency without diminishing performance and DM intake. The potential for acidosis in finishing cattle was diminished when maize by-products partially replaced maize grain. However, a combination of maize bran and steep liquor with distillers solubles offered greater protection from acidosis than when solvent-extracted germ meal was added to this blend, due to a lower dietary energy content (Herold et al., 1998a; Herold et al., 1998b; Herold, 1999; Herold et al., 1999; Herold et al., 2000).
Maize germ meal from various industries has also been tested in Brazil, China and Ethiopia, often as a substitute for maize grain. It can usually replace part of the maize in the diet, except in a lamb trial where maize germ meal was detrimental to performance (Silva et al., 2013b). It should be noted that extrapolating the results of those trials (where the nature and composition of maize germ meal is not always stated) to all types of maize germ meal is not recommended.
Table 1. Performance trials with maize germ meal in growing ruminants:
Country |
Animals |
Experiment |
Results |
Reference |
Brazil |
Nellore x Limousin bulls 320 kg |
Maize germ meal included at up to 45% in diets containing 25% forage and 75% concentrate |
Up to 45% maize germ meal provided increased body and carcass weights, without affecting carcass yields. |
Miotto et al., 2009 |
Brazil |
Nellore steers,
344 kg |
Partial substitution (70%) of maize with maize germ meal (42% diet DM) |
No differences in nutrient digestibility. |
Watanabe et al., 2014 |
Brazil |
Nellore steers,
343 kg |
4% maize germ meal used as source of fat |
No changes in DM intake, performance (growth, FCR) and carcass dressing. |
Ezequiel et al., 2006 |
Argentina |
Crossbred zebu bulls, 135 kg |
Supplementation up to 0.9% LW with maize germ meal of a diet based on Chloris gayana hay |
Supplementation at 0.6% LW gave the best DM intake and diet DM digestibility. |
Bocanegra et al., 2012 |
Brazil |
Holstein x zebu dairy calves |
Partial to total substitution of maize with maize germ meal (up to 98% of the concentrate DM) |
No effect on intake and performance (growth, FCR) and best economic results with 75% substitution. |
Signoretti et al., 1997 |
Brazil |
Dutch Black Pied and zebu crossbred calves |
Partial to total substitution of maize with maize germ meal (up to 84% of the concentrate DM) in starter diets. |
No effect on feed intake, weight gain and animal measurements. |
Signoretti et al., 1995 |
China |
Holstein dairy calves, 110 kg |
Partial substitution of maize and forage with DDGS and maize germ meal (up to 18% diet DM) |
Not effect on growth, rumen development and nutrient digestibility. |
Xu Jun et al., 2014 |
Brazil |
Crossbred heifers, 350 kg |
Full substitution of maize with maize germ meal (24% diet DM) diets based on cottonseed hulls and soybean hulls. |
No difference in carcass characteristics and composition of Longissimus dorsi muscle, but higher concentrations of conjugated linoleic acid, trans-vaccenic acid (7.69%) and lower n-6:n-3 ratio in this muscle. |
Kazama et al., 2008 |
Brazil |
Santa Inês lambs, 17 kg |
Partial to full substitution of maize with maize germ meal (up to 24% diet DM) |
Maize germ meal had no effect on meat chemical composition, but improved the nutritional quality of the lipid fraction (increased the polyunsaturated: saturated fatty acids ratio and the
n-6:n-3 ratio). |
Urbano et al., 2014 |
Brazil |
Santa Inês lambs, 17 kg |
Partial to full substitution of maize with maize germ meal (up to 24% diet DM) |
Maize germ meal decreased DM intake, nutrient digestibility, performance (growth and final liveweight) and carcass characteristics. |
Silva et al., 2013b |
Ethiopia |
Small East African goats |
Maize germ meal included at up to 30 g/kg LW0.75/d in a diet based on Chloris gayana hay and Maerua angolensis |
Supplementation with maize germ meal at 25 g/kg LW0.75/d and Maerua angolensis at 20 g/kg LW0.75/d gave the best performance and N retention. |
Ondiek et al., 2010 |
Maize germ
Maize germ with a high oil content should be used in limited amounts since it contains mostly unsaturated fat, which can be detrimental to rumen function and can reduce fibre digestion if fed for long periods (Ewing, 1997).
Digestibility and degradability
Maize germ from dry-milling ethanol production had the fastest rate of fermentation compared to bran or dried distillers grain with solubles (DDGS) (Tedeschi et al., 2009). It also had higher DM degradation rates than DDGS and soybean meal. Rumen protein degradability was 72% in maize germ from dry milling compared with 44-48% for DDGS (Abdelqader et al., 2009b).
Dairy cattle
Maize germ from wet milling ethanol production was found a viable energy source for mid-lactation dairy cows. Maize germ (protein 13%, fat 44% DM) included at 3.6% in the diet of Holstein cows supported milk production and protein yield equal to whole cottonseeds and tallow, but milk fat percentage and fat yield were less from maize germs than cottonseeds. Milk fatty acid composition from cows fed maize germs contained more of cis-9, trans-11 conjugated linoleic acid (Miller et al., 2009).
Maize germ from dry milling ethanol production was found to be a suitable alternative source of fat for energy in lactating dairy cows. Fat from maize germ may be relatively protected. Feeding dairy cows with maize germ (protein 16%, oil 20% DM) at 7 and 14% of diet DM increased milk yield and energy-corrected milk, as well as fat percentage and yield compared to cows fed a control diet. Milk protein yield tended to decrease as the concentration of maize germ increased in the diet. Concentrations of monounsaturated and polyunsaturated fatty acids in milk fat increased with maize germ inclusion, at the expense of saturated fatty acids. Intake was highest at the 14% inclusion rate (Abdelqader et al., 2009a).
Growing cattle
In the USA, maize germ (protein 12%, fat 45% as fed) was found to be a suitable source of supplemental fat in cattle finishing diets. Growth and carcass characteristics of crossbred steers and heifers offered finishing diets containing 10% dried maize germ were similar to those obtained with 4% tallow. Addition of maize germ might decrease the incidence of liver abscesses (Montgomery et al., 2005).