Zea mays

Maize, Indian corn, Corn, Maize grain, Hominy feed, Maize-and-cob meal, Maize cobs, Maize gluten feed, Maize gluten meal, Maize-germ oil cake

There are many types of maize and the grain may be yellow, white or red. Yellow maize contains a pigment, cryptoxanthin, which is a precursor of vitamin A. It can also affect the colour of pig fat; however, this pigment is valuable in poultry diets as it gives the meat and egg yolks a desirable colour. 

The maize kernel contains two kinds of protein. Zein, in the endosperm, makes up the greatest part but is deficient in the essential amino-acids, tryptophan and lysine. Glutelin occurs in lesser amounts in the endosperm and also in the germ and is a better source of these two amino-acids (553). 

Plant breeding technology has led to the development of hybrid maize and particularly to high lysine varieties. A high lysine variety (Opaque-2) is nutritionally superior but still requires methionine supplementation. A newer variety, Floury-2 has both increased methionine and lysine content. 

Maize oil has a high proportion of unsaturated fatty acids and is an excellent source of linoleic acid but the use of maize grain should be restricted in pig diets because it may cause soft fat in the carcass. 

Maize is a poor source of certain trace elements and vitamins (available niacin) but has useful amounts of biotins and carotenoids (554). Phosphorus present is fairly available because of phytase activity within the grain. The low Ca:P ratio necessitates the inclusion of ground limestone or similar to supplement the Ca level. 

Fungal toxins (zearalenone, aflatoxin and ochratoxin) may be problems in badly stored grain. Damp conditions at harvest and open storage contribute to this. Fusarium, which produces zearalenone, causes adverse effects especially on sow productivity when the level exceeeds 3mg/kg. 

Grain varieties differ markedly in storage characteristics because of husk cover and endosperm type. `Improved', high yielding varieties have soft endosperm, attractive to garin beetles, and moths and poor husk cover, leaving the cob tips open to fungal attack and discolouration. Local varieties, although lower yielding, are more easily stored with minimum loss of quality (557). 

Fresh grain is stored most economically in a trench silo; the moisture content should be 30% and it should be crushed before ensiling. 

All types of maize grain should be ground before feeding except for sheep; even for poultry the grains must be crushed. Maize meal cannot be stored long as it is likely to become rancid, whereas dried grains have a good keeping quality. When maize is dry-milled to produce flour, the bran and the germ are first separated. Wet milling for the manufacture of starch or starch derivates (e.g., corn syrup) yields a number of by-products. The wet-milling process is usually carried out in accordance with the following flow diagram (435). 

                          MAIZE
                            |
          +------------ Steeping
          |                 | 
     Steepwater             | 
          |                 | 
     Concentration    Degerminating - Germ -- Extraction --- Oil
       |                    |                      |        
       |                    |                 GERM OIL MEAL
       |                    | 
      Mix --  Coarse ---- Screening - Fine --------+
       |       fibre        |         fibre        |
       |                    |                      |
       |                    |                      |
      Dry                 Separation -- Gluten -- Mix
       |                    |                      |
       |                    |                     Dry
       |                  Pure Starch              |
       |                                           |
 MAIZE GLUTEN FEED                          MAIZE GLUTEN MEAL          

Alternatively, the steepwater can be evaporated and used as feed under the designation maize solubles. 

USES. 

MAIZE GRAIN. Maize is palatable and suitable for all classes of livestock. It is rich in energy and low in fibre and minerals. Both the protein level and the biological value of the protein are low. To fully utilize the high productive value of maize, these deficiencies have to be counterbalanced by proper supplementation. 

Maize can supply part of the protein requirement in pig and poultry diets. It generally requires supplementation with protein- 

rich feeds (soya or alternatives) and amino-acids (lysine and methionine) in diets for pigs and poultry. Young ruminants will also require protein supplementation but in older ruminants, urea or poultry manure may be used (see UREA, POULTRY EXCRETA). 

The digestibility and palatability of maize can be increased by processing, roasting, dry rolling, flaking, etc. Flaking is the most common method. The grains are steam-cooked and then passed between rollers while still hot and soft. Flaked maize passes through the alimentary tract about 25% more rapidly and has about 5% higher digestibility; also, it is more palatable than cracked maize. Flaked maize should not be stored a long time before feeding. 

(see CONCENTRATES AND SUPPLEMENTS) 

(Alternatives: Cassava and other starchy rootcrops and fruits, other cereals, sugarcane juice, molasses) 

HOMINY FEED 

This by-product of dry milling, consisting of the bran coating and the maize germ, is palatable to all classes of farm animals. It approaches maize grain in feeding value, but it contains more fat because the germ is included and may produce soft carcasses when fed in large amounts to pigs. The optimum level in pig rations is about 20-25%. In diets for cattle and poultry it has practically the same value as maize grain. Hominy feed is often erroneously called maize bran, a name which should be reserved for bran coating without germ. 

MAIZE-AND-COB MEAL (ground ear-maize). 

This is the entire maize ear including the cobs, which comprise about 20% of the weight. If the entire maize ear including the husks is 

ground, the end product is called ground snapped maize. Maize-and-cob meal is valuable for full-grown ruminants, and there is almost no difference in the performance of feedlot animals receiving maize-and-cob meal and animals feeding on shelled maize. For horses, maize-and-cob meal is usually preferred to shelled maize as it is less likely to form a doughy mass in the stomach. The high content of fibre restricts the use of maize-and-cob meal in poultry diets. Pigs can tolerate 25-50% in the diet depending on age. The meal should be well dried; otherwise it is likely to mould in a hot climate. 

MAIZE COBS. 

This is a low-quality roughage comparable to poor hay. It is unpalatable, and if not dried it becomes mouldy within a few days in a hot climate. Preferably it should not constitute more than half of the roughage except for feedlot cattle. 

MAIZE GLUTEN FEED. 

This by-product of the wet milling of maize is suitable for all farm animals. It is most widely used for dairy cows, but it should not be fed alone as it is not very palatable. The unbalanced amino-acid composition restricts its use in poultry and pig rations. As maize gluten feed contains the colouring pigment of the grain, it is valuable in poultry rations. The maximum recommended level of maize gluten feed is 10% for growing chickens and 16% for layers, 10% for growing pigs and 16% for fattening pigs. 

MAIZE GLUTEN MEAL. 

Despite the unbalanced amino-acid composition of this by-product, it gives good results in pigs and poultry when mixed with soybean meal or meat meal. It is not very palatable and is mostly used for cattle. 

MAIZE-GERM OIL MEAL (cake or maize oil-meal cake). 

This product is a valuable feed for all farm animals but pigs. Meal with a high fat content is likely to cause soft back fat if led in large quantities. It should not be used as the only source of protein for poultry. Maximum recommended daily rations for cattle are 2 kg per day and for pigs 0.5 kg per day.