Maize grain options for dairy cows
Maize grain can be fed as earlage, high moisture corn or dry grain. Product form has implications for pricing, logistics, losses and feed value.
|Table 6. Composition, harvest, processing and storage method of maize production options17|
||Composition||Harvest and processing method||Storage method||ME MJ/kgDM|
+ 80-100% husks
+ <20% stover
|Precision chopper with ear picker||Silage
(bunker, bag or
|High moisture corn||100% kernels||Combine and mill||Silage
(bunker, bag or
|Dry grain||100% kernels||Combine, drying and cracking or grinding||Dry grain in bins||13.6|
|Table 7. Nutritional value of maize product options18|
||Drymatter %||Starch %DM||NDF %DM||Crude Protein %|
|High moisture corn||68-72||69-72||8-10||10|
Dry Maize Grain
Maize grain is normally harvested at 23-26% moisture (74-76% DM), transported to a drier and air dried to 14% moisture (86% DM). Dry grain has advantages for transport because very little water has to be shipped. It is also very stable and will hold its quality for long periods as long as it is kept dry. Dry grain needs to be processed to allow cows to efficiently utilise the nutrients it contains (see pages 15-17 for more details).
The feed value of dry grain is characterised by high energy density and a lower rumen degradation rate when compared to high moisture corn (HMC) or maize earlage.
Alkalised maize is made by combining maize grain with urea and a range of other ingredients including soya and enzymes. There are a number of commercially available products which can be used. They work on the principle of converting urea to ammonia which is a powerful preservative. Maize grain is harvested at 65 - 82% moisture, processed, mixed with urea and other ingredients and stored under airtight conditions. Alkalised maize has a higher crude protein content (more N from the urea) and higher digestibility than dry maize grain.
High Moisture Corn
High moisture corn is typically harvested when the maize grain is between 68-72% drymatter using a combine. The grain is rolled prior to fermentation. The key advantages of high moisture corn are that it can be harvested prior to normal grain harvest maturity, there is no drying cost and it is very high in feed value. Dr. Mike Hutjens (University of Illinois, USA) likens this product to “rocket fuel”.
High moisture corn is not as easy to transport as dry grain. It must be ensiled and there is a loss in drymatter during the ensiling to feed-out process. High moisture corn has a potential for aerobic instability (heating at feed-out time) and because it has a relatively high moisture content for a concentrate, it will not flow through most in-shed feeding system.
Maize earlage is an ensiled product that has a feed value and yield that falls between that of maize grain and maize silage. It is normally harvested at 55-65% drymatter using a snapper head on a forage harvester.
Earlage is normally harvested several weeks prior to grain harvest and because it is an ensiled product there is no requirement for drying. Earlage delivers some physically effective fibre which makes it safer to feed than other concentrate options.
Earlage must be ensiled and there is a loss in drymatter during the ensiling to feed-out process. It contains more water and is less energy dense than dry grain so the transport cost per unit of energy is higher. Earlage has a potential for aerobic instability (heating at feed-out time)
and it will not flow through in-shed feeding systems.
17 Mahlkow-Nerge, K. 2002. Earlage and Corn Cob Mix. Is their inclusion in high maize diets useful? Milchpraxis 4/2002 pg. 197-200.
18 Hutjens, M. 2011. Harvest sooner with snaplage. Hoards Dairyman Aug 2011 p 529.