Maize harvest and clamp management

As maize harvest approaches, Tom Goatman, DairyCo extension officer, outlines how harvest and clamp management can affect maize quality.

 At harvest

  • Cob ripeness will indicate true maturity
  • As tempting as it is to harvest as soon as possible, you need to be patient and ensure crop is harvested at      the correct maturity (firm dough) to maximise starch levels
  • See John Morgan’s article on DM testing for crop maturity.
  • Chop length can have a big influence on the performance of the maize and the stability of the crop in the clamp
  • Factors such as DM and the percentage of maize in the diet will determine chop length
  • Keep the chop length shorter with drier crops in order to aid consolidation but you can get away with a longer chop length with wetter crops
  • Talk to your nutritionist about which chop length is best suited to your system (typically 16-20mm), then talk to your contractor to make sure they can meet those requirements
  • Remember contractors chopping maize for biogas will be using a much smaller chop length (6-8mm) which is not suitable for feeding livestock
  • Check the chop length on the first load into the clamp!
  • Make sure all material is spread in a thin layer in the clamp, and properly compacted in order to remove air and avoid aerobic spoilage
  • Forage harvesters can deliver a large amount of maize to the clamp in one load, so you need to make sure there are enough machines working the clamp
  • Once consolidated, seal the clamp properly to ensure no air can penetrate the clamp.


Feeding out

  • Avoid opening the maize clamp too early!
  • The temptation can be to feed maize on the day it’s harvested, due to the forage stock situation at this time of year, but waiting a while will make a real difference
  • Initial fermentation should be complete within 3-7 days – achieving and maintaining anaerobic conditions are important to promote a fast, efficient fermentation and successfully preserve the crop
  • Opening the clamp within this time period will let air in, this really affects the fermentation process
  • Research demonstrates that the starch digestibility of maize silage improves with the length of time spent in the clamp 
  • This is because the starch is found in a matrix with prolamin (this is a storage protein in the plant). Storage increases the length of time for proteolysis (protein breakdown) to occur, degrading the prolamin and making the starch more available to the rumen.