Nutritionist > Dairy
Silage and feeding
In any fermentation storage system, temperature and the presence of moisture is sufficient for toxin production. But, oxygen will act as the switch which turns mycotoxin production on or off during storage.
The amount of mycotoxin in contaminated silage samples increases as the ensilement method changes from airtight, upright silos to concrete capped and uncapped silos. The highest forage concentrations of mycotoxins are found in horizontal storage methods such as bunker silos and feed piles which are left open to oxygen.
Where greater amounts of mycotoxins are found, poor management of the upright or bunker silo results in oxygen entering the stored feed. In scientific studies, well managed bunker silos, covered with plastic and weighted with tyres, did not have significantly greater levels of mycotoxins than well managed upright silos.
In a plastic covered storage system, oxygen penetration is slowed but not eliminated. The longer the silage is stored, the greater the opportunity for significant fungus growth and mycotoxin contamination. In one study the levels of DON increased in the silo slowly over time even when properly covered.
There is no such thing as an oxygen proof silo. We would all like to think this is true, but in practical terms our current technologies are not perfect. When one examines a plastic layer under a microscope, he will find tiny holes through which oxygen slowly flows. This is especially true of plastic that is stretched for wrapping bales. Any damage to the plastic further increases the flow of oxygen from a trickle to a river and must be repaired as quickly as possible.
A checklist of practices to prevent mycotoxin contamination in silage:
- Purchase corn and other feed varieties resistant to foliar, ear rot, and stalk rot diseases
- Purchase varieties resistant to ear and stalk boring insects.
- Harvest corn and haylage at the recommended maturity and moisture level for your storage system. DO NOT let corn stand in the field after reaching maturity or killing frost.
- Be sure chopper knives are sharp and cut at the correct length to improve packing
- Harvest forages as quickly as possible and pack tightly with the proper weight of tractor matched to the right number of packing hours and filling rate.
- Be sure the silo is sealed to exclude oxygen. Use plastic covers secured by tyres on bunkers.
- Patch any holes in plastic covers, bags, or wrapped bails as soon as possible
- Discard obviously spoiled feed or layers of feed.
- Since mycotoxins are highly soluble in water, do not allow rain to wash through upper layers of spoiled feed.
- Clean out leftover feed from feeding bunks regularly.
- Consider the use of an inoculant in silage or acid additive in high moisture corn to enhance fermentation and storageability.
- Match the rate of feed removal from the silo face to the size of the herd. For example bunker silo faces should be removed at four to six inches and upright silo face at three to four inches per day. Use the higher rate during the warm seasons.
- When confronted with a toxicity problem, stop feeding the contaminated feed.
- In consultation with your veterinarian or nutritionist, consider the use of a mycotoxin adsorbent to be mixed with the feed. Contact your Alltech representative for more information.
