Using Preservatives

 Knowledge Nuggets | Fact Sheets | Research Papers

Knowledge Nuggets

  • An effective hay harvesting system is designed to reduce field losses and spoilage losses from microbial activity in high moisture hay. Fresh cut forages range from 70 – 80% moisture which must be reduced to “safe” levels (generally from 16 – 18%) prior to baling.
  • A “browning” effect can result from heating which reduces carbohydrate levels and binds some of the protein making it undigestable due to the higher moisture levels in moist hay.
  • Harvesting hay at moisture levels above 18 – 20% reduces field losses by reducing leaf shattering and by decreasing the amount of exposure time to adverse weather. However, storing moist hay usually results in mold growth and elevated temperatures.
  • Mold growth that occurs in baled forages increases dustiness, reduces palatability and can impact animal health.
  • Moisture and temperature are the fundamental control variables for storage and the role of a preservative is to prevent microbial growth and activity.
  • Moist hay preservation systems are most cost effective when used on high quality forages for high production livestock or when rain delays to harvesting are distinct possibilities.
  • When used as a preservative on high moisture forages, anhydrous ammonia prevents overheating by destroying the bacteria and molds. It effectively reduces field harvesting losses and makes the harvesting operation less weather dependant.
  • Anhydrous ammonia can also be used as a source of non-protein nitrogen to improve the feeding value of low quality forages by increasing protein content and assisting in the breakdown of the fibre fraction of mature forages.
  • The response to anhydrous ammonia is controlled by moisture content of the forage (minimum 12% moisture required), the time of ammoniation, air temperature, and the amount of ammonia provided.
  • When anhydrous is used as a preservative for high moisture forages the ammonia must be applied at 2% of forage dry weight. When anhydrous is used to improve the feeding value of low quality forages the ammonia must be applied at 3 – 5% of forage dry weight.
  • For anhydrous to be effective, the forages must be stacked, covered with plastic, and completely sealed for up to 4 weeks.
  • Propionic Acid is the most effective organic acid preservative for baling moist hay that is commercially available.
  • Rates of proprionic acid application vary depending on the moisture content of the forage and because organic acids function as fungicides they must be applied to contact as much of the surface as possible, which is usually at the pick-up on the baler.
  • Organic acids can be corrosive to equipment and a neutralized solution is recommended.
  • Different microbial products have been developed as an aid to ensiling and although they can be very effective for silage they have limited effectiveness when used for hay preservation.
Fact Sheets

Ammoniating Low Quality Forages - video

Ammonia Treatment of Low Quality Forages - available in PDF format only

Forage Preservatives

Feeding Livestock During Feed Shortages - SK

Hay Preservatives

Heated Bales: Management and Handling - Frequently Asked Questions

Preserving Baled Hay With Organic Acids

Preventing Mouldy Hay Using Proprionic Acid

Hay Dessicants and Preservatives

Research Papers

Comparison of the fermentation characteristics, aerobic stability and nutritive value of barley and corn silages ensiled with or without a mixed bacterial innoculant. - available in PDF format only

How to Maintain Forage Quality during Harvest and Storage

Use of forage innoculants with or without enzymes to improve preservation and quality of whole crop barley forage ensiled as large bales - available as PDF format only
  For more information about the content of this document, contact Grant Lastiwka.
This document is maintained by Janet Fletcher.
This information published to the web on December 1, 2003.
Last Reviewed/Revised on March 2, 2017.

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