High-Ammonia Forages

Posted: 01 Sep,2022 by agriking Category: All Agri-King Articles, Beef Nutrition, Dairy Nutrition, Silo-King Tags: Agri-King, ammonia issues, Dr. Dave Jones, forage, livestock micro-minerals

By Dr. David Jones, Ph.D., P.A.S.

Along with amino acids and peptides, ammonia is part of the soluble protein (or ‘A’ fraction) of routine protein analysis. It is generated by the deamination (removal of nitrogen-containing amino groups) of proteins, which reduces the overall quality of the protein. Ammonia is a source of nitrogen for rumen bacteria (in particular the cellulolytic bacteria), in which they can use it to generate amino acids used to synthesize bacterial protein. Should its concentration of forages get too high there will be an energy and metabolic cost to the animal. This article will focus on ruminant animals as they are more affected by elevated ammonia concentrations than non-ruminant animals.

Fermented Forages and Ammonia

Important facts to know regarding ammonia and fermented forages (haylage/balage, grass silage, and corn silage):

As forage DM decreases (moisture increases) the ammonia concentration of the forage increases (Tables 1, 2, and 3, ANALAB 2022).
Alfalfa haylage and grass silage will have a dramatic decrease in ammonia concentration as dry matter content increases, whereas there is little to no effect in corn silage (Tables 1, 2, and 3, ANALAB 2022).
An increase in forage pH, along with a decrease in dry matter, allows for more clostridia and proteolytic activity in the forage, which increases ammonia concentrations. This is exaggerated if dirt is brought into the forage during harvest because of increased clostridia counts (Schauff, Bailey, and Gengelbach. 2022).
Silage packed too loosely and filled too slowly tends to have elevated concentrations.
Application of manure/nitrogen around harvesting will increase fermentable protein, causing an increase in ammonia and nitrate concentrations.

Ammonia concentrations in fermented forages are considered elevated when they exceed 12-15% of the crude protein (dry matter basis) in a forage analysis (Kung and Shaver, 2001). A rule of thumb when interpreting ammonia analysis on your forage reports is the following:

Less than 12% of CP is optimal.
12 to 15% of CP is a potential issue.
Greater than 15% of CP is an issue and should be addressed.

Interpreting Forage Concentrations

High concentrations in forages alone are not a cause for alarm as long as the total nitrogen fractions in the diet are in balance. Ammonia enters the rumen directly from feed and is produced in the rumen from non-protein nitrogen sources (e.g., urea) and nitrates. Therefore, we must consider the total combined ammonia available to ruminants when monitoring a diet for potential effects. If concentrations cause an increase in diet soluble protein (or total rumen degradable protein), then some negative effects can occur with a ruminant animal. Also, there needs to be consideration of the potential for biogenic amine compounds (putrescine, histamine, and ethanolamine) that can be produced from the deamination of various amino acids along with it.

Taking Action

If high-ammonia forages are fed, cattle need to be monitored for the following signs:

Elevated blood urea nitrogen (BUN) or milk urea nitrogen (MUN)
Loss of body condition (converting ammonia to urea is an energy-utilizing metabolic process)
Loose manure
Abortions/resorbed fetus/poor calf health
Reduced dry matter intake
Reduced performance (milk production/body weight gain)
Pulmonary edema
Abdominal pain
Frothy salivation
Gasping
A central nervous system disorder, generically called “bovine bonkers,” which causes stampeding, ear twitching, trembling, and convulsions
Various clostridia diseases (black leg, botulism, hemorrhagic bowl syndrome, etc.)

Minimize ammonia in fermented forages by taking the following steps:

Treat with Silo-King® for an efficient fermentation
Harvest at optimal dry matter and maturity
Avoid manure/nitrogen application during the growing season
Minimize soil contamination during harvest
Fill the bunker/pile/silo quickly, pack tightly, and cover immediately

Things to consider should fermented forage have an elevated ammonia concentration:

Dilute or remove high-ammonia forage
Add a fermentable source of sugar (e.g. molasses) to the diet to assist the rumen bacteria in using ammonia as a source of nitrogen
Reduce or remove urea and other non-protein nitrogen sources from the ration
Add Micro XX® to the diet

If there is concern that ammonia concentrations in your forage may be elevated, contact your local Agri-King Area Manager for assistance. Agri-King’s ANALAB can test forages for concentration, and we can adjust rations based on the forage on your farm. AK

Complete references available upon request.