February 19, 2020
Should I feed this moldy hay?
According to Rachel Endecott (Previous MSU Extension Beef Cattle Specialist) Moldy hay (or other moldy feedstuffs) won’t always contain dangerous or poisonous compounds; however, the presence of mold itself can negatively impact animal performance and health. Feedstuffs with considerable mold can produce close to a 5% decrease in energy content for ruminant animals. Moldy feed is understandably less palatable and could result in lower than target intakes of nutrients. The end result is decreased milk production, decreased growth, respiratory issues, and declining resistance to disease.
Many molds are capable of producing mycotoxins. Mycotoxins are produced by a fungus. Dramatic decreases in milk production can occur, calf performance can suffer, and abortions can result from the consumption of mycotoxins. Mycotoxin effects accumulate over time, and the presence of more than one mycotoxin can increase fungal spread. Mycotoxin content is not necessarily related to the amount of mold present.
If ranchers are concerned about a mold or mycotoxin problem, the first step is to send in a sample for mold count and identification. The MSU Schutter Diagnostic Lab on campus or a commercial feed testing laboratory can test the hay. The mold spore count can provide a guide for how (or if) the hay should be fed. In addition, the identification of mold species can rule out or rule in mycotoxin. If mycotoxin-producing species are present, another test to determine mycotoxin concentration can be conducted. Concentrations of as little as 20-40 parts per billion of some mycotoxins can cause negative effects to livestock.
Montana State University, U.S. Department of Agriculture and Montana Counties Cooperating. MSU Extension is an equal opportunity/affirmative action provider of educational outreach.