We had a very wet June this year and baling hay has been a tough thing for most farmers in the state. Moisture levels have a direct effect on hay quality. What I have found to be a consistent number in the literature is 20% moisture maximum. To be more specific:
- Small squares to be 20% or less,
- Large round, 18% or less and
- Large squares, 16%
Hay baled at 20% moisture or higher has a high probability of developing mold, which will decrease the quality of hay by decreasing both protein and total nonstructural carbohydrates (TNC) AKA energy! The mold will also make the hay less palatable to livestock and could potentially be toxic, especially for horses. Even hay baled between 15%-20% moisture will experience what is known as "sweating". Sweating, in regard to hay bales, refers to microbial respiration, which will create heat and result in dry matter (DM) loss. A good rule of thumb is that you should expect a 1% DM loss per 1% decrease of moisture after baling. As an example, hay baled at 20% moisture that is stored and dried down to 12%; will result in 8% DM loss.
Understandably, June was a double edged sword in regards to losing quality by not baling, or losing quality by baling with moisture levels that are too high. Therefore, my recommendation to ensure adequate livestock nutrition this winter is to have a forage analysis done on the hay baled this year. Once you have those results, develop a corresponding supplemental feed program, if necessary, based on the nutritional requirements of your livestock. The short video below from Clif Little explains how to take forage samples for testing.