Hay bales stored outdoors that do not form a good protective thatch layer can mold up and the dry matter losses can penetrate deep within the bale.
(OSU Beef Team Newsletter)
Forming a Protective Thatch on Your Hay Bales
A thatch forms from oxidation of the exposed outer layer of grasses to sunlight and moisture on the outside of a bale. This layer can be a protective barrier from the elements, protecting the inner contents of the bale.
Factors that INCREASE the probability of thatch formation include:
Fine stemmed grasses
Factors that DECREASE the probability of thatch formation include:
Course stemmed grasses
Woody stems and weeds
*If you have re-seeded a right-of-way with a lot of annuals, it would be best to not store that hay too long outdoors if baled. You could feed it right away or store those bales inside. Hay bales from annual grasses are more prone to weathering and will lose quality more rapidly if stored outdoors due to the course and hollow stems in those grasses.
We have 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, this month has been 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. Remember that grains are doing exceptionally well this year, so far. This could possibly result in reasonable grain prices for the winter months…
That is the question many farmers have been facing the past week. As I mentioned last week, we need sunshine to cure hay. If hay is made before it is dry enough, it can mold or even catch fire. If farmers wait to cut hay, quality goes down. If they cut hay and it gets rained on, it may be okay if it does not lie on the ground too long. If it rains and it is a week or more before it dries out, it will start to mold and rot, then it is lost. Many years we have a period like this and it is not good. We need rain and we need sunshine. It seems we should get one or the other, but lately, we have received neither. So the question many faced on Sunday was to cut or not to cut hay? Which is right and which is wrong? Hopefully by the time you read this, farmers will know the answer and hopefully, they were right.