There were quite a few acres of forages cut for hay in the past week. Hay quality is determined by M&M, and I don't mean the candy. In this case M&M stand for maturity and moisture content. Maturity is the single biggest factor that determines hay quality. In both cool and warm season forages, across grass and legume species, quality declines rapidly as the plant matures. Quality measures include crude protein, energy content, and fiber content. As the forage plant moves from vegetative to reproductive growth, crude protein and energy content decrease while fiber content increases. If high quality hay is the goal, then forages should be cut in the late vegetative growth stage.
Most beef cattle operations do not need dairy quality hay. Good quality hay for most beef cattle operations can be made by cutting grass forage at the boot to early heading stage or growth. The University of Kentucky fact sheet entitled "Quality Hay Production" lists the value of fescue cut at the late boot to early head stage as 14% crude protein and 68% digestibility (TDN). When that forage is allowed to continue to mature and is cut at the seed formation stage, quality declines to 7.5% crude protein and a 56% digestibility (TDN). Unfortunately, hay production at the seed formation stage of growth is common for much of our first cutting hay. Regardless of the forage quality at the time it is cut, that quality will be lower by the time it is baled due to wilting and harvesting dry matter loss.
This brings us to the other "M" factor, which moisture. Forage plants continue to respire after they are cut until their moisture level falls below 40 percent. This respiration results in dry matter loss that typically averages 5 to 6 percent. Another quality loss associated with moisture is handling. Baling and raking are responsible for additional quality losses. The more that cut forage is raked or tedded after it has dried to below 40% moisture, the higher the dry matter losses become. Baling and raking can account for 10 to 25% dry matter loss, with an average loss of around 15%.
While baling at higher moisture contents can reduce the dry matter loss associated with mechanical handling of the forage, once the forage is in a baled form, moisture content is important to prevent losses associated with excessive heating. The general rule of thumb is that hay in small rectangular bales should be baled at less than 22% moisture and large round bales should be made at less than 18% moisture. If hay is baled above these moisture contents then additional dry matter is lost to excessive heating and mold production.
Source: Rory Lewandowski, Extension Educator Wayne County and Crossroads EERA