I have been ask by numerous producers how many days past the target window of 28 days of growth does maturity cause a rapid decrease in the quality of the hay.
The two most important criteria used in evaluating hay quality are the crude protein (CP) content and the energy value. Though both are important, low digestible energy is usually the main limiting factor in Southern livestock rations. Therefore, the emphasis with regard to forage quality of hay should generally be on improving the digestible or available energy value.
Factors that can influence hay quality include plant species, plant variety, weeds, insect damage, diseases, weather at harvest and harvesting techniques. However, once a hay field has been established, hay quality is most likely to be affected by two other factors, both of which are under the control of the producer: fertilization and stage of maturity at harvest.
Nitrogen fertilization will, up to a point, increase the protein content of grass hay. Fertilization with other nutrients such as phosphorus, potassium, magnesium and sulfur may also influence the amounts of these elements that are present in forage as well as other quality factors.
Periodic soil testing followed by applying the recommended nutrients will allow the levels of specific nutrients in forage tissue to be adequate for animals. Fertilization may also improve hay palatability to animals and thus influence animal performance by increasing intake. Although important in obtaining good hay yields, fertilization normally has little or no influence on the energy level of hay.
The single most important producer-controlled factor influencing hay quality is stage of maturity at harvest. This is where many livestock producers can most easily and dramatically improve hay quality. The state of maturity at harvest influences the palatability, CP content and especially the digestible energy level. In general, the best time to harvest for a good yield as well as high energy and CP levels is in the boot stage (just before seed-head emergence) for warm grasses. Around 28 days of growth is the target window to cut and bale hay. Every day past 35 days hay quality drastically decreases. If a producer waits until past the recommended stage to cut hay, the fiber content increases, and palatability and digestibility decline. Waiting until later will increase the number of bales or tons of hay produced, but nutritive value decreases.
In addition to requiring more fuel, time and labor to store the hay, the further past the optimum stage that hay is harvested, the poorer animal performance will be because of low digestible energy and high fiber. Poor quality hay passes more slowly through the animal’s digestive system, causing lower intake of low quality hay, which further reduces animal performance.
If you have any further questions, please contact Clint Perkins with the Smith County Extension Office, 1517 W. Front St. in Tyler, or call 903-590-2980.