Smooth bromegrass and other cool-season grass hay fields are growing rapidly and seedheads will soon be appearing. When do you typically cut your grass hay? Ideally, cutting your grass hay so the grass nutrient content matches with the nutritional needs of your livestock is best.
Crude protein and energy concentration declines in grass hay as plants become stemmy and mature. With smooth bromegrass for example, research has shown that crude protein content declines rapidly between boot and mature seed stages. Crude protein levels in well fertilized hay harvested at early heading range from 10-18%, but drop rapidly after heading. Decreases in crude protein levels by as much as one-half percent per day after heading have been recorded.
As this happens, the types of livestock that can be fed that hay with little or no supplements become more limited
For Sandhills sub-irrigated meadows, haying typically starts in early July. However, if harvest occurs around the third week of June, then that hay will have significantly higher crude protein content. Earlier meadow harvest will have lower initial hay yield, but it will also provide a longer regrowth period and extra growth for fall grazing.
So, a good approach is to plan what type of livestock will receive the grass hay from each field. Young livestock need high nutrient concentrations so cut that hay before or just when heads begin to emerge. If the hay will go to mature dry cows instead, let the grass produce a bit more tonnage and cut it after it is well headed out, but before seeds develop.
Matching your hay harvest with your plan of use can pay handsome dividends in lower costs and less supplementing. — Jerry Volesky, Nebraska Extension
