Selecting grasses for pure stands is much different than species selection for pastures. With pastures it’s “the more the merrier”: A diversity of species, both grasses and legumes, on average should perform better than any single species. The weather and soil conditions that challenge one species may benefit one or more others.

However, when establishing a straight stand of grass for hay or silage, it’s usually better to use one species — and one variety of whatever grass you choose. That’s because there are considerable differences in heading date among cool-season grasses and also between varieties.

The initial heading date for the earliest varieties of several grasses, including timothy, orchardgrass, ryegrass and bromegrass, can be two weeks earlier than for a late-heading variety. The differences in heading dates are even greater when taking into account both species and variety. Therefore, choose a grass species that best meets your needs: Not only heading date but tolerance to your harvest style and soil drainage conditions. There’s a grass species to meet almost any situation, but the differences are great enough that this decision shouldn’t be taken lightly.
Reed canarygrass, for instance, will tolerate a wide range of drainage conditions including periodic flooding but isn’t the best species if high quality is near the top of your “gotta have” list. Timothy may be a good option if you sell hay because it’s favored by horse owners. (Perhaps because timothy is the only species some of them recognize!) It will grow well during the spring but not during the heat of summer. Orchardgrass is high-yielding but requires aggressive management and is more susceptible than several other species to winter damage, particularly ice sheets.

In recent years, the cool-season grass species generating the most interest is endophyte-free tall fescue. There are dozens of tall fescue varieties on the market, most which head at about the same calendar date as do the latest-maturing orchardgrass varieties — and endophyte-free varieties are widely available.
In recent Cornell University trials, the newer varieties of tall fescue didn’t have an advantage in yield or quality over some varieties that were released a few years ago. However, that’s not necessarily bad news since most tall fescue varieties combine good forage quality with high yield potential, often topping university grass trials that include several grass species. Tall fescue was injured on some farms by last winter’s “polar vortex,” but has survived severe winter conditions in the Northeast for a decade with only occasional damage.

Farmers are increasingly including grasses in the rations of high-producing dairy cattle and with excellent results. One Wisconsin trial involved replacing part of the alfalfa in a dairy ration with tall fescue, and milk production went up by 5 pounds per cow (from 90 to 95 pounds) with no change in dry matter intake.
Can grass completely replace alfalfa in dairy rations? Research at the University of Minnesota found that tall fescue and orchardgrass had higher yield and quality than did alfalfa, and forage analyses predicted that both milk per acre and milk per ton would be higher for the two grasses. However, even though the neutral detergent fiber (NDF) in grass is more highly digestible than alfalfa NDF, the digestion rate is slower; this may limit the amount of grass that can be fed to high-producing dairy cows.

It also may be a problem in high-forage diets where a significant part of the forage is hay crop (versus corn silage). Grasses are a particularly good fit for high corn silage rations due to their low nonfiber carbohydrate (NFC) content. The farms that have the most success feeding grass put a high priority on harvesting any grass that will be fed to high-producing cows when it’s still in the boot stage.

There’s an old saying, “When you see the head, the quality is dead.” However, grass cut after heading can still be harvested as hay or silage and fed to other dairy animals. When harvesting headed grasses for silage, make sure you continually check dry matter content because after-heading grass sometimes dries “on the stem” and very little time is needed between mowing and chopping. If necessary, reduce the theoretical length of cut (TLC) because long, dry grass particles don’t pack well — in a drive-over pile or bunker silo it can be like trying to pack a stack of mattresses!