It’s pretty clear Mother Nature would prefer that you kept your baler parked for the month of May.

And whoever it was that said, “make hay while the sun shines?” Well, he must have been talking about June or July because the weather statistics make it clear that the odds are against you bumping into two consecutive sunny days in May.

The problem is that, for cool season grass hay makers, May is the time it needs to be done—at least if you’re interested in putting up quality forage.

“May really is the time to harvest cool season grass hay such as fescue,” says University of Missouri Extension Agronomist Tim Schnakenberg. “It’s a real challenge to get it put up but letting those grasses mature takes quite a toll on quality.”

Schnakenberg cites a University of Tennessee study which compared the quality of fescue baled at three different stages of maturity and the performance impact of each when fed to 500-lb. heifers.

Fescue harvested in the late boot to head stage had a protein content of 13.8 percent and digestibility of 68 percent.

Moving harvest to the early bloom stage, about nine days later, brought protein down to 10.2 percent and digestibility dropped to 66 percent.

Hay harvested 11 days later—in the early milk stage—had a protein content of 7.6 percent and digestibility of 56 percent. In terms of quantity, the early-cut hay produced 1334 pounds per acre, the middle hay produced 1838 and the late-baled hay yielded 2823 pounds per acre.

The effect of harvest timing followed right on through to animal performance. Heifers fed the highest quality hay gained 1.39 pounds per day compared to 0.42 pounds for the lowest quality. Dry matter intake dropped from 13 pounds per day to 8.6.

The real eye-opener, Schnakenberg points out, is that pounds of hay fed per pound of gain went from 10.1 for the high quality hay to 22.5 for the low quality stuff. The “medium” hay ranked at 13.5 pounds of hay per pound of gain.

“It certainly depends on your situation and the nutritional needs of your cattle at a given time but it’s pretty clear that, the longer you have to wait to bale cool season grass hay, the lower the quality is going to be and that translates into cattle performance,” he explains. “The lower quality hay used in this research was cut in the early milk stage. We see a lot of hay cut later than that so the quality and the performance will be even worse than it was in this trial.”

In southeast Kansas, former Kansas State University Extension Area Agronomist Gary Kilgore uses a simple rule of thumb: From the time fescue begins to head until green seed forms, you’re losing about one-half of one percent of protein per day.

That’s roughly a three-week period so the quality sleighride will slide from about 16 percent down to around 6 percent, depending on temperature.

In the quality versus quantity dilemma, Kilgore suggests growers shoot for 12 percent protein hay. That, he says, will deliver about 80 percent of the all the dry matter you’ll ever get and what you miss will be the low-quality and tough-to-digest lignin that forms as the grass matures.

Brome, he notes, won’t drop in quality as rapidly as fescue but the trend is the same.