If farmers want their livestock to eat more and gain more weight, they’d better make hay while the afternoon sun shines.

Scientists with USDA’s Agricultural Research Service say a new study shows that sheep, goats and cattle all prefer grass hays harvested in the afternoon compared with those cut in the morning.

One possible explanation: Plants’ carbohydrate production is at its peak at midday. The animals may remember afternoon-harvested hay is easier to digest and gives them more energy. Other studies have shown animals can be conditioned to choose higher-energy feeds.

It’s long been known that livestock grazing tends to peak in the afternoon. This led researchers to explore whether cutting hay later in the day could boost consumption.

Scientists let the animals try afternoon-cut hay and morning-cut hay before offering both in a side-by-side comparison. Sheep, goats and cattle all consumed an average of 50 percent more of the preferred hays. Their preference held true even though the hay offered was from harvests on three different days.

The scientists also noted the livestock’s top picks among the afternoon hays to make sure cutting time was the key factor in the animals’ choices. Each hay underwent 15 comparisons.

Scientific contact: Dwight Fisher, USDA-ARS Plant Science Research, Raleigh, N.C., phone (919) 515-7597, e-mail Dwight_Fisher@ncsu.edu