Livestock farmers use dramatically less water than they did 60 years ago to produce milk, meat and eggs, according to a new analysis from the University of Nebraska.

A gallon of milk was produced five times as water-efficiently in 2016 compared with 1960, pork was produced four times as efficiently, and chicken, turkey and eggs were produced about three times as efficiently, according to the study published in the journal Environmental International.

"When you see the figures, that's a big deal," said Mesfin Mekonnen, a professor at the University of Nebraska and the study's lead author. "But still, livestock uses a lot of water."

The improvement in the water efficiency has little to do with daily use of water on the farm — giving the animals water to drink, cleaning their living space and processing their manure, Mekonnen said.

"That part accounts for only 2% of the water footprint," he said in an interview. "The feed production from growing the crop to animal feed — that provides about 98%."

Better animal genetics and breeding mean that animals are more efficient at converting food into meat, milk and eggs. Animals are much bigger now than in 1960, but they eat only slightly more feed.

Also, because of improved seed technology, the grain grown to feed livestock requires less water than a few decades ago, and farmers have found new types of feed to supplement the row crops they feed the animals. Livestock now often consume energy-rich distiller grains, a byproduct of biofuels that reduce the need for additional volume of water-intensive crops.

"The improvement they made is in selecting the proper breed, how they feed them, what they feed them," he said.

Overall, annual water usage to produce beef, pork, chicken, turkey, milk and eggs dropped 36% from 1960 to 2016, the study found.

Mekonnen said there is still a lot of room for improvement in how American agriculture uses water.

"Producers and the big companies, they have to think of the full supply chain, what feed to feed the animals and how to produce it more efficiently," he said.