Ridley Inc., the Mankato-based producer of animal feed and nutritional supplements for livestock and chickens, is being acquired by Kentucky-based Alltech for $428 million.

Ridley, which employs 700 and reported 2014 sales of $569 ­million, announced the all-cash deal Thursday. The deal is expected to close by the end of the second quarter.

Privately owned Alltech is one of the world’s largest animal health companies with 3,500 employees in 128 countries.

“This transformative transaction … allows Alltech to deliver better performance and value to livestock and poultry producers across the globe,” said Alltech President Pearse Lyons. “We will be able to bring our advanced ­nutrition technology to market faster and more effectively.”

The sale price represents a 23 percent premium on the stock of Ridley, which is traded on the Toronto Stock Exchange. The acquisition price is $40.75 a share in Canadian dollars, compared with a Wednesday close for Ridley of $33.94.

“Alltech is a technological leader with a broad global footprint,” said Ridley CEO Steven VanRoekel in a statement. “We are also joining a financially strong company that is committed to investing in science and innovation.”

VanRoekel could not be reached for further comment, but he told the Mankato Free Press that the sale would have no effect on Ridley’s workforce or its Mankato headquarters. He said the company will be run by its existing management team.

Ridley’s line of animal feed and nutritional products includes pets and horses, as well as farm animals.