(Reuters) -Carl Icahn has decided to drop his proxy fight against Kroger Co over the treatment of pregnant pigs, the billionaire investor said on Monday, days after losing a similar battle at McDonald's Corp.

Icahn is withdrawing his nominees to Kroger's board, he said in a statement to shareholders of both the companies.

The activist investor nominated two directors to the supermarket chain's board in March, a month after taking on McDonald's.

Icahn has criticized the companies for their treatment of animals, saying confining pigs in crates during their pregnancy is inhumane. He pushed McDonald's to change how it sources its pork - a move the burger chain said was "completely unfeasible".

"I was surprised and initially disheartened by the disappointing McDonald's vote," Icahn said, after the fast-food restaurant's shareholders re-elected all of its directors in May, ending Icahn's attempt to clinch two board seats.

Icahn, who also criticized wage disparities at Kroger, said these campaigns were different from his typical fights as both the companies are performing well financially.

The grocer has previously said it is not directly involved in raising or processing of any animals and that its board and committees directly oversee its animal welfare strategies.

"We will continue to engage with stakeholders and shareholders to inform our policies," a Kroger spokesperson said in response to Icahn's move.

The news was first reported by the Wall Street Journal on Sunday.

(Reporting by Deborah Sophia in Bengaluru; Editing by Devika Syamnath)