A wealthy investor has launched a bid to gain seats on the board of McDonald’s Corp to improve the welfare of animals used by the US fast food giant. Billionaire investor Carl Icahn has launched a proxy fight for two seats on the board aiming to challenge the treatment of pigs by the fast-food chain’s suppliers. Icahn, who holds 200 shares of McDonald’s stock, recently slammed McDonald’s for failing to end the use of gestation crates for pregnant pigs in its supply chain, saying the practice causes unnecessary suffering. In a statement confirming Icahn’s nominations for two directors, the burg…