Borden is filing for bankruptcy protection, the second major US dairy to do so in as many months. American refrigerators are increasingly stocked with dairy substitutes like soy and almond milk, hammering traditional milk producers like Borden, which was founded in 1857. Dean Foods, the nation’s largest milk producer, filed for bankruptcy protection in November. Both dairies are based in Dallas. Borden Dairy Co. _ whose smiling mascot Elsie the cow first appeared on milk cartons in the 1930s _ says it will continue operations during its financial restructuring.