Dairy farmers founded Land O’Lakes Inc. nearly a century ago to boost their sweet-cream butter sales. Now the Arden Hills, Minn., cooperative is looking beyond butter to help its 2,000 dairy members navigate tough times in the sector. Milk is suffering from years of declining consumption. Tastes have changed, in part because plant-based alternatives to cheese, milk and butter have expanded and lured shoppers with a halo of health. Revenue checks to milk producers are in a five-year slump, and trade fights have damped U.S. dairy exports to Mexico and China.Land O’Lakes, one of the largest dairy producers in the U.S., with $13.7 billion in sales for 2017, is responding in several different ways. It is developing new products, such as squeezable butter, which launched last year. It is marketing different kinds of cheeses and trying to make more nutritious dairy ingredients for big food brands and retailers. The company is also making acquisitions to broaden its array of product offerings.