US Patent 3,295,983 (granted Jan. 3, 1967) describes a method of rearing silkworm larvae on artificial feed containing 0.001 to 5 percent propionic acid or its salts, such as calcium propionate, to speed larval growth. Two examples with mulberry-leaf-powder feeds report survival and average larval weight at 10 and 15 days in data tables. The patent lists three claims and cited references, and is assigned to Ajinomoto Co. and Katakura Industry Co. of Japan.