Dr. Eric C. Mussen, of The University of California Davis, in the USA also recommends feeding brewer's yeast, a low-cost substance similar to pollen in its nutritional content.
Dr. Eric C. Mussen, wa University of California Davis, e USA o kgothalletsa ho fepa tomoso ya thitelo, e theko e tlaase e tshwanang le peo e phofshwana ya yona.