1. Feedlot Research Group, West Texas A&M University, Canyon, TX 79016
2. Escuela de Medicina Veterinaria, Colegio de Ciencias de la Salud, Universidad San Francisco de Quito USFQ, Quito 170901, Ecuador
3. USDA-ARS Conservation and Production Research Laboratory, Livestock Nutrient Management Unit, Bushland, TX 79012
4. Texas A&M University, Department of Animal Science, College Station, TX 77845