1. School of Fisheries, Aquaculture and Aquatic Sciences; Auburn University; Auburn Alabama 36849 USA
2. Department of Mathematics; Auburn University; Auburn Alabama 36849 USA
3. Department of Veterinary Hygiene and Management, Faculty of Veterinary Medicine; Cairo University; Giza 12211 Egypt
4. Department of Agricultural Economics and Rural Sociology; Auburn University; Auburn, Alabama 36849 USA