Nutritional evaluation of gizzard erosion positive brown fish meal in starter diets for Nile tilapia, Oreochromis niloticus

Toxic brown fish meal that caused severe gizzard erosion in broiler chicks was used as the sole protein source in starter diets for Nile tilapia. Brown fish meal was assayed using 4-day-old broiler chicks to test its toxicity. Growth performance was compared among fish fed diets containing three levels of toxic brown fish meal and a control diet which contained non-toxic fish meal. Fish fed the diets containing the toxic fish meal exhibited reduced growth and protein utilization. Fish fed the nontoxic fish meal diet had significantly better weight gain (WG), 98.88 mg/day, specific growth rate (SGR), 5.30%/day, protein efficiency ratio (PER), 2.60, and apparent net nitrogen utilization (ANNU), 43.33%, than those fed the diets containing the toxic fish meal, named 1, 2 and 3, respectively, which showed WG 66.75, 57.94, and 62.04 mg/day, SGR 4.75, 4.53, and 4.65%/day, PER 2.06, 2.20, and 2,27, and ANNU 33.89, 37.17 and 37.34. There were no significant differences among dietary treatments in survival and Nile tilapia fry fed diets containing toxic brown fish meal did not have any detectable signs of macroscopic or microscopic pathology.