Abstract:
A feeding trial was conducted to evaluate the dietary threonine requirement of African catfish (Clariasgariepinus) using farm made diets. Five isonitrogenous (40% crude protein) diets were formulated to contain graded dietary threonine (0, 0.3, 0.5, 0.6, 0.7)g/100g of protein in dry matter (DM). Fifteen (15) apparently healthy fish with initial weight 6.12±0.11g per tank in triplicate were randomly distributed into glass tanks in five places which sum up to fifteen glass tanks. The fish were fed twice daily at 8:00-9:00hrs and 16:00-17:00hrs for 70days. Weight of the fish were taken bi-weekly to evaluate growth performance. The results showed that mean final weight, mean weight gain, specific growth rate and protein efficiency ratio increased with increasing dietary threonine levels up to 0.5g, there after decreased and there were significantly (P<0.05) different whereas feed conversion ratio decreased with increasing dietary threonine up to 0.5g which was the least and best conversion of feed to flesh, there after increased and there were significant (P<0.05) differences in the results. There were slight variation in the carcass minerals content across the treatment. Haematological indices showed that haemaglobin (Hb), pack cell volume (PCV) and red blood cell (RBC) were not significantly affected except white blood cell (WBC). The amino acid (AA) analysis inferred that fish fed 0.5g/100g of dietary threonine (Diet 3) had the best concentration and significantly (P<0.05) different in isoleucine, leucine, phenylalanine, proline, glutamic, glycine, threonine, serine and aspartic. However, dietary threonine influenced the concentration of these amino acid at 0.5g/100g of protein. Based on the fourth degree polynomial regression analysis of SGR against dietary threonine levels, the optimum dietary threonine level for African catfish (C. gariepinus) was estimated to be 1.7% of protein 40% (0.68g/100g)
