EFFECT OF SOME DIETARY PROTEIN BLENDS ON GROWTH AND NUTRIENT UTILIZATION OF AFRICAN MUD CATFISH (Clarias gariepinus) Burchell (1822)

Abstract

This study was carried out to determine the effects of dietary protein blends on growth and nutrient utilization of African Mud catfish Clarias gariepinus sub-adult (350±0.04g). The fish were reared in an indoor culture system for a period of 12 weeks on ten experimental diets. The control diet had fishmeal as the sole protein source; three diets had soybean, groundnut and moringa in addition to fishmeal while the other six diets consisted of other non-fishmeal diets. The fish were fed at 3% body weight. The growth response was assessed using mean final weight (MFW), mean weight gain (MWG), percentage weight gain (PWG), specific growth rate (SGR), feed conversion ratio (FCR), relative growth rate (RGR), protein efficiency ratio (PER) and survival rate. At the end of the feeding trial the carcass nutrients were characterized: proximate composition, minerals, free fatty acids and amino acid profile. The result showed that there were significant differences (P<0.05) in final weight, weight gain, percentage weight gain, specific growth rate and relative growth rate while there was no significant difference (P>0.05) in feed conversion ratio, protein efficiency ratio and percentage survival. Highest specific growth rate and relative growth rate was recorded in fish fed blends of fish meal, blood meal and soybean; fishmeal, groundnut cake (DT4) and (DT3) diets of 1.09±0.15, 111.82±2.63 respectively. Although the highest MFW, MWG and % survival 666.67±57.74, 316.67±57.74, 100±0.00 was recorded in fish fed fishmeal and soybean (DT2) diet and the least PWG (52.78±4.81) was also recorded in fish fed DT2 diet. The highest FCR (1.32±0.35) was recorded in fish fed soybean and blood meal (DT5) this is not significantly different (P>0.05) from that of fish fed DT1 diet. However, the best FCR of 0.97±0.35 was recorded for fish fed fish meal only (DT1) diet. The ash content of the fish carcass fed ranged from 8.97±0.00 – 16.64± 0.00. There were no significant differences (P<0.05) on all the values of ash in the fish carcass. The crude protein content of the fish carcass ranged from 51.86±0.01 – 62.14±0.00. There were significant differences (P<0.05) among the crude protein values of the fish on the diets. Fish fed DT2 diet performed better in weight gained than fish fed DT1 diet which had the best feed conversion ratio. Meanwhile, fish fed groundnut and blood meal (DT8) diet had the highest percentage weight gain, balanced amino acid profile as well as the least cost of production of the feed. The results showed that all the diets supported growth and nutrient utilization positively when fishmeal is replaced with other plant protein sources in the diets of African Mud Catfish Clarias gariepinus. There were significant differences (P<0.05) in all the mineral contents of the fish fed dietary blends of protein. The Free Fatty Acid (FFA) composition of Clarias gariepinus shows that the values ranged from 9.00 ±0.00 – 11.93±0.01mg/100g. The highest FFA content of (11.93±0.01mg/100g) was recorded in fish fed diet DT4 and lowest content of (9.00±0.00mg/100g) in fish fed diet DT10. There were significant differences (P<0.05) in FFA content of the fish fed diets DT3, DT4, DT5, DT6, DT7, DT9 and DT10. However, there were no significant differences (P>0.05) among fish fed diets DT1, DT2, and DT8.