Résumé
A comparative study on the growth performance of African catfish (Clarias gariepinus) fed shrimp based diet (SBD), chicken offal based diet (COBD) and coppens feed was carried-out for 22 weeks in concrete tanks measuring 3.5 x 1.7 x 1.5 m3. Triplicate groups of 40 juveniles with average length of 9.15 ± 0.17cm and weight of 20.00 ± 2.58g were stored in each tank. A total of 360 juveniles were used throughout the study. Fish were fed daily at 3% of their body weight through-out the duration of the experiment. The nutrient composition of the 3 nutrients differed significantly at p<0.05. Weight gain (WG) (g) was highest (17189.33 ± 506.61g) in fish fed diet A (Coppens feed), followed by 15045.33±202.42 g (diet B) (SBD) and least (14357.33 ± 108.25 g) (diet C) (COBD). The Growth rate (GR) was highest in fish fed with diet A (111.62 ± 3.29 g/day), followed by 97.69±1.31 g/day (diet B), and least (93.23±0.70 g/day) in diet C. Specific growth rate (SGR) was highest in juveniles fed diet A (2.02 ± 0.02 %/day), followed by 1.94±0.01 %/day for diet B, and least (1.91±0.01 %/day) for diet C. Mean growth rate (MGR) was highest in juveniles fed diet A (11.88 ± 0.29 mg/day), followed by 11.74±0.15 mg/day for diet B, and least (11.69±0.09 mg/day) in fish fed diet C. The WG, GR and SGR varied significantly between the juvenile fish group fed the 3 diets at p<0.05, while MGR did not vary significantly between fish group fed the 3 diets at p>0.05. Fish fed diet A had a higher feed consumption (FC) (41650.00 ± 315.34 g/kg), than that fed diet B (39034.24 ± 86.34 g/kg) and then diet C (38276.00 ± 342.97 g/kg). Juveniles fed Coppens feed did better, with a feed conversion ratio (FCR) of 2.42 ± 0.06, followed by 2.59±0.04 for diet B and 2.67 ± 0.03 for fish fed diet C. Feed conversion efficiency (FCE) was higher in fish fed diet A (41.26±0.94 %), followed by 38.54 ± 0.54 % (diet B) and least (37.52 ± 0.51 %) (diet C). The FC and FCR varied significantly between the fish fed the 3 diets at p<0.05, while FCE was not significantly different between the 3 treatment groups at p>0.05. The water parameters of the culture water varied significantly between each treatment groups (p<0.05), and were within the rage suitable for normal growth of fish. Though coppens feed yielded better growth performance and feed utilisation, the use of COBD and SBD is recommended for fish farmers in Nigeria. More researches should be carried out on using chicken offals and shrimps in fish feed formulation.
Résumé
A three-factor three level Response surface methodology central composite retortable design (CCRD) was adopted to study the effect of feed composition (X1), feed moisture content (X2) and screw speed (X3) on proximate compositin, amino acid and sensory evaluation during extrusion of pearl millet and cowpea flour mixtures for the purpose of fura production. The mean observed value of protein for the fura extrudates ranged from 11.2 – 16.8%. Analysis of variance indicates that linear and quadratic effects significantly (P<0.05) affected the protein content of fura extrudates as expected. The mean value of lysine for the extrudates ranged from 5.1 - 6.6g/100g protein and the methionine content ranged from 1.3 - 3.8g /100g protein. The regression models fitted to the experimental data showed high coefficients of determinants with R2 = 0.96, 0.94, 0.94, 0.85 and 0.80 for protein (CHON), carbohydrate (CHO), fat (FAT), ash (ASH) and water (HOH) respectively. The R2 = were 0.90, 0.85, 0.86, 0.92, 0.88, 0.85 and 0.93 for lysine, i/leucine, leucine, valine, methionine – cystine, threonine and tryptophan respectively. The coefficients shows good fit. The importance of process variables on system parameters and physical properties could be ranked in the following order: Feed Composition (X1)>Feed Moisture (X2)>Screw Speed (X3). The optimum values obtained for feed composition, feed moisture and screw speed are 36.5% cowpea level, 22.3% feed moisture content and 186.7 rpm respectively. The corresponding optimum values of lysine, protein content, expansion ratio and bulk density are 6.6g/100g protein, 16.6%, 2.8 and 0.52 Kgm-3 respectively. The data obtained from the study could be used for control of product characteristics and possible projection for the commercial production of fura or any enriched protein based food from the blends pearl millet and cowpea.