scholarly journals Pengaruh pemberian mikrokapsul probiotik Bacillus cereus P22 dan Staphylococcus lentus L1k pada pakan terhadap kinerja pertumbuhan, respons imun, dan resistensi ikan lele, Clarias gariepinus Burchell 1822 yang diinfeksi Aeromonas hydrophila

2018 ◽  
Vol 17 (2) ◽  
pp. 143
Author(s):  
Lilik Setiyaningsih ◽  
Widanarni Widanarni ◽  
Angela Mariana Lusiastuti3 ◽  
Munti Yuhana
Keyword(s):  
Bacillus Cereus ◽  
Growth Performance ◽  
Aeromonas Hydrophila ◽  
Clarias Gariepinus ◽  
Bacterial Count ◽  
Negative Control ◽  
Total Bacterial Count ◽  
African Catfish ◽  
Feed Conversion ◽  
Significant Difference

The aimed of this research was to evaluate the effects of dietary probiotic microcapsules B.cereus P22 and S. lentus (L1k) at different dose and frequency on growth performance, immune response and resistance of African catfish infected with A. Hydrophila. Probiotics used in this study were B. cereus P22 and S. lentus L1k encapsulated by spray draying method. The research was carried out for 56 days with eight treatments and four replications. The treatments were K- (negative control), K+ (positive control), A (feed supplemented with 0,5% of microencapsulated probiotic, fedevery day), B (feed supplemented with 0,5% of microencapsulated probiotic, fed once every three days), C (feed supplemented with 1% of microencapsulated probiotic, fed every day), D (feed supplemented with 1% of microencap-sulated probiotic with an administration once every three days), E (feed with 2% of microencapsulated probiotic with an administration every day) and F (feed with 2% of microencapsulated probiotic with an administration once every three days). On day 42, all of the fish except K- were challenged by intramuscular injection of A. hydrophila (108 CFU ml-1). In 40 days after infection, there were no significant difference on survival rate (SR) between treatments (p> 0.05). Treatment E displayed the higher growth rate (4,54±0,02%), total probiotic B. cereus (P22) and S . lentus (L1k) (4.06± 0.09 log CFU g-1; 4.02±0.08 log CFU g-1) than other treatments; whereas treatment D showed the best feed conversion rasio(1.191±0.013), and treatment F offered the highest total bacterial count (7.11±0.53 log CFU g-1). An administration of 2% microencapsulated probiotic in every day frequency demonstrated the better growth performance, immune res-ponse and resistance of African catfish to A. hydrophila compare with other treatments. AbstrakPenelitian ini bertujuan untuk mengkaji dosis dan frekuensi pemberian mikrokapsul probiotik melalui pakan terhadap kinerja pertumbuhan, respons imun, dan resistensi ikan lele yang diinfeksi Aeromonas hydrophila. Penelitian ini meng-gunakan Bacillus cereus P22 dan Staphylococcus lentus L1k yang telah dienkapsulasi melalui metode spray draying. Penelitian ini dilaksankan selama 56 hari dengan delapan perlakuan dan empat ulangan, terdiri atas perlakuan K- (kon-trol negatif), K+ (kontrol positif), A (pakan+mikrokapsul probiotik dosis 0,5% frekuensi setiap hari), B (pakan+mikro-kapsul probiotik dosis 0,5% frekuensi tiga hari sekali), C (pakan+mikrokapsul probiotik dosis 1% frekuensi setiap hari), D (pakan+mikrokapsul probiotik dosis 1% frekuensi tiga hari sekali), E (pakan+mikrokapsul probiotik dosis 2% fre-kuensi setiap hari) dan F (pakan+mikrokapsul probiotik dosis 2% frekuensi tiga hari sekali). Ikan diuji tantang dengan A. hydrophila pada hari ke 42 dengan kepadatan 108 CFU ml-1 secara intramuscular (kecuali K- diinjeksi dengan phos-phate buffer saline). Setelah 40 hari pascainjeksi, laju sintasan tidak menunjukkan perbedaan yang signifikan antarperlakuan (p>0,05).Perlakuan E menunjukkan laju pertumbuhan (4,54±0,02%) dan total probiotik B. cereus (P22) dan S. lentus (L1k) (4,06±0,09 log CFU g-1; 4,02±0,08 log CFU g-1) tertinggi; sementara perlakuan D memberikan hasil nisbah konversi pakan terbaik (1,191±0,013), perlakuan F menunjukkan total bacterial count tertinggi (7,11±0,53 log CFU g-1). Hasil penelitian menunjukkan bahwa dosis 2% yang diberikan setiap hari memberikan hasil yang lebih baik dalam meningkatkan laju pertumbuhan, respons imun, dan resistensi ikan lele terhadap A. hydrophila. 

scholarly journals Efficacy of nano zinc oxide dietary supplements on growth performance, immunomodulation and disease resistance of African catfish Clarias gariepinus

2020 ◽  
Vol 142 ◽  
pp. 147-160
Author(s):  
HH Mahboub ◽  
K Shahin ◽  
AW Zaglool ◽  
EM Roushdy ◽  
SAA Ahmed
Keyword(s):  
Zinc Oxide ◽  
Growth Performance ◽  
Antioxidant Status ◽  
Body Weight Gain ◽  
Control Diet ◽  
Clarias Gariepinus ◽  
African Catfish ◽  
Feed Conversion ◽  
Zno Nps ◽  
Significant Difference

Zinc (Zn) is an important trace element in fish diets that is required for growth, immunity and antioxidant defense mechanisms. The current study assessed the effects of both organic and nanoparticle zinc oxide (ZnO and ZnO-NPs, respectively) on growth performance, immune response and the antimicrobial effect against Pseudomonas aeruginosa in African catfish Clarias gariepinus. Fish were fed either a control diet or diets supplemented with organic ZnO at concentrations of 20 and 30 mg kg-1 or ZnO-NPs at concentrations of 20 and 30 mg kg-1. After 60 d, a subset of the fish was injected intraperitoneally with 3 × 107 CFU ml-1 of P. aeruginosa. Results showed that body weight gain, feed conversion ratio and specific growth rates were significantly increased in ZnO-NPs20 compared to all other groups. The dietary supplementation with 20 mg kg-1 of ZnO-NPs improved the antioxidant status of fish. Moreover, IgM, lysozyme and nitric oxide showed a significant increase in the fish which received the ZnO-NPs20-supplemented diet. A significant upregulation of growth and stress-related genes was seen in the ZnO-NPs20-supplemented group compared to other groups. However, there was no significant difference in the expression of immune-related genes among ZnO-NPs20, ZnO-NPs30 and ZnO30 groups. These findings highlight the potential use of nano-ZnO for improving growth performance, antioxidant status, immunological status and antibacterial activity against P. aeruginosa in African catfish.

Effects of dietary Phaeodactylum tricornutum supplementation on gustation, stomach histology and growth performance of African catfish, Clarias gariepinus (Burchell, 1822)

2020 ◽  
Vol 15 (2) ◽  
pp. 1-7
Author(s):  
Oluyemi K. Gbadamosi ◽  
W. Obe Bernadine
Keyword(s):  
Body Weight ◽  
Growth Performance ◽  
Feed Intake ◽  
Phaeodactylum Tricornutum ◽  
Clarias Gariepinus ◽  
Nutrient Utilization ◽  
African Catfish ◽  
Feed Conversion ◽  
Percentage Survival ◽  
Significant Difference

This study assessed the effects of microalga Phaeodactylum tricornutum supplement on the gustation, stomach histology, growth performance and nutrient utilization of Clarias gariepinus juveniles. One hundred and fifty (150) C. gariepinus juveniles of mean weight 20.05±0.05g were distributed into 15 plastic tanks (40×30×35) cm3. Five graded levels (0.00 (control), 0.50, 1.00, 1.50, and 2.00g/100g of P. tricornutum supplements were included in the diets of C. gariepinus denoted as Control, PT1, PT2, PT4 and PT5, respectively. Fish were fed for 56 days at 5% body weight. Results at the end of the experiments showed that the highest body weight was recorded in fish fed 1.5g/100g P. tricornutum diets. The best feed conversion ratio, specific growth rate, protein efficiency ratio and percentage survival was found in PT3. There was significant difference (p<0.05) in the feed intake of fish with PT4 having the highest feed intake. The stomach histology revealed increase in the gustation cells in the stomach of experimental fish with increasing levels of P. tricornutum supplementation. This study showed that the inclusion of P. tricornutum supplement at 1.5g/100g level in the diet of C. gariepinus juveniles improved the gustation, growth performance and nutrient utilization of C. gariepinus. Keywords: Microalgae, Aqua feed, Nutrition, Gustation, African catfish

scholarly journals Prevalence and antibiotic susceptibility of Aeromonas hydrophila isolated from freshwater fishes

2016 ◽  
Vol 4 (3) ◽  
pp. 411 ◽  
Author(s):  
Halima Sarder ◽  
Tahsin Khan ◽  
Mihir Lal Saha ◽  
Nusrat Jahan Punom ◽  
Shankar Chandra Mandal ◽  
...  
Keyword(s):  
Aeromonas Hydrophila ◽  
Antibiotic Susceptibility ◽  
Reference Strain ◽  
Bacterial Count ◽  
Freshwater Fishes ◽  
Total Bacterial Count ◽  
Bacterial Isolates ◽  
Biochemical Tests ◽  
Anabas Testudineus ◽  
Significant Difference

Aeromonas hydrophila is an opportunistic microorganism. It is a secondary biological agent that contributes to the occurrence of fish diseases and its deterioration. This research was undertaken to determine the prevalence of A. hydrophila in some freshwater fishes collected from three different fish markets of Dhaka City and to test their antibiotic susceptibility. Total bacterial count and total aeromonas on different aeromonas selective media were enumerated using serial dilution technique. Bacterial isolates were characterized to identify A. hydrophila using biochemical tests and with comparison to reference strain (ATCC 7966). The lowest Aeromonas count was detected to be 2.83±0.40×102 cfu/g in Anabas testudineus and the highest was 1.03±0.153×103 cfu/g in Oreochromis mossambicus. On market basis highest aeromonas count was found in Anando Bazar (8.10±1.09×102 cfu/g) and lowest in Hatirpool Bazar (5.63±0.90×102 cfu/g) with no significant difference. Maximum susceptibility to amikacin and gentamicin was observed whereas all of the isolates were found resistant to a commonly used antibiotic amoxycillin. The obtained results point that antimicrobial susceptibility was more or less similar regardless of the origin of the samples collected. All the fishes investigated in this study contained A. hydrophila in their different organs.

scholarly journals Effects of Ortho-Phosphate on Growth Performance, Welfare and Product Quality of Juvenile African Catfish (Clarias gariepinus)

Fishes ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 3 ◽  
Author(s):  
Sebastian Strauch ◽  
Judith Bahr ◽  
Björn Baßmann ◽  
Adrian Bischoff ◽  
Michael Oster ◽  
...  
Keyword(s):  
Plant Growth ◽  
Growth Performance ◽  
Clarias Gariepinus ◽  
Phosphate Fertilizer ◽  
African Catfish ◽  
Feed Conversion ◽  
Fish Welfare ◽  
P Fertilizer ◽  
Skin Coloration

Ortho-phosphate inside recirculation aquaculture systems is limited as a consequence of precipitation and regular water exchange rates. To improve plant growth in coupled aquaponics, phosphate fertilizer addition to hydroponics can increase PO43−-P concentrations inside the process water. We investigated the effects of four PO43−-P concentrations (<10 (P0), 40, 80, 120 mg L−1) in rearing water on growth performance, feed efficiency, and welfare traits of juvenile African catfish (Clarias gariepinus Burchell, 1822). By trend, optimum specific growth rate of 2.66% d−1 and feed conversion ratio of 0.71 were observed at 40 and 80 mg L−1 PO43−-P. Higher PO43−-P significantly affected skin coloration, swimming activity and external injuries, with the palest and inactive fish combined with most external injuries in the P120 group. Mineral and protein contents in the fish remained unaffected, while fat content inside the fillets enriched with increasing PO43−-P. Inorganic P in blood plasma increased significantly, while phosphate concentrations inside the fillet remained unchanged. We suggest that PO43−-P concentrations of 40 to 80 mg L−1 do not reduce the performance of African catfish aquaculture, while increased values of 120 mg L−1 affect fish welfare. This allows limited addition of PO43−-P fertilizer in coupled aquaponics with African catfish to support plant growth.

scholarly journals Effect of environmental regulated water temperature variations on survival, growth performance and haematology of African catfish, Clarias gariepinus

Our Nature ◽  
2017 ◽  
Vol 15 (1-2) ◽  
pp. 26-33
Author(s):  
Johnny O. Ogunji ◽  
Jude Awoke
Keyword(s):  
Blood Cell ◽  
Water Temperature ◽  
Growth Performance ◽  
Crude Protein ◽  
Clarias Gariepinus ◽  
African Catfish ◽  
Good Growth ◽  
Corpuscular Haemoglobin ◽  
Significant Difference ◽  
Mean Corpuscular Haemoglobin

A 56 day study was carried out to evaluate effect of temperature changes on survival, growth performance and haematology of Clarias gariepinus fingerlings fed housefly maggot meal (magmeal) diet. Ninety (90) Clarias gariepinus fingerlings, (initial mean weight 4.33±0.03g) were subjected to different environmental regulated temperature conditions in three locations (laboratory, outdoor, greenhouse). The observed average temperature was 26.53±0.01°C, 26.06±0.01°C and 31.52±0.00°C for laboratory, outdoor, greenhouse, respectively. Ten fingerlings stocked per experimental tank were fed in triplicates at 5% body weight in two portions per day. It was observed that different water temperatures affected fish growth. All experimental fish in the greenhouse died after 8 days of exposure. This happened around 14.00 hrs when water temperature reached 40°C. There was no significant difference (P<0.5) in final weight, weight gain, food conversion ratio and standard growth rate among the fish reared in the laboratory (26.53°C) and outside tanks (26.06°C), respectively. The initial carcass crude protein (Cp) value was 58.97%. At the end of the experiment fish reared in the laboratory had a crude protein value of 63.97±0.06% Cp and those reared outdoor (26.06°C) had 71.28±0.00% Cp. No significant difference in values of packed cell volume; white blood cell; haemoglobin and mean corpuscular haemoglobin concentration was found between fish reared in laboratory (26.53°C) and outside (26.06°C). However, the red blood cell (RBC); mean corpuscular haemoglobin and mean corpuscular volume showed significant difference (P>0.05). The result confirms that Clarias gariepinus fingerlings reared at a mean temperature of 26°C (within the recorded optimal temperature range for good growth) performed well. Clarias gariepinus fingerlings are not able to survive when water temperature reaches to 40oC.

scholarly journals Comparative Assessment of Growth Performance and Nutrients Utilization of African Catfish (Clarias gariepinus, Burchell 1882) Fed Chicken Offal and Shrimp-Based Diets

2019 ◽  
pp. 1-11
Author(s):  
Elvis Monfung Ayim ◽  
Ettah Akpang Ivon ◽  
Raymond Odey Ajang ◽  
Akaninyene Paul Joseph
Keyword(s):  
Growth Rate ◽  
Growth Performance ◽  
Juvenile Fish ◽  
Clarias Gariepinus ◽  
Feed Consumption ◽  
African Catfish ◽  
Fish Feed ◽  
Feed Conversion ◽  
Treatment Groups ◽  
Fish Group

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.

scholarly journals Effect of duckweed meal dietary inclusion on growth performance and survival of African catfish fingerlings

2020 ◽  
Vol 38 (1) ◽  
pp. 84-104
Author(s):  
Yuniel Méndez ◽  
Yenny Torres ◽  
Yilian Pérez ◽  
Misleidi Romás ◽  
Edilmar Cortés
Keyword(s):  
Growth Performance ◽  
Clarias Gariepinus ◽  
Food Sources ◽  
Average Weight ◽  
African Catfish ◽  
Feed Conversion ◽  
Randomized Design ◽  
Absolute Growth ◽  
Four Levels ◽  
Lemna Perpusilla

Currently, the use of unconventional food sources in the inclusion of fish diets is cause of great interest. The growth performance of African catfish (Clarias gariepinus) was evaluated, with the inclusion of duckweed meal (Lemna perpusilla) in four levels (0, 6, 12 and 18 %) in the diet. African catfish with an average weight of 1.27 ± 0.03 g, were distributed in a completely randomized design, with 16 experimental cages (four replicates/treatment). The fingerlings were fed for 48 days of experimentation. An analysis of variance and a Duncan´s test were performed. No significant differences were found (p< 0.05) for the first two levels evaluated, but with the rest there were differences, as the percentage of inclusion of the duckweed meal in the ration increased. Final weight was decreasing, as well as absolute growth rate, increase in daily weight, feed conversion ratio and food efficiency. Survival throughout the experiment was between 72 y 65 % in all treatments. The inclusion of duckweed meal in the diet did not affect the parameters of water quality. It was concluded that the L. perpusillase meal can be included up to 12 % in diets for African catfish fingerlings, without affecting the growth performance.

scholarly journals Histometry and Growth Performance of African Catfish, Clarias gariepinus, (Burchell, 1822) Fed Probiotics Supplemented Diets

2019 ◽  
pp. 1-10
Author(s):  
K. Gbadamosi Oluyemi
Keyword(s):  
Growth Performance ◽  
Specific Growth ◽  
Clarias Gariepinus ◽  
African Catfish ◽  
Feed Conversion ◽  
Experimental Diet ◽  
Lactobacillus Pentosus ◽  
Biological Performance ◽  
Commercial Probiotics ◽  
Mucosal Fold

The histometry, organosomatic parameters and growth performance of African catfish, Clarias gariepinus fed with commercial probiotics, Lactobacillus pentosus supplemented diet was assessed in the present study. Six experimental diets were formulated, at different inclusion levels of Lactobacillus pentosus of 0, 102,104, 106, 108and 1010 cfu in T1, T2, T3, T4, T5 and T6 respectively. C. gariepinus were stocked into concrete tanks of 1.93 m by 1.93 m by 1.09 m. Each experimental diet was fed to three replicate groups of fish for 42 days. At the end of the feeding, histometrical parameters like mucosal fold length, mucosal fold breadth, mucosal fold area improved with increasing supplementation levels of L. pentosus. There was also significantly better P > 0.05 organosomatic parameters in all treatments with increasing level of supplementation. The best growth performance in term of specific growth rate (SGR) and feed conversion ratio (FCR) was observed in Treatment 3 as 10.49±0.23 and 1.56±0.22 respectively. The enhanced growth performance and histometry in fish fed diets with L. pentosus supplementation resulted in the best biological performance in African catfish at 1.0 g per 100 g of feed representing 104 cfu supplementation level. Therefore the present study shows that L. pentosus can be recommended as an important probiotic in aquaculture.

scholarly journals Growth performance of Clarias gariepinus fed varying dietary phosphorus levels

2017 ◽  
Vol 4 (3) ◽  
pp. 215-220
Author(s):  
Ezike Christopher Onyemaechi ◽  
Chukwuka Doris Queen ◽  
Echor Felix Okaliwe
Keyword(s):  
Growth Performance ◽  
Control Diet ◽  
Clarias Gariepinus ◽  
Palm Kernel ◽  
Fish Growth ◽  
Control Fish ◽  
African Catfish ◽  
Dietary Phosphorus ◽  
Significant Difference ◽  
And Control

One hundred and twenty (120) juveniles of African catfish Clarias gariepinus were obtained in May 2015 from a reputable Fish Farm in Enugu to the University Research Farm (latitude 074o North and 082o South, longitude 068o East and 076o West with annual mean temperature of 30oC). The fish were fed for 49 days from June – July 2015 with diets containing 4 different inclusion levels of phosphorus T1 [0.6% P], T2 [0.8% P], T3 [1.00% P], T4 [1.2% P] and T5 [0% P] which served as control diet, to determine optimum P requirement for fish growth at probability level of P < 0.05 between various treatments and control. Each diet was formulated to contain 40% crude protein composed of yellow maize, soybean cake, palm kernel cake and fish meal. Fish fed with graded levels of phosphorus were significantly higher (P < 0.05) than control in FW and MDWG. There was however no significant difference (P > 0.05) in FCR and PER between T1, T2, T4 and control but T3 was significantly (P < 0.05) better in FCR (0.33) than control (0.39). Similarly, T3 was significantly (P < 0.05) higher in PER than control. Fish in T3 had the best growth performance indicative that 1% P is the optimum requirement for the growth of C. gariepinus.Res. Agric. Livest. Fish.4(3): 215-220, December 2017

scholarly journals The effect of dietary L-carnitine on the growth performance in fingerlings of the african catfish (Clarias gariepinus) in relation to dietary lipid

1993 ◽  
Vol 69 (1) ◽  
pp. 289-299 ◽  
Author(s):  
Els Torreele ◽  
Ad van Der Sluiszen ◽  
Johan Verreth
Keyword(s):  
Growth Performance ◽  
Lipid Level ◽  
Clarias Gariepinus ◽  
Live Weight ◽  
Growth Efficiency ◽  
Dietary Lipid ◽  
African Catfish ◽  
Feed Conversion ◽  
Energy Retention ◽  
Dietary Lipid Level

The effect of dietary L-carnitine on the growth and growth efficiency of African catifish (Clarias gariepinus, Burchell 1822) fingerlings was investigated. Six dietary levels of L-carnitine, varying from the conrol level (about 125 mg/kg) to 3920 mg/kg, were each tested at two dietary lipid levels (96 and 155 g/kg). The diets were isonitrogenous and were fed to thirty-six experimental groups of 100 fish weighing 5 g at a feeding level of 25·2 g/kg live weight(w)0.8 per d, during 18 d. The average final weight varied from 19·1 to 28·0 g. At a dietary lipid level of 96 g/kg the metabolic growth increased from 30·8 to 36·5 g/kg w0.8 per d. At the higher dietary lipid level the metabolic growth increased from 30·9 to 35·4 g/kg w0.8 per d. To assess the dose–response relationship between dietary L-carnitine and growth performance in the African catfish a linear-plateau model was fitted to the experimental data. According to this model, metabolic growth was at a maximum at L-carnitine levels of 500 mg/kg and above at a lipid level of 96 g/kg and at L-carnitine levels of 684 mg/kg and above at a lipid level of 155 g/kg. The fitted maximum metabolic growth was higher at a dietary lipid level of 96 g/kg (35·9 g/kg w0.8 per d) than at 155 g/kg (34·7 g/kg w0.8 per d). Feed conversion improved significantly with increasing dietary levels of L-carnitine, reaching a fitted plateau at L-carnitine levels of 448·8 and 236·7 mg/kg respectively for the high and low dietary fat levels. Other growth efficiency variables, e.g. protein efficiency ratio, protein retention and energy retention improved accordingly. Taking into consideration that all fish received the same amount of feed, the results of the present study demonstrate that the positive effect of increased levels of dietary L-carnitine is the result of an improved feed utilization, probably because of a stimulated protein-sparing action.

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