Effects of dietary vitamin A level on growth, feed utilization and survival of juvenile North African catfish (Clarias gariepinus)

I U Udo

Department of Fisheries and Aquatic Environmental Management, Faculty of Agriculture, University of Uyo, Uyo - Nigeria
dorime_2004@yahoo.com

Abstract

Vitamin A is a nutrient that is vital to growth and development. Fish cannot synthesize it and must be obtained from the diet. Hence, the present study was conducted to determine the effect of dietary vitamin A supplementation on growth performance and feed utilization of African catfish (C. gariepinus) by formulating three different diets containing 0 (Control) 833, and 1666 IU kg^-1 vitamin A. these were designated NoRE, 833RE and 1666RE respectively and were fed to triplicate groups of 20 juveniles each with initial average weights of 15.9±0.27 g maintained at 25.5±2°C for 113 days. The results revealed that the final mean weight of fish was significantly higher in diets 1666RE and 833RE than in NoRE. However, there was no significant difference between diet 833RE and 1666RE. Daily weight gain and specific growth rate was higher in diet 1666RE whereas feed conversion and protein efficiency ratio were both higher in diets NoRE and 833RE. Based on these results, it is recommended that diet for fingerling C. gariepinus should contain vitamin A at a level of 833-1666 IU kg^-1 for optimum growth and efficient feed utilization.

Key words: aquafeed, ingredient, nutrient, production, supplementation

Introduction

Since the introduction of aquaculture to Africa, some decades ago, there have been a lot of innovations, technological advancement and progress in the areas of genetics, seed propagation, pond construction and farm management. In spite of the breakthrough recorded in the fish farming, most farmers in Africa still rely heavily on the imported feed ingredients and commercial feed from European countries which makes fish farming expensive. According to Gabriel (2009) fish feeds represents the bulk of the total cost of production.  This has contributed in no small measures to the slow pace at which aquaculture is advancing in Africa.

The success of commercial aquaculture depends on the variety of factors relating to the field of Biology, Engineering and Economics. One key biological component is the availability of suitable diets that are efficiently digestible and provides the required nutrients for the optimum growth (Mokolensang 2003). The development of a satisfactory diet for the production of aquaculture demands a comprehensive understanding of nutritional requirements to assess the quality of the ingredients that comprise a feed (Lazo and Davis 2000). Nowadays, vitamins are important essential nutrients for most animal species which plays an important role such as vision, immune defenses, maintenance of body linings and skin, bone and body growth, normal cell development and reproduction.

Vitamin A is a fat-soluble vitamin that plays an important role in vision, bone growth, reproduction, cell division, cell differentiation, growth and general maintenance of animal. Requirement for vitamin A by most finfishes and crustaceans is high (Moren et al 2004; Hu et al 2006) and at the same time fish feed industry is expanding. Traditional extensive fish culture system is giving way for semi-intensive and intensive production system; hence dietary vitamin A cannot be met through consumption of live food in the pond. Fishes lacks the capacity of vitamin A synthesis and requires a dietary source of vitamin A for their normal growth (Henandez 2005). In view of these facts, culturists supplement vitamin A in their fish diet to ensure the requirement is met. This research work was therefore conducted to check the dietary supplementation level of vitamin A needed for optimum growth and survival of C. gariepinus.

Materials and Methods

The experimental set up was done in Department of Fisheries and Aquatic Environmental Management, University of Uyo, Uyo, Akwa Ibom State between July and October 2014.

Collection and Processing of Feed Ingredients

Feed ingredients used in this experiment include soybeans, fishmeal (Ethmalosa fimbriata), palm kernel cake and white maize which were procured from Uyo main market. The ingredients were brought to the processing unit where they were finally processed as follows:

Soybean was toasted until it became brown in colour and the chaff was blown out before grinding it into powders. Fishmeal, white maize and palm kernel cake were also grounded into powder.

Biochemical composition

Ten grammes of sample was taken and the excess moisture was removed using a filter paper (Rajendran 1973). Then the sample was dried in a hot air oven at a constant temperature of 60°C until the wet sample was dried completely. The dried samples were used for estimation of protein (Lowry et al 1951), carbohydrate (Dubois et al 1956), lipid (Folch et al 1957) and the ash content was determined by burning oven-dried sample in a muffle furnace at 550°C (AOAC 1995).

Feed formulation

Diet for this experiment was formulated using feed formulation software for windows (Winfeed 2.8) which formulates feed by linear programming technique. All diets were formulated on dry matter basis using the proximate compositions of the feed ingredients. Diets formulated are shown on table 2.

Feed milling and drying

Diets formulated in percentage were then converted to weight basis. The ingredients were measured using Camry kitchen weighing balance into a mixer where they were mixed thoroughly. Five percent of cassava starch was used as a binder. Hot water was then added into the mixture and mixing continued. After 10 minutes, they were then pelleted using manual pelletizer of 2 mm die ring and dried accordingly. Vitamin was dissolved in liquid hexane at 100 mg: 0.25 liter of liquid hexane. This was sprayed on the pellets according to different treatments and then air-dried for 15 minutes.

Experimental fish

Two hundred fingerlings of C. gariepinus were procured from Prime Park Farm located at No. 13 Aka Itiam Street Uyo in Uyo Local Government Area, Akwa Ibom State – Nigeria. The experimental fish were transported in an opened-top 20-litre plastic container half-filled with water to the experimental site. Allowance was made for 2 % mortality during transportation. The fish were acclimated for one week in the hatchery unit of the fish farm. During this period the fish were fed ad libitum with 45 per cent crude protein diet.

Experimental procedures

Nine tarpaulin tanks (3000 liter each) were used for the experiment. The tanks were washed, dried and filled with water supplied from the bore-hole; water level used in stocking the fish was 20 cm from the bottom. The setup took the form of completely randomized design (CRD). One hundred and eighty juvenile C. gariepinus were randomly distributed into the nine experimental tanks (20 per tank). These were assigned to three treatments and replicated thrice. The control (treatment 1) diet was prepared with all the ingredients without vitamin A supplementation. Fish in treatment 2 were fed diet of 833 IU kg^-1mg vitamin A supplementation while fish in treatment 3 were fed diet of 1666 IU kg^-1 vitamin A supplementation.

Stocking, feeding and water management

One hundred and eighty juvenile of C. gariepinus having a mean body weight of 15.9±0.27 were randomly stocked in the nine tanks with the same water levels. They were fed thrice a day at 5% body weight (BWD) at the hours of 8, 12 and 18 for 113 days. The feeding rate was adjusted accordingly during each sampling date. Water was changed according to the result of the routine water analysis. Physico-chemical parameters such as pH, temperature, ammonia and dissolved oxygen were monitored thrice a week to ensure optimum water quality.

Data collection

Data on fish growth were recorded weekly. The weight of individual fish was measured with an electronic top loading weigh balance (Mettle Toledo, model PB 602). The experimental tanks were inspected daily to remove dead. Fish daily weight gain, feed conversion ratio, specific growth rate and survival were recorded. The following growth parameters were determined:

i) Daily Weight Gain (g) (DWG) = (FW – IW)/N, Where: DWG=Daily weight gain, FW=Final weight of fish, IW=Initial weight of fish, N=number of days of the experiment.

ii) Specific Growth Rate (SGR): = (In FBW – In IBW)/N × 100, Where: FBW= Final body weight at each harvest, IBW= Initial body weight, In= Natural logarithm N=Number of days

iii) Feed Conversion Ratio (FCR) = Dry weight of feed fed (g)/Weight gain (g)

iv) Survival Rate (SR) in % = (Total fish number harvested/ Total fish number stocked) 100

v) Protein Efficiency Ratio (PER) = Weight gain/protein intake

Physico-chemical parameters

Physico-chemical parameters such as pH, temperature, ammonia and dissolved oxygen were checked thrice a week to ensure optimum water quality. Every week water quality was monitored according to APHA, (1995), throughout the experimental period.

Statistical analysis

Data obtained were subjected to one-way analysis of variance (ANOVA). The means from the various treatments were compared for significant differences (P<0.05), using Duncan’s multiple range test with the aid SPSS V.19 for windows.

Results

Water quality

Physico-chemical parameters of the cultured water are shown in table 3 and fluctuated slightly. These were within the optimum range recommended for the culture of freshwater fishes in the tropical region (Boyd and Lichtkoppler 2014).

Effect of supplementation of vitamin A on growth performance and feed utilization of Juvenile North African Catfish (C. gariepinus)

Table 4 shows the growth response and nutrient utilization; C. gariepinus fed diets supplemented with varying levels of retinol for 113 days. The highest daily weight gain was recorded in diet 1666RE while the lowest was seen in the control diet (NoRE). The specific growth rate also followed the same pattern.

Result of the analysis shows that there was a significant difference among the final weights of fish in the different treatments. The final weight was significantly higher in both diet 833RE and 1666RE than in the control diet (NoRE).  There was no significant difference between 833RE and 1666RE diets.

Values for feed conversion ratio were significantly higher in the NoRE while the lowest value was recorded in 833RE. The highest protein efficiency ratio was achieved in 833RE while the lowest was achieved in NoRE. However, the rates of fish survival in all the experimental treatments were grossly similar.

Generally, the fish showed good appetite to all the treatment diets, attested to by the increase in body weight (fig 1). The growth trend shows that there was similar growth pattern until the 8^th sampling date when fish fed diet 1666RE started growing faster than the fish fed both the control (NoRE) and diet 833RE.

Figure 1: Growth treand of clarias gariepinus during the 113 days culture

Discussion

The range of values measured for the pH, dissolved oxygen (DO), temperature and hardness of water fell within the range for optimal fish production (Boyd and Lickotoper 2014). Generally, water quality monitoring revealed that the difference in the mean weight of C. gariepinus in the three treatments was not as a result of the difference in the physico-chemical parameters.  

Adequate vitamin A supplementation in fish diets under intensive rearing is essential for survival and growth performance (Blomhoff and Blomhoff, 2006). Levels of vitamin A supplementation in this study was within the optimal dietary vitamin A requirement (1000-2000 IU kg⁻¹) for catfishes (Siluroidei) reported by Wilson and Moreau (1996). Although these values are assumed to be adequate for larger fish, certain vitamin A requirements may be affected by other factors, such as size, age, growth rate and stage of sexual maturity, as well as environmental stressors such as disease, water temperature and water quality. According to NRC (1993) signs of deficiency include exophthalmia, ascites and oedema.

The growth of the fish fed the control diet with no vitamin A was the lowest among all dietary groups. The increase in final weight, daily weight gain and specific growth rate with increased level of vitamin A supplementation is similar to the findings of Jeyaraj et al (2012) who found that feed consumption, protein consumption, feed conversion efficiency, protein efficiency ratio, growth, percentage growth, relative growth rate, Assimilation and metabolism was higher in feed IV containing 400 mg kg^-1 of vitamin A (equivalent to 1332 IU kg^-1). This level is in the normal range of dietary vitamin A requirements reported for most fish species (Mohammed et al 2003; Moren et al 2004).

Feed conversion ratio (FCR) and protein efficiency ratio (PER) were better when fish were fed diet 833RE but not significantly different from those fed diet 1666RE. This is similar to Hu et al (2006), who reported that the best FCR and PER is recorded at the region of 666 IU kg^-1 diet of retinol. No diet related mortality was observed in diets 833RE and 1666RE. However, we observed hemorrhages at the fin base of catfish fed control diet. An observation similar to the findings of Mohammed et al (2003) and Hu et al (2006) for greasy grouper and juvenile hybrid tilapia, Oreochromis niloticus×O. aureus respectively as a sign of vitamin A deficiency.

Conclusion

• Juveniles Clarias gariepinus have different growth performance and feed utilization efficiency under the different levels of vitamin A (retinol).

  
  

• Optimum dietary vitamin A level necessary for higher net growth performance of the fish is 1666 IU kg^-1 while 833 IU kg^-1 diet is needed for the efficient feed conversion, better protein efficiency and survival of African catfish.

  
  

• This new information is useful in designing the practical cost efficient diets for the intensive culture of this species.

Acknowledgement

We thank the Department of Fisheries and Aquatic Environmental Management University of Uyo, Uyo – Nigeria for the Logistical support.

References

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Received 22 April 2016; Accepted 17 October 2016; Published 1 February 2017

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