Effect of Different Feed Ingredients on Growth and Level of Intestinal Enzyme Secretions in Juvenile Labeo rohita, Catla catla, Cirrhinus mrigala and Hypophthalmicthys molitrix  

Nida Ismat1 , Muhammad Ashraf1 , Muhammad Naeem2 , Muhammad Hafeez ur Rehman1
1 University of Veterinary and Animal Sciences, Lahore, Pakistan
2 Bahul-Din-Zikryia University, Multan, Pakistan
Author    Correspondence author
International Journal of Aquaculture, 2013, Vol. 3, No. 16   doi: 10.5376/ija.2013.03.0016
Received: 22 May, 2013    Accepted: 03 Jun., 2013    Published: 18 Jun., 2013
© 2013 BioPublisher Publishing Platform
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Ismat, 2013, Effect of Different Feed Ingredients on Growth and Level of Intestinal Enzyme Secretions in Juvenile Labeo rohita, Catla catla, Cirrhinus mrigala and Hypophthalmicthys molitrix, International Journal of Aquaculture, Vol.3, No.16 85-91 (doi: 10.5376/ija.2013. 03.0016)


Feed ingredients are the basic units in feed formulation. Behavior of individual ingredient dictates the overall performance of feed. Therefore, current studies were conducted to investigate the biological value of each ingredient in both Chinese and Indian major carps before their merger into feed formula to enhance fish growth and cut down feed cost. Trial contained two treatments and a control randomly received two glass aquaria (3×2×2 ft) with 10 fish in each. Fishes in control group were fed on rice polish, T1 on soybean meal and T2 on cotton seed meal @ 3 % of wet biomass of fish for 30 days. Labeo rohita, Hpophthalmichthys molitrix and Cirrhinus mrigala gained maximum weight on rice polish whereas Catla catla on soybean meal. Amylase concentrations were similar in fishes fed on rise polish except Hypophthalmichthys molitrix which secreted significantly low amylases. Values of lipase were the highest in Catla catla when fed on soybean meal. Cirrhinus mrigala did equally well on all ingredients while Hypophthalmichthys molitrix did very poorly. Protease concentrations slightly varied but variations were prominent from species to species. Protease concentrations in Catla catla were similar when fed on rice polish and soybean meal, however, Cirrhinus mrigala displayed higher protease concentrations when fed on cotton seed meal. These studies reveal that various fish species respond to a variety of ingredients in its own way hence acceptability and digestibility criteria should be given due importance during ingredient selection and feed formulation for particular fish species.

Feed ingredients; Enzymes; Catla catla; Hpophythylmichthys molitrix; Labeo rohita

Aquaculture is gaining considerable importance all over the world as a mean of improving world fish production which is currently on decline due to dwindling output from capture fishery (FAO, 2009). Expansion in aquaculture is strictly related to improvement in nutrition, and up gradation of fish husbandry practices- a challenge for future development in aquaculture. Mass scale fish production heavily depends on the amplification of proper feeding protocols to satisfy nutritional requirements of the cultured species.

As the aquaculture industry grows, the need for specialized feeds designed for particular production system and species increases proportionately. To date, nutritionists and feed manufacturers have concentrated their efforts on determining the feasibility and selection of wide variety of feedstuffs available to the feed industry for preparation of cost effective feeds. Currently appropriate quality fish feeds in desired quantity are not available. Majority of people use their own farm made feeds in variety of shapes and forms. Mash form is the most popular and convenient for use. Limited knowledge is available about nutrient requirements of different stages of fish and there is very poor know how about the suitable ingredients for balanced and effective feeds. Poor information on different digestive processes in fish alimentary canal is another hindrance to proper feed formulation for particular fish species. On account of which selection of different ingredients from large expanse available in the market is really a challenging job which can ensure viable growth, guaranteed health ultimately maintaining the economics of the fish business.
Feed taken in by fish undergoes through several mechanical and chemical processes. Once chewed and broken down into small pieces, feed is exposed to various enzymes which include proteases, lipases and amylases (Caruso et al., 2009). The ability of fish to metabolize a diet depends on the availability of appropriate digestive enzymes, which mediate specific degradation pathways modulating both physical and chemical nature of foods (Phillips, 1969). The measurement of specific activities (proteases, amylases and lipases) may provide information about the whole digestive capability and efficiency of fish species under culture (Buddington et al., 1997). Several previous studies (Smith, 1980; Reimer, 1982; Ugolev and Kuzmina, 1994; Hidalgo et al., 1999; Tengjaroenkul et al., 2000; Lundstedt et al., 2002) have shown that the distribution and activity of digestive enzymes within the gut is affected by feeding habits. Fish usually display high versatility in their feeding habits that is reflected in different anatomical and functional features; both nutritional and physiological. These characteristics allow them the exploitation of a wide range of food resources, thus improving their adaptation to changing environmental conditions.
Level of digestion and its ultimate absorption into the body warrants the feed efficiency and growth of fish which is all dependent on presence of variety of enzymes. Digestive processes in fish are less known than in mammals. The data obtained so far on enzymes in fish show that the digestive enzymes are qualitatively similar to those observed in other vertebrates. Several comparative studies of the digestive enzymes in different fish species have been reported (Hofer and Schiemer, 1981; Hofer, 1982; Jonas et al., 1983; Kuz’mina and Kuz’mina, 1990; Kuzmina and Smirnova, 1992) but very rare on our locally culturable fish species. The aims of this study were to determine the growth and activity of digestive enzymes including protease, amylase and lipase in different culturable herbivorous fish varieties when fed on variable plant feed ingredients. The results from this study will be used as a basis to develop feed formulation from species specific feed ingredients, so that optimal nutritional values and cost–effectiveness can be obtained in different feed formulations.
1 Results
1.1 Growth
Catla catla, Cirrhinus mrigala,and Labeo rohita grew equally but significantly higher than Hpophthalmichthys molitrix when fed on rice polish. In other two ingredients Catla catla displayed better growth on soybean meal while Cirrhinus mrigala on cotton seed meal. Growth in Labeo rohita was the second highest to Catla catla when fed on soybean meal and to Cirrhinus mrigala when fed on cotton seed meal. Hypothalmicthys molitrix grew the least in all dietary treatments. Catla catla, however, showed contradictory results, it gained maximum weight on soybean meal, then rice polish and lowest but equivalent to Hypophthalmichthys molitrix on cotton seed meal (Table 1).

Table 1 Growth comparison of different fish species fed on different feed ingredients

Amylase secretion level remained uniform when fishes were fed on rice polish except Hypophthalmichthys molitrix where level was significantly lower than its counterparts. Though highest value was observed in Cirrhinus mrigala but level of significance was not as prominent as observed in former species. Much lower amylase concentrations were observed in Catla catla, Labeo rohita and Hypophthalmichthys molitrix when fed on soybean meal and cotton seed meal (Table 2). Cirrhinus mrigala again topped other species in amylase secretions when fed on cotton seed meal.

Table 2 Concentrations of amylase in different fish species when fed on different feed ingredients (IU/min/mL)

1.3 Lipases

Catla catla showed the highest lipase activity when fed on soybean meal while lipase activity was the highest in Cirrhinus mrigala when fed on rice polish. Lipase secretion levels were similar and quite lower than its counterparts in Hypophthalmichthys molitrix in all the ingredients fed (Table 3). Catla catla secreted lowest concentrations when fed on cotton seed meal while the second highest when fed on rice polish. Labeo rohita did equally well in all the ingredients but levels were quite higher than Hypohthalmichthys molitrix but lower than Catla catla and Cirrhinus mrigala in some combinations (Table 3).

Table 3 Concentrations of lipase in different fish species when fed on different feed ingredients (IU·min-1·mL-1)

1.4 Proteases

Though proteases also varied from species to species and from ingredient to ingredient but variations were less prominent as have been observed in former enzymes. Proteases showed higher activities in all the fish species except Hypophthalmichthys molitrix which elicited poor secretions. Level of proteases was same in all the ingredients when fed to Hypophthalmichthys molitrix and significantly lower than its counterparts in the same treatment groups. Its protease levels were comparable to Cirrhinus mrigala when fed on soybean meal and to that of Catla catla when it was fed on cotton seed meal (Table 4).

Table 4 Concentrations of protease in different fish species when fed on different feed ingredients (IU·min-1·mL-1)

1.5 Water Quality Parameters
Due to daily exchange of water all the physico-chemical parameters remained within the acceptable range (Table 5).

Table 5 Ranges of water quality parameters observed during the course of experiment

Growth and survival data are powerful tools for understanding the effects of quality of feed on growth and linked metabolic mechanisms in fish (Wang et al., 2005). Our findings favorably fit in and support this statement because we observed the highest and uniform growth in all the fish species when fed on rice polish. Change in species and type of feed significantly affected the fish growth which was very much evidentwhen Catla catla was fed on soybean meal (Table 1) or when Cirrhinus mrigala was fed on cotton seed meal. Growth comparison of Catla catla showed significantly higher growth when fed on soybean meal followed by rice polish and cotton seed meal. Hypophthalmichthys molitrix grew significantly less than its counterparts (Table 1). Findings of Yasmin (1987) support and confirm our findings who reported better performance of Cirrhina mrigala than Lobeo rohita and Catla catla in artificial feed supplemented pond. Our observations are quite in line with previous investigations because Cirrhinus mrigala elicited superior growth performance on all the feed ingredients than its counterparts. Findings of Ashraf et al.(2008) further verify our investigations who observed different growth responses when Cirrhinus mrigala fingerlings were fed on different feed ingredients. Hypothalmicthis molitrix generally showed poor growth in all the ingredients nevertheless it was selectively comparable with Cirrhinus mrigala when it was fed on soybean meal or with Catla catla when it was fed on cotton seed meal. 

The nature and composition of the diet administered strongly triggers the development and secretion of digestive enzymes which affects the metabolic capabilities of fish. These enzymes had been an effective tool for identification of particular components of animal’s diet (Kanou et al. 2000). When sea bream specimens were fed on protein rich and non-proteic diets, it reflected type of diet in the secretion of gut enzymes. Protein rich diets resulted in higher amounts of proteases while amylase and lipase levels were greater in fish fed low protein diets. Fish may adapt their metabolic functions to the dietary substrates, through a regulation in enzyme secretion, in order to improve the utilization of particular feed ingredients (Caruso et al., 2009). Results were quite interesting in current studies where all the enzymes studied viz. amylases, lipases and proteases differed in different species and when fed on different ingredients (Table 2, Table 3, and Table 4). These findings strongly suggest that secretions of intestinal enzymes are dependent both on fish species and type of diet. This emphasizes that there are dietary as well as anatomical adaptations in fish. Fernandez et al.(2001) pointed out that digestive adaptations in different species exhibit closer correlation with their diet rather than on their taxonomic category. Our studies support former part of their findings but contradict the later part further confirming that taxonomical differences do have bearing on digestive adaptations in fish. This view was also confirmed by the results of Kuzmina (1996a) who indicated that changes in digestive enzyme activity could be affected by feeding behavior and biochemical composition of feed. Chan et al. (2004) and German et al. (2004) investigated the digestive enzyme activities in four closely related prickle back fishes, including two herbivorous and two carnivorous species. Their results showed that the activities of digestive enzymes correlated more strongly with phylogeny rather than with the fish’s natural diets. Influence of the genetic strains on the activities of brush border enzymes was demonstrated in the crosses of Oreochromis mossambicus and O. aureus (Hakim et al., 2006) and in the silver perch Bidyanus bidyanus (Hakim et al., 2006). Furthermore, the activities of digestive enzymes were also influenced by many other factors such as the ages of the fishes (Kuzmina, 1996), temperature and season (Kuzmina et al., 1996b) and the composition of their diets (Zambonino Infante and Cahu, 2001). Significantly higher amylases were observed in Cirrhinus mrigala when fed on rice polish and soybean meal, higher lipase levels were evident in Catla catla and similarly variable proteases were present in different species when fed on different feed ingredients. Chaudhuri et al.(2012) measured enzymes (i.e. α-amylase, invertase, cellulose, alkaline protease and pepsin) from liver, stomach and intestine of ten carnivorous species and did not find any positive relationship between prey preferences and digestive enzymes. These studies further strength ours and suggest that enzyme patterns are more affected by phylogeny rather than adaptability. The findings of Essa et al.(2010) further support our view point who observed that Tilapia fed on diets containing different probiotics have appeared to improve the digestion of protein, starch and fat that could be due to higher level of enzyme activities, which may explain the better growth and feed utilization. Notwithstanding all these findings, the relationship between digestive enzyme activities and feeding habits in fishes is still not very clear.

The physicochemical parameters have an integral role in the life of fish and fluctuations in their values adversely affect the health and growth of fish (Soderherg, 1990). Throughout the experimental trial all the water quality parameters remained within the acceptable range due to constant flow and exchange of water in fish rearing tanks.
3 Materials and Methods
3.1 Experimental Fish Species
Locally available fingerlings of Labeo rohita, Cirrhinus mrigala, Catla catla and Hypophthalmicthis molitrix of uniform ageand sizewere collected from commercial rearing units and transferred to cemented circular tanks for acclimatization.
3.2 Experimental Design and Protocol
Fishes were stocked in glass aquaria of size (3×2×2 ft) with 250 L water holding capacity in each. There were 2 treatments (fish species vs. feed ingredients) with 4 and 3 levels in each respectively. Each treatment level was replicated. Rice polish served as control. Before stocking, all the aquaria were well cleaned with tube well water and then disinfected with 700 ppm KMnO4 solution. Ten fishes of each species were then randomly selected from the bulk stock and were weighed and measured. Aquaria were then filled with fresh tap water up to 1.5 ft level. After acclimatization fishes were randomly harvested from the main stock and transferred to individual aquarium @ 10 fish per aquaria of each species in the relevant replica assigned to each treatment. Average weight and length of Labeo rohita, Cirrhinus mrigala, Catla catla and Hypophthalmicthys molitrix were 3.12g, 7.5cm; 3.18g, 7.0cm; 3.98g, 10.0cm and 3.2g, 7.0cm respectively.
All the four species were split into four groups in such a way that each species receives single ingredient at the same time. After the completion of experimental trial fishes were randomly collected from each treatment, 2 fish from each replicate. Sample of each species were weighed and measured and then belly was excised. Gut was removed and wrapped up in aluminum foil and froze at 1 for safe extraction of digestive enzymes. Water from each aquarium was totally drained off and remaining fish stock was totally harvested, weighed and measured and then released into ponds.
3.3 Enzyme Extraction and Quantitative Estimation
The stored samples were transported in sample tubes to Biochemistry laboratory for extraction of digestive enzymes (amylases, lipases and proteases). The gut of each fish was collected in micro-centrifuge tube and homogenized with chilled tris HCl in homogenizer. Homogenate was centrifuged at 6000×g at 4 for 15 min; supernatant was collected and stored at 0 for enzyme estimation.
3.3.1 Amylase
Starch was used as the substrate in the determination of amylase activity (Bernfeld, 1955) where 1ml of properly diluted gut extract was incubated for 3 min at 37 with 1ml of 1% starch substrate (1 g soluble starch and 0.0067 M NaCl in 100 ml 0.02 M NaH2PO4, pH 6.9). The reaction was stopped by the addition of 2 ml 3.5- dinitrosalicylic acid reagent. The solution was then heated for 5 minutes in boiling water, cooled and 20 ml distilled water was added. The absorbance at 540 nm was read and a standard curve was plotted with maltose (0.1mg/mL~1.0 mg/mL distilled water), to convert readings into mg of maltose( The specific activity of amylase is defined as 1 mg of maltose produced minute-1 mg-1 protein at 37). The amount of soluble protein in the gut extracts was determined by the Lowry method (Lowry et al., 1951) using bovine serum albumin as a standard protein. 0.1 mL of gut extract sample was added to 0.1 mL of 2 N NaOH. The mixture was then hydrolyzed at 100 for 10 minute in boiling water bath, then cooled to room temperature and 1 ml of freshly mixed complex-forming reagent was added. After 10 minutes, 0.1 mL of Folin reagent was added and mixed using a vortex mixer. The absorbance was then read at 550 nm after 30 minutes.
Spectrophotometer was set at 540 nm wavelength level for assessment of absorption level of blank and standard. Samples were taken in cuvett tubes and turned the blank to 0. Again readings of each sample were taken on spectrophotometer and compared with standard.
Absorption of standard = A nm,
Absorption of sample = Y nm,
“A” absorption is due to = 1 mL (0.01mg of standard glucose in 1mL (glucose 10%) (1mg glucose /10 mL)
“1” is = 0.01 /A,
“Y” absorption is due to = (0.01/A) ×Y = “F” mg of amylase in sample
Activity of amylase (F×1000/180(MW of glucose) ×15= “Z” IU/ml
3.3.2 Lipases
Ten mmol NaOH was taken in burette for titration and then 3.5 mL phosphate buffer and 1 ml sample was taken in glass flask. Then 0.5 mL olive oil was added in the solution of phosphate buffer and stirred for 30 minutes at 37℃ in water bath. Then 1 mL acetic acid was added to this mixture and followed by addition of 3-4 drops of phenolphthalein indicator in enzyme mixture. The mixture was titrated with 10 mmol NaOH till the color turns pink.
= “Y” µM of oleic acid released min-1
= “Z” (IU) /min
3.3.3 Proteases
Total protease activity was evaluated using 1% azocasein in50mmol tris HCl, pH 7.5(Garcia-Carreno, 1992). Ten µL of enzyme extract was mixed with 0.5 mL of buffer (50 mmol Tris-HCl, pH 7.5); 0.5 mL of substrate solution was incubated for 10 min at room temperature. The reaction was stopped by adding 0.5mL 20% trichloroacetic acid and then centrifuged at 14000×g for 5 minutes. The absorbance of the supernatant was recorded at 366 nm. Standard curve was prepared using azocasein as substrate. Values of protease activity were then calculated by comparing sample values with those of observed in standard curve.
3.4 Physico-chemical Parameters
Temperature and dissolved oxygen were measured on daily basis by using D.O. meter (YSI 55 Incorporated, Yellow Springs, Ohio, 4387, USA). Electrical conductivity, total dissolved solids and salinity were recorded by salinity meter (Condi 330i WTW 82362 Weilheim Germany) while pH was measured by pH meter ((LT-Lutron pH-207 Taiwan) on weekly basis.
3.5 Statistical Analysis
Data were compared by the analysis of variance (ANOVA) at the 0.01 significance level. Significant differences in mean weights were revealed by Tukey’s Multiple Range Test for multi-group comparisons. The data with few replications for the enzyme assays were analyzed by applying the Least Significant Difference (LSD) test, which is less conservative than Tukey’s test. All data were expressed as Mean ± SD. The SPSS (Statistical Package for the Social Sciences) version 16.0 was used for all statistical analyses.
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