Growth performance and chemical composition of Cirrhinus mrigala ( mori ) under the effect of chromium chloride hexahydratre

A nutritional trial was conducted for 90 days to investigate the effect of different levels of chromium chloride hexahydrate on Cirrhinus mrigala growth and body composition using two types of corn (gelatinized and non-gelatinized). Six test diets were prepared using three levels of chromium chloride hexahydrate (0.0, 0.2 and 0.4 mg kg). Fifty Cirrhinus mrigala fingerlings were distributed randomly among six groups each group each with two replicates. The result showed that Cirrhinus mrigala fed on gelatinized corn diet with 0.2 mg kg chromium chloride hexahydrate showed maximum growth as compared to non-gelatinized corn. In case of body composition results revealed that fish fed on gelatinized corn with 0.4 mg kgshowed maximum deposition of dry matter, crude fat, crude protein and gross energy while ash retention was observed maximum in non-gelatinized corn with 0.2 mg kg It is concluded and suggested for Cirrhinus mrigala that gelatinized corn and chromium chloride hexahydrate in fish diet are very effective in growth and body composition.


Introduction
Fish is a main source of protein containing essential amino acids and minerals.In socioeconomic fabric of South-Asian countries fish occupies significant position [1].Fish is a basic nutrient provider that's why world has greatly relied on it.We are facing food shortage now a day especially in the form of protein [2].For fish culturing intensive and semi-intensive fish cultures are mostly used.
Cirrhinus mrigala with other major carps is commonly cultured in sub-continent.Nutrition is a serious issue in fish farming because it signifies almost 50% production cost [3].For feed formulation large amount of seed of animal and plant origin feed is produced in Pakistan.Fish meal is rich source of protein and globally used as dietary protein source in fish feed formulation, but there is some problems in using fish meal such as high prices, reduced supply, uneconomical and instability

Experimental fish and acclimatization
The fingerlings of Cirrhinus mrigala (1 to 2 inches) were bought from fish seed hatchery, Satiana road Faisalabad, Pakistan.Before starting experimental trial C. mrigala fingerlings were acclimatized for two weeks with feed T2 (NG/0.0Cr2Cl3.6H2Omg/kg).After acclimatization period experimental diets were given to C. mrigala fingerlings at 4 % live wet body weight.

Experimental design
This experimental trial was carried out for 90 days.After acclimatization 600 fingerlings of uniform size were allocated to six aquaria each with two replicate.For replica of each treatment aquaria were divided into halves.These aquariums having dimension 90cm L×30cm W×45cm H with 29L water capacity.Using air pumps with capillary system oxygen was supplied to the system (5-6ppm) and was monitored on daily basis.Fecal matter collection and manual water exchange were also performed daily.

Feed Ingredients and Preparation of Experimental Diets
Six experimental diets were prepared with various graded levels of chromium chloride hexahydrate and corn (G & NG).Corn was grounded to make powder then add suitable amount of water to make it dough, placed this dough in autoclave at 15 psi for 60 minutes to get maximum gelatinization.After gelatinization of corn this mass was placed in oven at 60 o C for one hour.The dried mass was positioned on hammer mill having 0.5 mm screen and then stockpiled in air tights jars until use.Corn was used as a carbohydrate source.Gelatin and casein were used in fish feed as a source of protein while lipid sources were sunflower oil and cod liver oil.All dry ingredients weighted carefully, ground and mixed thoroughly and add sufficient amount of water (50 ml) to make it dough mix this mixture for half an hour.Spread this mixture in tray then placed in oven for drying purpose [13].This material was grounded to make pellets (2 mm).Pellets were steamed for five minutes.These pellets were dried at 60 o C in oven.Chromic oxide was added in experimental diets as an inert marker at the rate of 1% of total diet.Six test diets were prepared supplemented with carbohydrates (G/NG) and different graded levels of chromium chloride hexahydrate; T1 (G/0.0 mg Kg -1 ), T2 (NG/ 0.0 mg Kg -1 ), T3 (G/0.2mg Kg -1 ), T4 (NG/0.2mgKg -1 ), T5 (G/0.4 mg Kg -1 ) and T6 (NG/0.4mg Kg -1 ).Using linear formulation method all experimental diets were prepared through winfeed 2.6 (Winfeed U.K) ltd., Cambridge,U.K).

Feeding protocol
After acclimatization of two weeks C. mrigala fingerlings were shifted to six glass aquaria each with a replicate.Every aquarium had fifty fingerlings of uniform size dispersed arbitrarily.Experimental diets were given to C. mrigala fingerlings at the rate of 4 % live wet body weight [14] twice a day.

Fecal collection
On daily basis C. mrigala fingerlings were shifted in partitioned aquaria after feeding period of three hours for collection of fecal matter.By siphoning with care fecal matter was collected and dried at room temperature on daily basis.For all chemical analysis enough quantity of fecal matter required that's why continued fecal collection for 120 days.

Growth studies
On fortnight basis morphometric characteristics i.e. body weight (g) and total body length (cm) of C. mrigala, fifteen from each treatment were measured.Total length was measured from tip of mouth to the anterior tip of tail fin using 30cm ruler.Weight balance was used to measure body weight.The fingerlings were shifted into their particular aquaria again after recording all data.The growth of fingerlings was determined by following calculations:

Statistical analysis
At the end of experiment obtained data of growth and body composition was subjected to one-way analysis of variance, ANOVA.The differences among means were compared by Tukey's honesty significant difference test and considered significant difference test P<0.05.

Results
This nutritional trial showed following results for growth and body composition of C. mrigala.

Growth performance
The results of growth performance are given in table 1 that showed maximum body weight gain (6.42g), increase in body length (2.63cm) and specific growth rate (0.77) in experimental group-T3 that was treated with gelatinized corn diet with chromium chloride hexahydrate at level of 0.2 mg kg -1 (Table 2).T3 showed significant (P<0.05)variations with other treated groups.

Body composition
The achieved results of body composition showed that chromium chloride hexhydrate at level of 0.4 mg kg -1 had positive effect on dry matter deposition in group-T5 (Table .3).Similar findings were reported by [8] who concluded that at level of 0.3 mg Kg -1 Cr2CO3.6H2Omaximum deposition of dry matter was observed in Labeo rohita.Our results are consistent with the results of [19] who stated that maximum dry matter deposition in dorsal muscles of Nile tilapia at level of 400 ug kg -1 .Reported that at level of 0.5 4mg kg -1 lipid contents were highest in fish body.Chromium chloride hexahydrate and gelatinized carbohydrates had positive effects on lipids contents because both are involved in increasing digestibility and metabolism of fishes.In case of crude protein significant variation were observed among different treatments and in experimental group-T5 maximum deposition of crude protein was recorded (Table 3).Results of other researchers like [8, 18, 20] favors the current study they stated that chromium had beneficial effect on nutrient crude protein retention in fish body meat.While dissimilar results were reported by [21] who concluded that Lcartinine had no positive effect on body meat of tilapia.In this study gross energy values were significantly different among various treatments and maximum value of gross energy was observed for group-T5 which contains 0.4 mg kg -1 chromium chloride hexahydrate and gelatinized corn (Table 3).These results are in accordance with [8] who concluded that chromium chloride hexahydrate at level of 0.5 mg kg -1 had beneficial effect on gross energy values for Labeo rohita.

Conclusions
The obtained results of present research work showed that chromium chloride hexahydrate with gelatinized corn at level of 0.2 mg kg -1 showed maximum growth performance of Cirrhinus mrigala while chromium chloride hexahydrate at level of 0.4 mg kg -1 showed positive effects on chemical composition of C. mrigala.High protein profile fish can be produced by using gelatinized corn with 0.4 mg kg -1 level of chromium in future.A little research work had done using chromium chloride hexahydrate in fish feed more research is needed in this field.
i. Increase in wet body weight (g) by following formula Average body weight of 1 st observed fortnight __ Average body weight of next observed fortnight.ii.Increase in net total body length (cm) Average body length of 1 st observed fortnight __ Average body length of next observed fortnight iii.Specific growth rate (SGR) evaluated by using the following formula vi.Weight gain= Final weightinitial weight Analytical method Required samples of experimental diets and body meat of all replicates were homogenized using mortar pestle distinctly and analyzed chemically by AOAC (1990) protocols; for dry matter at 105 0C oven drying, for crude protein microkjeldhal apparatus, gross energy by oxygen bomb calorimeter, electric furnace for ash and chloroform methanol extraction method [15] through 10454 soxtec system HTz for crude fat extraction.SGR= In (Final wet body weight)-In (Initial wet body weight) ×100 (Time duration (Days)

Table 1 . Growth performance of Cirrhinus mrigala fed on various experimental diets
The antioxidant ButylatedHydoxy Toluene was added at 0.02% of the added oil.