Effect of ginger (Zingiber officinale) in the nutrition of african catfish-A cholesterol reducer and fertility enhancer

The African catfi sh (Clarias gariepnus) [1], is a species of catfi sh of the family Clariidae and is an important fi sh species in both aquaculture and capture fi sheries [2]. It contributes 22% of animal protein in sub-saharan Africa and 40% of animal protein for consumption in Nigeria [3]. In Africa, this catfi sh has been reported to be the biggest in size in terms of length and weight and popularly cultivated species [4]. In Nigeria, Catfi sh culture started from inception with aquaculture and is majorly the only hope of fi sh supply sustainability. Recently all over the world, there is a decline in landing from capture fi sheries which is an indication that fi sh stocks have exceeded the point of maximum sustainable yield. Apart from Tilapia, African catfi sh belonging to the family of Claridae is the most commonly cultivated fi sh in Nigeria. The steady rise in catfi sh culture has greatly boosted aquaculture growth in Nigeria. However, the problem of inadequate availability of stock has hampering its production. Although, induced breeding (hypophysation) has been introduced and widely used throughout Nigeria to increase the production of farmraised catfi sh [5]. Currently, natural materials (medicinal plants) such as bitter leaf, scent leaf, bitter kola have been widely accepted as feed additives to enhance feed utilization and aquaculture productive, performance and sustainability [6]. Phytogenic feed additives, also known as phytobiotics Abstract


Introduction
The African catfi sh (Clarias gariepnus) [1], is a species of catfi sh of the family Clariidae and is an important fi sh species in both aquaculture and capture fi sheries [2]. It contributes 22% of animal protein in sub-saharan Africa and 40% of animal protein for consumption in Nigeria [3]. In Africa, this catfi sh has been reported to be the biggest in size in terms of length and weight and popularly cultivated species [4]. In Nigeria, Catfi sh culture started from inception with aquaculture and is majorly the only hope of fi sh supply sustainability.
Recently all over the world, there is a decline in landing from capture fi sheries which is an indication that fi sh stocks have exceeded the point of maximum sustainable yield. Apart from Tilapia, African catfi sh belonging to the family of Claridae is the most commonly cultivated fi sh in Nigeria. The steady rise in catfi sh culture has greatly boosted aquaculture growth in Nigeria. However, the problem of inadequate availability of stock has hampering its production. Although, induced breeding (hypophysation) has been introduced and widely used throughout Nigeria to increase the production of farmraised catfi sh [5]. Currently, natural materials (medicinal plants) such as bitter leaf, scent leaf, bitter kola have been widely accepted as feed additives to enhance feed utilization and aquaculture productive, performance and sustainability [6]. Phytogenic feed additives, also known as phytobiotics Abstract A twelve weeks nutritional study was carried out to study the effect Zingiber offi cinale on the growth performance, blood profi les, eggs and sperm quality of juvenile African catfi sh (Clarias gariepinus). in which juvenile African catfi sh (Clarias gariepinus) were fed Five diets containing 35% CP were formulated having varying inclusion levels (0, 5, 10, 15 and 20 %) of ginger (Zingiber offi cinale) for Diet 1, 2, 3, 4 and 5 respectively. One hundred (100) juvenile African catfi sh (94.24±0.02g) were randomly selected, divided into fi ve dietary treatments and stocked at the rate of 10 juveniles per tank (120L) and replicated two times. The fi sh were fed add libitum twice daily and weight changes were recorded every two weeks. At the end of the feeding trials, blood samples were taken, the sperm and egg sacs were excised from the fi sh samples selected and the sperm and eggs were collected for analysis. Data collected on weight changes, feed-intake, blood parameters and sperm volume, percentage motility, sperm density, percentage livability and death percentage were subjected to one way analysis of variance (ANOVA) using Completely Randomized Design (CRD).
Citation: Olaniyi  products are plant derived products, used in animal feeding to improve performance through amelioration of feed properties, promotion of production performance and improving the quality of animal origin food/feed [7]. Also, ginger being a natural and readily available additive could be used as fertility booster in fi sh which might also be a possible solution to the inadequacies of fi ngerlings supply, hence increasing the African catfi sh market in Nigeria.
Ginger is a fl owering plant whose rhizome is commonly used as spice and fl avouring agent. It is cultivated nationwide [8]. Ginger is a spice and medicinal plant that has been used in the pharmaceutical , food and chemical industries. It contains ant-oxidative and androgenic activities which has used in diseases treatment in many countries worldwide [9], Ginger and its constituents have antiemetic, antithrombotic, antihepatotoxic, anti infl ammatory, stimulant, cholagogue.
Androgenic and antioxidant properties. As antioxidants it protect DNA and other important molecules from oxidation and damage, and can improve sperm quality and consequently increase fertility rate in men [10]. Ginger, boost metabolism, immune systems as well as effective in decreasing sperm DNA fragmentation (SDF) in infertile men [11].
A study has revealed that inclusion of ginger root powder in laying hens diet increased their egg production and weight compared with control laying hens [12]. It was also reported that, ginger roots essential oil signifi cantly increased the relative uterus weight, egg weight, fertility and hatchability rates in the female quail compared to the control birds. In fi sh, ginger has been successfully used to control an Aeromonas hydrophila infection in rainbow trout [13]. In addition, ginger has been used as immune-modulatory agent in animals and fi sh to reduce the losses caused by diseases in aquaculture [13,14].
These studies therefore, investigate the effect of ginger in the nutrition, blood profi le and reproduction of African catfi sh.

Experimental site
This experiment was conducted at the fi shery unit of Teaching and Research Farm, Ladoke Akintola University of (LAUTECH), Ogbomoso, Oyo state Nigeria.

Processing of ginger (test ingredient)
The dried ginger was obtained from a local market in Ogbomoso. The ginger were sun dried to a constant weight, ground to fi ne powder and stored in an air tight container prior the use for the experiment.

Experimental diets
The ingredients such as maize, wheat offal, GNC, soybean, fi sh meal, oyster shell, bone meal, premix, lysine, salt and vegetable oil were procured from a reputable feed mill in 0gbomoso. Five isonitrogenous (35%CP) diets were formulated in which diet 1 contained (0% ginger), diet 2(5% ginger), diet 3 (10% ginger), diet 4 (15% ginger) and diet 5 (20% ginger).The ingredients were mixed thoroughly with varying percentage of ginger and then pelletized to reduce dustiness for proper and easy acceptance by the juvenile. The pellets were sundried to constant weight and packed into air tight sack and stored for use.

Experimental fi sh
Two hundred (200) juvenile African catfi sh were obtained from a reputable farm in ogbomoso and acclimatized for the period of two weeks after which, one hundred (100) juvenile African catfi sh (94.24±0.02g) were randomly selected and divided into fi ve (5) dietary treatments. The fi sh were stocked at the rate of 10 juveniles (4male:6 females) per tank (120L) and replicated two times (due to the number of fi sh within the weight ranges selected for the study). The water used was exposed for three days to allow oxygen dissolution into the water. The waste and faeces in all the tanks were siphoned every day to prevent pollution.

Feeding and weighing
The fi shes were fed experimental diet (add libitum) twice daily, both in the morning and evening (8:00hrs and 16:00hrs).
Fishes were weighed every two weeks for the period of twelve weeks using an electronic digital weighing balance, the record of the feed consumption was also taken.

Data collection
Data such as fi sh weight and feed intake were collected during the feeding trial and the following parameters -Mean blood samples were dispensed into a tube containing Ethylene diamine tetra acetate (EDTA) to avoid clotting of the blood sample and Eppendorf tubes for serum samples preparation.
The samples were preserved with ice cubes and taken to the laboratory for analysis.

Milts and eggs collection
Three male and female fi shes were randomly selected from all the treatments for milt and egg collection. The fi shes were deoxidized and the testes excised and eggs were siphoned from the female ovum with the use of hose. After which the sperm and eggs were viewed under the computer microscope.

Milt count
Concentration of sperm will be determined by counting the numbers of spermatozoa in sample dilute with distilled water (100x) in a Burkerhaemocytometer under 400x magnigication.

Percentage motility
Each sample were estimated using large microscope at 400x magnifi cation, immediately after addition of 20ul distilled water as an activating solution. During spermatozoa activation, immotile sperm cell (ISC) was counted, when the activation stopped, whole sperm cell (WSC) as counted, motile sperm cell (MC) was calculated.

Milt and egg analysis
The milt was analyzed with the use of a computer aided system and the data were, mathematically elaborated to obtain numerical indices expressing the statue of the ejaculation and egg production. The eggs were analysed to determine the volume, weight, colour and number of eggs.

Chemical analysis
Proximate composition of test ingredient (ginger), fi sh sample and experimental diets were determined according to the methods of Association of analytical chemist [15].

Statistical analysis
All data collected during experimental period were subjected to a one-way analysis of variance (ANOVA) using completely randomized design in accordance with SPSS and Duncan's multiple range tests was employed to reveal signifi cant differences among the means.

Results
The gross composition of experimental diets is as shown in Table 1and it revealed all the ingredients used for the fi ve diets formulated for the experiment. The proximate composition of ginger ( ZingiberOffi cinale) in Table 2 were as follows : crude protein 8.75%, crude fi bre 9.2%, ether extract 4.6%, moisture 6.6% and ash 6.2% .
The proximate composition of the experimental diets is as shown in Table 3. All the diets had averagely 34.75% crude protein, 5.09% crude fi bre, 6.80%, ether extract, 7.69% ash, 43.23% nitrogen free extract.
The growth performance and nutrient utilization of juvenile African catfi sh fed ginger based diets was revealed in Table   4 Ether extract is highest (21.01%) in T5 and lowest (15.24%) in T4, moisture content of T2 is the highest (9.01%) while the highest was recorded in T4 (2.24%). T4 has the highest ash and   NFE value (13.01and 9.66%) respectively, ash content (7.45%) is low in T1 while NFE is lowest (5.99%) in T2.

Haematology and serum
Haematology of the experimental fi sh is presented in Table 6. Highest PCV (48%) was discovered in treatments fi ve (T5) while the lowest PCV value (40%) was found with T2.  Table 7. All serum indices parameters were signifi cantly different (P<0.05) except urea. It was revealed in Table 7

Sperm and eggs quality
The sperm quality of juvenile African catfi sh fed ginger based diets in Table 8 recorded highest pH value (7.75) was obtained in T1 while the lowest (7.50) was recorded in all the other treatments (T2, T3,T4 and T5). T1 also has the highest volume (4.50ml), T3 and T4 has the lowest (2.00ml).   The egg quality of juvenile African catfi sh fed ginger based diets in Table 9, revealed that for parameters ( volume, weight and number ) T5 has the highest value (40.00ml, 36.50g ,25600) respectively while for parameters (volume, weight, number) T1 has the least value (25.00ml, 24.00g and 16800) respectively

Discussion
Medicinal plants have been reported to be growth promoters and immune boosters in livestock and fi sh nutrition [6,[16][17][18]. The fi ndings of the present study on growth performance of Clarias gariepinus juvenile fed ginger supplemented diets revealed that there was an increase in all the treatments for all parameters, as compared to the control. There was a signifi cant increase in the fi nal weight and weight gain of fi sh fed 15% inclusion of ginger than the fi sh fed the control diet.
The same trend was observed for the ADWG, PWG, TFT, SGR, PI and PER. The present study agrees with Iheanacho, et al. [18], who reported signifi cant increase in weight gain(WG), specifi c growth rate (SGR) and fi nal weight (FW) when C.gariepinus juvenile were exposed to varying concentrations (0.25, 0.50, 0.75 and 1.0g/35L) of ginger as compared to the control. The high proximate content of ginger may be an infl uence on the positive response to growth in treated fi sh, especially at 15% inclusion level of ginger which has the best response in all the parameters.
Carcass composition was signifi cantly affected by intake of ginger. Moisture content increased with increase in ginger inclusion levels and was least value of 2.24% was found in T4. This agreed with the fi ndings of Ali, et al. [19]. This could be attributed to corresponding decrease in the energy level of diets. Fanullah and Jafri [20], reported a strong inverse relationship between moisture content of fi sh and the energy level of their diets. The Ash content of fi sh fed the inclusion level of ginger were signifi cantly different (p<0.05). The highest was recorded in T4 (15% inclusion level of ginger) while the lowest value (7.45) was obtained in T1. Crude fi bre was high in T3 and this might be as a result of low ash and crude fi bre content of the tested ingredient (ginger) as was also observed by Erdal, et al., [21]. Crude protein of fi sh decreased with increase in ginger inclusion and recorded the highest in T4. This enhanced the crude protein content of C. gariepinus.
Blood is a vital special circulatory tissue, composed of cells suspended in a fl uid intercellular substance (plasma) with the major function of maintaining homeostasis [22]. Packed Cell Volume (PCV), also known as haematocrit(Ht or Hct) or erythrocyte volume fraction (EVF), is the percentage of red blood cells in blood [23] and is involved in the transport of oxygen and absorbed nutrients [22]. In this present study PVC values increased from initial value of 45.50% in fi sh fed the control diet (T 1 ) to fi nal value of 48.00% in fi sh fed 1.6g ginger diet (T 5 ) which contradicts Korzhuev (1964) [23] who stated that fi sh haematocrit values ranged between 20% and 35%. The results obtained falls within the range of 20% and 50% in agreement with Etim, et al. [24], who also stated that PCV values above 50% are rarely reported. Increased PCV results to an increased primary and secondary polycythemia [22], however, Sotolu and Faturoti [25] reported that lower PCV values is attributed to anaemia, thus the present study reveals that there is no tendency for anaemia.
Red blood cell is involved in the transport of oxygen carried to the tissues and carbondioxide returned to the lungs in the body [22,26,27]. The red blood cell (RBC s ) increased from the   initial value of 3.45% in the fi sh fed control diet (T1) to the fi nal value of 3.86% in fi sh fed 15% ginger diet (T4). These values were higher than 1.9x10 12 L -1 reported for Clarias gariepinus juveniles [28].
The fi nal white blood cell counts (WBC) of C.gariepinus juveniles fed ginger included diets ranged between 7.60cmm in fi sh fed 15% ginger based diet (T4) and 10.00cmm in fi sh fed 20% ginger-based diets (T) and were generally lower and signifi cantly different from the initial WBC count (12.00cmm; T 1 ). [29] stated that increasing or decreasing numbers of WBC s are normal physiological reactions to toxicants and these shows the response of the immune system under toxic conditions. However, Soetan, et al., 2013 [30], stated that animals with low white blood cells are exposed to high risk of disease infections while those with high counts are capable of generating antibodies in the process of phagocytocis and have high degree of resistance to diseases. They also have high degree of resistance to entrance adaptability to local environmental and disease prevalent conditions [22,[31][32][33].
Mean corpuscular volume (MCV) indicates the status or size of the RBCs and refl ects a normal or an abnormal cell division during the production of RBC. The result gotten from the present study showed that fi sh fed with 10% ginger diet (T 3 ), gave the highest volume (559.00Fl) while the fi sh fed 5% ginger diet (T 2 ), had the least (120.00Fl) MCV value.
These values are higher when compared to 79.20-105.32μg/ml reported for Heteroclarias [34]. This increase may be attributed to the swelling of the RBCs as a result of low oxygen condition and impaired water balance in fi shes exposed to metal pollution [35].

Serum biochemical indices
In fi sh, proteins are among the main energy sources which play an important role in the maintenance of blood glucose [39]. The observed increase in the total protein content of fi sh in the study fed diet containing 0.02g of ginger could be linked with the level of anti-nutrients present in the diets. Yadav, et al.
2003 [40], who also reported a decrease in serum total protein content in Channa punctatus induced with stem-bark extract of Croton tiglium. Decrease in total protein in the fi sh fed control diet maybe exposed to toxic levels of toxicants which could be attributed to either a state of hydration and change in water equilibrium in the fi sh or a disturbance in protein synthesis within the liver or both [41].
The slight decrease of serum albumin in the study which can be observed in fi shes fed 0.04g and 0.08g of ginger diet might be due to their degradation and utilization for metabolic purposes. The higher values of ALT in the study(5% ginger) may occur due to the blood serum enzyme in the experimental fi sh effi ciently utilized amino acids for metabolic purposes, confi rming the observation of Adesina [42]. Transaminases are important enzymes for monitoring the health status of fi sh [43] and leak out into the bloodstream from dying or damaged liver cells. Increased levels of transaminases in the blood serum of fi sh are usually associated with dying or damaged liver cells while a decrease could suggest leakage of enzymes into the serum [1,44], which is observed in the study. Increased level of AST in the study which is observed in 15% ginger might be due to stress or due to increased levels of anti-nutrients at higher inclusion.
It increase in response to stress [45] and this can be observed in the study. The lower AST values recorded in fi sh fed control and15% ginger based diets corroborated the report of [46] that there was inhibition of AST and ALT activities in the liver of catfi sh after intoxication with dietary ochratoxin.
The observation also agreed with that of Dienye and Olumuji, et al. 2014 [38], who reported elevated ALT, AST and ALP.
Activities in fi sh fed 30% M. Olefera leaf meal diet and above which suggested hepatic cellular damage leading to their leakage into the bloodstream [47]. This is also similar to [48], who reported that increase in serum protein, albumin and globulin level maybe as a result of immune response to certain constituents of the extracts which can be observed in the study. Khahil, et al. [49], also reported that ginger when administered as bath treatment signifi cantly decreased both ALT and creatinine levels in serum of Clarias gariepinus infested with gill monogenia, Bello, et al. [50], also reported that the decrease observed in ALT, ALP and ALB activities might be attributed to stress induced during fi sh sampling for blood collection, capturing and handling procedure The increased sperm motility, sperm density and sperm alive after 12 weeks of treatment with 20% inclusion revealed that with ginger powder boosts the fertilizing ability of semen.
A study of male rats on effects of ginger on reproductive functions proved that ginger enhanced fertility in male especially in sperm characteristics which might be as a result of potentability of antioxidant and androgenic properties. In this study, sperm pH is slightly above neutral across all the treatments with the fi shes fed the control diet having the highest pH value (7.75) while pH values were uniform (7.50) in all other treatments. The milt volume decreased as inclusion levels increased, the fi shes fed the control meal recorded the highest value (4.50ml) and the lowest ( (0.59ml) in the fi shes fed the control diet. It was also recorded that there was signifi cant difference in the spermatocrit of all treatments, the fi shes fed the control diet obtained the highest value (44%), while the least rate (27.50%) was obtained in the fi shes fed 15% of ginger meal.
This study revealed that egg volume, weight and number (40ml,36.50g,25600) respectively were signifi cantly increased in fi shes fed ginger diet inclusion at 20% (treatment 5). This is in agreement with Cek and Yilmaz [51], who reported that the number of eggs is determined based on its weight, the relationship between egg weight and number is also observed in this study. The result obtained from this study also agrees with the fi ndings of Zhao, et al. [11], on the effect of ginger powder on laying performance of laying hens who recorded that egg mass was quadratically increased by ginger powder supplementation at levels up to 20g/kg of diet .This study suggests that ginger has a favourable effect on egg quality of African catfi sh (volume, number and weight).Furthermore, the increased egg quality shows that treatment with ginger powder improves and enhanced rate of fertilization in eggs.

Conclusion
The result obtained in this study revealed that, inclusion of 15% ginger (treatment 4) in the diet of African catfi sh generally increased the growth optimally and reduced the serum biochemical indices to the minimal level required by the fi sh.
Although, ginger inclusion as high as 20% enhances carcass, egg quality and sperm fertility. However, it can be concluded that 15% ginger based diet can be included in the diet of African catfi sh to enhance a better performance.

Recommendation
15% of ginger inclusion in the diet of African catfi sh is therefore recommended for growth, good carcass quality as well as boosting reproduction (milt and egg) without health deterioration