The objectives of the present study were to evaluate the effects of graded levels of a new commercial probiotic Hydroyeast Aquaculture® (0, 5, 10 and 15 g/Kg diet) on both sexes of adult Nile tilapia Oreochromis niloticus, referred to treatments No. T1, T2, T3 and T4, respectively, for males and T5, T6, T7 and T8 treatments for females, on their growth performance, feed and nutrients utilization and carcass composition for 8 weeks.
The obtained results showed that tested probiotic at level of 15 g /kg diet (T4) and 10 g /kg diet (T7) for adult males and females O. niloticus respectively, significantly (P ≤ 0.05) enhancing fish growth, feed intake and nutrients utilization, as well as realized slight improving of fish carcass composition.
Hence, it could be concluded that Hydroyeast Aquaculture® probiotic is useful at levels of 15 g /kg diet (T4) and 10 g /kg diet (T7) for enhancing production performance of adult males and females Nile tilapia (O. niloticus) respectively, so may be using of this probiotic led to economic efficiency especially, for fish farming and hatcheries.
Hormones, antibiotics, ionophers and some salts compounds have been used as growth promoters and to some extent to prevent diseases. However, their inadequate applications show a negative effect on aquaculture production and environment (Góngora, 1998). Functional additive, like probiotics, is a new concept on aquaculture (Li and Gatlin III, 2004) where the additions of microorganisms on diets show a positive effect on growth caused by the best use of carbohydrates, protein, and energy (Irianto and Austin, 2002). It further diminishes mortality by disease, antagonism to pathogen, and better microbial intestinal balance in the environment (Holmström et al., 2003).
The use of probiotics for farm animals has increased considerably over the last 15 years. Once ingested, the probiotic microorganisms can modulate the balance and activities of the gastrointestinal microbiota, whose role is fundamental to gut homeostasis. The most important benefits of yeast and bacterial probiotics upon the gastrointestinal microbial ecosystem in ruminants and monogastric animals (equines, pigs, poultry, fish) were reported in the recent scientific literature (Chaucheyras-Durand and Durand, 2010). Nowadays, a number of preparations of probiotics are commercially available and have been introduced to fish, shrimp and molluscan farming as feed additives, or are incorporated in pond water (Wang et al., 2005).
Tilapias are the most successfully cultured fish in the world because of their fast growing and high efficiency to utilize the natural and artificial supplemented feeds (Ishak, 1980). Tilapias have become increasingly popular for farming as they are able to reproduce rapidly, easily bred in captivity, tolerate to a wide range of environmental conditions, highly resistant to diseases, and most important of all, have good flavour. Though the fish originated inAfrica, Asian countries have become the leading producers of these fishes (Rana, 1997). Tilapias are second only to carps as the most widely farmed freshwater fish in the world (FAO, 2010).
Food availability and quality are known to influence both fecundity and egg size in tilapia (Coward and Bromage, 2000). So, brood stock nutrition is recognized as a major factor that can influence fish reproduction and subsequent larval quality of many fish species (Izquierdo et al., 2001). The development of cost effective and nutrient optimized brood stock feeds for tilapia is both pertinent and crucial. Yet, many studies revealed the positive effects of probiotics on growth performance in different O. niloticus stages such fry (Abdel-Tawwab et al., 2008; Lara-Flores et al., 2010; Abdelhamid et al., 2012; Abdel-Tawwab, 2012) and fingerlings (Mehrim, 2009; Ghazalah et al., 2010; Khalafalla, 2010). However, no any attempts were designed concerning the effects of probiotics on growth performance of adult fish. Therefore, the objectives of the present study were to evaluate the effects of graded levels of a new dietary probiotic Hydroyeast Aquaculture® on both sexes of adult Nile tilapia Oreochromis niloticus, concerning their growth performance, feed and nutrients utilization and carcass composition for 8 weeks.
Materials and Methods
The Experimental Management
This study was conducted in Fish Research Unit, Faculty of Agriculture, MansouraUniversity, Al-Dakahlia governorate, Egypt. Both sexes of healthy adult Nile tilapia O. niloticus, with an average initial body weight (83.4 ± 0.001 g) for adult males and (80.1 ± 0.002 g) for adult females were purchased from Integrated Fish Farm at Al-Manzala (General Authority for Fish Resources Development – Ministry of Agriculture) Al-Dakhalia governorate, Egypt. Fish were stocked into rearing tanks for two weeks as an adaptation period, and fed on a basal diet during this period. Fish in both sexes (males and females), were distributed separately into eight experimental treatments (as three replicates per treatment) (Table 1). Fish in each treatment were stoked at 10 fish/ m3 per tank. Each tank (1m3 in volume) was constructed with an upper irrigation open, an under drainage, an air stone connected with electric compressor. Fresh under ground water was used to change one third of the water in each tank every day.
Table (1): Details of the Experimental Treatments
The tested probiotic Hydroyeast Aquaculture® formula was showed in Table (2), which producing by Agranco corp., Gables, International Plaza Suite, No. 307, 2655 Le Jeune Rd., 3rd Floor, Coral Gables, Fl 33134, USA.
Table (2): Formula of The Tested Probiotic, Hydroyeast Aquaculture®
The commercial diet, as basal ration (BR), used in the present study contains 25% crude protein, it was purchased from Al-Manzala manufacture for fish feed, Integrated Fish Farm at Al-Manzala (General Authority for Fish Resources Development - Ministry of Agriculture), Dakhalia governorate, Egypt. This commercial diet ingredients and proximate chemical analysis according to the manufacture's formula, as shown in Table (3). The diet was ground to add the tested probiotic (Hydroyeast Aquaculture®) at levels of 0, 5, 10 and 15 g/Kg diet, referred to treatments No. T1, T2, T3 and T4, respectively, for males and T5, T6, T7 and T8 treatments for females (Table 1) and then all diets were repelleted. The experimental diets were introduced by hand twice daily at 9 a.m and 15 p.m at 3% of the fish biomass at each tank. The feed quantity was adjusted bi-weekly according to the actual body weight changes.
Fish Sampling and Performance Parameters
At the start and at the end of the experiment, fish samples were collected and kept frozen till the proximate analysis of the whole fish body according to AOAC (2000). Energy content in experimental fish was calculated according to NRC (1993), being 5.64 and 9.44 kcal/g for CP and EE, respectively.
Growth performance parameters of both sexes of adult O. niloticus such as average total weight gain (AWG), average daily gain (ADG), relative growth rate % (RGR), specific growth rate %/day (SGR) and survival rate % (SR) were calculated. Feed conversion ratio (FCR), feed efficiency % (FE), protein efficiency ratio (PER), protein productive value % (PPV) and energy utilization % (EU) were calculated according to the following equations:
AWG (g/fish) = [Average final weight (g) – Average initial weight (g)].
ADG (g/fish/day) = [AWG (g) / experimental period in days (d)].
RGR = 100 [AWG (g)/Average initial weight (g)].
SGR (%/day) = 100 [In final body weight - In initial body weight] / experimental period in days (d).
FCR = Feed Intake, (g)/Live weight gain (g).
FE = 100 [Live weight gain (g)/Feed Intake, (g)].
PER = Live weight gain (g)/protein intake (g).
PPV (%) = 100 [Final fish body protein content (g) – Initial fish body protein content (g)]/crude protein intake (g).
EU (%) = Retained energy x 100/consumed feed energy
SR = 100 [Total No. of fish at the end of the experimental/Total no. of fish at the start of the exsperiment].
Table (3): Ingredients and Proximate Chemical Analysis (% On Dry Matter Basis) of The Experimental Basal Diet
The obtained data for males or for females were statistically analyzed using general liner models (GLM) procedure according to SAS (2001) for users guide. The differences between means of treatments were compared for the significance (P ≤ 0.05) usingDuncan's multiple rang test (Duncan, 1955), as described by Bailey (1995).
Growth Performance Parameters
Growth performance parameters of adult males O. niloticus illustrated in Table (4) revealed that T4 (15 g Hydroyeast Aquaculture®/Kg diet) was the best treatment followed by T2 (5 g Hydroyeast Aquaculture®/Kg diet) and T3 (10 g Hydroyeast Aquaculture®/Kg diet), which were gave significantly (P ≤ 0.05) final body weight, AWG, RGR, ADG and SGR than the control (T1). But, no significant (P ≥ 0.05) differences between T2 and T3 for final weight, AWG and ADG, as well as in SR among all treatments.
Table (4): Effects of Hydroyeast Aquaculture® Probiotic On Growth Performance of Adult Male O. Niloticus
Data of growth performance parameters of adult females O. niloticus revealed that T7 (10 g Hydroyeast Aquaculture®/Kg diet) was the best treatment followed by T6 (5 g Hydroyeast Aquaculture®/Kg diet), which were gave significantly (P ≤ 0.05) increased final body weight, AWG, RGR, ADG and SGR than T8 (15 g Hydroyeast Aquaculture®/Kg diet) and the control (T5). However, no significant (P ≥ 0.05) effects in SR among all treatments (Table 5).
Table (5): Effects of Hydroyeast Aquaculture® Probiotic On Growth Performance of Adult Female O. Niloticus
Feed and Nutrients Utilization
Results of feed nutrients utilization parameters of adult males O. niloticus were shown in Table (6), whereas T4 gave the highest significantly (P ≤ 0.05) increased FE, PER and the best FCR followed by T2 compared with the control (T1) and T3. In contrast, PPV or EU increased significantly (P ≤ 0.05) in T1 followed by T2 compared with T3 and T4. However, no significant (P ≥ 0.05) differences in FI among all treatments.
Table (6): Effects of Hydroyeast Aquaculture® Probiotic on Feed and Nutrients Utilization of Adult Male O. Niloticus
Adult females' O. niloticus fed 10g Hydroyeast Aquaculture®/kg diet (T7) showed a significant (P ≤ 0.05) increase in FI, FE, PER and the best FCR followed by fish fed 5g Hydroyeast Aquaculture®/kg diet (T6) compared with the control (T1). However, treatment No. 6 gave significantly (P ≤ 0.05) increase of PPV and EU among all treatments (Table 7).
Table (7): Effects of Hydroyeast Aquaculture® Probiotic on Feed and Nutrients Utilization of Adult Female O. Niloticus
Generally, the differences between males and females within all treatments concerning, feed and nutrients utilization parameters may be due to the differences in sexes, metabolism, physiological responses and sexual behaviors of fish during this stage of life.
Fish Carcass Composition
Proximate chemical analysis of the whole adult males' O. niloticus body at the start and at the end of the experiment is summarized in Table (8). These data indicated that there were significant (P ≤ 0.05) increases of DM and EC content in the control group (T1) compared with the dietary inclusion of Hydroyeast Aquaculture® (T2, T3 and T4), but CP content was increased significantly (P ≤ 0.05) in T1 or T2 than the T3 and T4. However unclear trend was observed in EE, where the increasing in EE content was not significant in T1 compared with T3 and T4 and significant as compared with T2. In contrast, of these results ash content increased significantly in T3 and T4 compared with T2 and the control T1. Generally, proximate chemical analysis of the whole fish body at the start, revealed higher DM, EE and EC than in the end of the experiment, but CP and ash were lower at the start than at the end of the experiment.
Table (8): Effects of Hydroyeast Aquaculture® Probiotic on Carcass Composition of Adult Male O. Niloticus
Adult female O. niloticus fed 5g Hydroyeast Aquaculture®/kg diet (T6) showed significant (P ≤ 0.05) increase in DM, CP and EC contents among all treatments. However, both of EE and ash contents recorded the same trend, whereas increased insignificantly in the control group (T5) compared with T7 and T8 and significantly increased compared with T6. In general, unclear trend was recorded in proximate chemical analysis of the whole adult females' O. niloticus body at the start and at the end of the experimental period, which there were higher DM and CP than in the end of the experiment, but EE and ash were lower at start than at the experimental end. Meanwhile, no any remarkable changes were observed in EC content at the start and the end of the experimental period (Table 9).
Table (9): Effects of Hydroyeast Aquaculture® Probiotic on Carcass Composition of Adult Female O. Niloticus
The positive effects in the present study, of Hydroyeast Aquaculture® probiotic on adult males and females Oreochromis niloticus growth performance and feed utilization, was found by Eid and Mohamed (2008), where they proved that Biogen® and Prmifer® improved the growth performance, feed conversion, protein efficiency ratio and apparent protein digestibility for monosex tilapia fingerlings compared to fish fed the control diet. Moreover, El-Ashram et al. (2008) concluded that, super Biobuds® can improve body gain, survival and enhance resistance to challenge infection. Yet, Abdelhamid and Elkatan (2006) found that dietary supplementation of Biobuds® slightly improved body weight gain but reduced the survival rate of tilapia fingerlings. El-Haroun et al. (2006) and El-Haroun (2007) reported that Biogen® dietary supplementation improved growth performance and feed utilization, carcass protein and fat percentages as well as economical profit in Nile tilapia and catfish culture, respectively. In this respect, also Mehrim (2009) reported that dietary probiotic (Biogen®) had significantly (P ≤ 0.05) increased all growth performance parameters of O. niloticus compared with the control group. Yet, Marzouk et al. (2008) found that probiotics (B. subtillis and Saccharomyces cerevisae) revealed significant improvement in growth parameters of O. niloticus. However, Shelby et al. (2006) noted that the probiotic used with juvenile channel catfish diet had lack effect on specific growth promoting. Also, He et al. (2009) found that supplementation of dietary DVAQUA® showed no effects on growth performance, feed conversion and survival rate of the hybrid tilapia (Oreochromis niloticus ? × O. aureus ?). The reasons for the differences between fish species have not been elucidated, but might be due to the differences in aquaculture and physiological conditions, composition of the probiotic and the type of basal ingredients in diets.
In this context, many studies concluded a positive effect of using viable microorganisms in probiotic mixtures into diets of fish (Pangrahi et al., 2005; Barnes et al., 2006; Abo-State et al., 2009). According to, the results of the present study and those obtained by other attempts; it seems that probiotics may stimulate appetite and improve nutrition by the production of vitamins, detoxification of compounds in the diet, and by breakdown of indigestible components (Irianto and Austin, 2002). Also, Varley (2008) cited also that probiotics show real benefits in the synergistic effects with the beneficial bacteria in making inroads into improving gut health.
Probiotics improve feed conversion efficiency and live weight gains (Saenz de Rodriguez et al., 2009). So, the supplementation of commercial live yeast, S. cerevisiae, improved growth and feed utilization (Abdel-Tawwab et al., 2008). Yet, similar results were obtained when S. cerevisiae was added to fish diet for Israeli carp (Noh et al., 1994) and Nile tilapia (Lara-Flores et al., 2003). Moreover, Mehrim (2009) found similar positive effects of Biogen® on growth performance, feed conversion ratio and carcass composition of O. niloticus. Rawling et al. (2009) reported that daily feed intake was significantly higher in red tilapia (O. niloticus) fed Sangrovit® (Phytobiotics Gmbh, Etville, Germany) supplemented diets compared to control and that feed utilization was not significantly affected suggesting that improved growth was likely to be due to improved appetite of fish fed diets containing Sangrovit®. The improved fish growth and feed utilization may possibly be due to improved nutrient digestibility. In this regard, Tovar et al. (2002), Lara-Flores et al. (2003), and Waché et al. (2006) found that the addition of live yeast improved diet and protein digestibility, which may explain the better growth and feed efficiency seen with yeast supplements. Also, De Schrijver and Ollevier (2000) reported a positive effect on apparent protein digestion when supplementing turbot feeds with the bacteria Vibrio proteolyticus.
Growth of fish and feed conversion together with carcass composition are generally affected by species, genetic strain, sex, stage of reproductive cycle, etc., leading to different nutritional requirements. (Jauncey, 1998). In this respect, yeast supplementation significantly affected the whole-fish body composition (Abdel-Tawwab et al., 2008). These results suggest that yeast supplementation plays a role in enhancing feed intake with a subsequent enhancement of fish body composition, as well as yeast supplements significantly affected ash content of O. niloticus (Abdel-Tawwab, 2012). On the other hand, changes in protein and lipid content in fish body could be linked with changes in their synthesis, deposition rate in muscle and/or different growth rate (Abdel-Tawwab et al., 2006).
In this topic, Khattab et al. (2004) reported that crude protein, total lipids and ash were significantly (P < 0.01) affected by protein level and increasing stocking density rate of tilapia fish. Yet, Abdelhamid et al. (2007) reported that increasing dietary Betafin® (betaine) level caused a significant improve of O. niloticus body composition. On the other side, the results in the present study are in close agreement with those of EL-Haroun et al. (2006), Mohamed et al. (2007), and Eid and Mohamed (2008) for tilapia and EL-Haroun, (2007) for catfish. In addition, Mehrim (2009) found positive effects of inclusion of Biogen® at a level of 3g/kg on carcass composition of mono-sex O. niloticus fingerlings. Also, who reported that these positive effects in carcass composition of experimental fish may be due to the dietary probiotic Biogen®, which caused the good growth performance of treated fish compared with the control group, as present findings of adult males and females O. niloticus growth performance (Tables 4 & 5), respectively.
From the forgoing results, it could be concluded that Hydroyeast Aquaculture® probiotic is useful at levels 15 g /kg diet (T4) and 10 g /kg diet (T7) for enhancing production performance of adult males and females Nile tilapia O. niloticus respectively, so may be using of this probiotic led to economic efficiency especially, for fish farming and hatcheries.