Probiotic Performance on Fish Fry during Packing, Transportation Stress and Post-transportation Condition

MATERIALS AND METHODS

Catla catla fry [initial Total Length (TL) = 1.97 cm and initial total weight (BW) = 800 mg] were collected from Subam Aquafarm, Kalidaikurichi, India and stocked into 2 tanks (capacity: 2000 L) for conditioning. During this time one tank was treated with probiotic at the rate of 10 ppm for 2 h. The other tank was not treated with probiotic. The fry from both treatment and control tanks were packed in plastic bags with at a density of 400 fry L^-1. The fry that previously received probiotic treatment were packed in water containing probiotic whereas the fry from the control tank was packed in water without probiotic. Six replicates (bags) were maintained for each treatment. The individuals were packed in the late evening (05:30 pm) and transported to the Center for Aquaculture Research and Extension (CARE), Palayamkottai, India, where the trial was conducted during August 2006. After arriving at CARE, the bags were left unpacked for 13 h. They were unpacked next day morning at 07:00 am. Survival was recorded immediately after unpacking. Fry from each bag was transferred to individual, shallow, plastic container (capacity: 60 L) at 25 fry L^-1. A post-stocking growth trial was conducted in the following manner (Fig. 1):

Treatment A
Fry that were treated with probiotic prior to and during transportation were treated with probiotic post-transportation (probiotic/probiotic).

Treatment B
Fry that were treated with probiotic prior to and during transportation were not treated with probiotic post-transportation (probiotic/no probiotic).

Treatment C
Fry that were not treated with probiotic prior to and during transportation were treated with probiotic post-transportation (no probiotic/probiotic).

Fig. 1:	Schematic diagram showing trial methodology

Treatment D
Fry that were not treated with probiotic prior to and during packing were not treated with probiotic post-transportation (no probiotic/no probiotic).

Probiotic was added at the rate of 10 ppm per day after water exchange, but before first feeding. The fry were fed ad libitum three times (08:30, 13:30 and 18:30 h) per day. The unfed feeds were siphoned out before feeding. Growth and survival were monitored for five days post-transportation.

RESULTS AND DISCUSSION

In the present study, treatment with probiotic prior to and during transportation resulted in higher fry survival immediately after transportation. Fry in water containing probiotic had a mean survival of 98.4% whereas fry not treated with probiotic had a mean survival of 92.5% (Table 1). Continuing probiotic treatment after transportation improved fry survival (Table 2) and fish size. Survival of the fry receiving probiotic was the highest survival (95.2%) and greatest final fry weight (1060 mg) five days post-transportation. Fry that were not treated with probiotic at any time during the trial gave the poor survival (89.5%) and lowest final weight (820 mg). Survival and final mean weight of fry that were treated with probiotic only prior to and during transportation were 91.3% and 970 mg, respectively and were marginally higher than those fry that were treated with probiotic only after transportation (91.2% and 930 mg, respectively). The growth and survival data of probiotic application before, during and after transportation were statistically significant with no application of probiotics.

Transportation stress is one of the primary contributing factors of fish disease and mortality in aquaculture. Under natural conditions fish often experience brief periods of stress, bringing about a temporary disturbance of homeostasis (Van-Weerd and Komen, 1998). Probiotics are inoculated into the rearing water to improve culture conditions or incorporated in the food of fish through diet (Nogami et al., 1997; Moriarty, 1998; Corre et al., 2001).

Probiotics composed of microbial cultures of yeast and bacteria widely used to improve the health of humans and livestock (Irianto and Austin, 2002). In black tiger shrimp, scallop, flounder, Atlantic salmon, rainbow trout and turbot, the growth and survival plus water and sediment quality of the farm environment were improved and the microbial flora in fish intestine, rearing water and feces were stabilized by addition of probiotics (Gatescope, 1994; Riquelme et al., 1997; Byun, 1997; Rengpipat et al., 1998; Robertson et al., 2000). The influence of microbial flora from the rearing water on the gastrointestinal flora of the cultured animal is widely recognized (Sugita et al., 1981).

Rengpipat et al. (1998) reported that probiotics added to shrimp diets did not affect water quality. However, when probiotics was added to the rearing water, the water quality slightly improved as compared to the case without probiotics (Corre et al., 2001; Chen and Chen, 2001). The inoculation of probiotics to the water during the transport in the present experiment remarkably influences water quality in terms of survival and growth.

Table 1:	Percentage survival of Catla catla treated with probiotic after 13 h of packing/transportation stress
Different alphabet between the row statistically significant at p<0.05 by students, t-test

Table 2:	Cumulative survival (%) of Catla catla fry during the post-transportation trial
Different alphabet between the row statistically significant at p<0.05 by students, t-test

The introduction of probiotics into the water before and during transport appeared to enhance not only survival but also growth of C. catla fry. The similar result was achieved on Japanese flounder by Taoka et al. (2006). Post transportation growth trials also showed that the introduction of probiotics to the rearing water accelerated the growth of C. catla and improved the survival significantly. The survival rate in the probiotic group was significantly higher than that in the control group. So the transportation stress tolerance of fish is enhanced by probiotics. The present study showed that probiotic treatment enhances not only the transport stress tolerance in cultured fish but also increased survival, growth and resistance to the pathogen by probiotics has been widely reported.

The probiotics application, as proved here, enhanced the resistance of the organisms to chemical-physical changes and to pathogen infections, as previously observed in other species (Westerdahl et al., 1991; Havenaar et al., 1992; Salminen et al., 1998), suggesting that probiotics might be a good alternative to the use of antibiotics in aquaculture. The results obtained in this study represent the first step towards the development of an environmentally friendly aquaculture. Moreover, since the products of aquaculture are devolved to human consumption, the use of probiotics as a live microbial feed supplement may represent a guarantee of a safer product for human health. The relevance of this study is that different from most of the work so far carried out on the use of probiotics. The treatment with probiotic improves the performance of fish fry after packing and transportation stress, but the magnitude of performance improvement depends on the length and timing of application

CONCLUSION

The trial clearly demonstrated the benefit of using probiotic in fish hatcheries. probiotic application prior to and during transportation increases fry survival immediately and for at least five days post-transportation. Extending probiotic application beyond transportation extended the effect of probiotic on fry survival. For this reason, probiotic use is recommended prior to, during and after the occurrence of stress. Probiotic is equally effective when used either ahead of transportation or after transportation. However, use ahead of transportation is recommended for reducing mortalities in transport. For the best results, probiotic should be used ahead of, during and after transport. Probiotics treatment also improves the growth of fish fry. This effect is probably because the treated animals are able to recover much faster from the stress than their untreated counterparts.

ACKNOWLEDGEMENT

The Bengis Centre for Desert Aquaculture, The Albert Katz Department of Dryland Biotechnologies, Jacob Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, Israel is gratefully acknowledged for providing the postdoctoral fellowship grant to the first author.