Aquaculture Europe 2021

October 4 - 7, 2021

Funchal, Madeira

Add To Calendar 07/10/2021 14:30:0007/10/2021 14:50:00Europe/LisbonAquaculture Europe 2021COMMERCIAL FEED REPLACEMENT FOR A SUSTAINABLE AND SELF-SUFFICIENT INTEGRATED MARINE AQUAPONIC PRODUCTIONMezzanine-CasinoThe European Aquaculture Societyalistair@aquaeas.eufalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY

COMMERCIAL FEED REPLACEMENT FOR A SUSTAINABLE AND SELF-SUFFICIENT INTEGRATED MARINE AQUAPONIC PRODUCTION

 

Lorenzo Rossi1, Carlo Bibbiani1 , Alberto Pardossi2 , Chiara Sangiacomo1, Baldassare Fronte1*

 

 1  Department of Veterinary Science, University of Pisa, Pisa, Italy

 2 Department of Agriculture Food and Environment, University of Pisa, Pisa, Italy.

 

 * baldassare.fronte@unipi.it

 



Introduction

 Since Aquaculture is asked to produce sustainable animal proteins for the future growing world population, the large use of commercial feeds may represent a relevant bottleneck. Grains such as soybean, corn, wheat, barley, and  even more precious raw materials such as fish oil and fishmeal, are commonly produced far away from the consumption sites. Moreover, their intensive production represents itself a severe hazard in terms of environmental pollution, soil and sea overexploitation, and biodiversity reduction. Yet, the overseas transportation of large quantities of raw materials  and final products is characterized by a very high Carbon Footprint. In this context, an  environmentally sustainable alternative to  intensive  aquaculture  might be  the Integrated Multi-Trophic Aquaculture approach.  Stemming from IMTA, the Self-sufficient Integrated MultiTrophic AquaPonic system (SIMTAP , H2020 PRIMA-Programme ) encompasses  four  consecutive trophic levels , starting from microalgae, deposit-  and filter-feeder organisms (DFFO), fish and plants, reared in a recirculating system using saltwater.

In the SIMTAP system, micro- and macro-algae are raised for feeding DFFO, which in turn are harvested for feeding (or partially sold) fish; finally, solid fish wastes  “feed-back” DFFO, while  soluble wastes such as nitrogen and phosphorous are absorbed by hydroponically grown halophytes, salt-tolerant glicophytes and macro-algae , w ith that bio-remediat ing the recirculating water.

The DFFO are heterotrophic species such as polychaetes, bivalves, and echinoderms, which may represent a sustainable, nutritionally valuable, alternative to fish oil and fish meal in fish nutrition.

 To evaluate how the use of these organisms may affect  the growth performances of carnivorous fish species, two different trials have been carried out so far. The first consisted in  the diet inclu sion of increasing rates of mussels , until totally replacing the commercial feed . In the second trial,  the commercial feed was fully replaced by a mixture of mussels and clams.

Material and Methods

 All the experimental procedures were approved by the  Organism for  Animal  Welfare of the University of Pisa and the Italian Ministry of Health (authorization code: B290E.N.AHZ) .  The trials were carried out using six  cylindric 420  L tanks of the SIMTAP system located at the Department of Agricultural Food and Environment of the University of Pisa (Pisa, Italy).

J uveniles of Gilthead Sea Bream (Sparus aurata ) were used and  daily  fed at 3% ( on dry matter base )  of their  live body weight (BW) .  The  diet ingredients used were the following: INVE©  O. range  P15 as  commercial feed; frozen mussels (Mytilus platensis) and clams (Chamelea gallina) as feed replacers. T he  fish  biomass of each tank was weighed  every week in order to adjust the  amount  of diet to be supplied ; then, Feed Conversion Rate (FCR), Condition factor (Kf) and Specific Growth Rate (SGR) were calculated per each tank and dietary treatment . On day 0 and at the end of the experiment, fish were weighed and measured individually (total length, TL). At the end of the experiments , 25 fish from each tank were also euthanized  with an overdose of tricaine methanesulfonate (MS222©), dissected for abdominal viscera and liver weight determination, and calculating Viscera-Somatic  (VSI)  and Hepato-Somatic  (HSI) indexes.

Experiment 1: 1, 243 fish  (mean weight 4.95±1.120 g; mean total lengths 7.39±0,600 cm)  were distributed in the 6  dietary treatments: F100M0 (100% feed), F80M20 (80% feed, 20% mussels), F60M40 (60% feed and 40% mussels), F40M60 (40% feed, 60% mussels), F20M80 (20% feed, 20% mussels) and F0M100 (100% mussels). After tawing, mussels were minced, and  diets supplied 4 time per day.

Water temperature, salinity and pH approximately maintained at  24 °C, 32 g L_1, 7.6, respectively, and DO above 6 mg L-1.

 Experiment 2: 1,255 fish (mean weight 6,78± 1,41 g; mean total lengths 8,06±0,65 cm )  were  used. Again, f ish were divided into 2 dietary treatments and 3 replicates : F100 (100% feed) and M100, this latter consisting of  a mixture of  50%  and  50%  tawed and minced mussels and clams , respectively. W ater temperature, salinity and pH were  kept at 22 °C, 25 g L-1, 7.5, respectively ,  and DO above 6 mg L-1.

Statistical analysis: One-Way ANOVA followed by Tukey-Kramer HSD (Honestly Significant Difference) for the Experiment 1 and Student’s test for the Experiment 2 were used for statistical analysis of growth performance parameters. Differences were considered significant at P<0.05.

Results

Experiment 1: t hawed minced mussels showed significantly higher palatability than  dry commercial  feed, with fish  intensively  competing for catching mussel particles . On day 0 , groups F100M0, F0M100 showed significantly lower (P<0.05)  initial BW (4.76±1.074 and 4.76±1.042 g, respectively) than groups F80M20, F60M40 and F40M60 (4.86±1.076, 5.10±1.216 and 5.17±1.078, respectively) . T hese differences  were not anymore  significant on  day 28 and 35 while on day 42 the group fed 100% mussels  (F0M100) showed the lowest BW (13.02±2.608) , significantly different (P<0.05) from the group fed 100% commercial feed (14.69±3.498) . Moreover, this latter group showed a significantly lower  (P<0.05) BW than the group fed 60% commercial feed and 40% mussels (15.57±3.327). T he group F0M100 showed the highest cumulative FCR (1.11), followed by the group F80M20 (1.06),  F20M80  (1.04),  F40M60  (1.02),  F100M0 (1.01), and F60M40 (0.98). 

 

Experiment 2: as observed in  Experiment 1, fish fed on thawed minced mussels and clams  showed higher competiti veness  for the  diet than those fed on commercial feed. Regarding initial  BW  and TL  no  significant differences  were observed among treatments: 6.82±1.446 g and 8.08±0.638 cm for F100 and 6.75±1.378 g and 8.04±0.657 cm for M100.  On day  48 of  the  experimental period,  treatment  F100 showed  significantly  higher BW and TL than M100: 23.62±4.471 g and 11.66±0.837  cm for F100 , 20.83±3.943 and 11.40±0.704 cm for M100.  Mean  weight gain was significantly higher  for treatment F100  than for M100: 3,522.12±90.015 g and 2,884.16±150.177 g, respectively. Also,  FCR w as  significantly different among treatments : 0.88±0.050 for F100 and 1.05±0.062 for M100.  Statistical analysis of TL, SGR, Kf, VSI and HSI data of both experiments is in progress.

Discussion and Conclusion

In general, results suggest better Gilthead Sea Bream  growth  performances when  mixed diets  are used. In fact, the use of mussels as only diet ingredient reduced fish growth b y 11.3% and 16.4%  in comparison to commercial feed and  to  a  diet consisting of a mixture 60% commercial feed and 40% mussels , respectively. Similar results were observed also when a diet consisting of 50% mussels and 50% clams rather than mussels only was used.  Probably, the enrichment of the wet diet mixture with the introduction of additional ingredients such as polychaetes and/or echinoderms , may improve its nutritional value and fish growth performances enhanced. 

Acknowledgments

 The Authors thanks Blue Resolution® association (Monsummano Terme – Italy) for kindly supplying frozen mussels and clams. SIMTAP is part of the PRIMA Programme supported by the European Union.