Introduction and methods
The current global growth of Penaeus vannamei aquaculture has increased the search for alternative protein sources to fishmeal. Meals derived from polychaetes (Hediste diversicolor) have emerged as promising candidates due to their high protein content and favorable amino acid profile for shrimp nutrition, suggesting benefits in protein digestibility and in the physiological resilience of shrimp under environmental stress conditions . Additionally, preliminary studies indicate that the partial inclusion of polychaete meal in diets for P. vannamei maintains growth and improves certain indicators of health and feed efficiency . Therefore, the present study aims to evaluate the effects of including polychaete meal in diets for P. vannamei, considering its influence on growth, nutrient digestibility, and resilience to stress.
First, three isolipidic, isoproteic, and isoenergetic diets were formulated using fishmeal (FM) and polychaete meal from H. diversicolor at different inclusion levels: 50% and 100% (POLI50 and POLI100). The polychaete was cultured at the IEO (Santander) and fed with organic by-products (brewer's spent grain). Subsequently, Penaeus vannamei individuals were distributed in triplicate for each experimental treatment and maintained in individual 90 L tanks within a RAS system, at a density of 222 shrimp/m3 per tank for 43 days. Individual growth was recorded every 15 days, and feces were collected daily. At the end of the experiment, zootechnical parameters were calculated. Last, nutritional analyses and markers in the feces (yttrium) were analyzed to determine the digestibility of the experimental treatments.
Results and discussion
The results indicate that the partial or total inclusion of polychaete meal (Hediste diversicolor) in diets for Penaeus vannamei did not significantly affect growth parameters or nutritional efficiency compared to the control diet based on fishmeal (FM). Furthermore, the final weight of the shrimp showed similar values between the control diet and the experimental treatments (Table 1), as observed in previous studies , where the replacement of fishmeal with alternative meals derived from polychaetes maintained the growth of L. vannamei under controlled conditions.
Likewise, polychaete meal showed an apparent digestibility coefficient (ADC %) (85.97 ± 0.680) similar to that of fishmeal (87.63 ± 1.250), in agreement with the results of , where the inclusion of marine worm meal up to 100% replacement did not compromise weight gain, digestibility, or survival.
Table 1. Growth performance and nutritional indexes of P.vannamei fed with the experimental protein sources.
FM
POLI 50
POLI 100
Final weight (g)
9.53±0.835
9.15±0.824
9.56±0.827
Survival (%)
86.7±2.635
86.7 ±2.635
86.7 ±2.635
SGR (%)
4.79±0.190
4.73 ±0.187
4.83 ±0.188
FCR (feed g/ shrimp g)
1.74±0.188
1.81 ±0.188
1.72 ±0.188
DFR (% gay-1)
5.81±0.488
5.95 ±0.488
5.78 ±0.488
GEC (srimp g/ feed g)
1.53±0.211
1.52 ±0.211
1.54 ±0.211
Note: SGR (Specific Growth Rate); FCR (Feed Convertion Rate); DFR (Daily Feeding Rate); GEC (Growth Efficiency Coefficient).
No statistically significant differences were observed in survival or in feed efficiency parameters, such as the Growth Efficiency Coefficient (GEC) or the Daily Feeding Rate (DFR). This could be attributed to bioactive compounds present in H. diversicolor, such as peptides and natural digestive enzymes, and the good digestibility, palability and ideal aminoaci profile, which may facilitate nutrient absorption and retention. Previous studies suggest that certain polychaetes can enhance protein digestibility and enzymatic activity in the hepatopancreas of crustaceans, which could explain this trend.
Last, it is worth highlighting that the use of marine polychaetes fed with by-products to feed shrimp during the pre-growing phase represents an excellent alternative to fishmeal, as it maintains growth, feed conversion ratio, protein efficiency ratio, and survival, while also promoting circular economy practices and the sustainability of aquaculture production.
Acknowledgment
This abstract is part of the R&D&I project PID2023-149570OB-I00, funded by MICIU/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR . It has also been funded by the Spanish Ministry of Science and Innovation with NextGenerationEU funds from the European Union (PRTR-C17.I1) and from the Government of Cantabria (Spain) through the ThinkInAzul program.M. Querol-Edo holds a predoctoral FPU contract (FPU24/00525) associated with the "ZeroFloc" Project PDI2023-149570OB-I00 and funded by MICIU/AEI/10.13039/501100011033.
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