With the constant evolution in feed regulation, the emergence of new environmental constraints and the global reduction of crucial raw materials such as fish meal, it is becoming more challenging to combine high productivity with sustainable practices. Many studies have already shown that the growth performance of feeds subjected to high replacement levels of fish meal are not adequate in terms of palatability and nutritional efficiency.
M. HERAULT1, A. NUNES2, V. FOURNIER1
AQUATIV – ZA du Gohélis 56250 ELVEN, FRANCE Tel: 33 (0) 2 97 93 80 80 www.aquativ-diana.com
LABOMAR/Instituto de Ciências do Mar – Fortaleza, CEARA, BRAZIL firstname.lastname@example.org
One of the explanations for the loss of performance is the reduction of specific low molecular weight active nitrogen compounds (peptides, nucleotides, amino acids derivatives…) when fish meal levels are reduced. These compounds boost animal growth and are not found in plant-based raw materials traditionally used in shrimp feeds. AQUATIV, manufacturer of Functional Hydrolysates for Aquafeeds, makes the most of its industrial worldwide network (8 subsidiaries including 3 plants in South & Central America) to have access to high quality fisheries and aquaculture raw materials (squid, sardine, tuna, tilapia, shrimp…). Some of these ingredients, when hydrolyzed under the right conditions, are able to generate a very high level of low molecular weight nitrogen compounds. These are highly palatable and contain nutritional and bioactive properties which enhance the performance of marine shrimp feeds. A trial managed by Alberto Nunes at LABOMAR’s aquaculture facilities (Fortaleza, Brazil) was conducted to assess Litopenaeus vannamei growth performance when fed a Low Fish Meal diet supplemented with AQUATIV’s Functional Protein Hydrolysates.
MATERIALS AND METHODS
After a nursery and acclimation period, size-graded shrimp (2.28 g ± 0.01, CV < 10%) were randomly assigned to 30 cylindrical tanks (500 L/0.57 m² tanks; clear water; seawater recirculating system) under 70 shrimp/m². Shrimp were fed for 72 days with a Low Fish Meal (LFM) diet containing 37% crude protein (CP) and 9% crude fat (CF). The LFM diet served as the base for the formulation of other experimental diets which contained either one of the four AQUATIV’s Functional Protein Hydrolysates (FPH 1, 2, 3 & 4) at 5% or 3% of Whole Squid Meal (WSM, 69% CP & 5% CF) (Table 1). Experimental diets were lab-extruded and then evaluated for feed texture (water absorption and dry matter leaching) at LABOMAR, using an in-house procedure.
Shrimp were fed in excess with experimental diets (n=5) three times a day using a 150 cm² feeding tray per tank, with collection of feed waste before each new ration. Individual feed rations were adjusted daily based on feed remains observed from the previous day.
Water quality was controlled daily (T°, DO, S‰) in each tank. Intermediate weight sampling (n = 10 per tank) was carried out on the 24th and 48th days of the trial period. At the end of the trial, shrimp were counted and individually weighted. Survival, feed intake, growth rate and FCR (Feed Conversion Ratio) were then calculated.
Results were statistically analyzed through a one way ANOVA followed, when appropriate, by a post hoc Fisher's least significant difference (LSD) test.
RESULTS AND DISCUSSION
There was no statistical difference between treatments for water quality parameters (salinity: 35 ± 1.3 ppt, pH: 7.95 ± 0.42; temperature: 28.9 ± 0.93°C), as well as for feed texture (water absorption and dry matter leaching) and for survival rate (means: 84.5 ± 3.2%, table 2). At the end of the trial, all diets containing AQUATIV’s FPH performed better than the LFM control and WSM diets. However, only AQUATIV’s FPH 3 diet promoted a significantly higher shrimp growth rate than the one observed for WSM diet (figure 1). Nevertheless, growth rates observed for other FPH diets were all 10% higher than the growth rate observed for WSM diet.
Due to a high variability in the result, there was no significant difference among dietary treatments for apparent feed intake and FCR. However, it may be seen that growth differences observed between FPH diets and LFM or WSM diets, were mostly explained by the FCR differences. Thus, diets containing FPH showed, on average, a FCR which were 17% and 11% lower than the ones observed for LFM and WSM diets, respectively (table 2).
Despite a higher protein content in WSM, AQUATIV’s FPH 1 & 3 (squid-based FPH) contain much more soluble nitrogen compounds than WSM (Table 3). AQUATIV’s FPH molecular weight profiles also indicated a high proportion of peptides <1000Da (34% to 63% of soluble proteins) compared to WSM (3%). The increased dietary level of small peptides clearly impacted shrimp and feed performances. This provided strong evidence of the importance of these low molecular weight nitrogen compounds in shrimp feeds. In addition to traditional dietary amino acid profiles, it is critical that feeds also display peptide molecular weight profiles.
It is now well documented that small peptides show many biological properties (palatability, hormone- like, antimicrobial, antioxidant…). The hydrolysis process for a same raw material results in a higher peptide recovery than the ordinary meal manufacturing process.
The present study has shown it is possible to significantly boost L. vannamei feed performance, and ultimately shrimp production, with low fish meal diets, thanks to the supplementation of Aquativ’s Functional Protein Hydrolysates. Although WSM is traditionally used as an attractant and/or a growth factor in shrimp feeds, this study has found that AQUATIV’s Functional Protein Hydrolysates act as more powerful growth accelerator due to a more appropriate and proprietary manufacturing process.