Abstract
Conventional aquaculture feed materials available in Australia are expensive, which has prompted the search for alternatives that would be cost-effective and locally available. The present study was undertaken in order to maximize the use of a tuna hydrolysate (TH), which was produced locally from the tuna-processing discards. The growth performance, biochemical status, antioxidant capacity and liver health of juvenile barramundi (Lates calcarifer) were assessed. Two series of isonitrogenous and isocaloric diets labelled as TH50, TH75 (non-fermented tuna hydrolysate) and FTH50, FTH75 (fermented tuna hydrolysate) were formulated to replace FM at 50% and 75%, respectively. A basal diet without the TH supplementation was used as a control. The experimental diets were fed to the triplicate groups of fish three times a day for 56 days. The results of the experiment revealed that fish fed on both fermented and non-fermented TH-containing diets significantly reduced (p < 0.05) the final body weight, weight gain and specific growth rate compared to the control. The highest apparent digestibility coefficients for dry matter, protein and lipid were obtained in the control group, and decreased with the increasing level of TH in the diets. However, the whole-body proximate compositions and the blood biochemical indices of fish were not affected by the TH inclusion in the diets. The fish fed on TH diets of TH50, FTH50 and TH75 exhibited reduced (p < 0.05) glutathione peroxidase (GPx) activity compared to the control; whereas the FTH75 exhibited no difference with the control. The excessive inclusion of TH in the diets of TH75 and FTH75 resulted in cytoplasmic vacuolization, with an increased amount of lipid accumulation, and necrosis in the liver tissue. These results indicated that the replacement of the FM protein with TH at 50% and 75% inclusion levels negatively affected the growth performance, feed utilization, and digestibility in juvenile barramundi; and it also increased the potential risk of hepatic failure in the fish. Further investigation is, therefore, required in order to optimize the TH levels in the fish diets which would be suitable for the growth of fish, as well as for maintaining the enhanced biochemical response in juvenile barramundi.
Highlights
Fish-processing industries produce a large volume of fish waste across the globe as the fillets are often the only desired product in the market (Knuckey et al, 2004)
The feed conversion ratio (FCR) was significantly higher in the fish fed on TH75 diet compared to the fish which were fed on all the other diets, except for the fermented-tuna hydrolysate (TH) group of the same replacement level—FTH75
No significant difference was observed in the FCR among the groups of fish fed on the control, TH50, and FTH50 diets
Summary
Fish-processing industries produce a large volume of fish waste across the globe as the fillets are often the only desired product in the market (Knuckey et al, 2004). FPH, because of their short-chain peptides and well-balanced amino acids, are absorbed by animals and facilitate the biological nutrients uptake (Carvalho et al, 2004). Beneficial effects, such as growth enhancement, feed utilization, and survival, have been reported for the inclusion of FPH at moderate levels (5% to 30%) in the fish diets, these bioactive substances have been reported to result in an increase in the innate immune response (Liang et al, 2006), gut enzymatic activity (Cahu et al, 1999), disease resistance (Khosravi et al, 2015b), and stimulation of digestibility (Kousoulaki et al, 2013). In addition to good nutritive values and functional properties, some authors have reported that FPH plays a substantial role in the fish health as promoters for antioxidant and antimicrobial activities (Bougatef et al, 2010; Chalamaiah et al, 2012)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
