From fish‐processing waste to feed additives for crayfish

Abstract

This research studied the in vitro compatibility of Cherax quadricarinatus digestive proteases and crude enzyme extracts recovered from fish‐processing waste to evaluate their potential use as feed additives to increase digestion efficiency in decapod crustaceans. The sources of exogenous enzymes were: Pleoticus muelleri (Pm), Artemesia longinaris (Al), and Illex argentinus (Ia). The midgut glands of early (7.2 ± 0.34 g) and advanced juveniles (13.8 ± 1.49 g) of C. quadricarinatus were used for all the assays. The compatibility and synergy between crayfish and exogenous enzymes were evaluated through sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) electrophoresis and the hydrolysis of azocasein and four different meals. SDS–PAGE gels demonstrated that crayfish bands remained active when their enzymes were combined with the enzymes from Pm and Ia. An apparent enzymatic synergism was found when Pm and crayfish proteases were incubated together at pH 6 and 8 with azocasein (p ˂ 0.05). The ability to hydrolyze the different feed ingredients varied among the enzyme combinations assayed. Our findings suggest that fish waste has potential as a source of proteases, adding value to these processing residues and promoting a zero‐waste industry. Enzymes obtained from Pm and Ia are suitable to be used as food additives for crayfish. The results should be validated through feeding trials.

Exogenous proteases from seafood processing waste as functional additives in rainbow trout aquaculture

“…A fish farm from Junín de los Andes (Neuquén, Argentina) provided the viscera from O. mykiss. Two different fish sizes were utilized because previous works demonstrated that exogenous enzymes could exert varied effects depending on the organism's weight (Rodriguez et al, 2017(Rodriguez et al, ,2019. Stomachs and intestines with pyloric caecas of ten fish weighing 21.1 ± 3.02 g (Om1, n = 5) and 58.3 ± 5.73 g (Om2, n = 5) were sampled.…”

“…Electrophoresis was carried under 30 mA per gel with a constant power supply unit at 4°C. After electrophoresis, gels were stained as described by Rodriguez et al (2019).…”

“…Consequently, enzymes extracted from seafood processing waste could be valuable for the aquaculture food industry as enzyme additives. Rodriguez et al (2017), Rodriguez et al, (2019) successfully extracted exogenous proteases from different fishery wastes and showed the potential for some proteases to be exploited as feed additives for aquaculture. However, such research aimed to improve the digestion of tropical species as Nile tilapia ( Oreochromis niloticus ) and Australian redclaw crayfish ( Cherax quadricarinatus ) (Meade et al, 2002; Trewavas, 1983).…”

Also in Crayfish: How Phytase Inclusion Avoids Phytic Acid Effects on Hepatopancreas Enzymes of Redclaw Cherax quadricarinatus

“…In view of this, we decided to work with the redclaw as a decapod crustacean model through in vitro assays. Previous research on this species involved the incubation of an ingredient with enzymes [36], a pH drop [37], and bioreactors with a semipermeable membrane [38], checking its performance for nutritional studies. Tis work carried out a completely randomized in vitro assessment of the efects of PA and phytase on the enzymatic activities of the hepatopancreas of C. quadricarinatus, and the hydrolysis products released.…”