Protein hydrolyzates, silk

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientifically accepted study

Data source

Reference

Reference Type:

publication

Title:

Effects of different dietary levels of fish protein hydrolysates on growth, digestive enzymes, gut microbiota, and resistance to Vibrio anguillarum in European sea bass (Dicentrarchus labrax) larvae

Author:

Y.P. Kotzamanis, E. Gisbert, F.J. Gatesoupe, J. Zambonino Infante, C. Cahu

Year:

2007

Bibliographic source:

Comparative Biochemistry and Physiology, Part A 147 (2007) 205–214

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Four compound diets were formulated (Table 1). In diets S19 and C19, the protein hydrolysate – consisting of sardine silage (SH, 42% crude protein) and a commercial enzymatic FPH (CPSP, Concentré Protéique soluble de Poisson, Sopropêche,
Boulogne-sur-Mer, France, 82% crude protein), respectively – was incorporated at a level of 19%. The remaining of the dietary protein fraction was supplied by fishmeal (Norse LT 94). The diet with 19% CPSP (C19) corresponded to the one that gave the best results when tested by Cahu et al. (1999), and was used as a control. In diets S10 and C10, replacement of fishmeal with sardine silage or CPSP was limited to 10%. The ingredients were mixed with water, pelletized and dried at 60 °C for 25 min. The pellets were then sieved to obtain a particle size of 200–400 μm.

At 17 and 26 dph, 20 larvae from each rearing tank were sampled before the daily food distribution to count bacteria, according to the methods previously described (Gatesoupe, 1995).

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

fish protein hydrolysates

IUPAC Name:

fish protein hydrolysates

Details on test material:

Two fish protein hydrolysates (FPH) were incorporated into four diets prepared for start-feeding sea bass larvae, at two different levels (10%
and 19% of total ingredients): a commercial FPH, CPSP, in which the molecular mass of the main fraction of soluble peptides (51%) was between
500–2500 Da, and an experimental FPH obtained by acidic silage of sardine offal, SH, with a main portion of soluble peptides (54%) ranging
from 200 to 500 Da.

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

other: European sea bass (Dicentrarchus labrax) larvae

Study design

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

33 d

Results and discussion

Effect concentrations

Duration:

33 d

Dose descriptor:

LOEC

Effect conc.:

19 other: %

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Any other information on results incl. tables

Sublethal observations / clinical signs:

After 3 days of challenging with V. anguillarum, the larvae fed on diet S19 until 16 dph presented a significantly lower

mortality rate than those of groups C10 and C19 in one-way analysis (9 vs. 19–23%, Table 6). Meanwhile, mortality was

between 0% and 2% in control bottles without infection, except in one corresponding to diet S10 (5%). Two-way analysis of

variance indicated that the dose of FPH had no effect on mortality after infection, and that interaction was not significant,

whereas the difference due to the type of hydrolysate was highly significant.

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Conclusions:

In the present study, two types of fish protein hydrolysates and two dietary inclusion levels were tested in the diets of sea bass larvae from mouth opening until day 33. The main differences between the hydrolysates related to the molecular weight distribution of their peptides and their degree of solubility, both of which originated from the different hydrolysis procedures applied. The results indicated that SH hydrolysates were less soluble and contained a larger proportion of short peptides, namely di-/tripeptides, than CPSP hydrolysate. Amino acid analysis was not performed, since little
variation was observed in the amino acid composition of either FPH or fishmeal produced from different fish species (Hertrampf and Piedad-Pascual, 2000).
The incorporation of CPSP hydrolysates (treatment C10) in the diet at a concentration of 10% effectively improved growth, survival and the intestinal development of sea bass larvae. At 15 dph, the diets with low replacement rates for fishmeal by FPH (10% of total ingredients) produced improved growth of sea bass larvae with respect to diets with higher replacement rates of 19%, such as those already tested by Cahu et al. (1999).
After that day and until the end of the trial (day 33), the best growth and survival rates were obtained with the low dose of CPSP, whereas the worst was observed with the low dose of the experimental sardine hydrolysate