Enhanced Mineral Digestibility, and Tissue Retention in Rainbow Trout (Oncorhynchus Mykiss) Fed Lupin Meal with a Solid-State Fermentation (SSF) Dietary Supplement

Simon J. Davies; Ehab El Haroun; Hien Van Doan; Peter H. Bowyer

doi:10.2478/aoas-2025-0056

Enhanced Mineral Digestibility, and Tissue Retention in Rainbow Trout (Oncorhynchus Mykiss) Fed Lupin Meal with a Solid-State Fermentation (SSF) Dietary Supplement

Annals of Animal Science

Volume 26 (2026): Issue 1 (January 2026)

By: Simon J. Davies, Ehab El Haroun, Hien Van Doan and Peter H. Bowyer

Open Access

|Jan 2026

Figures & Tables

Table 1.

Feed formulations, proximate compositions, and element concentrations of the basal and control trout diets with Synergen SSF addition for rainbow trout

	LC (basal)	FMR (fishmeal reference)
Ingredients (g/kg)
Yellow lupin	300.00	0.00
Herring meal¹	250.00	638.62
Soya bean meal²	180.71	0.00
Fish oil³	137.15	119.97
Corn starch⁴	70.14	229.40
Soya protein concentrate⁵	50.00	0.00
Carboxyl-methyl-cellulose⁶	5.00	5.00
Vitamin/mineral premix⁷	5.00	5.00
Ascorbyl-phosphate⁸	1.00	1.00
Yttrium oxide⁹	1.00	1.00
Synergen™ ^**	–	–
Proximate composition (%)
Dry matter (DM)	99.30	99.23
Crude protein (N*6.25)	43.07	44.01
Crude lipid	20.47	19.80
Crude fibre	2.70	–
Ash	6.60	6.70
Gross energy (MJ/kg)	21.66	23.21
Element concentrations
Ca (g/kg)	78.01	157.61
P (g/kg)	80.26	136.17
K (g/kg)	104.30	64.42
Na (g/kg)	44.55	86.67
Mg (g/kg)	17.78	13.40
S (g/kg)	38.05	54.11
Fe (g/kg)	1.58	1.36
Zn (mg/kg)	644.74	777.46
Mn (mg/kg)	801.62	67.86
Cu (mg/kg)	133.56	73.42

1 LT94 herring meal (CC Moore, UK);

2 HP100 (Hamlet, DK);

3 Epanoil (Seven Seas, UK);

4 Sigma Aldrich, UK;

5 SPC 60 (BioMar, DK);

6 Sigma Aldrich, UK;

7 PNP fish: ash 78.7%, Ca 12.1%, Mg 1.56%, P 0.52%, Cu 0.25 g/kg, vit. A 1.0 µg/kg, vit D₃ 0.1 µg/kg, vit. E 7 g/kg (Premier Nutrition, UK);

8 Rovimix (DSM, UK);

9 Sigma Aldrich, UK.

{ label (or @symbol) needed for fn[@id='j_aoas-2025-0056_tfn_010'] } LC = yellow lupin control diet; FMR = fishmeal reference diet.

** Synergen™ (S) added at two levels 0.1 and 0.05 representing two diets LS0.1 and LS0.5.

Histological sections of the 47th–48th vertebrae of fish fed the experimental diets (4 fish per triplicate, total of 12 sampled fish per treatment group). Vertebral and scale morphology, remodelling and mineralisation were then assessed by histomorphometry and colorimetric assays. No significant effects of diet on the measured parameters were detected for the parameters assessed. However, more uniform mineralisation is observed in the centrum region of vertebrae taken for rainbow trout fed the higher SSF Synergen^TM diet. This could be due to greater calcium and phosphorous bioavailability

Table 2.

Tissue mineral concentrations of liver, muscle, vertebrae, and caudal fin in experimental fish with Synergen SSF (S) supplemented lupin diets respectively and fishmeal reference (FMR diet) (± SD)

	Diet
	LC	LS0.1	LS0.5	FMR
1	2	3	4	5
Liver
P (mg/g)	11.72±0.27	11.68±0.45	11.40±0.54	11.64±0.20
K (mg/g)	11.54±1.13	11.56±0.46	11.70±0.31	11.85±0.59
S (mg/g)	8.43±0.56	8.59±0.23	8.58±0.57	8.84±0.34
Na (mg/g)	4.23±0.51	4.29±0.09	4.32±0.31	4.69±0.16
Mg (mg/g)	0.74±0.05	0.77±0.02	0.75±0.04	0.76±0.04
Ca (mg/g)	0.38±0.10	0.46±0.12	0.44±0.29	0.45±0.08
Cu (mg/g)	0.30±0.02	0.28±0.02	0.27±0.02	0.26±0.07
Fe (mg/g)	0.19±0.05	0.17±0.03	0.18±0.02	0.15±0.03
Zn (mg/g)	0.15±0.01 a	0.16±0.02 a	0.16±0.01 a	0.20±0.01 b
Mn (µg/g)	4.12±0.12 a	4.39±0.49 ab	4.90±0.34 b	2.70±0.27 c
Muscle
K (mg/g)	14.73±0.80	14.59±0.30	14.13±0.65	14.97±0.09
P (mg/g)	8.59±0.27	8.59±0.29	8.43±0.17	8.77±0.15
S (mg/g)	7.64±0.05	7.71±0.11	7.64±0.25	8.00±0.27
Na (mg/g)	2.42±0.06	2.38±0.06	2.38±0.09	2.19±0.14
Mg (mg/g)	0.99±0.04	0.98±0.03	0.94±0.02	0.96±0.01
Ca (mg/g)	0.81±0.11	0.98±0.09	1.05±0.24	0.83±0.12
Zn (µg/g)	16.27±0.18	17.41±1.00	17.33±0.68	17.51±0.77
Fe (µg/g)	12.03±1.78	11.98±1.39	11.89±1.82	11.94±1.63
Mn (µg/g)	0.61±0.20 ab	0.77±0.23 a	0.93±0.07 a	0.40±0.18 b
Vertebrae
Ca (mg/g)	93.81±9.01	91.29±6.02	87.50±3.99	90.68±7.73
P (mg/g)	56.69±4.44	55.99±3.00	54.66±2.09	55.88±4.06
Ca:P	1.65±0.03 a	1.63±0.02 b	1.60±0.02 c	1.62±0.02 bc
Na (mg/g)	15.99±0.75	16.11±0.47	16.91±0.13	15.74±0.62
K (mg/g)	7.38±0.85	7.38±0.47	8.06±0.25	7.96±0.69
S (mg/g)	3.30±0.06	3.32±0.08	3.43±0.15	3.44±0.09
Mg (mg/g)	2.11±0.18	2.09±0.07	2.08±0.05	2.02±0.12
Zn (µg/g)	76.68±7.82	85.33±0.72	85.79±12.72	93.95±8.80
Mn (µg/g)	12.30±3.32 a	13.14±0.70 a	14.21±2.25 a	6.23±1.06 b
Caudal fin
Ca (mg/g)	106.90±5.08	103.90±4.67	107.32±2.58	98.90±2.63
P (mg/g)	62.07±4.36	59.73±7.46	58.97±3.73	51.91±4.13
Na (mg/g)	44.62±1.14 ab	33.16±5.51 c	39.14±2.54 bc	48.82±3.21 a
K (mg/g)	5.30±0.28 a	7.41±0.38 b	6.81±0.81 b	5.39±0.24 a
S (mg/g)	5.40±0.06 a	5.32±0.22 a	5.42±0.10 a	5.80±0.05 b
Mg (mg/g)	2.25±0.10 ab	2.36±0.18 a	2.36±0.08 a	2.05±0.05 b
Zn (µg/g)	95.78±7.11	95.15±12.54	104.29±3.86	102.57±6.40
Mn (µg/g)	15.37±3.21 a	16.38±1.21 ab	19.71±2.40 b	8.30±1.33 c

[i] Ca = total calcium; P = total phosphorus; Mg = total magnesium; K = total potassium; S = total sulphur; Fe = total iron; Zn = total zinc; Mn = total manganese; Na = total sodium; Cu = total copper; Co = total cobalt; Cr = total chromium.

[ii] LC = yellow lupin control diet; LS0.1 = yellow lupin basal + Synergen™ (S) (0.1%); LS0.5 = yellow lupin basal + Synergen™ (0.5%); FMC = fishmeal reference/control diet.

[iii] Values expressed as a mean of 3 replicates (9 fish per tank, 27 per treatment group) ± SD; Statistical tests: ANOVA + Fisher’s LSD.

Table 3.

Apparent macronutrient digestibility coefficients (ADC) (%) and apparent mineral bioavailability coefficients (ABAC) (%) of the experimental lupin-based and fishmeal-based rainbow trout diets with SSF (S) (± SD)

	Diet
	LC	LS0.1	LS0.5
ADC (%)
DM	96.97±0.43	96.71±0.21	97.08±0.69
CP	83.65±0.02 a	85.26±0.03 b	85.55±0.03 c
CL	89.11±0.77	88.93±0.10	90.43±0.79
CF	33.99±1.05 a	35.52±1.60 a	44.69±2.62 b
GE	66.29±0.62 a	68.41±0.83 b	71.76±0.15 c
ABAC (%)
Ca	0.67±1.57 a	13.80±1.62 b	20.20±0.77 c
P	55.02±0.72 a	63.86±0.69 b	73.53±0.47 c
Mg	33.43±0.03 a	42.91±0.64 b	51.27±0.45 c
K	92.14±0.05 a	93.30±0.06 b	94.04±0.11 c
S	53.82±0.35 a	58.97±0.37 b	62.00±0.72 c
Fe	41.77±2.19 a	48.34±1.99 b	39.59±0.83 a
Zn	29.39±0.96 a	30.41±2.68 a	41.59±3.96 b

[i] DM = dry matter; CP = crude protein; CL = crude lipid; CF = crude fibre; GE = gross energy; Ca = total calcium; P = total phosphorus; Mg = total magnesium; K = total potassium; S = total sulphur; Fe = total iron; Zn = total zinc. LC = yellow lupin control diet; LS0.1 = yellow lupin basal + Synergen™ (0.1%); LS0.5 = yellow lupin basal + Synergen™ (0.5%); FMC = fishmeal reference/control diet.

[ii] Values expressed as a mean of 3 replicates (9 fish per tank, 27 fish per treatment group) ± SD; Statistical tests: ANOVA + Fisher’s LSD.

Table 4.

Proteolytic enzyme activities in digesta and mucosa of fish fed the lupin-based diet, with and without SSF (S) inclusions

	Diet
	LC	LS0.1	LS0.5
Digesta
TAP^* (U/g)	17.50±3.75	16.03±1.26	17.71±1.32
Trypsin (U/g)	68.18±21.31	66.97±14.02	65.03±13.89
Chymotrypsin (U/g)	325.50±129.00	290.29±27.89	368.57±98.38
ALP (U/g)	51.64±8.94 a	78.92±17.14 b	79.37±20.56 b
LAP (U/g)	5.91±1.27 a	7.61±2.85 b	8.50±1.06 b
Mucosa
ALP (U/g)	216.73±56.31	203.24±57.98	169.73±68.43
LAP (U/mg)	837.87±225.36	737.07±113.59	692.20±102.33

TAP = total alkaline protease; ALP = alkaline phosphatase; LAP = L-leucine aminopeptidase.

* 10⁻³. Values expressed as a mean of 3 replicates (8 fish per tank, 24 total per treatment group) ± SD. Statistical tests: ANOVA + Fisher’s LSD.

Table 5.

Bone histomorphometric indices of the 47th–48th vertebrae of rainbow trout fed the experimental diets respectively

	Diet
	LC	LS0.1	LS0.5	FMR
CTI	7.04±1.31	7.32±0.43	6.76±0.83	7.88±0.79
VPA	6.72±1.44	6.23±0.87	6.57±0.74	5.99±1.14

[i] CTI = centrum thickness index; VPA = vertebrae perimeter: centrum area ratio.

[ii] Values expressed as mean ± S.D. Statistical tests: ANOVA (n = 3).

[iii] (4 fish per triplicate tank, 12 fish total per treatment group).

References

Authors

Metrics

Articles in this issue

DOI: https://doi.org/10.2478/aoas-2025-0056 | Journal eISSN: 2300-8733 (formerly 1642-3402) | Journal ISSN: 1642-3402

Journal RSS Feed

Language: English

Page range: 375 - 385

Submitted on: Sep 9, 2024

Accepted on: May 12, 2025

Published on: Jan 30, 2026

Published by: National Research Institute of Animal Production

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

lupin meal,

solid-state fermentation (SSF),

rainbow trout,

mineral digestibility and retention

Related subjects:

Medicine,

Veterinary medicine

© 2026 Simon J. Davies, Ehab El Haroun, Hien Van Doan, Peter H. Bowyer, published by National Research Institute of Animal Production
This work is licensed under the Creative Commons Attribution 3.0 License.

Volume 26 (2026): Issue 1 (January 2026)

Enhanced Mineral Digestibility, and Tissue Retention in Rainbow Trout (Oncorhynchus Mykiss) Fed Lupin Meal with a Solid-State Fermentation (SSF) Dietary Supplement

Figures & Tables

Table 1.

Figure 1.

Table 2.

Table 3.

Table 4.

Table 5.

Paradigm

My account