Effects of Dietary Yeast Culture on Humoral and Mucosal Immunity, Gut Microbiota, Hepatic Antioxidant and Stress Responses in Rainbow Trout, Oncorhynchus mykiss

Seyyed Morteza Hoseini; Morteza Yousefi; Evgeny Vladimirovich Kulikov; Yury Anatolyevich Vatnikov

doi:10.2478/aoas-2025-0093

Effects of Dietary Yeast Culture on Humoral and Mucosal Immunity, Gut Microbiota, Hepatic Antioxidant and Stress Responses in Rainbow Trout, Oncorhynchus mykiss

Annals of Animal Science

Volume 26 (2026): Issue 3 (August 2026)

By: Seyyed Morteza Hoseini, Morteza Yousefi, Evgeny Vladimirovich Kulikov and Yury Anatolyevich Vatnikov

Open Access

|Sep 2026

Figures & Tables

Table 1.

Growth performance and feed efficiency of rainbow trout fed the control diet or diets supplemented with 10⁷ (Y7) and 10⁸ (Y8) cfu/g yeast. Data are mean ± SD of three replicates

	Initial weight (g)	Final weight (g)	SGR (%/d)	WG (%)	FCR
Control	10.1±0.06	19.9±0.40	2.24±0.05	96.0±2.98	1.02±0.03
Y7	10.1±0.15	19.8±0.59	2.25±0.06	96.3±3.54	1.01±0.04
Y8	10.0±0.15	19.5±0.21	2.22±0.08	94.7±4.80	1.03±0.05
P-value	0.966	0.641	0.863	0.866	0.855
F-value	0.467	0.479	0.151	0.148	0.161

[i] SGR: specific growth rate; WG: weight gain; FCR: feed conversion ratio.

Table 2.

Blood leukocytes of rainbow trout fed the control diet or diets supplemented with 10⁷ (Y7) and 10⁸ (Y8) cfu/g yeast. Data are mean ± SD of three replicates

	WBC (1000 cell/µL)	Lymphocyte (%)	Neutrophil (%)	Monocyte (%)
Control	18.0±7.94	90.7±0.58	7.33±0.88	2.00±1.00
Y7	21.7±7.51	90.3±3.79	7.67±2.52	2.33±1.53
Y8	19.3±4.93	89.7±2.08	8.00±1.00	2.33±1.53
P-value	0.812	0.887	0.903	0.943
F-value	0.216	0.123	0.103	0.059

Table 3.

Intestinal total bacteria, LAB and Vibrio sp. counts of rainbow trout fed the control diet or diets supplemented with 10⁷ (Y7) and 10⁸ (Y8) cfu/g yeast. Data are mean ± SD of three replicates

	Total viable cell (log_cfu/g ww)	LAB (log_cfu/g ww)	Vibrio sp. (log_cfu/g ww)
Control	7.03±0.31 b	2.84±0.10 a	2.73±0.21 c
Y7	6.07±0.31 a	3.33±0.27 b	2.07±0.15 b
Y8	6.60±0.26 ab	3.43±0.26 b	0.80±0.13 a
P-value	0.019	0.038	<0.001
F-value	8.16	5.95	106
Cohen’s d	Control vs. Y7 = 3.14	Control vs. Y7 = 2.65	Control vs. Y7 = 3.71
		Control vs. Y8 = 3.22	Control vs. Y8 = 11.6
			Y7 vs. Y8 = 9.01

[i] LAB: lactic acid bacteria.

[ii] Different letters (a, b, c) within a column show significant difference among the treatments (Duncan).

Hepatic superoxide dismutase (A), catalase (B), glutathione peroxidase (C), reduced glutathione (D) and malondialdehyde (E) of rainbow trout fed the control diet or diets supplemented with 10⁷ (Y7) and 10⁸ (Y8) cfu/g yeast. Data are mean ± SD of three replicates. Different letters above the bars show significant differences among the treatments (Duncan). Values above the bars show effect size (Cohen’s d) of the treatment compared to control

Lysozyme and ACH50 activities in plasma (A and B) and skin mucus (C and D) of rainbow trout fed the control diet or diets supplemented with 10⁷ (Y7) and 10⁸ (Y8) cfu/g yeast. Data are mean ± SD of three replicates. Different letters above the bars show significant differences among the treatments (Duncan). Values above the bars show effect size (Cohen’s d) of the treatment compared to control

Bactericidal activities in plasma (A-C) and skin mucus (C-F) of rainbow trout fed the control diet or diets supplemented with 10⁷ (Y7) and 10⁸ (Y8) cfu/g yeast. Data are mean ± SD of three replicates. Different letters above the bars show significant differences among the treatments (Duncan). Values above the bars show effect size (Cohen’s d) of the treatment compared to control

Table 4.

Biochemical responses of rainbow trout fed the control diet or diets supplemented with 10⁷ (Y7) and 10⁸ (Y8) cfu/g yeast and exposed to 24-h crowding stress. Data are mean ± SD of three replicates

		Cortisol (ng/mL)	Glucose (mg/dL)	ALT (U/mg pr)	AST (U/mg pr)
Before stress	Control	32.0±7.94 a	44.0±7.55 a	14.7±2.52 a	29.3±5.68 a
	Y7	30.3±8.08 a	44.7±4.93 a	15.3±3.21 ab	29.0±6.56 a
	Y8	33.0±7.21 a	43.7±4.61 a	15.0±2.65 ab	26.7±4.51 a
After stress	Control	165±11.5 c	141±25.4 c	43.0±7.54 c	77.7±13.0 c
	Y7	104±13.5 b	97.0±5.20 b	21.0±4.36 ab	54.3±6.51 b
	Y8	99.7±10.5 b	98.0±11.5 b	23.0±3.00 b	55.3±6.51 b
P-value	Yeast	<0.001	0.014	0.002	0.0.25
	stress	<0.001	<0.001	<0.001	<0.001
	Interaction	<0.001	0.013	0.001	0.047
F-value	Yeast	20.0	6.29	11.7	5.09
	stress	369	137	48.7	89.8
	interaction	19.7	6.40	12.9	3.98
Cohen’s d
Control before–after		4.70	5.90	5.63	5.17
Y7 before–Y7 after		5.08	10.3	-	3.88
Y8 before–Y8 after		6.10	6.72	-	5.20
Control after–Y7 after		4.88	2.90	3.69	2.39
Control after–Y8 after		5.90	2.45	3.79	2.29

[i] ALT: alanine aminotransferase; AST: aspartate aminotransferase.

[ii] Different letters within a column show significant differences among the treatments (Duncan)

References

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DOI: https://doi.org/10.2478/aoas-2025-0093 | Journal eISSN: 2300-8733 (formerly 1642-3402) | Journal ISSN: 1642-3402

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Language: English

Page range: 1051 - 1059

Submitted on: May 21, 2025

Accepted on: Aug 8, 2025

Published on: Sep 26, 2026

Published by: National Research Institute of Animal Production

In partnership with: Paradigm Publishing Services

Publication frequency: 4 issues per year

Keywords:

antioxidant,

feed additive,

probiotic,

immunological parameters,

gut bacteria

Related subjects:

Medicine,

Veterinary medicine

© 2026 Seyyed Morteza Hoseini, Morteza Yousefi, Evgeny Vladimirovich Kulikov, Yury Anatolyevich Vatnikov, published by National Research Institute of Animal Production
This work is licensed under the Creative Commons Attribution 4.0 License.

Volume 26 (2026): Issue 3 (August 2026)

Effects of Dietary Yeast Culture on Humoral and Mucosal Immunity, Gut Microbiota, Hepatic Antioxidant and Stress Responses in Rainbow Trout, Oncorhynchus mykiss

Figures & Tables

Table 1.

Table 2.

Table 3.

Figure 1.

Figure 2.

Figure 3.

Table 4.

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