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Differential Regulation of Ruminal Microbial Community Structure and Functional Pathways in Sheep Supplemented with Linseed Oil or Sunflower Oil
State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
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Animals 2026, 16(11), 1581; https://doi.org/10.3390/ani16111581 (registering DOI)
Submission received: 7 April 2026
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Revised: 18 May 2026
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Accepted: 20 May 2026
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Published: 22 May 2026
(This article belongs to the Section Small Ruminants)
Simple Summary
This study evaluated the effects of dietary polyunsaturated fatty acid (PUFA) supplementation on growth performance, serum biochemistry, ruminal fermentation, and microbial communities in Hu sheep. Thirty male Hu sheep (n = 10/group) were assigned to control (4% rumen-bypass palmitic acid), linseed oil (LO, ω-3), or sunflower oil (SO, ω-6) groups. PUFA supplementation did not affect growth performance or rumen morphology, but reduced serum creatinine, uric acid, and high-density lipoprotein. Orthogonal comparative analysis showed that the addition of PUFA reduced acetate and propionate, while increasing butyrate, isovalerate, and total volatile fatty acids (TVFAs); the SO group showed higher propionate, butyrate, and TVFAs but a lower A/P ratio than the LO group. PUFA reshaped the rumen microbiota, increasing Bacteroidetes and Firmicutes, decreasing Proteobacteria and Desulfobacterota, and altering multiple genera. Alpha diversity increases, while beta diversity separates the PUFA group from the control group. Functionally, LO enriches carbohydrate and energy metabolism, while SO enriches nucleotide metabolism. In summary, Linseed Oil and sunflower oil improve serum indicators and rumen fermentation through different microbial and functional pathways without harming growth.
Abstract
This study evaluated the effects of dietary PUFA supplementation on growth performance, serum biochemical indices, rumen morphology, ruminal fermentation, and rumen microbial communities in Hu sheep. Thirty healthy male Hu sheep (80 days old; 18.70 ± 0.72 kg) were randomly assigned to three groups (n = 10/group) and fed a basal diet supplemented with 4% rumen-bypass palmitic acid fat powder (POS), 4% linseed oil (LO; rich in ω-3 PUFA), or 4% sunflower oil (SO; rich in ω-6 PUFA). PUFA supplementation did not affect average daily gain or rumen tissue morphology (p > 0.05), but it significantly reduced serum creatinine, uric acid, and high-density lipoprotein concentrations (p < 0.05). Orthogonal comparative analysis showed that supplementing with PUFA significantly reduced acetate and propionate, while increasing isobutyrate, butyrate, isovalerate, and TVFAs (p < 0.05). The levels of propionate, butyrate and TVFAs in the SO group were higher than those in the LO group (p < 0.05), and the ratio of acetate to propionate was lower (p < 0.05). Supplementing with PUFA reshaped the rumen microbiota, increasing the relative abundances of Bacteroidota, Firmicutes, Euryarchaeota, Cyanobacteria, and Actinobacteriota, while decreasing Proteobacteria and Desulfobacterota (p < 0.05). At the genus level, Prevotella and Rikenellaceae_RC9_gut_group were enriched in both groups with added PUFA, while Prevotellace-UCG-001 was specifically enriched in the LO group; in contrast, Prevotella_7, Succinivibriaceae_UCG-001, Prevotella_9, and Dialist all showed a decrease (p < 0.05). The alpha diversity increased, while the beta diversity showed significant differences between the group with added PUFA and the control group. Functionally, LO enriches carbohydrate and energy metabolism, while SO enriches nucleotide metabolism. In summary, linseed oil and sunflower oil improved serum indices and ruminal fermentation without impairing growth, but through distinct microbial and functional pathways.
