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Veterinary world2026; 19(3); 905-919; doi: 10.14202/vetworld.2026.905-919

Synergistic effects of Ferula asafoetida extract and condensed tannins from raisin pomace on in vitro cecal fermentation kinetics and nutrient digestibility in horses.

Abstract: The equine hindgut depends on microbial fermentation for efficient nutrient utilization but remains vulnerable to dysbiosis, hindgut acidosis, and suboptimal fiber digestion. Growing restrictions on antibiotic and synthetic feed additives have increased interest in natural phytogenic compounds. Medicinal plant extracts and condensed tannins are promising candidates to modulate microbial activity, improve fermentation efficiency, and enhance nutrient digestibility. This study aimed to investigate the individual and combined effects of hydroalcoholic extract of and condensed tannins extracted from raisin pomace on equine cecal fermentation parameters and nutrient utilization using gas production and batch culture techniques. Unassigned: A 2 × 2 factorial design was used with four treatments: control (C; basal diet only), extract (A; 30 mg), condensed tannins from raisin pomace (G; 50 mg), and their combination (A × G). Fecal inoculum was collected from four healthy 14-month-old Arabian geldings adapted for 14 days to a forage-based maintenance diet. Fermentation kinetics were evaluated over 120 h using the gas production technique and fitted to the Gompertz model. Parallel batch cultures measured pH, ammonia-nitrogen (NH-N), and apparent disappearances of dry matter (DM), crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF). Data were analyzed using PROC GLM in SAS with Tukey-Kramer post-hoc tests (p < 0.05). Unassigned: Cumulative gas production at 120 h was significantly higher in G (340.5 mL) and A × G (340.3 mL) than in C (228.8 mL) (p < 0.01), with faster fermentation rates and shorter lag times (p < 0.01). Terminal pH values remained stable (6.33-6.40) across treatments with no indication of acidosis. NH-N concentrations were elevated in G (26.0 mg/dL) and A × G (25.5 mg/dL) compared with C (24.5 mg/dL) (p < 0.01). Apparent digestibility improved markedly: DM increased from 64.5% (C) to 70.3% (G), CP from 60.3% (C) to 66.9% (G), with parallel positive trends observed for ADF and NDF (p < 0.01). Unassigned: Supplementation with extract and condensed tannins from raisin pomace, especially in combination, enhanced fermentation efficiency, accelerated substrate degradation, and improved nutrient digestibility while maintaining stable pH in an equine cecal model. These findings indicate strong potential for these phytogenic compounds as sustainable natural feed additives to optimize equine hindgut function. validation, dose optimization, and long-term microbiome studies are recommended to confirm practical efficacy and safety in horses.
Copyright: © Dehghan, et al.
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Publication Date: 2026-03-13 PubMed ID: 42046684PubMed Central: PMC13110502DOI: 10.14202/vetworld.2026.905-919Google Scholar: Lookup
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Summary

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Overview

  • This study investigated how a herbal extract from Ferula asafoetida and condensed tannins extracted from raisin pomace affect fermentation and nutrient digestion in the horse hindgut, using in vitro cecal fermentation techniques.
  • The research found that these natural compounds, particularly when combined, improved fermentation efficiency, increased nutrient digestibility, and maintained healthy pH levels, suggesting their potential as natural feed additives for horses.

Background

  • The hindgut (cecum and colon) in horses is essential for microbial fermentation, which helps break down fiber and other nutrients that horses cannot digest alone.
  • Problems such as dysbiosis (microbial imbalance), hindgut acidosis (low pH), and poor fiber digestion can impair horse health and nutrient absorption.
  • Natural phytogenic compounds like medicinal plant extracts and condensed tannins are increasingly studied due to restrictions on antibiotics and synthetic additives in animal feed.
  • Ferula asafoetida is a medicinal plant known for its bioactive compounds; condensed tannins are plant-derived polyphenols from grape derivatives such as raisin pomace.

Objective

  • To evaluate the effects of hydroalcoholic extract of Ferula asafoetida (referred to as “A”), condensed tannins from raisin pomace (“G”), and their combination (“A × G”) on cecal fermentation and nutrient digestibility in horses using in vitro techniques.

Methods

  • A 2 × 2 factorial design with four treatments was used:
    • Control (C): basal diet only
    • Extract (A): basal diet + 30 mg Ferula asafoetida extract
    • Tannins (G): basal diet + 50 mg condensed tannins from raisin pomace
    • Combination (A × G): basal diet + both extract and tannins
  • Fecal inoculum was collected from four healthy 14-month-old Arabian geldings adapted to a forage-based diet for 14 days to simulate cecal microbes.
  • Gas production over 120 hours was measured to assess fermentation kinetics using the Gompertz model, providing data on the volume of gas produced, lag time, and fermentation rate.
  • Batch cultures assessed:
    • pH to check for acidosis
    • Ammonia-nitrogen (NH-N) concentration as an indicator of protein fermentation
    • Apparent disappearance (digestibility) of dry matter (DM), crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF)
  • Statistical analysis was done using SAS PROC GLM with Tukey-Kramer post-hoc tests and significance set at p < 0.05.

Results

  • Cumulative gas production over 120 hours was significantly higher for tannins (G; 340.5 mL) and the combination (A × G; 340.3 mL) compared to control (228.8 mL), indicating enhanced fermentation activity.
  • Fermentation rates were faster and lag times (delay before fermentation begins) were shorter in tannins and combination groups (p < 0.01).
  • Terminal pH values remained stable across all treatments (6.33–6.40), showing no indication of hindgut acidosis.
  • NH-N concentrations were increased in G (26.0 mg/dL) and A × G (25.5 mg/dL) compared to control (24.5 mg/dL) (p < 0.01), suggesting greater protein metabolism.
  • Apparent digestibility improved with supplementation:
    • Dry matter digestibility increased from 64.5% (control) to 70.3% (G)
    • Crude protein digestibility increased from 60.3% (control) to 66.9% (G)
    • Positive trends were also observed for fiber fractions ADF and NDF (p < 0.01)

Conclusions

  • Ferula asafoetida extract and condensed tannins from raisin pomace, particularly combined, significantly improved in vitro cecal fermentation efficiency and nutrient digestibility without negatively affecting pH.
  • These natural phytogenic compounds show strong potential as sustainable feed additives to optimize hindgut function in horses.
  • The stable pH suggests they could enhance fermentation without causing hindgut acidosis, a major concern for horse health.
  • Further studies are needed to optimize doses, validate in vivo effects, and understand long-term impacts on the equine microbiome and safety.

Implications

  • Natural plant extracts and tannins may serve as effective alternatives to antibiotics and synthetic additives for maintaining or improving equine gut health.
  • Enhanced nutrient digestibility can translate into better feed efficiency and potentially reduce feed costs or improve health outcomes in horses.
  • This research supports sustainable approaches in horse nutrition by utilizing byproducts like raisin pomace, adding value to agricultural waste.

Cite This Article

APA
Dehghan H, Moghaddaszadeh-Ahrabi S, Hashemzadeh-Farhang H, Shahbazi P, Nobari B. (2026). Synergistic effects of Ferula asafoetida extract and condensed tannins from raisin pomace on in vitro cecal fermentation kinetics and nutrient digestibility in horses. Vet World, 19(3), 905-919. https://doi.org/10.14202/vetworld.2026.905-919

Publication

Veterinary world
ISSN: 0972-8988
NlmUniqueID: 101504872
Country: India
Language: English
Volume: 19
Issue: 3
Pages: 905-919

Researcher Affiliations

Dehghan, Hossein
  • Department of Animal Science, Ta.C., Islamic Azad University, Tabriz, Iran.
Moghaddaszadeh-Ahrabi, Sima
  • Department of Animal Science, Ta.C., Islamic Azad University, Tabriz, Iran.
Hashemzadeh-Farhang, Hossein
  • Department of Pathobiology, TaMS.C., Islamic Azad University, Tabriz, Iran.
Shahbazi, Parisa
  • Department of Pathobiology, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran.
Nobari, Babak
  • Registered Animal Nutritionist at Nutrition Society of Australia, Melbourne, Victoria, Australia.

Conflict of Interest Statement

The authors declare that they have no competing interests.

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