Evaluation of an in vitro system to simulate equine foregut digestion and the influence of acidity on protein and fructan degradation in the horse’s stomach.
Abstract: The aim of this study was to improve an in vitro system in order to gather optimized information on the digestion of different forages in the horse's upper gastrointestinal tract. Therefore, foregut digestion of several forages was simulated in vitro (Part 1). The effect of different pH values on in vitro fructan degradation of two selected grasses (Part 2) was tested subsequently. Part 1: We hypothesized that our system produces representative results simulating digestive processes in the upper alimentary tract, but neglects microbial fermentation. In vitro digestion of six forages (grass mixture for horses, grass mixture for cows (GMC), tall fescue, English perennial ryegrass (ER), white clover, lucerne) was performed in two phases with pepsin and pancreatin. The results are consistent with current data from in vivo studies, including a degradation of crude protein and monosaccharides as well as a relative increase in fibres. Interestingly, a loss of fructan was measured in two feedstuffs (ER/GMC: 4.1/4.4% DM fructan before and 0.59/0.00% DM after simulated foregut digestion). Part 2: As fructans are thought not to be fragmented by digestive enzymes, another hypothesis was developed: acidic hydrolysis leads to a degradation of fructans. To evaluate the influence of gastric pH on the digestion of fructan and protein, different pH values (2, 3 and 4) were adjusted in a second series of in vitro foregut digestion trials with ER and GMC. As expected, the highest degradation of protein was seen at the lowest pH (protein in ER/GMC at pH 2: 6.11/8.28% DM and at pH 4: 7.73/10.64% DM), whereas fructan degradation was highest at pH 4 (fructan in ER/GMC at pH 2: 1.63/1.95% DM and at pH 4: 1.31/0.91% DM). We presume that not only acidic hydrolysis but also plant enzymes cause the loss of fructans in an acidic environment.
Journal of Animal Physiology and Animal Nutrition © 2017 Blackwell Verlag GmbH.
Publication Date: 2017-06-20 PubMed ID: 28627065DOI: 10.1111/jpn.12635Google Scholar: Lookup
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Summary
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The research aims to enhance a laboratory system to better replicate digestion of various grasses in a horse’s upper gastrointestinal tract. It found that the digestive system shows a decrease in protein and certain sugars, and an increase in fiber content. Lower acidity was linked to higher protein degradation, while higher acidity was associated with higher fructan (a type of sugar) degradation.
Improvement of In Vitro Digestion System
- The study focused on improving a laboratory (in vitro) system to efficiently simulate the horse’s upper gastrointestinal tract and its reactions during digestion of different varieties of grasses.
- Researchers expected the system to accurately replicate digestion processes, excluding microbial fermentation which isn’t included in this artificial process.
- Six distinct types of forage were digested in two phases using the enzymes pepsin and pancreatin. These grasses included a grass mix for horses and cows, tall fescue, English perennial ryegrass, white clover, and lucerne.
- Corresponding with real life data, the digestion led to degradation of crude protein and monosaccharides (simple sugars), and an increase in fiber content.
- Interestingly, fructan, a type of sugar, was noticeably less in two types of grasses after the digestion simulation.
Influence of Acidity on Protein and Fructan Degradation
- The researchers hypothesized that acidic hydrolysis, a process which breaks down substances in an acidic environment, leads to the degradation of fructans.
- This theory was tested by adjusting the simulated gastric pH to different levels (2, 3, and 4) and noting the effects on both protein and fructan digestion.
- Results showed that protein degradation was greatest at the lowest pH (highest acidity), and conversely, fructan degradation was greatest at the highest pH (lowest acidity).
- The study concludes that not only acidic hydrolysis but also plant enzymes contribute to the breakdown of fructans in an acidic environment.
Cite This Article
APA
Strauch S, Wichert B, Greef JM, Hillegeist D, Zeyner A, Liesegang A.
(2017).
Evaluation of an in vitro system to simulate equine foregut digestion and the influence of acidity on protein and fructan degradation in the horse’s stomach.
J Anim Physiol Anim Nutr (Berl), 101 Suppl 1, 51-58.
https://doi.org/10.1111/jpn.12635 Publication
Researcher Affiliations
- Institute of Animal Nutrition, Vetsuisse-Faculty, University of Zurich, Zurich, Switzerland.
- Institute of Animal Nutrition, Vetsuisse-Faculty, University of Zurich, Zurich, Switzerland.
- Institute for Crop and Soil Science, Julius Kuehn Institute, Federal Research Centre for Cultivated Plants, Braunschweig, Germany.
- Institute for Crop and Soil Science, Julius Kuehn Institute, Federal Research Centre for Cultivated Plants, Braunschweig, Germany.
- Institute of Agricultural and Nutritional Sciences, Group Animal Nutrition, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
- Institute of Animal Nutrition, Vetsuisse-Faculty, University of Zurich, Zurich, Switzerland.
MeSH Terms
- Animals
- Digestion / physiology
- Fructans / chemistry
- Fructans / metabolism
- Horses / physiology
- Models, Biological
- Poaceae / chemistry
- Proteins / chemistry
- Proteins / metabolism
- Stomach / physiology
Citations
This article has been cited 7 times.- Wei M, Chen P, Zheng P, Tao X, Yu X, Wu D. Purification and characterization of aspartic protease from Aspergillus niger and its efficient hydrolysis applications in soy protein degradation. Microb Cell Fact 2023 Mar 3;22(1):42.
- Stang FL, Bjerregaard R, Müller CE, Ergon Å, Halling M, Thorringer NW, Kidane A, Jensen RB. The effect of harvest time of forage on carbohydrate digestion in horses quantified by in vitro and mobile bag techniques. J Anim Sci 2023 Jan 3;101.
- Malsa J, Courtot É, Boisseau M, Dumont B, Gombault P, Kuzmina TA, Basiaga M, Lluch J, Annonay G, Dhorne-Pollet S, Mach N, Sutra JF, Wimel L, Dubois C, Guégnard F, Serreau D, Lespine A, Sallé G, Fleurance G. Effect of sainfoin (Onobrychis viciifolia) on cyathostomin eggs excretion, larval development, larval community structure and efficacy of ivermectin treatment in horses. Parasitology 2022 Sep;149(11):1439-1449.
- Gandarillas M, Keim JP, Gapp EM. Associative Effects between Forages and Concentrates on In Vitro Fermentation of Working Equine Diets. Animals (Basel) 2021 Jul 26;11(8).
- Glatter M, Borewicz K, van den Bogert B, Wensch-Dorendorf M, Bochnia M, Greef JM, Bachmann M, Smidt H, Breves G, Zeyner A. Modification of the equine gastrointestinal microbiota by Jerusalem artichoke meal supplementation. PLoS One 2019;14(8):e0220553.
- Lucke A, Liesegang A, Kümmerlen D, Czarniecki M, Wichert BA. Adaptation of an in-vitro digestion model with different zinc-supplementation strategies on nutrient degradation of piglets. Heliyon 2024 Jun 30;10(12):e33300.
- Kara K, Altınsoy A. Comparison of forages’ digestion levels for different in vitro digestion techniques in horses. Vet Med Sci 2024 Mar;10(2):e31373.
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