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Food, fibre and pharmaceuticals from animals
RESEARCH ARTICLE

Metagenomic comparison of the microbial load colonizing lucerne hay and gum astralagus (Astragalus glycyphyllos) in ruminants

Mehtap Güney https://orcid.org/0000-0002-0613-3600 A * and Şükrü Önalan B
+ Author Affiliations
- Author Affiliations

A Department of Animal Science, Faculty of Agriculture, Van Yuzuncu Yil University, Van 65080, Türkiye.

B Department of Fish Diseases, Faculty of Fisheries, Van Yuzuncu Yil University, Van 65080, Türkiye.

* Correspondence to: mguney@yyu.edu.tr

Handling Editor: Joaquin Castro Montoya

Animal Production Science 65, AN24303 https://doi.org/10.1071/AN24303
Submitted: 20 September 2024  Accepted: 5 April 2025  Published: 5 May 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing

Abstract

Context

Rumen microbiota plays an important role in the evaluation of roughages. Gum astragalus hay is a non-traditional roughage in ruminant feeding, and it is curious how it affects rumen microbiota in comparison with lucerne hay (LH).

Aim

This study compares the in vitro true digestibility and rumen fermentation parameters of lucerne hay (LH) and gum astralagus hay (Astragalus glycyphyllos, AG), as well as the metagenomic profile of the bacterial community in sheepruminal fluid following 48 h in vitro incubation with either forage type.

Methods

The study was carried out in vitro in a Daisy incubator. A total of 100 samples, including 48 samples from each of the experimental roughages and two blind samples, were weighed into F57 bags for in vitro incubation with ruminal fluid, obtained from the rumen of two sheep fed on roughage and brought to the slaughterhouse from a private enterprise.

Key results

Crude protein (CP) content of AG was higher (P < 0.0014) and ADF content (P < 0.001) was lower than LH. After 48 h incubation of roughage samples, AG was superior to LH in terms of in vitro true digestibility parameters (true digestion of roughages, true dry matter digestion, and true organic matter digestion; P < 0.001). Taxonomy results of bacteria colonizing both roughages were obtained at genus and species level, according to the Shannon and Simpsons index. The bacterial community of the genus Provetalla was dominant in both forages, whereas Pseudomonas genus bacteria were observed in AG, but not in LH. According to the total Operational Taxonomc Units (OTU) in the samples, it was observed that LH and AG had similarity, as well as diversity in terms of species. Due to the current shortage of roughage, it is very important to consider AG as an alternative source of roughage in animal nutrition.

Conclusions

The differences in nutrient composition between the two roughage types also indicate differences in the composition and density of bacterial microbiota. These results were very important for improving the nutrient utilization efficiency of roughages in the desired direction.

Implication

The nutrient composition and in vitro digestion parameter results of AG were comparable to LH, and there were similarities, as well as differences, in the colonized bacterial community in both roughages.

Keywords: alfalfa hay, Astragalus glycyphyllos, digestibility, in vitro, lucerne hay, metagenomical comparision, rumen fermentation, rumen microbiota, ruminant.

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