The Effects of Adding Walnut Green Husk on the Quality of Alfalfa Mixed Silage, Protein Degradation, Microbial Community, and Their Interrelationships

TL;DR

Adding walnut green husk to alfalfa silage improves its quality, reduces protein breakdown, and promotes beneficial microbes, making it a sustainable feed additive for livestock.

Contribution

This study demonstrates that walnut green husk is a novel, sustainable additive that enhances silage quality and protein utilization in ruminant feed.

Findings

WGH addition reduces organic acids and mold, improving silage fermentation quality.

WGH increases rapidly degradable protein and digestibility while decreasing protease activity and slow degradable protein.

WGH enriches beneficial lactic acid bacteria and reduces harmful microbes in silage.

Abstract

What are the main findings?
Adding walnut green husk (WGH) to alfalfa silage significantly improves fermentation quality, characterized by reduced organic acid content and the absence of mold.WGH addition linearly decreases non-protein nitrogen (NPN), protease activity, and slowly degradable protein (PB3), while linearly increasing rapidly degradable protein (PB1) and in vitro dry matter digestibility (IVDMD).WGH enriches the microbial community by increasing the relative abundance of beneficial Lactiplantibacillus and Levilactobacillus, which are negatively correlated with protein degradation factors.

Adding walnut green husk (WGH) to alfalfa silage significantly improves fermentation quality, characterized by reduced organic acid content and the absence of mold.

WGH addition linearly decreases non-protein nitrogen (NPN), protease activity, and slowly degradable protein (PB3), while linearly increasing rapidly degradable protein (PB1) and in vitro dry matter digestibility (IVDMD).

WGH enriches the microbial community by increasing the relative abundance of beneficial Lactiplantibacillus and Levilactobacillus, which are negatively correlated with protein degradation factors.

What are the implications of the main findings?
This study identifies WGH, an agricultural by-product, as an effective silage additive that mitigates protein degradation, offering a strategy to improve the utilization efficiency of alfalfa protein in ruminant production.The findings support a sustainable approach to waste management by recycling walnut green husks, contributing to a circular economy model in agriculture.The optimal inclusion level of 120 g/kg WGH provides a practical guideline for farmers to enhance silage nutritional value and reduce feed costs.

This study identifies WGH, an agricultural by-product, as an effective silage additive that mitigates protein degradation, offering a strategy to improve the utilization efficiency of alfalfa protein in ruminant production.

The findings support a sustainable approach to waste management by recycling walnut green husks, contributing to a circular economy model in agriculture.

The optimal inclusion level of 120 g/kg WGH provides a practical guideline for farmers to enhance silage nutritional value and reduce feed costs.

Objectives: This experiment was conducted to investigate the effects of adding walnut (Juglans regia L.) green husk (WGH) on the quality of alfalfa mixed silage, protein degradation, microbial community, and their interrelationships. Methods: Alfalfa (Medicago sativa L.) fresh grass and WGH dried powder were used as raw materials to prepare three mixed silages of alfalfa fresh grass with 80 g/kg (A1), 120 g/kg (A2), and 160 g/kg (A3) of WGH dried powder, respectively, with alfalfa fresh grass silage as the control group (CK). After 60 days of ensilage, samples were taken and analyzed, with three replicates per treatment. Results: WGH treatment significantly improved alfalfa silage fermentation and nutritional quality. It reduced undesirable fermentation products while promoting beneficial lactic acid bacteria and preventing mold growth. Increasing the WGH ratio enhanced dry matter content and digestibility, with only a minor effect on crude protein. These results suggest that WGH is an effective silage additive for improving both fermentation characteristics and feed value. With the increase in the proportion of WGH, the proportions of rapidly degradable protein (PB1) and medium rate degradable protein (PB2) increased linearly, while the proportions of free amino acid nitrogen (FAA-N), peptide nitrogen (Peptide-N), slow degradable protein (PB3) and binding protein (PC) decreased linearly and the protease activity decreased significantly (p < 0.05). Bacterial community analysis showed that the relative abundance of Lactiplantibacillus and Levilactobacillus in the silage increased after WGH was added, while the relative abundance of Acetobacter, Pantoea, Weissella and Serratia decreased. Conclusions: Compared with pure alfalfa silage, the addition of WGH has a positive effect on silage quality, protein degradation and bacterial community structure, and the addition of WGH with 120 g/kg is more suitable.

Figures