Effects of different protein sources on nutrient disappearance, rumen fermentation parameters and microbiota in dual-flow continuous culture system

Ao Ren,Hui Mi,Bin Zhang,Weijun Shen,Zhiliang Tan,Tao Ran,Chuanshe Zhou,Jinjia Zhu

doi:10.1186/s13568-022-01358-1

Abstract

Scarce high-quality protein feed resources has limited the development of animal husbandry. In this study, we used a dual-flow continuous culture system to evaluate effects of difference dietary protein sources including soybean meal (SBM), cottonseed meal (CSM), and rapeseed meal (RSM), on nutrient disappearance, rumen fermentation, and microbiota of XiongDong black goats. Dietary proteins of either CSM, RSM or SBM had no effect on nutrient disappearance (P > 0.05). CSM or RSM significantly reduced (P < 0.01) the pH and enhanced (P < 0.01) the ammonia nitrogen (NH3-N) concentration in fermentation liquid compared to SBM. The short-chain fatty acids (SCFAs) contents were greater (P = 0.05) and acetate was lower (P < 0.01) in SBM than those in RSM and CSM, whereas propionate was greater (P < 0.01) in RSM than that in SBM, consequently reducing the acetate to propionate ratio (A/P) in RSM. Bacteroidetes, Firmicutes, and Proteobacteria were detected as the dominant phyla, and the relative abundances of Spirochaetae (P < 0.01) and Chlorobi (P < 0.05) declined in the CSM and RSM groups as compared to those in the SBM group. At the genus level, Prevotella_1 was the dominant genus; as compared to SBM, its relative abundance was greater (P < 0.01) in CSM and RSM. The abundances of Prevotellaceae_Ga6A1 and Christensenellaceae_R7 were lower (P < 0.05) in CSM, whereas Eubacterium_oxidoreducens_group, and Treponema_2 were lower (P < 0.01) in both CSM and RSM, and other genera were not different (P > 0.10). Although the bacterial community changed with different dietary protein sources, the disappearances of nutrients were not affected, suggesting that CSM and RSM could be used by rumen bacteria, as in case with SBM, and are suitable protein sources for ruminant diets.

Highlights

Proteins derived from plants, animals, and non-protein nitrogen are commonly used as crude protein (CP) sources in ruminant diets
Rumen fermentation and the microbial profile could be appropriately modified when goats were fed diets from different dietary protein sources, this could be due to the differences in the structure and degradability of different protein sources (Wang et al 2009)
The degradability of CP in the rumen is considerably related to the ruminal ammonia nitrogen (NH3-N) concentration, and McCarthy et al (1989) reported a greater Ammonia nitrogen (NH3-N) concentration in Soybean meal (SBM) than that in corn gluten meal due to the higher ruminal degradability of SBM

Summary

Introduction

Proteins derived from plants, animals, and non-protein nitrogen are commonly used as crude protein (CP) sources in ruminant diets. Soybean meal (SBM) has been the main protein source because of its relatively high concentration of CP and rumen-undegraded protein (RUP) and its well-balanced amino acid (AA) composition (Cherif et al 2018). Mi et al AMB Express (2022) 12:15 and enhance farm profits has increased (Cherif et al 2018) Several agricultural byproducts such as rapeseed meal (RSM) and cottonseed meal (CSM), which are costeffective and available, have recently been used as protein sources in ruminant diets. Differences in the chemical characteristics of diets are the main factors that affect digestibility, rumen fermentation characteristics and microbial exploitability of protein from different sources (Huang et al 2019; Klevenhusen et al 2017). SBM and RSM could be partially replaced with feed grade urea or slow-release urea, without affecting milk performance or diet digestibility (Sinclair et al 2012)

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Conclusion