Production of Protein Feed from Sweet Sorghum Stalk by the Two-Step Solid State Fermentation

Chen Hongzhang Wang Yumei

doi:10.4172/2155-6202.1000112

Abstract

Ensiling of agricultural straw produces feed with low protein content. To get high protein feed with high production and low cost, a two-step solid state fermentation was designed and several factors were optimized to maximize the yield. Candida tropicalis was first inoculated sweet sorghum stalk under aerobic condition for cell growth and protein content (PC) in the substrate after the first-step reached 26.3%. In the second-step, Lactobacillus rhamnosus was inoculated the sterilized substrate harvested from the first step, and cultured under anaerobic condition. After L. rhamnosus fermented at 40oC for 80 h, the protein content in the product reached 35.7%. The pilot-plant scale fermentation was carried out according to the optimized conditions. By the two-step fermentation, 200 tons of feed was produced from two tons of dry sweet sorghum stalk and the protein content in the product was 13.77%, higher than silage in sale. The two-step process, which was easy to operate, provided high protein feed from agricultural waste in a cost effective way and the optimization of fermentation conditions in the two-step fermentation provided theoretical guideline for plant-scale production.

Highlights

Sweet sorghum, because of its high yields and high sugar content, has attracted great attention as feedstuff and energy crop [1]
Ensiling is a process of solid state fermentation by mixed bacteria of nature, the silage obtained has a low protein content (4-8%) with poor palatability
Great attempts on microbial fermentation have been made to enhance protein content in agricultural straw for poultry feed [4,5,6,7], but there is no report about large scale production of high protein feed in markets

Summary

Introduction

Because of its high yields and high sugar content, has attracted great attention as feedstuff and energy crop [1]. Sweet sorghum stalks are mainly ensiled [2,3] or directly used as animal feed. Great attempts on microbial fermentation have been made to enhance protein content in agricultural straw for poultry feed [4,5,6,7], but there is no report about large scale production of high protein feed in markets. Solid state fermentation has the advantage of energy-saving and pollution-reducing [8,9], and it is usually applied in feed fermentation as its product can be utilized directly as feed. Solid state fermentation was chosen for conversion of sweet sorghum stalk to protein feed

Methods

Results

Conclusion