Preliminary Study On Preparation Of Feedstuffs From Straw

There are abundant straw resources in China. But the recycling rate of straw is very low.Mechanical pretreatment combined with enzymolysis and solid-state fermentation could helpto convert the straw into feedstuff to replace a certain part of grain in the feed of non-ruminant.This method could not only reduce the burden of feeding grain, but also convert the cropresidues into a value-added product. Converting the straw into monogastric animal feed opensup a new development area for feed industry, and may promote the sustainable developmentof agriculture, environment and animal husbandry.The effect of mechanical pretreatment on corn straw was studied in this work. And thencorn straw was cultured by Pediococcus acidilactici combining with the use of enzyme viasolid-state fermentation under the optimized process conditions. It was beneficial to degradedietary fiber, accumulate organic acids and improve the feed quality of the straw.The effects of different mechanical treatments methods on straw physical structure,chemical composition and the bioavailability were investigated. The study indicated that thesmallest and most symmetrical particles were obtained by ball milling, and the particle sizesof corn straw mainly (90%) distributed in the range of10~100μm. The water-holdingcapacity of corn straw powder reduced with the decreased particle size, and reduced by68.9%after ball milling when compared with original straw sample. The chemical composition andbioavailability of the straw were also changed after mechanical treatments. Ball mill crushedcorn straw had a1.3%decrease in neutral detergent fiber (NDF) content and a3.5%decreasein acid detergent fiber (ADF) content. Besides, the straw had a200%increase in soluble sugarcontent due to the breaking of hemicellulose chains. The content of total soluble sugar andreducing sugar of ball milling corn straw followed by hydrolysis of xylanase and cellulaseincreased by3.3fold and9.7fold than that without treatment, respectively. As a result,mechanical treatment could change the physical and chemical structure of corn straw, andmake it much easier to be degraded by enzymes. The smaller the particle sizes were, the moresignificant the influence was.Mechanical treatment increased the content of sugar with low bioavailability such asxylose. One strain with powerful utilization capability on xylose and without apparent glucoserepression was isolated according to the acid production ability. The colonizing ability of thisstrain was also taken into account. It was identified as pediococcus acidilactici by16S rDNAmethod, and named as Pediococcus acidilactici R30. The strain was finally selected as thefermentation strain.The optimal conditions of corn straw fermentation were obtained through mono factorexperiments and uniform design experiments. The final conditions were: processingtemperature of100℃, processing time of1min, xylanase and cellulase adding amount of200and30U·g-1corn straw, respectively, material to liquid ratio of1:1.1, fermentationtemperature of40℃, fermentation period of84h and inoculation of12%. After fermentation,the content of total acids was up to3.41±0.33%.The effects of fermentation on the quality improvement of straw feed were preliminarily studied. Results showed that the dietary fibre content was reduced after fermentation. TheNDF content was decreased from67.7%to61.2%, and the crude fibre content was decreasedfrom26.4%to20.5%. Furthermore, the contents of soluble sugar and reducing sugar wereincreased by1.8fold and2.9fold, respectively, and the crude protein content was improvedfrom6.89%to8.33%. The Lactobacillus population was7.9×108CFU·g-1.