การย่อยสลายในกระเพาะรูเมนของกากมันสำปะหลังที่หมักด้วยของเหลวจากกระเพาะรูเมนของโคเนื้อพื้นเมืองที่ทำการเพิ่ม จำนวนจุลินทรีย์จำเพาะ

Abstract

The objectives of this study were to investigate the changes of the rumen microbiome, fiber biodegradability and short chain fatty acid production by cassava pulp supplementation in Thai native cattle, including to evaluate the optimal condition toenhance nutritive value of cassava pulp through rumen microbial fermentation. This study was divided into two experiments. The first experiment aims to investigate the effects of cassava pulp supplementation in diet on the changes of rumen bacterial microbiome. The fistulated White Lamphun and the fistulated Thai mountain cattle were fed maize silage ad libitum and supplemented with 0.5 kg DM(dry matter)cassava pulpadded urea 0.5% DM in diet for 4 weeks. The rumen fluid were obtained from the fistulated cattle fed with whole crop maize silage (week 0), and supplemented with a cassava pulp for 1, 2, 3 and 4 weeks. Samples of rumen fluid were collected and analyzedto compare the changeof rumen microbiome and microbial activity. The 16S rRNA amplicon sequencing were used to investigate the changes in the ruminal microbes. The plant cell walls degradation activity was determined using in vitro digestibility. The production of pyruvic acid and short chain fatty acid (SCFA) were measured by HPLC. Bacterial community composition was significantly different in cattle supplemented with cassava pulp for 4 weeks compared to pretreatment (week0). As a result, Methanobrevibacter, Christensenellaceae, Lachnospiraceae, Prevotella, Ruminococcaceae, Vibrio and Rikenellaceae were higher relative abundance in the cattle supplemented with cassava pulp for 4 weeks. These differences affect to rumen bacterial activities with higher plant cell walls degradation lead to high concentration of acetic acid and propionic acid during substrate inoculation. The second experiment was to evaluate the optimal condition to enhance nutritive value of cassava pulp through rumen microbial fermentation. The rumen fluid was collected from the two fistulated Thai native cattle supplemented with cassava pulp for 4 weeks to use as inoculum. The cassava pulp was fermented with 0.85% sodium chloride solution (CON group) 10:1 ratio (wet weight) or mixed with rumen fluid (RF group) with ammonium chloride (NH4Cl) supplementation at various levels (0, 0.25, 0.5% DM). The cassava pulps were fermented under anaerobes at ambient temperature periods of 0, 7 and 14 days. The lactic acid concentration, short chain fatty acid concentration, pH value and chemical composition were determined by proximate analysis technique and detergent method. In vitro gas production kinetics and in vitro digestibility of cassava pulp were also investigated. The results obtained of this study indicated that rumen microbial can enhance nutritive value of cassava pulp. True protein content and short chain fatty acid concentration of cassava pulp were highest after fermentation with rumen microbial for 14 days, at the same time microbial biomass yield (MBY) was improved. However, the effect of NH4Cl on SCFA and true protein content were not observed. The optimum conditions for the cassava pulp nutrient enrichment using ruminal microbes found to be anaerobic at ambient temperature and time of fermentation for 14 days. Under these conditions, the fermented cassava pulp have the highest in SCFA, true protein content and also enrich microbial biomass yield.