Effects of Microbials Combination on Rumen Fermentation In Vitro and Growth Performance in Wether Goats

碩士 === 國立宜蘭大學 === 生物技術與動物科學系 === 103 === Feeding microbials to ruminants may modulate ruminal fermentation and enhance body metabolic efficiency. Yeast and lactic acid bacteria are commonly used as feed additives for ruminants. Yeast can create anaerobic environment in the rumen to enhance rumen...

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Bibliographic Details
Main Authors: Ting-Yi Du, 杜亭逸
Other Authors: Che-Ming J. Yang
Format: Others
Language:zh-TW
Published: 2015
Online Access:http://ndltd.ncl.edu.tw/handle/ax5u75
Description
Summary:碩士 === 國立宜蘭大學 === 生物技術與動物科學系 === 103 === Feeding microbials to ruminants may modulate ruminal fermentation and enhance body metabolic efficiency. Yeast and lactic acid bacteria are commonly used as feed additives for ruminants. Yeast can create anaerobic environment in the rumen to enhance rumen microbial activity, and stabilize rumen pH to promote cellulose dissolution. Lactic acid bacteria produce small and steady amount of lactate, thus can help lactilytic bacteria maintain activity in the rumen. When the ruminants have too much lactate in the rumen, lactilytic bacteria can act fast to consume it. Experiment 1 used microbials combination ( mainly lactic acid bacteria, 104 colony forming units/g and commercial yeast, 106 CFU/g ) to conduct dose-response experiment during in vitro rumen incubation. The aim was to evaluate dosage combination effect. Results showed that total gas production of control group was 17.5 mL, and supplying microbials increased the gas production. Therefore, the microbials combination might enhance activity of microorganisms, but not significantly. For ammonia concentration, control group was 21.6 mg/dL. The microbials with only yeast had a higher ammonia concentration than that of control group. As yeast dose reduced, ammonia concentration trended to decrease. Considering the potential of promoted microbial activity and reduced ammonia production, yeast of 106 CFU/g and bacteria of 104 CFU/g were chosen for the following experiments. Experiment 2 used lactic acid bacteria ( 104 CFU/g ) and yeast product ( 106 CFU/g ) combination to evaluate mixture supplementation ( 1 g/L ) to incubations with diets ( 7 g/L ) of various forage to concentrate ratios ( 30: 70, 50: 50, 70: 30 ) on methanogenesis and fermentative efficiency by ruminal microorganisms. Increasing concentrate in diets elevated total gas, methane, total volatile fatty acids, and ammonia production, and also increased estimated diet organic matter digestibility and digestible energy ( P<0.05 ). High concentrate diets also increased methane concentration of fermentation gas, methane and ammonia output per unit of organic matter digested, methane output per unit of digestible energy, and decreased acetate to propionate ratio ( P<0.05 ). Supplying the microbial combination had no significant influence on total gas, total volatile fatty acids, and ammonia production, and acetate to propionate ratio. However, methane production, methane concentration of fermentation gas, methane output per unit of organic matter digested, and methane output per unit of digestible energy or total volatile fatty acids were all decreased ( P<0.05 ). The results indicated that increasing concentrate in diets enhanced ruminal fermentation, but reduced energy fermentative efficiency. Adding microbials combination reduced methanogenesis, and improved fermentative efficiency of diets by ruminal microorganisms ( P<0.05 ). The effect in high forage diet was much more apparent (interaction, P<0.05). The animal experiment ( replicated 4 × 4 Latin square ) used two kinds ( PF, TS ) of commercial concentrate with bermudagrass straw to formulate diets ( forage to concentrate ratio = 55:45 ) and evaluated the effect of feeding active bacteria ( mainly lactic acid bacteria ) and yeast product combined to wether goats ( n = 8, BW = 28.5 kg, Experiment 3 ). Two diets had similar nutrient composition. However, TS diet had higher ( P<0.05 ) total tract CP digestibility, digestible CP intake, digestible CP intake per kg dry matter intake ( DMI ), and urinary urea nitrogen output per kg DMI and per kg DM digested. In addition, plasma urea nitrogen level also trended to be higher ( P<0.1 ). Feeding combined microbials had no influence on intake value and nutrient digestibility, but blood urea nitrogen levels before ( 0 h ) and after ( 2 h ) feeding were all decreased ( P<0.05 ). Urinary urea nitrogen to urinary nitrogen ratio also trended to decrease ( P<0.1 ). Daily weight gain of goats fed combined microbials trended to increase ( P<0.1 ). Feeding microbials combined had potential to improve nitrogen utilization in both diets, reflected in promoting growth in wether goats. The overall results of this study showed that adding microbials enhanced ruminal fermentation in vitro with a potential to reduce ammonia concentration and increase ammonia utilization efficiency. The animal experiment also confirmed that adding microbials decreased blood urea nitrogen levels and urinary urea nitrogen to urinary nitrogen ratio. It appeared that the effect of microbials in the rumen was decreasing waste products from protein in the diets. This reflected in higher gain weight, but did not affect feed cost per kg weight gain. It could be a strategy to shorten the time which domestic meat goats are ready for market.