• Animal Bioscience
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• 제34권6호
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• pp.1038-1048
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• 2021

Objective: The study aimed to evaluate the effect of storage time and formic acid (FA) on fermentation characteristics, epiphytic microflora, carbohydrate components and in vitro digestibility of rice straw silage. Methods: Fresh rice straw was ensiled with four levels of FA (0%, 0.2%, 0.4%, and 0.6% of fresh weight) for 3, 6, 9, 15, 30, and 60 d. At each time point, the silos were opened and sampled for chemical and microbial analyses. Meanwhile, the fresh and 60-d ensiled rice straw were further subjected to in vitro analyses. Results: The results showed that 0.2% and 0.6% FA both produced well-preserved silages with low pH value and undetected butyric acid, whereas it was converse for 0.4% FA. The populations of enterobacteria, yeasts, moulds and aerobic bacteria were suppressed by 0.2% and 0.6% FA, resulting in lower dry matter loss, ammonia nitrogen and ethanol content (p<0.05). The increase of FA linearly (p<0.001) decreased neutral detergent fibre and hemicellulose, linearly (p<0.001) increased residual water soluble carbohydrate, glucose, fructose and xylose. The in vitro gas production of rice straw was decreased by ensilage but the initial gas production rate was increased, and further improved by FA application (p<0.05). No obvious difference of FA application on in vitro digestibility of dry matter, neutral detergent fibre, and acid detergent fibre was observed (p>0.05). Conclusion: The 0.2% FA application level promoted lactic acid fermentation while 0.6% FA restricted all microbial fermentation of rice straw silages. Rice straw ensiled with 0.2% FA or 0.6% FA improved its nutrient preservation without affecting digestion, with the 0.6% FA level best.

• International Journal of Industrial Entomology and Biomaterials
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• 제4권2호
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• pp.127-131
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• 2002

The qualitative and quantitative changes of bacterial flora associated with the Pure Mysore (Multivoltine) and NB$_4$D$_2$ (Bivoltine) silkworm (Bombyx modi L.) midgut during third, fourth and fifth instars were studied. Larvae reared on mulberry leaves were dissected and their midgut bacterial populations were enumerated through serial dilution technique and after 72 hrs of incubation period at 28 $\pm$ 1$^{\circ}C$, the bacterial population was estimated. The results showed a highest mean value of 15$\times$10/ sup 6/ sup 6/ CFU/g and 28$\times$10/ sup 6/ CFU/g in Pure Mysore and NB$_4$D$_2$races, respectively, in midgut tissue of fifth instar larvae. The natural epiphytic microflora of mulberry leaves fed during the respective instars was also studied and found maximum 14$\times$10$^3$ CFU/g in leaves fed in third instars, followed by 5.3$\times$10$^3$ CFU/g and 2.1$\times$10$^3$ CFU/g in leaves fed during fourth and fifth instars, respectively. The bacterial flora colonized in midgut was found to be elaborating amylase, caseinase, gelatinase, lipase and urease enzymes. The highest percentages of isolates were amylase producers followed by protein and lipid splitters in Pure Mysore, whereas in NB$_4$D$_2$ protein splitter were dominated followed by lipase and amylase producers in NB$_4$D$_2$. The results indicate that the natural microflora may play a vital role in the digestion of ingested food materials in silkworms.