Effects of L-tryptophan, Fructan, and Casein on Reducing Ammonia, Hydrogen Sulfide, and Skatole in Fermented Swine Manure

  • Sheng, Q.K. (Institute of Animal Science and Veterinary Medicine, Shandong Provincial Academy of Agricultural Sciences) ;
  • Yang, Z.J. (Shandong Meishida Agriculture and Husbandry Technology) ;
  • Zhao, H.B. (Institute of Animal Science and Veterinary Medicine, Shandong Provincial Academy of Agricultural Sciences) ;
  • Wang, X.L. (Institute of Animal Science and Veterinary Medicine, Shandong Provincial Academy of Agricultural Sciences) ;
  • Guo, J.F. (Institute of Animal Science and Veterinary Medicine, Shandong Provincial Academy of Agricultural Sciences)
  • Received : 2014.12.01
  • Accepted : 2015.02.04
  • Published : 2015.08.01


The effects of daily dietary Bacillus subtilis (Bs), and adding L-tryptophan, fructan, or casein to fecal fermentation broths were investigated as means to reduce the production of noxious gas during manure fermentation caused by ammonia, hydrogen sulfide ($H_2S$), and 3-methylindole (skatole). Eighty swine ($50.0{\pm}0.5kg$) were equally apportioned to an experimental group given Bs in daily feed, or a control group without Bs. After 6 weeks, fresh manure was collected from both groups for fermentation studies using a $3{\times}3$ orthogonal array, in which tryptophan, casein, and fructan were added at various concentrations. After fermentation, the ammonia, $H_2S$, L-tryptophan, skatole, and microflora were measured. In both groups, L-tryptophan was the principle additive increasing skatole production, with significant correlation (r = 0.9992). L-tryptophan had no effect on the production of ammonia, $H_2S$, or skatole in animals fed Bs. In both groups, fructan was the principle additive that reduced $H_2S$ production (r = 0.9981). Fructan and Bs significantly interacted in $H_2S$ production (p = 0.014). Casein was the principle additive affecting the concentration of ammonia, only in the control group. Casein and Bs significantly interacted in ammonia production (p = 0.039). The predominant bacteria were Bacillus spp. CWBI B1434 (26%) in the control group, and Streptococcus alactolyticus AF201899 (36%) in the experimental group. In summary, daily dietary Bs reduced ammonia production during fecal fermentation. Lessening L-tryptophan and increasing fructan in the fermentation broth reduced skatole and $H_2S$.


Swine Manure;L-tryptophan;Fructan;Casein;Ammonia;$H_2S$;Skatole;B. subtilis


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