Ensaio de fermentação in vitro com aplicação de inóculo fecal equino

Abstract

This study aimed to evaluate the feces of horses as an inoculum source to apply to in vitro fermentation tests when roughage is used as the substrate. The design was completely randomized in a 2x2 factorial arrangement. The first factor is hydration time of the substrate: 0 and 12 hours; and the second factor evaluated was the feces dilution with nutritive solution (weight: weight): 1:1 and 1:3. The variables cumulative gas production and degradation of nutrients the design was completely randomized in split plots, with the effect of incubation time as subplots. Three stallions were used as feces donors. After 28 days of adaptation to the diet and management, the feces were collected directly from the rectum of animals. After collection, the feces had been mixed with the nutritive solution in the ratio (weight:weight): 1:1 and 1:3 and kept in a water bath at 39 ° C constantly sprayed with CO2. After one hour, the material was filtered and 10 ml of inoculum had been added to previously prepared bottles. The fermentation bottles were prepared as follows: put 1 g of Coastcross hay and 90 ml of nutritive solution was added at the moment of inoculation or 12 hours before inoculation procedure. The variables bacteria count after 24 h of inoculation, the dry matter degradation (DMD), the organic matter degradation (OMD) and the neutral detergent fiber degradation (NDFD) at 24, 48 and 72 h of fermentation, as well the ammonia nitrogen content (NH3-N), pH and the cumulative gases production over 72 h had been evaluated. The nonlinear regression model adjusted the cumulative gases production. The results were submitted to ANOVA 5%, and the averages compared by SNK test at 5%. There was no significant effect of hydration and dilution factors in OMD, NDFD, NH3-N and the concentration of Lactobacillus spp., Streptococcus spp., cellulolytic bacteria and total anaerobic bacteria. The significant dilution effect in the pH was observed and the significant hydration effect in DMD. The interaction between incubation time and the hydration time of the substrate was detected over the cumulative gases production, with values significantly different starting at eight hours of incubation until the end of process. There was no proper fit to the proposed model, since the L parameter was not significant. The soluble nutrients of the Coastcross hay became available due to the hydration process, therefore, has used for the initial development of the microorganisms reducing the lag phase period of 2.32 (without hydration) to 0.24 h. In conclusion, the hydration of the dehydrated substrate is a strategy that increases the fermentation substrate extension and degradation of dry matter. Moreover, lag phase time was reduced.