The rumen microbiome is thought to play an important role in maintaining normal gastrointestinal metabolism and nutrient absorption in ruminants. The present study was designed to investigate the effect of heat stress on the rumen microbiome of goats using 16S rRNA sequencing technology. Six female goats were randomly allocated into two control metabolic chambers: A and B (in which the temperature and humidity could be precisely controlled with a precision deviation of ± 0.5°C and ± 5%, with three goats/chamber). Dynamic changes in the rumen bacterial community were detected under 16 gradually increasing temperature and humidity indexes (THIs). Heat stress had no significant effect on alpha diversity but affected the main phyla and genera of the goat rumen microbiota. With a deeper level of heat stress, the TH groups formed a distinct cluster that differed from that of the control check (CK) group. The dominant phylum transitioned from Firmicutes to Bacteroidetes, and co-exclusion occurred between these two phyla. With the increase in THI, the content of probiotics in the Lachnospiraceae_ND3007_group (P < 0.05) decreased, and the abundance of pathogenic bacteria, such as Erysipelotrichaceae_UCG-004 and Treponema_2, increased; however, the difference between the groups was not significant (P > 0.05). Phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) was used to predict bacterial function, and we found that the ambient environment significantly affected the balance between carbohydrate and energy metabolism (P < 0.05). In conclusion, heat stress changed the composition of rumen microbes and affected metabolic function. This experiment provides a theoretical basis for exploring the effects of environmental factors on the rumen of goats.

Mulberry leaves, which have high nutritional value, have not been fully utilized. Few research systems have indicated whether mulberry leaves can replace traditional feed ingredients in goats. In this study, we investigated the effects of feeding white cashmere goats ensiled (Group E) or sun-dried mulberry leaves (Group S) on changes in ruminal microbial communities, rumen fermentation parameters and serum biochemical indices. The control group (Group C) received a typical total mixed ration (TMR). 16S rRNA gene sequencing revealed 209 genera belonging to 19 bacterial phyla dominated by Firmicutes and Bacteroidetes. Only the relative abundances of Erysipelotrichaceae_UCG-009 were significantly different among the three groups (p < 0.05). Physiological and biochemical findings revealed that only the serum leptin concentrations were significantly decreased when mulberry leaves were added to the diets (p < 0.05). Correlation analysis revealed that Ruminococcus_2 were significantly positively correlated with the butyrate concentration. These findings suggested that supplementation with mulberry leaves only induced minor changes in the abovementioned indicators, implying that the rumen fermentation status was still stable after adding mulberry leaves to the diets.

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Kefir is a kind of fermented milk that is produced by inoculating Kefir grains into milk, mainly consisting of bacteria and yeasts. Bacillus and their metabolites also have found some biotechnological applications in many aspects. The aim of the present study was to evaluate the mixed fermentation conditions by kefir and Bacillus. The results showed that kefir and Bacillus could be mixed fermentation, the suggested optimum fermentation conditions are the following: inoculum size was 4 mL of mixed fermentation agent for per 100 mL medium, the ratio to kefir and Bacillus is 2:1, fermentation temperature of 28 °C and fermentation time of 20 h. Under the optimum fermentation conditions, the viable cell counts of Lactic acid bacteria, yeast and Bacillus could above 1.0×1011, 4.0×1010, and 2.0×109CFU/mL respectively. After freeze-dried, by adding 10 % ( w/v ) skim milk, 3 % ( w/v ) glycerinum, 3 % trehalose and 1 % ( w/v ) Monosodium glutamate as for cryoprotectant, the viable cell counts could still above 107CFU/mL after 6 month.