Objectives This study sought to determine the effect of clove oil (CL) as a replacement to flavomycin antibiotic growth promoter (AGP) in a goat basal diet on proximate components, in vitro ruminal fermentation characteristics, and microbiome profile. Methods Six treatment groups were formulated using a goat basal diet without AGP and CL (NEGCON), diet with flavomycin AGP (POSCON), and AGP-diet supplemented with 0.5% (CL5), 1.0% (CL10), 1.5% (CL15), and 2.0% v/w (CL20) of clove oil. Nine independent replicate samples from each treatment group were homogenized, oven-dried, milled and analysed for proximate components. Each replicate sample (1 g) was inoculated with donor goats’ ruminal fluid in a pre-mixed phosphate buffer solution (pH 6.8) and incubated (39 °C) to record in vitro ruminal gas production, fermentation kinetics, volatile fatty acids (VFA), and detect archaeal and bacterial diversity using 16 s rRNA gene sequencing. Results Supplementation with CL in place of AGP linearly increased the organic matter content of the diets. Replacing the AGP with CL significantly decreased VFA production but had no effects on the in vitro fermentation characteristics. The abundance of Anaerovibrio spp. was higher at 1% CL supplementation but lower for NEGCON. Lactobacillus mucosae abundance was highest at 2% CL followed by 1.5% CL supplementation, while both control groups caused the lowest abundance. Conclusion It was concluded that CL can modulate rumen microbial communities by enhancing microbial diversity and promoting beneficial probiotic populations. However, the associated reduction in VFA production at higher supplementation levels suggests that CL could negatively affect the energy status of ruminants. Future in vivo studies are needed to validate these findings and determine the optimal inclusion level of CL that could enhance fermentation efficiency in goats.
Idowu et al. (Sun,) studied this question.