摘要:Fat rich microorganisms, such as microalgae <i>Schizochytrium </i>spp., are potential biotechnological tools in the modulation of rumen microbiome towards ecofriendly and high nutritional value end-products. However, limited in vivo trials have been reported on the topic. The aim of this study was to contribute to the knowledge on the effect of fat rich microalgae on the methanogenic and feed degrading particle-associated microbes in goats’ rumen content. For the trial, twenty-four goats were divided into four homogenous clusters (six goats/treatment) according to their fat corrected (4%) milk yield, body weight and age and individually were fed with alfalfa hay and concentrate feeds (F/C = 50/50). The concentrate of the control group (CON) contained no microalgae, while those of the treated groups were supplemented daily with 20 (ALG20), 40 (ALG40), and 60 (ALG60) g of <i>Schizochytrium </i>spp./goat. The relative abundances of total Archaea, methanogens, Methanomassiliicoccales, <i>Methanobrevibacter</i> spp., <i>Methanosphaera stadmanae</i> and <i>Methanobacterium formicicum</i> were significantly (<i>p</i> < 0.05) decreased in microalgae-fed goats compared to the CON ones. Moreover, a significant decline in the relative abundances of Firmicutes<i>, Ruminococcus flavefaciens, Butyrivibrio fibrosolvents,</i> and Neocallimastigales in the rumen particle-associated microbiota of microalgae supplemented goats were observed. In conclusion, goats’ diets supplementation with <i>Schizochytrium </i>spp., could be considered a sustainable nutritional strategy for methanogens inhibition in their rumen particle-associated microbiota.