Macroalgae Compound Characterizations and Their Effect on the Ruminal Microbiome in Supplemented Lambs.

Area of Science:

• Marine biology
• Animal nutrition
• Microbiome research

Background:

• Rumen function and microbiome are critical for livestock health and productivity.
• The impact of diverse macroalgae species on rumen microbial communities is not well understood.
• Marine macroalgae contain unique bioactive compounds with potential modulatory effects.

Purpose of the Study:

• To identify the bioactive compounds in three macroalgae species: Macrocystis pyrifera (Brown), Ulva spp. (Lettuce), and Mazzaella spp. (Red).
• To investigate the effects of these macroalgae on the rumen microbiome composition in Rambouillet lambs.
• To correlate macroalgae chemical composition with observed changes in rumen bacteria.

Main Methods:

• Macroalgae were analyzed for biocompounds using Gas Chromatography-Mass Spectrometry (GC-MS).
• Twelve lambs were fed control or diets supplemented with 5g of Red, Brown, or Lettuce algae.
• Rumen fluid was collected for 16S rRNA gene V3 amplicon sequencing to analyze microbial communities.

Main Results:

• Dominant rumen bacteria phyla (Firmicutes, Bacteroidota) were identified across all groups.
• Macroalgae supplementation significantly altered the relative abundance of these dominant bacterial groups.
• The abundance of fibrinolytic and cellulolytic bacteria, specifically Selenomonas, increased in lambs fed macroalgae.
• Volatile organic compounds (VOCs) such as anethole, beta-himachalene, and 4-ethylphenol were identified in macroalgae.

Conclusions:

• Marine macroalgae possess diverse bioactive compounds, including VOCs with antimicrobial and fermentation-modulating properties.
• Macroalgae supplementation can selectively modulate the rumen microbiome, favoring beneficial bacteria like Selenomonas.
• This research provides insights into using macroalgae as a feed additive to influence rumen function and potentially improve livestock performance.