# The impact of dietary supplementation with tannic acid on the digestion of nutrients, rumen microflora, rumen fermentation, and methane production in Liuyang black goats

## TL;DR

This study shows that adding tannic acid to the diet of Liuyang black goats reduces methane emissions and improves digestion by altering rumen microbes and fermentation.

## Contribution

The study demonstrates tannic acid's potential as a sustainable feed supplement to reduce methane in ruminants.

## Key findings

- Tannic acid significantly reduced methane emissions and fiber intake in goats.
- Tannic acid increased Firmicutes and decreased Methanobrevibacter and Prevotella in the rumen.
- Tannic acid altered rumen fermentation by increasing valerate and butyrate concentrations.

## Abstract

This study investigated the effects of dietary tannic acid on methane production, nutrient digestibility, rumen fermentation, and rumen microbiota in Liuyang black goats.

Twelve adult goats were randomly assigned to two groups: a control group and a treatment group that received 2% tannic acid in their diet. The experiment consisted of two stages, each comprising a 10-day adaptation period followed by and a 5-day sampling phase. Methane emission was measured using a mobile open-circuit respirometry system, while rumen fluid samples were analyzed for volatile fatty acids, ammonia nitrogen, and microbial composition by 16S rRNA sequencing.

The results indicated that the tannic acid significantly reduced overall methane emission (p<0.05), methane per dry matter intake (p<0.05), acid detergent fiber intake (p<0.05), and neutral detergent fiber intake (p<0.05). Microbial analysis showed increased relative abundance of Firmicutes (p<0.05) and decreased Methanobrevibacter and Prevotella. Before feeding, tannic acid led to a significant increase in the concentration of valerate in the rumen fluid (p<0.05), while the acetate to propionate ratio was significantly decreased (p<0.05). Three hours post feeding, the concentrations of both butyrate and valerate were significantly increased (p<0.05).

Dietary tannic acid effectively reduced methane emission and enhanced feed efficiency in Liuyang black goats by modifying rumen fermentation and microbial activity. These findings indicate the potential of tannic acid as a sustainable feed supplement for ruminants; nevertheless, the long-term effects on health and production necessitate more research.