Pilot Study of the Effects of Polyphenols from Chestnut Involucre on Methane Production, Volatile Fatty Acids, and Ammonia Concentration during In Vitro Rumen Fermentation

SIMPLE SUMMARY: In China, chestnut involucres, an agricultural byproduct, are not appropriately used and are regarded as agricultural waste. To reduce the environmental pollution caused by burning or misuse of chestnut involucres, the authors extracted polyphenols from the involucres of Castanea mollissima Blume (PICB) to produce a new additive. PICB is known to have beneficial effects on monogastric animals. However, the effects of PICB on ruminants need further investigation. This study shows that the addition of PICB to the ruminant diet can significantly reduce methane yields and the ratio of acetic acid to propionic acid, thus improving feed efficiency. The results contribute to the knowledge of tannins from a specific part of the Castanea mollissima Blume plant and provide a theoretical basis for the potential use of involucres. Such an application would limit environmental pollution caused by their disposal and reduce the negative influence of ruminants on the environment. ABSTRACT: Nutritional strategies can be employed to mitigate greenhouse emissions from ruminants. This article investigates the effects of polyphenols extracted from the involucres of Castanea mollissima Blume (PICB) on in vitro rumen fermentation. Three healthy Angus bulls (350 ± 50 kg), with permanent rumen fistula, were used as the donors of rumen fluids. A basic diet was supplemented with five doses of PICB (0%–0.5% dry matter (DM)), replicated thrice for each dose. Volatile fatty acids (VFAs), ammonia nitrogen concentration (NH(3)-N), and methane (CH(4)) yield were measured after 24 h of in vitro fermentation, and gas production was monitored for 96 h. The trial was carried out over three runs. The results showed that the addition of PICB significantly reduced NH(3)-N (p < 0.05) compared to control. The 0.1%–0.4% PICB significantly decreased acetic acid content (p < 0.05). Addition of 0.2% and 0.3% PICB significantly increased the propionic acid content (p < 0.05) and reduced the acetic acid/propionic acid ratio, CH(4) content, and yield (p < 0.05). A highly significant quadratic response was shown, with increasing PICB levels for all the parameters abovementioned (p < 0.01). The increases in PICB concentration resulted in a highly significant linear and quadratic response by 96-h dynamic fermentation parameters (p < 0.01). Our results indicate that 0.2% PICB had the best effect on in-vitro rumen fermentation efficiency and reduced greenhouse gas production.