Feeding cashew nut shell liquid decreases methane production from feces by altering fecal bacterial and archaeal communities in Thai local ruminants

Abstract

The effect of feeding cashew nut shell liquid (CNSL) on fecal fermentation products and microbiota was investigated in Thai native cattle and swamp buffaloes. Four of each animal were fed rice straw and concentrate diet with control pellets without CNSL for 4 weeks, followed by the same diet with pellets containing CNSL for another 4 weeks, so that CNSL was administered at a level of 4 g/100 kg body weight. Feces were collected the last 2 days in each feeding period. CNSL alkyl phenols were recovered from feces (16%–28%) in a similar proportion to those in the diet, indicating that most functional anacardic acid was not selectively removed throughout the digestive tract. In vitro production of gas from feces, particularly methane, decreased with CNSL feeding. The proportion of acetate in feces decreased with CNSL feeding, whereas that of propionate increased, without affecting total short‐chain fatty acid concentration. CNSL feeding changed fecal microbial community, particularly in swamp buffaloes, which exhibited decreases in the frequencies of Treponema, unclassified Ruminococcaceae, and Methanomassiliicoccaceae. These results suggest that CNSL feeding alters not only rumen fermentation but also hindgut fermentation via modulation of the microbial community, thereby potentially attenuating methane emission from the feces of ruminant animals.

Cashew nut shell liquid potentially mitigates methane emission from the feces of Thai native ruminant livestock by modifying fecal microbiota

“…The findings of the present study suggest that CNSL addition is useful for decreasing methane emission from fresh feces that contains more fermentable materials than feces left for an extended period of time. The mitigation of methane emissions was associated with an alteration in SCFA production patterns, which, in turn, was affected by shifts in fecal microbes, as has been reported previously in a CNSL feeding study (Tamori et al, 2021). As another option, instead of adding CNSL in its refined form, cashew shells, preferably finely ground, could be directly applied to feces for this purpose.…”

“…Therefore, an effective strategy for minimizing the amount of methane emissions from feces can be achieved by direct addition of CNSL at the early stage of fecal storage. Tamori et al (2021) reported that supplementing the diet of Thai native cattle and swamp buffaloes with CNSL altered fecal microbiota and lowered the methane production potential of the feces. They concluded that CNSL supplementation modifies not only rumen fermentation but also hindgut and fecal fermentation to suppress methane generation, which can contribute to mitigating the environmental burden associated with maintaining ruminant livestock, especially in regions where feces is often left untreated for extended periods.…”

“…Our previous study using Thai native ruminants revealed that dietary supplementation with CNSL lowered the methane production potential by altering the structure of the fecal microbial communities in the feces (Tamori et al, 2021). Those findings implied that CNSL supplementation is a potentially effective strategy for reducing methane from both the rumen and the feces of ruminants.…”

“…The protocol for this animal study was reviewed and approved by the Fresh feces samples (200 g/animal) were collected directly from the rectum of four Thai native cattle (512 AE 41 kg body weight) and four swamp buffaloes (560 AE 23 kg) just before feeding at 8:00 a.m. at the experimental farm of the Faculty of Agriculture at Kasetsart University in Kamphaeng Saen, Thailand. The animals were fed a locally formulated concentrate (1 kg/day) consisting of cassava, palm kernel meal, flaked corn, soybean meal, sugarcane molasses, urea, vitamin and mineral mixture, and rice straw (90% of ad libitum intake) once daily for 8 weeks, as described by Tamori et al (2021). The total diet contained 7.8-8.2% crude protein and 56.8-57.7% neutral detergent fiber (depending on the rice straw intake of individual animals).…”

“…Several factors that influence methane emission have been identified in previous studies; for example, temperature, moisture content, and duration of storage have all been found to have a marked effect on methane emissions from feces, followed by dietary conditions and the species of the ruminant animals (Zeeman, 1994). Our previous study using Thai native ruminants revealed that dietary supplementation with CNSL lowered the methane production potential by altering the structure of the fecal microbial communities in the feces (Tamori et al, 2021). Those findings implied that CNSL supplementation is a potentially effective strategy for reducing methane from both the rumen and the feces of ruminants.…”