Humic substances reduce ruminal methane production and increase the efficiency of microbial protein synthesisin vitro

Abstract

BACKGROUND: In ruminants, enteric CH 4 represents a major energy loss for the host and is a potent greenhouse gas that contributes to climate change. Previous studies have shown that humic substances (HS) may have beneficial effects on livestock nutrition. The present study investigated the effects of HS on in vitro CH 4 production and rumen fermentation. RESULTS: Total gas production was linearly increased with increasing HS after 12 h of incubation, although it was unaffected after 24 and 48 h. Increasing HS linearly decreased CH 4 at all time points. Increasing HS linearly decreased NH 3 -N concentration and the molar proportion of acetate at 12 h, whereas the efficiency of microbial protein (MP) production and total dry matter digestibility (TDMD) linearly increased, with starch digestion (SD) responding quadratically. After 48 h, HS linearly increased MP and TDMD, with neutral detergent fibre digestibility responding quadratically.CONCLUSION: Inclusion of HS effectively reduced CH 4 production and increased substrate disappearance and the efficiency of microbial protein synthesis in vitro. However, its effect on in vivo CH 4 production, rumen fermentation and ruminant production requires further investigation.

Effects of a recombinant fibrolytic enzyme on fiber digestion, ruminal fermentation, nitrogen balance, and total tract digestibility of heifers fed a high forage diet1

“…Furthermore, although the microassay we developed has the capacity to screen large numbers of recombinant enzymes for their synergy with mixed ruminal enzymes, it alone does not predict in vivo responses. Similar inconsistencies between in vitro and in vivo responses has been observed for other additives such as humic substances (HS) which were found to reduce CH 4 emission in batch cultures, but not in where HS consistently decreased CH 4 production when included at 3.6 mg•mL −1 of inoculum during a 48-h incubation in batch culture (Sheng et al, 2018), but not in the Rusitec (Terry et al, 2018b) or in heifers (Terry et al, 2018a).…”

Effects of sodium humate and glutamine combined supplementation on growth performance, diarrhea incidence, blood parameters, and intestinal microflora of weaned calves

“…As shown in increased linearly (Sheng et al, 2019). Taken together, these observations suggest that the increase in ADG of weaned calves caused by combined supplementation with HNa and Gln in this study may be attributed to improved efficiency of microbial protein synthesis and nutrient absorption.…”

“…Moreover, HNa or Gln supplementation increased weight gain and ADG of finishing pigs (Johnson & Lay, 2017; Kaevska et al, 2016). Surprisingly, in a vitro ruminal fermentation model, CH 4 and NH 3 ‐N production decreased linearly with increasing HAs, whereas the efficiency of microbial protein synthesis and total dry matter digestibility increased linearly (Sheng et al, 2019). Taken together, these observations suggest that the increase in ADG of weaned calves caused by combined supplementation with HNa and Gln in this study may be attributed to improved efficiency of microbial protein synthesis and nutrient absorption.…”

The Effect of Humic Mineral Substances from Oxyhumolite on the Coagulation Properties and Mineral Content of the Milk of Holstein-Friesian Cows

“…Recent years have seen growing interest in the use of humic substances in animal diets [7][8][9][10]. Humic substances (including humic and fulvic acids) are regarded as safe and natural feed additives with beneficial effects on animal welfare and on the quality of animal products.…”