Feed additives for methane mitigation: Recommendations for testing enteric methane-mitigating feed additives in ruminant studies.

There is a need for rigorous and scientifically-based testing standards for existing and new enteric methane mitigation technologies, including antimethanogenic feed additives (AMFA). The current review provides guidelines for conducting and analyzing data from experiments with ruminants intended to test the antimethanogenic and production effects of feed additives. Recommendations include study design and statistical analysis of the data, dietary effects, associative effect of AMFA with other mitigation strategies, appropriate methods for measuring methane emissions, production and physiological responses to AMFA, and their effects on animal health and product quality.

Predicting CO production of lactating dairy cows from animal, dietary, and production traits using an international dataset.

Automated measurements of the ratio of concentrations of methane and carbon dioxide, [CH]:[CO], in breath from individual animals (the so-called "sniffer technique") and estimated CO production can be used to estimate CH production, provided that CO production can be reliably calculated. This would allow CH production from individual cows to be estimated in large cohorts of cows, whereby ranking of cows according to their CH production might become possible and their values could be used for breeding of low CH-emitting animals. Estimates of CO production are typically based on predictions of heat production, which can be calculated from body weight (BW), energy-corrected milk yield, and days of pregnancy.

Application of biochar to anaerobic digestion versus digestate: Effects on N emissions and C stability.

Research attention is growing for biochar as amendment for anaerobic digestion (AD), as it may improve both the AD process and digestate properties. In this study, two biochars (from insect frass or the woody fraction of green waste, both pyrolyzed at 450 °C) were added (5 % w/w) during semi-continuous AD of organic kitchen waste and chicken manure. Biochar was mixed either during the AD process or to the digestate post-treatment.

Biochar amendment to cattle slurry reduces NH emissions during storage without risk of higher NH emissions after soil application of the solid fraction.

Cattle slurry storage is a major source of gaseous N emissions. The aim of this study was to evaluate the effects of biochar, clinoptilolite and elemental sulfur (S°) on (1) NH and greenhouse gas emissions during storage of cattle slurry and (2) after soil application of the enriched solid fractions; and (3) on the agronomic quality of the solid and liquid fractions. In the first phase, biochar was added to the slurry (10 g L); subsequently in the second phase, clinoptilolite (50 g L), S° (1 g L) and 40 g L extra biochar were added.

Screening tests for N sorption allow to select and engineer biochars for N mitigation during biomass processing.

Biochar amendment during biomass processing can improve those processes and products, and reduce the emissions of greenhouse gases and NH, resulting in ecologic and economic benefits. The potential positive effects of biochar are related to NH-N and NH sorption, which in turn are depending on different biochar characteristics. By knowing the relationship between biochar characteristics and NH-N and NH sorption, biochar production can be steered towards a higher N sorption or existing biochars can be selected for targeted applications for high N sorption.