Recent interest in greenhouse gas emissions from ruminants, such as cattle, has spawned a need for affordable, precise, and accurate methods for the measurement of gaseous emissions arising from enteric fermentation. A new head hood system for cattle designed to capture and quantify emissions was recently developed at the University of California, Davis. The system consists of two head hoods, two vacuum pumps, and an instrumentation cabinet housing the required data collection equipment. This system has the capability of measuring carbon dioxide, methane, ethanol, methanol, water vapor, nitrous oxide, acetic acid emissions and oxygen consumption in real-time. A unique aspect of the hoods is the front, back, and sides are made of clear polycarbonate sheeting allowing the cattle a full range of vision during gas sampling. Recovery rates for these slightly negative pressure chambers were measured ranging from 97.6 to 99.3 percent. This system can capture high quality data for use in improving emission inventories and evaluating gaseous emission mitigation strategies.

Societal pressure to reduce enteric methane emissions from cattle continues to increase. The present study evaluated the efficacy of the commercial essential oil feed additive Agolin^® Ruminant on reducing enteric gas emissions and improving milk parameters in dairy cattle. Twenty mid-lactation Holstein cows, blocked by parity and days in milk, were randomly assigned to a top dress treatment with Agolin or an un-supplemented control for a 56-day trial. Cows were group housed and individually fed twice daily. Enteric gas emissions, including methane, carbon dioxide, ammonia, and nitrous oxide, were sampled every 14 days for a 12 h period via head chambers connected to a mobile air quality laboratory. Cows supplemented with Agolin versus the control had less methane intensity (g/period/kg energy-corrected milk (ECM); p = 0.025). Ammonia was the most affected gas, with lower ammonia production (mg/period; p = 0.028), and ammonia intensity (mg/period/kg ECM; p = 0.011) in Agolin-fed versus control-fed cows. All cow performance variables, including dry matter intake, ECM, milk fat, milk protein, or feed efficiency were similar between treatments. Further research should evaluate how Agolin impacts ruminal flora, focusing on mechanistic impacts to fermentation.

Two methods were described to estimate interference in the measurements of infrared (IR) photoacoustic multi-gas analyzer (PAMGA). One is IR spectroscopic analysis (IRSA) and the other is mathematical simulation. An Innova 1412 analyzer (AirTech Instruments, Ballerup, Denmark) with two different filter configurations was used to provide examples that demonstrate the two methods. The filter configuration in Example #1 consists of methane (CH₄), methanol (MeOH), ethanol (EtOH), nitrous oxide (N₂O), carbon dioxide (CO₂), and water vapor (H₂O), and in Example #2 of ammonia (NH₃), MeOH, EtOH, N₂O, CO₂, and H₂O. The interferences of NH₃ as a non-target gas in Example #1 were measured to validate the two methods. The interferences of H₂O and NH₃ as target gases in Example #2 were also measured to evaluate the analyzer’s internal cross compensation algorithm. Both simulation and experimental results showed that the interference between the target gases could be eliminated by the internal cross compensation algorithm. But the interferences of non-target gases on target gases could not be addressed by the internal cross compensation, while they could be assessed by the IRSA and mathematical simulation methods. If the IR spectrum of a non-target gas overlaps with that of target gas A at filter A, it could affect not only gas A (primary interference), but also other target gases by secondary interference (because the IR spectrum of gas A overlaps with gas B at filter B and thus affects gas B measurements). The IRSA and mathematical simulation methods can be used to estimate the interference in IR PAMGA measurements prior to purchase or calibration of the unit.

Animal manure is a source of greenhouse gas (GHG) emissions and other pollutants and nuisances such as ammonia and odors. There are several technologies to reduce emissions on animal farms including manure additives; however, few have been proven effective and easy to apply to dairy lagoon systems. The present research aimed at testing the ability of the commercial additive “SOP LAGOON” to reduce emissions of GHGs (i.e., carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O)), as well as ammonia (NH₃) and odors from lagoon stored liquid manure. Emissions of GHGs, NH₃ and odors were measured in the laboratory from barrels filled with 65 L of manure treated with SOP LAGOON or left untreated as a control. Manure was collected from a commercial dairy that is located in Solano County, California. Emissions of GHGs and NH₃ were continuously measured for one week using flux chambers placed on top of the barrels and connected to a mobile air emissions laboratory. The effects of the untreated control, versus the two respective treatment additive doses of 30.8 and 61.6 g/m³ of manure were compared to each other. The low dose was selected based on the manufacturer recommendation and the high dose was selected by doubling the low dose. Results showed that SOP LAGOON applied at the high dose (61.6 g of SOP LAGOON per m³ of manure) versus the control greatly reduced (p < 0.05) emissions of CO₂, CH₄, N₂O and NH₃ by 14.7%, 22.7%, 45.4% and 45.9%, respectively. Furthermore, the high dose of SOP LAGOON treated samples versus the control samples showed less odor intensity (p < 0.05). There was no significant effect of the low dose of SOP LAGOON on the emissions of different gases. The HIGH dose of SOP LAGOON might decrease the number of methanogens and hydrolytic microorganisms and their excreted enzymes during manure storage. Further studies are needed to investigate the mechanism of emission reduction using SOP LAGOON.

The objective of this study was to determine if a commercial feed additive blend composed of quebracho, chestnut tannins, and saponins (TAN; Silvafeed BX) could reduce enteric GHG and ammonia (NH₃) emissions without negatively effecting the productive performance of dairy cows. Twenty mid lactation Holstein dairy cows were blocked by DIM and parity in a randomized complete block design, and were assigned to 1 of 2 treatments: TAN (n = 10) or control with no TAN (CON; n = 10). The treatments were administered as a top dress at each of 2 daily feedings with TAN supplemented at a rate of 0.07% of dietary DM. Cow blocks were sampled for enteric gaseous emissions in head chambers (HC) for a 12 h period on their respective treatment d 0, 16, 32, and 48. After the enteric emission sampling period concluded, collected urine and manure were combined into a manure slurry at 1:1.7 (urine wt:feces wt) per cow. Manure slurry methane (CH₄), carbon dioxide (CO₂), nitrous oxide (N₂O), and NH₃ emissions were measured for 24 h. Supplemental TAN decreased enteric production (g/HC period or mg/HC period gas) of CH₄, CO₂, and N₂O over the trial period, and tended to increase NH₃ production in TAN-supplemented cows. Gaseous emission yield (g or mg gas/kg HC DM intake) did not differ between TAN- and CON-supplemented cows for CH₄, CO_2, or N₂O, although TAN-supplemented cows had greater NH₃ yield. Methane, CO₂, N₂O, and NH₃ intensity (g or mg gas/kg PM ECM) were not affected by TAN supplementation. Supplemental TAN did not effect slurry GHG emissions, although it increased NH₃ emissions. No differences in ECM, milk fat yield, milk protein yield, and DMI in TAN-supplemented cows versus CON-supplemented cows were noted.