257 Effects of feeding different levels of quebracho (Schinopsis balansae) extract in a high-roughage total mixed ration on seasonal manure gas emissions

Our objective was to investigate how quebracho tannin (QT; Schinopsis balansae) fed at differing rates within a roughage-based diet affected manure gas emissions of growing steers. The utilization of ruminant species is required for efficient production of human-edible protein to meet global nutrient demands. However, gaseous byproducts from ruminant production systems, such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are deleterious to the environment. It is estimated that CO2, CH4, and N2O from managed waste and grazed lands account for roughly 54% of emissions from the livestock sector within the United States, with approximately 80% being associated with beef and dairy cattle. Supplementation of condensed tannins is a plausible method for improving environmental efficiency through the mitigation of enteric CH4 and shifting route of N excretion. During two experimental periods, 12 crossbred steers (236 ± 16 kg) were fed a roughage-based diet at maintenance level with the addition of QT at 0, 1.5, 3, and 4.5% of DM serving as dietary treatments. Following adaptation, feces were collected and gas fluxes measured using vented static chamber technique with manure incubated on the soil surface at two locations, College Station and Stephenville, during two periods corresponding to winter and spring. The daily flux of CO2 was influenced by soil moisture and temperature (r = 0.34; P < 0.01), whereas CH4 and N2O were associated with soil moisture. Cumulative CO2 and gross CO2 equivalent (CO2e) exhibited a dietary treatment effect at College Station (P ≤ 0.01), with a linear reduction with increased dietary QT. At both locations, we observed significance or tendencies for period effects for CO2, CH4, N2O, and CO2e (P ≤ 0.07) with period 2 having higher gas production. Within certain environments, QT supplementation could potentially reduce manure gas emissions, but additional investigation into animal variation is required.

Evaluation of Low-Cost Hydrogen Sulfide Monitors for Use in Livestock Production

Direct-reading gas monitors warn workers of the risk of potentially fatal hydrogen sulfide (H2S) exposures that may arise during manure handling. Low-cost, low-maintenance H2S monitors are available from many manufacturers, but differences in their features and performance make selection challenging for farmers. Moreover, little information is available on the practical maintenance and performance of these devices in agricultural environments. The objective of this study was to provide information to agricultural workers to aid in the selection, maintenance, and use of low-cost H2S monitors. This laboratory study evaluated the performance of several low-cost monitors over a simulated period of use of one year in a swine barn. Four models were exposed to H2S concentrations of 1 to 10 ppm over 18 weeks to examine the drift in reported concentration and changes in the alarm reaction time. Over the simulated barn year, the performance of alarm-only monitors declined faster than that of monitors displaying the H2S concentration. Of concern was the high-level (20 ppm) alarm failures after an equivalent of 139 days (Altair) and 289 days (BW Clip) in a swine barn, well within the monitor’s reported shelf-life. Models displaying concentration exhibited fewer failures but were inaccurate in the displayed concentration when challenged with 20 ppm of H2S. The T40 Rattler provided consistently higher readings (+2.3 ppm), and the Pac 3500 showed consistently lower readings (-3.4 ppm) when challenged with 20 ppm. This study confirms the need for routine bump tests for these low-cost monitors to ensure that the monitor reacts to the presence of H2S, even if the manufacturer does not recommend this procedure. Most importantly, agricultural workers should inspect and bump test these monitors prior to any potentially high-risk activity, such as manure agitation, pumping, or pressure washing, to ensure that the monitor appropriately detects and warns users. Keywords: Calibration, Direct-reading monitors, H2S, Hydrogen sulfide monitors, Manure gas, Safety, Sensors.