Use of bedding materials in beef bedded manure packs in hot and cool ambient temperatures: Effects on ammonia, hydrogen sulfide, and greenhouse gas emissions

Throughout the Upper Midwest, producers have observed increased land and fertilizer prices, resulting in increased popularity of confinement feeding facilities such as mono-slope and hoop barns with bedded packs. Environmental and public pressure has been placed on the agriculture community to reduce ammonia (NH3), hydrogen sulfide (H2S), and greenhouse gas (GHG) emissions from concentrated animal feeding operations (CAFOs). This study was conducted to determine the effects of bedding material (corn stover (CS), bean stover (BS), wheat straw (WS), or pine wood chips (PC)) and ambient temperature (15°C (COOL) or 30°C (HOT)) on NH3, CH4, CO2, N2O, and H2S flux in air samples collected in the headspace above lab-scale bedded packs. All bedded packs were housed at 18°C for an initial three weeks before being placed in their respective environmental chambers at 15°C or 30°C for the remainder of the 6-week study period. Significant two-way interactions of bedding material by temperature for NH3 flux were observed (p = 0.0094). Ammonia flux was greater at higher temperature, while CS bedding had the lowest NH3emissions compared to the other bedding materials. A significant two-way interaction of bedding material by temperature for H2S flux was observed (p \u3c 0.0001), with significantly greater H2S produced in the headspace of COOL-BS packs compared to all other treatments. Additionally, a significant (p = 0.0357) two-way interaction of temperature by age of the bedded pack was observed for H2S flux. Hydrogen sulfide flux appeared to be influenced by low bedded pack pH to a greater extent than by increase in temperature. Greenhouse gas emissions tended to be higher from bedded packs in HOT treatments. A significant (p = 0.0422) interaction among bedding material, temperature, and age of the bedded pack was observed for CH4. Significantly greater CH4flux was observed in the headspace above HOT-BS and HOT-CS at week 6 compared to all other treatments. A significant two-way interaction of bedding material by temperature was observed for CO2flux (p = 0.0189). The largest CO2levels were observed above WS bedding material regardless of temperature. Nitrous oxide flux decreased over the 6-week study for all bedded packs, while WS and PC bedded packs produced the greatest N2O flux. The results indicate that feedlot operators maintaining bedded pack facilities will have the greatest reduction in NH3emissions when using CS bedding, regardless of ambient temperature. To reduce CH4emissions, producers should avoid allowing BS and CS bedded packs that are maintained for longer than six weeks in HOT (30°C) temperatures; frequent cleaning during summer months is recommended. Based on the CO2equivalents of CH4and N2O, producers should consider PC as an option to reduce GHG emissions

Use of bedding materials in beef bedded manure packs at hot and cold ambient temperatures: Effects on odorous volatile organic compounds and odor activity values

Beef cattle producers are beginning to raise cattle in confinement facilities such as slatted-floor barns, hoop barns, and mono-slope facilities. Hoop and mono-slope facilities typically use bedding packs as part of their manure management system, with crop residues being the most commonly used bedding material. This study was conducted to determine the effects of bedding material, i.e., corn stover (CS), bean stover (BS), wheat straw (WS), or pine wood chips (PC), and environmental ambient temperature, i.e., cold (15°C) or hot (30°C), on the concentrations of odorous volatile organic compounds (VOCs) in air samples collected in the headspace above lab-scale bedded packs over a 42-day period. Total aromatic compounds, sulfide compounds, straight-chain fatty acids (SCFAs), and branched-chain fatty acids (BCFAs) were measured and used to calculate total odor activity values (OAVs) for each bedding and temperature effect. No significant three-way interactions for bedding material × ambient temperature × age of bedded pack were observed. Significant bedding material × ambient temperature interactions were observed for total aromatic compounds and total sulfide compounds (p = 0.0455 and p = 0.0083, respectively). The concentration of total aromatic compounds was greater for all hot treatments compared to cold treatments, with hot-CS and hot-WS bedding types (389.83 and 365.5 ng L-1, respectively) significantly (p \u3c 0.05) greater than all other bedding types, while total aromatic compounds were lowest (87.09 ng L-1) for BS across cold treatments. Total sulfide compounds from cold-PC (51.69 ng L-1) were significantly (p = 0.0143) greater than all other treatments. Within hot treatments, total sulfide compounds were similar across all bedding materials. Total SCFAs for both cold and hot treatments decreased significantly from weeks 4 to 6. Total SCFA concentrations within weeks were significantly (p \u3c 0.0001) greater for WS and CS compared to BS and PC but similar across bedding materials at week 6. Total BCFA concentrations from bedded packs containing CS and WS were significantly (p \u3c 0.0001) higher at week 4 compared to concentrations from bedded packs containing BS or PC. As bedded packs aged, total BCFA concentrations for all bedding materials were similar at week 6. Total OAVs decreased over time for both hot and cold treatments, although cold treatments had significantly (p \u3c 0.0001) lower total OAVs regardless of the age of the bedded pack. Aromatic compounds generated 72.6% of the total OAV over the 42-day study. Bedding types BS and PC had the lowest total OAVs across all weeks. The results indicate that feedlot operators maintaining bedded pack facilities will achieve the greatest overall odor reduction when using BS or PC bedding material, no matter the ambient temperature