Innovative cooling strategies: Dairy cow responses and water and energy use.

Producers in the western United States commonly use spray water at the feed bunk and fans in the lying area to mitigate heat stress in dairy cows. Often, spray water cycles on and off with fans turning on when a preset air temperature is reached. Although this method can be effective, innovative strategies are needed to reduce water and energy use. We evaluated the effectiveness and resource efficiency of 4 cooling treatments on behavioral and physiological responses in dairy cows housed in a freestall barn: (1) conductive cooling in which mats with recirculating evaporatively cooled water were buried under sand bedding (Mat; activated at 18.9°C); (2) targeted convective cooling in which evaporatively cooled air was directed toward the cows through fabric ducts with nozzles at both the feed bunk and lying areas (Targeted Air; activated at 22°C); (3) evaporative cooling, with spray water in the feed area and fan over the freestalls (Baseline; activated at 22°C); and (4) evaporative cooling with half the amount of spray water used in the Baseline and the fan moved to the feed bunk (Optimized Baseline; activated at 22°C). In a crossover design, 8 groups of cows (4/group) producing an average (± standard deviation) of 37.5 ± 4.5 kg/d of milk were tested for 3 d per treatment. For ethical reasons, beginning at 30°C, the Mat treatment was supplemented with Baseline cooling and the Targeted Air treatment had spray water at the Optimized Baseline rate. We recorded body temperature, posture, and location within the pen every 3 min for 24 h/d, and respiration rates every 30 min daily from 1000 to 1900 h. Daily air temperature averaged (±SD) 26.3 ± 7.1°C during 24 h and 33.3 ± 4°C from 1000 to 1900 h. We used pairwise comparisons of each treatment to Baseline to evaluate response variables. Milk production did not differ across treatments, nor did time spent lying (51 ± 2%/d on average). Respiration rates did not differ across treatments overall (61 ± 3 breaths/min), but on an hourly basis, cows in the Mat treatment had a significantly higher rate than those in Baseline, at h 10 and 11 (70 vs. 58-59 breaths/min). Body temperature averaged 38.7 ± 0.05°C across treatments and was 0.2 to 0.3°C higher in the Mat treatment than in Baseline at h 10, 11, 20, 21, and 22. These results collectively indicate that the Mat treatment did not effectively reduce indicators of heat load compared with Baseline. In contrast, Targeted Air and Optimized Baseline were both effective but differed in aspects of efficiency. Targeted Air used the least amount of water but the most energy of all options tested. In conclusion, more efficient heat abatement options were identified, particularly an Optimized Baseline strategy, which cut water use in half, required the same amount of energy as the Baseline, and maintained similar physiological and behavioral responses in cows.

Personal exposure of dairy workers to dust, endotoxin, muramic acid, ergosterol, and ammonia on large-scale dairies in the high plains Western United States.

Dairy workers experience a high degree of bioaerosol exposure, composed of an array of biological and chemical constituents, which have been tied to adverse health effects. A better understanding of the variation in the magnitude and composition of exposures by task is needed to inform worker protection strategies. To characterize the levels and types of exposures, 115 dairy workers grouped into three task categories on nine farms in the high plains Western United States underwent personal monitoring for inhalable dust, endotoxin, 3-hydroxy fatty acids (3-OHFA), muramic acid, ergosterol, and ammonia through one work shift. Eighty-nine percent of dairy workers were exposed to endotoxin at concentrations exceeding the recommended exposure guidelines (adjusted for a long work shift). The proportion of workers with exposures exceeding recommended guidelines was lower for inhalable dust (12%), and ammonia (1%). Ergosterol exposures were only measurable on 28% of samples, primarily among medical workers and feed handlers. Milking parlor workers were exposed to significantly higher inhalable dust, endotoxin, 3-OHFA, ammonia, and muramic acid concentrations compared to workers performing other tasks. Development of large modern dairies has successfully made progress in reducing worker exposures and lung disease prevalence. However, exposure to endotoxin, dust, and ammonia continues to present a significant risk to worker health on North American dairies, especially for workers in milking parlors. This study was among the first to concurrently evaluate occupational exposure to assayable endotoxin (lipid A), 3-hydroxy fatty acids or 3-OHFA (a chemical measure of cell bound and noncell-bound endotoxins), muramic acid, ergosterol, and ammonia among workers on Western U.S. dairies. There remains a need for cost-effective, culturally acceptable intervention strategies integrated in OHS Risk Management and production systems to further optimize worker health and farm productivity.

A survey of particulate matter on california dairy farms.

Over the past 30 yr, individual California dairy operations have grown in size; however, little is known about the distribution and determinants of particulate matter (PM) concentrations on these dairies. Elevated exposure to PM is associated with respiratory and cardiovascular health effects, particularly in occupational settings. The purpose of this study was to quantify the concentrations of PM and all inhalable PM (0-100 µm) on California dairies. Samplers were placed at various locations (e.g., milking parlor, grain storage area, drylot corral, and freestall barns) on 13 different dairies to collect PM and all inhalable PM during the 2008 summer months. The PM and all inhalable PM concentrations varied between different areas on a dairy and from dairy to dairy. Geometric mean concentrations for PM and inhalable PM were 24 µg m (range, 2-116 µg m) and 332 µg m (range, 74-1690 µg m). A key variable for explaining variation in PM concentrations with a mixed effects model was regional background ambient concentrations of PM No significant differences were observed in mean concentrations between upwind and downwind fence line concentrations (adjusted geometric mean ratio [AGMR] = 0.7; 95% CI, 0.4-1.3), although significant differences were found between upwind and central location mean values (AGMR = 0.5; 95% CI, 0.3-0.8; < 0.01). These results indicate dairy PM sources and, thus, elevated occupational exposure. Covariates, such as the age of the dairy and number of cows in the freestall barn and drylot corral, were important variables in explaining PM concentration variability. Levels of PM were lower compared with dairies in other U.S. states and other countries.

Activation of inflammatory responses in human U937 macrophages by particulate matter collected from dairy farms: an in vitro expression analysis of pro-inflammatory markers.

BACKGROUND: The purpose of the present study was to investigate activation of inflammatory markers in human macrophages derived from the U937 cell line after exposure to particulate matter (PM) collected on dairy farms in California and to identify the most potent components of the PM. METHODS: PM from different dairies were collected and tested to induce an inflammatory response determined by the expression of various pro-inflammatory genes, such as Interleukin (IL)-8, in U937 derived macrophages. Gel shift and luciferase reporter assays were performed to examine the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Toll-like-receptor 4 (TLR4). RESULTS: Macrophage exposure to PM derived from dairy farms significantly activated expression of pro-inflammatory genes, including IL-8, cyclooxygenase 2 and Tumor necrosis factor-alpha, which are hallmarks of inflammation. Acute phase proteins, such as serum amyloid A and IL-6, were also significantly upregulated in macrophages treated with PM from dairies. Coarse PM fractions demonstrated more pro-inflammatory activity on an equal-dose basis than fine PM. Urban PM collected from the same region as the dairy farms was associated with a lower concentration of endotoxin and produced significantly less IL-8 expression compared to PM collected on the dairy farms. CONCLUSION: The present study provides evidence that the endotoxin components of the particles collected on dairies play a major role in mediating an inflammatory response through activation of TLR4 and NF-κB signaling.

Characterization of endotoxin collected on California dairies using personal and area-based sampling methods.

Endotoxin, found in the cell wall of gram negative bacteria, is an important contributor to the biological activity of agriculture particulate matter (PM). We analyzed endotoxin in PM collected on 13 California dairies and from the breathing zone of 226 workers during the summer months of 2008. Two particle size fractions were measured: PM(2.5) and inhalable PM. Recombinant factor C assays were used to analyze biologically active endotoxin, while gas chromatography coupled with mass spectrometry in tandem was used to quantify total lipopolysaccharide. Biologically active endotoxin concentrations in the inhalable PM size fraction from area-based samples ranged from 11-2095 EU/m(3) and from 45-2061 EU/m(3) for personal samples. Total endotoxin in the inhalable PM size fraction ranged from 75-10,166 pmol/m(3) for area-based samples and 34-11,689 pmol/m(3) for personal samples. Area-based geometric mean concentrations for biologically active endotoxin and total endotoxin in PM(2.5) and inhalable PM size fractions were 3 EU/m(3), 149 EU/m(3), 60 pmol/m(3), and 515 pmol/m(3), respectively. Personal geometric mean concentrations in the inhalable PM size fraction were 334 EU/m(3), and 1178 pmol/m(3). Biologically active and total endotoxin concentration variation was best explained by meteorological data, wind speed, relative humidity, and dairy waste management practices. Differences in endotoxin concentration and composition were found across locations on the dairy.

Greenhouse gas and alcohol emissions from feedlot steers and calves.

Livestock's contributions to climate change and smog-forming emissions are a growing public policy concern. This study quantifies greenhouse gas (GHG) and alcohol emissions from calves and feedlot steers. Carbon dioxide (CO) methane (CH), nitrous oxide (NO), ethanol (EtOH), and methanol (MeOH) were measured from a total of 45 Holstein and Angus steers and 9 Holstein calves representative of four different growth stages commonly present on calf ranches and commercial feedlots. Individuals from each animal type were randomly assigned to three equal replicate groups of nine animals per group. Steers were fed a high concentrate diet and calves a milk replacer and grain supplement. Cattle and calves were housed in groups of three animals in an environmental chamber for 24 h. The CO, NO, EtOH, and MeOH concentrations from the air inlet and outlet of the chamber were measured using an INNOVA 1412 monitor and CH using a TEI 55C methane analyzer. Emission rates (g head h) were calculated. The GHGs were mainly produced by enteric fermentation and respiration and differed across life stages of cattle. Compared with dairy cows, feedlot steers produce relatively less GHG. In general, ethanol and methanol, the most important volatile organic compound (VOC) group in the dairy sector, were below the lower limit of detection of the gas analyzer. The present data will be useful to verify models and to enhance GHG emission inventories for enteric fermentation, respiration, and fresh excreta for numerous cattle life stages across the beef industry.

Identification and quantitation of volatile organic compounds emitted from dairy silages and other feedstuffs.

High ground-level ozone continues to be an important human, animal, and plant health impediment in the United States and especially in California's San Joaquin Valley (SJV). According to California state and regional air quality agencies, dairies are one of the major sources of volatile organic compounds (VOCs) in the SJV. A number of recently conducted studies reported emissions data from different dairy sources. However, limited data are currently available for silage and otherfeed storages on dairies, which could potentially contribute to ozone formation. Because the impact of different VOCs on ozone formation varies significantly from one molecular species to another, detailed characterization of VOC emissions is essential to include all the important contributors to atmospheric chemistry and especially atmospheric reactivity. The present research study identifies and quantifies the VOCs emitted from various silages and other feedstuffs. Experiments were conducted in an environmental chamber under controlled conditions. Almost 80 VOCs were identified and quantified from corn (Zea mays L.), alfalfa (Medicago sativa L.),and cereal (wheat [Triticum aestivum L.] and oat [Avena sativava L.] grains) silages, total mixed ration (TMR), almond (Amygdalus communis L.) shells and hulls using gas chromatography-mass spectrometry and high performance liquid chromatography. The results revealed high concentrations of emitted alcohols and other oxygenated species. Lower concentrations of highly reactive alkenes and aldehydes were also detected. Additional quantitation and monitoring of these emissions are essential for assessment of and response to the specific needs of the regional air quality in the SJV.

Determination of volatile organic compound emissions and ozone formation from spraying solvent-based pesticides.

Large-scale agricultural activities have come under scrutiny for possible contributions to the emission of ozone precursors. The San Joaquin Valley (SJV) of California is an area with intense agricultural activity that exceeds the federal ozone standards for more than 30 to 40 d yr(-1) and the more stringent state standards for more than 100 d yr(-1). Pesticides are used widely in both agricultural and residential subregions of the SJV, but the largest use, by weight of "active ingredient," is in agriculture. The objective of the study was to determine the role of pesticide application on airborne volatile organic compounds (VOC) concentrations and ozone formation in the SJV. The ozone formation from the pesticide formulation sprayed on commercial orchards was studied using two transportable smog chambers at four application sites during the summers of 2007 and 2008. In addition to the direct measurements of ozone formation, airborne VOC concentrations were measured before and after pesticide spraying using canister and sorbent tube sampling techniques. Soil VOC concentrations were also measured to understand the distribution of VOCs between different environmental compartments. Numerous VOCs were detected in the air and soil samples throughout the experiment but higher molecular weight aromatic hydrocarbons were the primary compounds observed in elevated concentrations immediately after pesticide spraying. Measurements indicate that the ozone concentration formed by VOC downwind of the orchard may increase up to 15 ppb after pesticide application, with a return back to prespray levels after 1 to 2 d.

Corrigendum to Raiten et al. Understanding the Intersection of Climate/Environmental Change, Health, Agriculture, and Improved Nutrition: A Case Study on Micronutrient Nutrition and Animal Source Foods.

[This corrects the article DOI: 10.1093/cdn/nzaa087.].

Effects of feeding lubabegron on gas emissions, growth performance, and carcass characteristics of beef cattle housed in small-pen environmentally monitored enclosures during the last 3 mo of the finishing period.

The development of technologies that promote environmental stewardship while maintaining or improving the efficiency of food animal production is essential to the sustainability of producing a food supply to meet the demands of a growing population. As such, Elanco (Greenfield, IN) pursued an environmental indication for a selective ß-modulator (lubabegron; LUB). LUB was recently approved by the United States Food and Drug Administration (FDA) to be fed to feedlot cattle during the last 14 to 91 d of the feeding period for reductions in gas emissions/kg of unshrunk final BW and HCW. A 4 × 2 factorial arrangement of treatments was used with the factors of dose (0.0, 1.38, 5.5, or 22.0 mg·kg-1 DM basis) and sex (steers or heifers). Three 91-d cycles were conducted (112 cattle/cycle) with each dose × sex combination being represented by a single cattle pen enclosure (CPE; 14 cattle/CPE) resulting in a total of 168 steers and 168 heifers (n = 6 replicates/dose). There were no interactions observed between dose and sex for any variable measured in the study (P ≥ 0.063). Five gases were evaluated for all pens based on CPE concentrations relative to ambient air: NH3, CH4, N2O, H2S, and CO2. Cumulative NH3 gas emissions were reduced by feeding cattle 5.5 and 22.0 mg·kg-1 LUB (P ≤ 0.023) and tended (P = 0.076) to be lower for the cattle fed 1.38 mg·kg-1 LUB compared with the negative controls (CON). The cumulative NH3 gas emission reductions of 960 to 1032 g, coupled with HCW increases (P ≤ 0.019) of 15 to 16 kg for all LUB doses vs. CON, led to reductions in NH3 gas emissions/kg HCW for all three LUB treatments (P ≤ 0.004). Similar to HCW, reductions in NH3 gas emissions/kg of unshrunk final BW were observed for all LUB doses (P ≤ 0.009) and were attributable to both decreases in NH3 gas emissions and numerical increases in BW. Dose had no effect on cumulative emissions or emissions standardized by BW or HCW for the other four gases (P ≥ 0.268). LUB is a novel tool to reduce emissions of NH3 gas per kilogram of unshrunk live BW and hot carcass weight.

Effect of dietary monensin on the bacterial population structure of dairy cattle colonic contents.

To determine the effect of monensin, a carboxylic polyether ionophore antibiotic, on the bacterial population structure of dairy cattle colonic contents, we fed six lactating Holstein cows a diet containing monensin (600 mg day(-1)) or an identical diet without monensin. Fresh waste samples were taken directly from the animals once a month for 3 months and assayed for their bacterial population structure via 16S rRNA gene sequence analysis. In total 6,912 16S rRNA genes were examined, comprising 345 and 315 operational taxonomic units (OTUs) from the monensin fed and control animals, respectively. Coverage estimates of the OTUs identified were 87.6% for the monensin fed and 88.3% for the control colonic content derived library. Despite this high level of coverage, no significant difference was found between the libraries down to the genus level. Thus we concluded that although monensin is believed to increase milk production in dairy cattle by altering the bacterial population structure within the bovine gastrointestinal tract, we were unable to identify any significant difference in the bacterial population structure of the colonic contents of monensin fed vs. the control dairy cattle, down to the genus level.

Lung antioxidant and cytokine responses to coarse and fine particulate matter from the great California wildfires of 2008.

The authors have previously demonstrated that wildfire-derived coarse or fine particulate matter (PM) intratracheally instilled into lungs of mice induce a strong inflammatory response. In the current study, the authors demonstrate that wildfire PM simultaneously cause major increases in oxidative stress in the mouse lungs as measured by decreased antioxidant content of the lung lavage supernatant fluid 6 and 24 h after PM administration. Concentrations of neutrophil chemokines/cytokines and of tumor necrosis factor (TNF)-alpha were elevated in the lung lavage fluid obtained 6 and 24 h after PM instillation, consistent with the strong neutrophilic inflammatory response observed in the lungs 24 h after PM administration, suggesting a relationship between the proinflammatory activity of the PM and the measured level of antioxidant capacity in the lung lavage fluid. Chemical analysis shows relatively low levels of polycyclic aromatic hydrocarbons compared to published results from typical urban PM. Coarse PM fraction is more active (proinflammatory activity and oxidative stress) on an equal-dose basis than the fine PM despite its lower content of polycyclic aromatic hydrocarbons. There does not seem to be any correlation between the content of any specific polycyclic aromatic hydrocarbon (or of total polycyclic aromatic hydrocarbon content) in the PM fraction and its toxicity. However, the concentrations of the oxidation products of phenanthrene and anthracene, phenanthraquinone and anthraquinone, were several-fold higher in the coarse PM than the fine fraction, suggesting a significant role for atmospheric photochemistry in the formation of secondary pollutants in the wildfire PM and the possibility that such secondary pollutants could be significant sources of toxicity in the wildfire PM.

Greenhouse gas, animal performance, and bacterial population structure responses to dietary monensin fed to dairy cows.

The present study investigated the effects of a feed additive and rumen microbial modifier, monensin sodium (monensin), on selected variables in lactating dairy cows. Monensin fed cows (MON, 600 mg d(-1)) were compared with untreated control cows (CON, 0 mg d(-1)) with respect to the effects of monensin on the production of three greenhouse gases (GHG), methane (CH(4)), nitrous oxide (N(2)O), and carbon dioxide (CO(2)), along with animal performance (dry matter intake; DMI), milk production, milk components, plasma urea nitrogen (PUN), milk urea nitrogen (MUN), and the microbial population structure of fresh feces. Measurements of GHG were collected at Days 14 and 60 in an environmental chamber simulating commercial dairy freestall housing conditions. Milk production and DMI measurements were collected twice daily over the 60-d experimental period; milk components, PUN, and MUN were measured on Days 14 and 60. The microbial population structure of feces from 6 MON and 6 CON cows was examined on three different occasions (Days 14, 30, and 60). Monensin did not affect emissions of methane (CH(4)), nitrous oxide (N(2)O), and carbon dioxide (CO(2)). Over a 24-h period, emissions of CH(4), N(2)O, and CO(2) decreased in both MON and CON groups. Animal performance and the microbial population structure of the animal fresh waste were also unaffected for MON vs. CON cows.

Understanding the Intersection of Climate/Environmental Change, Health, Agriculture, and Improved Nutrition: A Case Study on Micronutrient Nutrition and Animal Source Foods.

With a growing global population, the demand for high-quality food to meet nutritional needs continues to increase. Our ability to meet those needs is challenged by a changing environment that includes constraints on land and water resources and growing concerns about the impact of human activity including agricultural practices on the changing climate. Adaptations that meet food/nutritional demands while avoiding unintended consequences including negatively affecting the environment are needed. This article covers a specific case study, the role of animal source foods (ASFs) in meeting micronutrient needs in a changing environment. The article covers our understanding of the role of ASFs in meeting micronutrient needs, evidence-based approaches to the development of nutrition guidance, the current issues associated with the relation between animal production practices and greenhouse gas emissions, and examples of how we might model the myriad sources of relevant data to better understand these complex interrelations.

Carbon and blue water footprints of California sheep production.

While the environmental impacts of livestock production, such as greenhouse gas emissions and water usage, have been studied for a variety of US livestock production systems, the environmental impact of US sheep production is still unknown. A cradle-to-farm gate life cycle assessment (LCA) was conducted according to international standards (ISO 14040/44), analyzing the impacts of CS representing five different meat sheep production systems in California, and focusing on carbon footprint (carbon dioxide equivalents, CO2e) and irrigated water usage (metric ton, MT). This study is the first to look specifically at the carbon footprint of the California sheep industry and consider both wool and meat production across the diverse sheep production systems within California. This study also explicitly examined the carbon footprint of hair sheep as compared with wooled sheep production. Data were derived from producer interviews and literature values, and California-specific emission factors were used wherever possible. Flock outputs studied included market lamb meat, breeding stock, 2-d-old lambs, cull adult meat, and wool. Four different methane prediction models were examined, including the current IPCC tier 1 and 2 equations, and an additional sensitivity analysis was conducted to examine the effect of a fixed vs. flexible coefficient of gain (kg) in mature ewes on carbon footprint per ewe. Mass, economic, and protein mass allocation were used to examine the impact of allocation method on carbon footprint and water usage, while sensitivity analyses were used to examine the impact of ewe replacement rate (% of ewe flock per year) and lamb crop (lambs born per ewe bred) on carbon footprint per kilogram market lamb. The carbon footprint of market lamb production ranged from 13.9 to 30.6 kg CO2e/kg market lamb production on a mass basis, 10.4 to 18.1 kg CO2e/kg market lamb on an economic basis, and 6.6 to 10.1 kg CO2e/kg market lamb on a protein mass basis. Enteric methane (CH4) production was the largest single source of emissions for all CS, averaging 72% of total emissions. Emissions from feed production averaged 22% in total, primarily from manure emissions credited to feed. Whole-ranch water usage ranged from 2.1 to 44.8 MT/kg market lamb, almost entirely from feed production. Overall results were in agreement with those from meat-focused sheep systems in the United Kingdom as well as beef raised under similar conditions in California.

Alcohol, volatile fatty acid, phenol, and methane emissions from dairy cows and fresh manure.

There are approximately 2.5 million dairy cows in California. Emission inventories list dairy cows and their manure as the major source of regional air pollutants, but data on their actual emissions remain sparse, particularly for smog-forming volatile organic compounds (VOCs) and greenhouse gases (GHGs). We report measurements of alcohols, volatile fatty acids, phenols, and methane (CH4) emitted from nonlactating (dry) and lactating dairy cows and their manure under controlled conditions. The experiment was conducted in an environmental chamber that simulates commercial concrete-floored freestall cow housing conditions. The fluxes of methanol, ethanol, and CH4 were measured from cows and/or their fresh manure. The average estimated methanol and ethanol emissions were 0.33 and 0.51 g cow(-1) h(-1) from dry cows and manure and 0.7 and 1.27 g cow(-1) h(-1) from lactating cows and manure, respectively. Both alcohols increased over time, coinciding with increasing accumulation of manure on the chamber floor. Volatile fatty acids and phenols were emitted at concentrations close to their detection limit. Average estimated CH4 emissions were predominantly associated with enteric fermentation from cows rather than manure and were 12.35 and 18.23 g cow(-1) h(-1) for dry and lactating cows, respectively. Lactating cows produced considerably more gaseous VOCs and GHGs emissions than dry cows (P < 0.001). Dairy cows and fresh manure have the potential to emit considerable amounts of alcohols and CH4 and research is needed to determine effective mitigation.

Effects of sodium bisulfate on alcohol, amine, and ammonia emissions from dairy slurry.

Sodium bisulfate (SBS) is extensively used in the poultry industry to reduce ammonia and bacterial levels in litter. It is also used in the dairy industry to reduce bacterial counts in bedding and ammonia emissions, preventing environmental mastitis and calf respiratory stress. The present study measured the effect of SBS on the air emission of ammonia, amine, and alcohol from a dairy slurry mix. Amine flux was undetectable (<5 ng L(-1)) across treatments. Application of SBS decreased ammonia, methanol, and ethanol emissions from fresh dairy slurry. Ammonia emissions decreased with increasing levels of SBS treatment. The 3-d average ammonia flux from the control (no SBS applied) and the three different SBS surface application levels of 0.125, 0.250, and 0.375 kg m(-2) were 513.4, 407.2, 294.8, and 204.5 mg h(-1) m(-2), respectively. The ammonia emission reduction potentials were 0, 21, 43, and 60%, respectively. Methanol and ethanol emissions decreased with an increase in the amount of SBS applied. The 3-d average methanol emissions were 223.7, 178.0, 131.6, and 87.0 mg h(-1) m(-2) for SBS surface application level of 0, 0.125, 0.250, and 0.375 kg m(-2), with corresponding reduction potentials of 0, 20, 41, and 61, respectively. Similar emission reduction potentials of 0, 18, 35, and 58% were obtained for ethanol. Sodium bisulfate was shown to be effective in the mitigation of ammonia and alcohol emissions from fresh dairy slurry.

Profiling of the Microbiome Associated With Nitrogen Removal During Vermifiltration of Wastewater From a Commercial Dairy.

Vermifiltration is a biological treatment process during which earthworms (e.g., Eisenia fetida) and microorganisms reduce the organic load of wastewater. To infer microbial pathways responsible for nutrient conversion, past studies characterized the microbiota in vermifilters and suggested that nitrifying and denitrifying bacteria play a significant role during this wastewater treatment process. In contrast to previous studies, which were limited by low-resolution sequencing methods, the work presented here utilized next generation sequencing to survey in greater detail the microbiota of wastewater from a commercial dairy during various stages of vermifiltration. To complement sequence analysis, nitrogenous compounds in and gaseous emissions from the wastewater were measured. Analysis of 16S rRNA gene profiles from untreated wastewater, vermifilter influent, and vermifilter effluent suggested that members of Comamonadaceae, a family of the Betaproteobacteria involved in denitrification, increased in abundance during the vermifiltration process. Subsequent functional gene analysis indicated an increased abundance of nitrification genes in the effluent and suggested that the nitrogen removal during vermifiltration is due to the microbial conversion of ammonia, a finding that was also supported by the water chemistry and emission data. This study demonstrates that microbial communities are the main drivers behind reducing the nitrogen load of dairy wastewater during vermifiltration, providing a valuable knowledge framework for more sustainable and economical wastewater management strategies for commercial dairies.

Impact of Feed Delivery Pattern on Aerial Particulate Matter and Behavior of Feedlot Cattle.

Fine particulate matter with less than 2.5 microns diameter (PM2.5) generated by cattle in feedlots is an environmental pollutant and a potential human and animal health issue. The objective of this study was to determine if a feeding schedule affects cattle behaviors that promote PM2.5 in a commercial feedlot. The study used 2813 crossbred steers housed in 14 adjacent pens at a large-scale commercial West Texas feedlot. Treatments were conventional feeding at 0700, 1000, and 1200 (CON) or feeding at 0700, 1000, and 1830 (ALT), the latter feeding time coincided with dusk. A mobile behavior lab was used to quantify behaviors of steers that were associated with generation of PM2.5 (e.g., fighting, mounting of peers, and increased locomotion). PM2.5 samplers measured respirable particles with a mass median diameter ≤2.5 µm (PM2.5) every 15 min over a period of 7 d in April and May. Simultaneously, the ambient temperature, humidity, wind speed and direction, precipitation, air pressure, and solar radiation were measured with a weather station. Elevated downwind PM2.5 concentrations were measured at dusk, when cattle that were fed according to the ALT vs. the CON feeding schedule, demonstrated less PM2.5-generating behaviors (p < 0.05). At dusk, steers on ALT vs. CON feeding schedules ate or were waiting to eat (standing in second row behind feeding cattle) at much greater rates (p < 0.05). Upwind PM2.5 concentrations were similar between the treatments. Downwind PM2.5 concentrations averaged over 24 h were lower from ALT compared with CON pens (0.072 vs. 0.115 mg/m³, p < 0.01). However, dry matter intake (DMI) was less (p < 0.05), and average daily gain (ADG) tended to be less (p < 0.1) in cattle that were fed according to the ALT vs. the CON feeding schedules, whereas feed efficiency (aka gain to feed, G:F) was not affected. Although ALT feeding may pose a challenge in feed delivery and labor scheduling, cattle exhibited fewer PM2.5-generating behaviors and reduced generation of PM2.5 when feed delivery times matched the natural desires of cattle to eat in a crepuscular pattern.