Search

Milk safety is a food safety concern in the U.S., and the cleanliness of on-farm milking systems directly affects raw milk quality. The conventionally accepted four-step procedure for milking system cleaning-in-place (CIP) includes: (1) warm water rinse, (2) alkaline wash, (3) acid wash, and (4) sanitizing rinse prior to the next milking event. Electrolyzed oxidizing (EO) water is an emerging technology that generates acidic and alkaline EO water by electrodialysis of a dilute sodium chloride solution. Previous studies have shown that EO water can be an alternative for conventional milking system CIP, both in pilot-scale milking systems and on commercial dairy farms. Recently, a one-step cleaning process has been adopted on an increasing number of dairy farms that combines the alkaline wash and acid wash to save chemical expenditure, water usage, energy cost, and time. By blending acidic EO water with alkaline EO water, a less corrosive but still effective blended EO water solution can be produced. Therefore, this study was undertaken to evaluate the blended EO water solution for one-step CIP using a pilot-scale milking system and compare the CIP effectiveness and cost with commercial one-step CIP chemicals. A Box-Behnken three-factor response surface method was used to determine the optimal cleaning time, the starting temperature of the blended EO water solution, and the acidic EO water percentage. Two commercial one-step CIP chemicals were used for comparisons of CIP effectiveness and cost. Results showed that a cleaning time of 17 min, a starting temperature of 59°C, and an acidic EO water percentage of 60% in the blended EO water solution could achieve the required 100% CIP performance and was comparable to the commercial one-step cleaning chemicals. Moreover, it was determined that the operating cost of one complete cleaning cycle, including the material cost and energy consumption, using blended EO water was 80% lower than using the commercial one-step cleaning chemicals. Overall, this study demonstrated that blended EO water has potential to be adapted as an alternative for onestep CIP for milking systems and possibility other food processing equipment. [ABSTRACT FROM AUTHOR]

Two lactating cow trials were conducted to evaluate the impact of diets differing in silage source (alfalfa/maize vs. grass/maize or maize/hay) and maize grain particle size (fine vs. coarse) on ammonia (NH3), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions from a freestall barn floor with two groups of 60 cows each. In addition, the effects of environment (temperature, humidity) and management (manure depth, time since manure removal) factors were evaluated. Manure (feces and urine), spilled feed, bedding, and spilled drinking water were allowed to collect on the solid concrete, sloped barn alleys and were scraped twice a day. Gas fluxes from the freestall floor were measured at 64 locations over a 12 h period using a fast-response, non-steady-state flux chamber and an infrared photoacoustic gas analyzer during 18 trial days over a 9-month period. Fluxes of ammonia from manure on the barn floor were within average reported values for these 165 g kg-1 crude protein diets. All gas fluxes were similar (p = 0.253 to 0.977) regardless of silage source and maize grain particle size. The highest average ammonia emissions coincided with higher environmental temperature at 30 NH3 g AU-1 d-1, while the highest average greenhouse gas emissions from the manure on the floor were 10 g AU-1 d-1 for CH4 and 580 g AU-1 d-1 for CO2. Time in hours since scraping the floor had little impact on the production of ammonia, but greenhouse gas loss from the barn floor was reduced after scraping. Air and manure temperatures were positively correlated with emissions of NH3, CO2, and CH4 (p = <0.0001). NH3 (g AU-1 d-1) = 10(1.03+0.019*Tair) (R2 = 0.38) for indoor air temperatures (Tair, °C) over the range from -5 °C to 32 °C (AU = 500 kg animal unit). Ammonia emissions were positively correlated with CO2 and CH4 gas emissions, suggesting that NH3 release from the manure was controlled to some extent by microbial activity and similar environmental factors. Nitrous oxide emissions remained <0.1 g AU-1 d-1 and were relatively constant for all diets and trials. [ABSTRACT FROM AUTHOR]

The quantity and quality of compost leachate depend on the age and composition of the composting materials and this study was undertaken to assess the changes in nutrient concentration and load of leachates coming from different compost mixtures and ages. Three different compost mixes (farm, food, yard waste composts) at different ages from flesh to maturity were leached with distilled and deionized water in laboratory column experiments. The leachate NO3-N concentration increased with the increase of compost age for all the compost mixtures. At maturity, the tot N content of the farm waste compost is more readily leached and NO3-N comprises a large proportion (> 68%) of the leachate tot N compared with the food (20 to 47%) and yard waste (1 to 19%) composts. The composting process and operation at early composting ages (0 to 9 weeks) pose less of a potential as a source of NO3-N than does the compost at maturity. The food waste had relatively higher leachate NH4-N load than the farm and yard waste composts, implying that the food waste compost had a greater potential as a source of NH4-N than the farm and the yard waste composts. At maturity the leachate NH4-N load (and concentration) was consistently low for all compost mixes, thus the composting operation poses less of a potential as source of NH4-N at maturity than at the early compost ages. Towards maturity, the leachate PO4-P load of the farm waste was higher than the leachate PO4-P load of the food and yard waste composts despite the lower P concentration of the farm waste compost than those of the food and yard waste composts. The results suggest that the form of P rather than its amount in the compost governs the leachate PO4-P content. The farm waste compost had a greater potential as a source of PO4-P than the food and the yard waste composts towards maturity. The amount of N and P was shown to vary with the compost mixture, compost age, and volume of leachate. These results can be used to assess at what stage of the composting period one would expect the greatest risk of potential N and P pollution for a specific compost mixture. Furthermore, appropriate best management practices (BMPs) could be applied to control these potential pollutants based on the findings of these study. [ABSTRACT FROM AUTHOR]

There is little information about the changes in physical and chemical properties of compost as a function of compost feedstocks and age of the compost mixture. As a consequence of this gap, the potential of compost to serve as a pollutant source relative to compost age (from initial mixing of raw feedstocks to mature compost) and feedstocks (i.e. % of food, manure, bedding, leaves, etc.) during the composting operation is not well known. This study was conducted to assess the variation of physical and chemical properties of compost under different mixes of source material and at differing ages (from freshly mixed to mature compost). The change in compost C:N ratio with age during composting was represented well (R² ≥ 0.81) by the equation Y = CNf (CNi-CNf)e(-X/r), where Y is the C:N ratio at any time X. CNf is the value of the C:N ratio as the composting time approaches infinity. CN is the initial C:N ratio at the beginning of the composting process and 1/r is the rate of decrease of the C:N ratio. The total (tot) N concentration of the mature composts was higher than the initial tot N concentration for all mixes investigated. There was a net decrease from the initial NH4-N concentrations at mixing to the final NH4-N concentrations at maturity for all compost mixtures. However, the variations of compost tot N and NH4-N concentrations with compost age were different between compost mixtures and years of experiment. The phosphorus (P) concentrations increased linearly with compost age. These results indicated that the potential of the compost as a source for N and P pollution changes during the composting process. The results also showed that the combination of C:N ratio, compost temperature, and compost NH4-N concentration could be used as simple but reliable indices for compost stability and maturity. [ABSTRACT FROM AUTHOR]

This observational study was conducted to assess the movement of nitrate and phosphorus into and through the soil profile beneath a compacted gravel compost pad. The accumulation of nitrate and phosphorus in the vegetated tilter strip immediately downslope of the pad was also evaluated. Soil samples were taken from the composting site and the immediate surrounding area in two transects each for the Control (outside of compost pad), Old Pad (combined manure stack and compost area), and Extension pad (compost only area). Each transect was divided into three sampling zones: within the pad, in an intermediate area between the pad and the filter strip, and within the filter strip. Compost samples from windrows of different ages and mixes were also taken for laboratory leaching test to determine the potential of tile composts as source of nitrogen and phosphorus. The NO3-N concentrations in the soil beneath the compost pad of the Old Pad and Extension transects were higher than the soil NO3-N concentrations at the same depths and locations in the control transect. These results indicate that the compacted gravel pad did not fully prevent the downward movement and accumulation of NO3-N beneath the pad. The NO-N concentrations in the soil surface of the pad, intermediate between the pad and filter strip, and the filter strip areas of the Control and Old Pad transects were not statistically different; suggesting that there was negligible NO3-N surface movement and transport from the pad area to the filter strip. The average Mehlich3-P concentration at the soil surface in the pad area was less than in the intermediate and the filter strip areas, indicating that there was surface runoff and downslope transport of phosphorus from the compost site to the filter strip. Statistical analysis showed that there was no significant difference in the Mehlich3-P concentration between the filter strip areas of the Old Pad and Control transects; suggesting that the downslope transport of phosphorus from the compost pad to the filter strip had not yet caused significant accumulation of phosphorus in the filter strip relative to the adjacent field. Leaching tests indicated that during the composting process, mature composts pose a greater potential as a source of NO3-N leaching than the freshly-mixed composts. In contrast, the composting process and operation poses a greater potential as a source of PO4-P during the early stages of composting than with older composts. [ABSTRACT FROM AUTHOR]