Myers, Cheyanne A.; de Haro Marti, Mario E.; Chahine, Mireille; Chibisa, Gwinyai E.

This study investigated the effects of feeding clinoptilolite (CLN; 2.5% of diet dry matter) with a particle size of either 30- or 400-µm on ruminal fermentation characteristics, measures of nitrogen (N) utilization, and manure ammonia-N (NH3) emissions in feedlot cattle. The impact of directly applying 30- or 400-µm CLN to the pen surface (2,250 kg/ha) on manure NH3–N emissions was also evaluated. Six beef heifers were used in a replicated 3 × 3 Latin square design with 21-d periods. Dietary treatments were 1) finishing ration with no supplement (CON), 2) CON + 30-µm CLN (CLN-30), and 3) CON + 400-µm CL (CLN-400). Intake was measured daily. To evaluate fermentation characteristics, ruminal fluid was collected on day 19. Indwelling pH loggers were used to measure ruminal pH from days 15 to 21. Blood was collected 3-h post-feeding on day 21 for metabolite analysis. Fecal grab and urine spot samples were also collected from days 19 to 21 to measure nutrient digestibility, route of N excretion, and in vitro NH3 emissions. There was no diet effect (P ≥ 0.12) on nutrient intake and apparent total tract digestibility, and ruminal short-chain fatty acid profile and pH. Ruminal NH3 concentration, which was lower (P = 0.04) for CLN-30 than CON heifers, did not differ between CON and CLN-400 heifers. Although there was no diet effect (P = 0.50) on plasma urea-N (PUN) concentration, proportion of urea-N excreted in urine was lower (P = 0.01) for CLN-30 than CON and CLN-400 heifers. Urinary NH3–N excretion, which was greater (P ≤ 0.04) for CLN-400 than CON heifers, did not differ between CLN-30 and CLN-400 heifers. Feeding CLN also increased (P ≤ 0.02) fecal excretion of potassium (K) and iron (Fe) and reduced (P = 0.01) urinary excretion of calcium (Ca). There was a treatment × time interaction (P = 0.01) for NH3 emission rate, which was greatest within the first 36 h of incubation and was lower for manure from CLN-400 compared to CON and CLN-30 heifers and pen surface application treatments. Cumulative NH3 emissions were lower (P < 0.01) for manure from CLN-400 compared to CON and CLN-30 heifers and the pen surface application treatments. Although surface application was ineffective, feeding 400-µm CLN to finishing cattle could result in a beneficial decrease in manure NH3 emissions. However, changes in fecal and urine excretion of minerals like K and Ca, which suggest a decrease in bioavailability, need to be considered when feeding CLN in finishing cattle diets.

Reza, Arif; Chen, Lide; Mao, Xinwei 

With increasing demand for meat and dairy products, the volume of wastewater generated from the livestock industry has become a significant environmental concern. The treatment of livestock wastewater (LWW) is a challenging process that involves removing nutrients, organic matter, pathogens, and other pollutants from livestock manure and urine. In response to this challenge, researchers have developed and investigated different biological, physical, and chemical treatment technologies that perform better upon optimization. Optimization of LWW handling processes can help improve the efficacy and sustainability of treatment systems as well as minimize environmental impacts and associated costs. Response surface methodology (RSM) as an optimization approach can effectively optimize operational parameters that affect process performance. This review article summarizes the main steps of RSM, recent applications of RSM in LWW treatment, highlights the advantages and limitations of this technique, and provides recommendations for future research and practice, including its cost-effectiveness, accuracy, and ability to improve treatment efficiency. 

Asghar, Sehrish; Chen, Lide; He, Brian

Wastewater from confined dairy operations requires efficient treatment to reduce its potential to pollute the surrounding environments. In this study, a novel intermittently-aerated-extended-idle sequencing batch reactor (IA-EI SBR) process was developed, evaluated, and optimized for simultaneously removing phosphorus (P) and nitrogen (N) from anaerobically digested liquid-dairy-manure (ADLDM) with lower carbon-to-nutrient-ratios. Four influential operating parameters including cycle-time of 5–9 h, intermittent-aeration strategy of 10–50 min/h, two feed-phases of 6–30 min, and idle-phase of 40–120 min were statistically analyzed using central-composite design coupled with response-surface methodology for optimal removal efficiencies of ortho-phosphorus (%OPremoval), total-phosphorus (%TPremoval), ammonia-nitrogen (%NH3-Nremoval), total-nitrogen (%TNremoval), and chemical oxygen demand (%CODremoval). Results showed that the interactions of cycle time-idle phase, and aeration strategy-feed phases were significant in affecting %TPremoval (p-value ≤ 0.005). The synergistic effect of aeration strategy-idle phase was significant for %TNremoval and %CODremoval (p-value ≤ 0.006), while the cycle time-feed phases interaction had significant effect on %NH3-Nremoval. The maximum simultaneous nitrification-denitrification (SND) efficiency of 85.7% was recorded under influent COD and TN loading of 3,999.2 and 785.7 mg L−1 at 30 min/h aeration time in 7 h. The quadratic regression models based on statistical analysis of the experimental results adequately described the IA-EI SBR performance and showed that the applied levels of operating parameters were highly correlated with all five responses (p-value ≤ 0.030). Operating conditions for optimal IA-EI SBR process efficiency determined by desirability analysis were cycle-time of 8 h, intermittent-aeration strategy of 36 min/h, feed-phases of 24 min, and idle-phase of 100 min. Under these optimal conditions, the corresponding removal efficiencies for OP, TP, NH3-N, TN, and COD of 82.64, 95.82, 92.92, 73.84, and 90.94%, respectively, were achieved in validation experiments.

Coats, Erik R.; Brinkman, Cynthia K.; Peters, Cody; MacInnis, Colton; Boyd, Brandon

Wastewater phosphorus removal achieved biologically is associated with the process known as enhanced biological phosphorus removal (EBPR). In contrast with canonical EBPR operations that employ alternating anaerobic–aerobic conditions and achieve asynchronous carbon and phosphorus storage, research herein focused on phosphorus removal achieved under aerobic conditions synchronously with volatile fatty acid (VFA) storage as polyhydroxybutyrate-co-valerate (PHBV). 90.3 ± 3.4 % soluble phosphorus removal was achieved from dairy manure fermenter liquor; influent and effluent concentrations were 38.6 ± 9.5 and 3.7 ± 0.8 mgP/L, respectively. Concurrently, PHBV yield ranged from 0.17 to 0.64 mgCOD/mgCOD, yielding 147–535 mgCODPHBV/L. No evidence of EBPR mechanisms was observed, nor were canonical phosphorus accumulating organisms present; additionally, the polyphosphate kinase gene was not present in the microbial biomass. Phosphorus removal was primarily associated with biomass growth and secondarily with biomass complexation. Results demonstrate that concurrent PHBV synthesis and phosphorus recovery can be achieved microbially under aerobic dynamic feeding conditions when fed nutrient rich wastewater.

Sapkota, Srijan; Reza, Arif; Chen, Lide

Dairy manure adds a substantial amount of nitrogen to wastewater due to its high levels of associated nutrients. Removal and recovery of ammonia nitrogen (NH3-N) from raw liquid dairy manure (RLDM) is greatly valued. This study was focused on the vacuum thermal stripping–acid absorption (VTS-AA) process for NH3-N from RLDM, followed by modeling and optimization. Using the response surface methodology (RSM)-based central composite design (CCD) approach, the critical operational parameters of the vacuum thermal stripping process, including temperature (50–70 °C), pH (9–11), vacuum pressure (35–55 kPa), and treatment time (60–90 min), were optimized. With the specified parameters set at temperature 69.9 °C, pH 10.5, vacuum pressure 53.5 kPa, and treatment time 64.2 min, the NH3-N removal efficiency attained was 98.58 ± 1.05%, aligning closely with the model prediction. Furthermore, the recovered ammonium sulfate ((NH4)2SO4) closely matched their commercial counterparts, confirming the effectiveness of the VTS-AA process in recovering NH3-N from RLDM. The distinct advantage of the employed technology lies in the concurrent energy demand reduction achieved by introducing a vacuum system. These findings contribute valuable insights into the practical implementation of the VTS-AA process for treating raw dairy manure, particularly in large-scale operational contexts.

Das, Ashish Kumar; Chen, Lide

Dairy wastewater (DW) contains a high concentration of organic and inorganic pollutants. In recent years, extensive research has been conducted to develop more efficient techniques for the treatment of DW. Electrochemical advanced oxidation processes (EAOPs) have gained significant attention among the various treatment approaches. EAOPs rely on electrochemical generation of hydroxyl radicals (•OH) which are considered highly potent oxidizing compounds for the degradation of pollutants in DW. In this paper, we provide an overview of the treatment of DW using various EAOPs, including anodic oxidation (AO), electro-Fenton (EF), photo electro-Fenton (PEF), and solar photo electro-Fenton (SPEF) processes, both individually and in combination with other techniques. Additionally, we discuss the reactor design and operating parameters employed in EAOPs. The variation in degradation efficiency is due to different oxidizing agents produced in specific approaches and their pollutant degradation abilities. In AO process, •OH radicals generated on electrode surfaces are influenced by electrode material and current density, while EF procedures use Fe2+ to create oxidizing agents both on electrodes and in the DW solution, with degradation mechanisms being affected by Fe2+, pH, and current density; additionally, PEF and SPEF approaches enhance oxidizing component production and pollutant degradation using ultraviolet (UV) light. Integration of EAOPs with other biological processes can enhance the pollutant removal efficiency of the treatment system. There is a scope of further research to exhibit the effectiveness of EAOPs for DW treatment in large scale implementation.

Glaze, J.B. ; Chahine, M.

In 2004 a mail-in survey was conducted to establish a baseline level of awareness and knowledge related to dairy beef quality assurance (BQA) issues in Idaho. A 30-question survey was mailed to every (n=736) registered Idaho dairy. Two-hundred seventy-three (37%) dairies participated and were categorized as small (n <201 cows; 53.5%), medium-sized (n=201 to 1,000 cows; 27.1%) or large (n >1,000 cows; 19.4%). The majority of respondents were dairy owners (83%). Eighty-nine percent of respondents indicated they followed BQA recommendations for animal care. The neck region in cows was used by 68% of respondents for i.m. injections and by 80% for s.c. injections. In calves, the values were 61 and 78%, respectively. Seventy-four percent of respondents indicated they had been trained for injections. Training methods cited included veterinarians (19.8%), dairy owners (16.8%), experience (9.9%), and BQA events or schools (4.5%). The importance of BQA in the dairy industry was rated 2.6 on a 5-point scale (0 = low; 4 = high). Participants rated the effect of dairy animals on the beef industry at 2.5. Plastic ear tags were the preferred method of animal identification, with 100% of large dairies, 97.3% of medium-sized dairies, and 84% of small dairies citing their use. Less than 10% used electronic identification for their animals. Almost half (48%) of large and medium-sized (49%) dairies and 32% of small dairies supported a national animal identification program. A mandatory identification program was supported by 41, 69, and 59% for small, medium-sized, and large dairies, respectively. The percentage of dairies keeping records was similar between small (93%), medium-sized (99%), and large (100%) dairies. Most small dairies (58%) used some form of paper records, whereas most medium-sized (85%) and large (100%) dairies used computers for record keeping. The preferred method to market cull cows by Idaho dairies was the auction market (64%), followed by order buyers (17%), direct to the packer (17%), private treaty sales (16%), and forward contracts (1%). To market calves, dairies used private treaty sales (52%), auction markets (42%), order buyers (14%), and forward contracts (1%). The results of this study will be used by University of Idaho Extension faculty in the design, development, and delivery of dairy BQA program information and materials.

Du, Xiaoxue ; Tejeda, Hernan ; Yang, Zhengliang ; Lu, Liang

Automatic milking systems (AMSs) have become increasingly common in the US in the past few years. Recent surveys from Idaho, one of the largest dairy-producing states, as well as from other states and countries, suggest that: 1. among farms adopting robotic milking systems, few are reporting less labor usage after adopting this labor-saving technology; 2. small farms rather than large farms are adopting (or more interested in adopting) robotic milking systems. In this article, we propose a series of new modeling strategies, which introduces the role of general-equilibrium effects to explain these new stylized facts. We show that: first, farms adopting labor-saving technology may, in fact, use more labor to compensate for the loss in the value of labor; second, when smaller farms experience more labor efficiency gains or value their leisure time (or off-farm income) more, they are more likely than larger farms to adopt the new technology. We contribute to the technology-adoption literature in two important ways. First, to our knowledge, this is the first article that introduces general-equilibrium effects to the technology-adoption literature. Second, this is also the first article that provides a theoretical perspective to explain the stylized facts in the adoption of robotic milking systems.

Chahine, Mireille ; de Haro Marti, Mario E. ; Matuk, Celina ; Aris, Anna ; Campbell, Joy ; Polo, Javier ; Bach, Alex

Feeding SDP during transition improves milk production and milk fat content.•No negative effect on reproductive performance when SDP is included in transition feed.•The inclusion of SDP in transition feed has no detrimental effect on health performance. Spray-dried plasma (SDP) proteins are recognized as safe, high-quality feed ingredients for livestock due to their immune modulatory components, including immunoglobulins, bioactive peptides and growth factors. The objective of this study was to investigate the effects of feeding a SDP product during the first 200 d of lactation on milk production and reproduction performance in dairy cows. Nine hundred ninety-eight Holstein cows, 260 d pregnant, were enrolled in a completely randomized design. Before calving, cows were fed a late gestation ration containing blood meal (BM; 13.3 g/kg of DM; Control; n = 503) or SDP (16.0 g/kg of DM; 250 g SDP/d; n = 495) replacing BM on N basis. After calving, Control cows were randomly distributed in two pens and fed a lactation ration containing 15.6 g/kg BM (DM basis). Cows on SDP were randomly distributed in 2 pens and fed a lactation ration that contained 18.3 g/kg SDP (DM basis. 400 g/d of SDP), which replaced BM. Cows were milked three times per day and milk production and composition were monitored monthly at one milking. First service consisted of a timed AI protocol applied to all cows that were > 44–50 DIM. Following AI, cows were examined daily for return to estrus or for confirmation of pregnancy by rectal palpation at 35–41 and 70–76 d after AI. At 72–78 DIM, cows not pregnant were enrolled into an intrauterine progesterone program. Cows fed SDP had greater milk yield (P < 0.01; 16.8 vs 16.4 kg/milking) and milk fat (P < 0.05; 35.5 vs 34.7 g/kg), but there were no differences in milk protein or in milk SCC between Control and SDP cows. Milk yield improvement in SDP cows was evident during the second month of lactation and onwards. No differences in pregnancy rate, overall conception rate, days at which pregnancy occurred or body condition score were observed between treatments. In conclusion, supplementation with SDP in dairy cows slightly increased milk yield and milk fat content without affecting reproductive parameters.

Brian He

As an alternative technology for phosphorus cycling, hydrochar produced from animal manure is a great vehicle to attain phosphorus from dairy manure and apply it back to cropland in an environmentally friendly manner. Hydrochar production by hydrothermal carbonization (HTC) greatly reduces the time to manage animal manure compared to traditional lagoon systems. Before being established as a practical technology for hydrochar production in continuous-flow operations, HTC in batch mode is the best way to systematically investigate and optimize the process conditions for high efficiencies. This study investigates specifically the effect of temperature ramp-up rates on the attainment of total phosphorus (TP) in hydrochar produced from dairy manure through batch-mode HTC operations. Experimental results revealed that the transition in temperature ramp-up greatly affected the TP attainment rate in hydrochar, depending on the pre-set processing temperatures and holding time. Statistical analysis confirms that such an effect is significant if the holding time is 30 min or less. This is due not only to the higher processing temperatures but also to the extra 5 to 15 minutes of processing time required for the ramp-up to the pre-set temperatures of 195°C to 255°C, at which point biomass decomposition has already occurred. It is concluded that the temperature ramp-up in batch HTC processes significantly affect the TP attainment rate in hydrochar produced from dairy manure. Before developing continuous-flow HTC systems, it is recommended that experimental results from batch operations be carefully interpreted.