Feed Spacer Research Articles

Catalytic performance of Co and Ni doped Fe-based catalysts for the hydrogenation of CO2 to CO via reverse water-gas shift reaction

Utilization of CO2 by converting it into CO via reverse water-gas shift (rWGS) reaction is of particular interest due to the direct use of CO as feedstock in many significant industrial processes. Here, Co and Ni doped Fe-based catalysts, supported over γ-Al2O3 were prepared by a wet-impregnation method and evaluated for hydrogenation of CO2 to CO at temperatures range of 450–650 °C and atmospheric pressure. The catalytic activity in rWGS reaction mainly depends on the oxide phase of the iron. It was found that introduction of Co- or Ni- in iron oxide catalyst significantly enhanced the activity as compared to the undoped Fe/Al2O3 catalyst. However, among the doped catalysts, Co-Fe/Al2O3 showed highest CO yield (48%) and stable time-on-stream performance for 40 h at 3:1 H2/CO2 feed ratio and space velocity of 1000 mL/gcat.min at 650 °C and atmospheric pressure. The better performance of Co-Fe/Al2O3 catalyst was due to the improved reducibility of iron-oxide after doping of Co- and formation of mixed oxide, which is non-selective for methane formation under the rWGS reaction conditions. The detailed characterization results on surface area, size, morphology, reducibility and thermal stability of the prepared Fe-based catalysts obtained by BET, particle size analysis, SEM, XRD, TPR, and TGA techniques were used to understand the role of dopant in enhancement of the observed catalytic activity.

Feed Spacer Geometries and Permeability Coefficients. Effect on the Performance in BWRO Spriral-Wound Membrane Modules

Reverse osmosis (RO) is the most widely used technology to desalinate brackish water and seawater. Significant efforts have been made in recent decades to improve RO efficiency. Feed spacer geometry design is a very important factor in RO membrane performance. In this work, correlations based on computational fluid dynamics and experimental work were applied in an algorithm to simulate the effect of different feed spacer geometries in full-scale brackish water reverse osmosis (BWRO) membranes with different permeability coefficients. The aim of this work was to evaluate the impact of feed spacers in conjunction with the permeability coefficients on membrane performance. The results showed a greater impact of feed spacer geometries in the membrane with the highest water permeability coefficient (A). Studying only one single element in a series, variations due to feed spacer geometries were observed in specific energy consumption ( S E C ) and permeate concentration ( C p ) of about 6.83% and 10.42%, respectively. Allowing the rolling of commercial membranes with different feed spacer geometries depending on the operating conditions could optimize the RO process.

Comparing membrane and spacer biofouling by Gram-negative Pseudomonas aeruginosa and Gram-positive Anoxybacillus sp. in forward osmosis

Bacteria of different Gram-types have inherently different outer cell structures, influencing cell surface properties and bacterial attachment. Dynamic biofouling experiments were conducted over four days in a bench-scale forward osmosis (FO) system with Gram-negative Pseudomonas aeruginosa or Gram-positive Anoxybacillus sp. Biofouling resulted in ∼10% decline in FO permeate water flux and was found to be significant for Anoxybacillus sp. but not for P. aeruginosa. Additionally, a stronger permeate water flux decline for P. aeruginosa in experiments with a superhydrophilic feed spacer demonstrated that mitigation methods require testing with different bacterial Gram-types. It was found that although permeate water flux decline can be affected by bacterial Gram-type the stable performance under enhanced biofouling conditions highlights the potential of FO for wastewater reclamation.

Impact of feeder space on laying hen feeding behavior and production performance in enriched colony housing

Current feeder space recommendations in laying hen welfare guidelines are inconsistent among and within countries. One determining criterion forming the recommendations (e.g. 12.0 cm/hen for the EU guideline) is that all birds can feed simultaneously. However, if there are other resources in the environment, as in enriched colony housing (ECH), it is unknown whether group-housed hens will choose to feed simultaneously. This study assesses the impact of feeder space on feeding behavior of 60 laying hens (W-36) in ECH using a ultra-high frequency radio-frequency identification-based tracking system. The feeder spaces investigated were 12.0, 9.5, 8.5 and 6.5 cm/hen, achieved by blocking portions of the overall feeder access to keep hens at the same stocking density. Each feeder space treatment, randomly assigned over the course of the experiment, lasted for 7 consecutive days. Feeding behaviors were characterized as daily time spent at the feeder (TS, min/hen-day), daily frequency of visits to the feeder (FV, #/hen-day), and maximum or average percentage of hens feeding simultaneously (MPB, APB, %). Group-average daily feed intake (FI, g/hen-day), water use (WU, g/hen-day), and hen-day egg production (HDEP, %) were also measured. The results revealed that at 12.0 cm/hen, where unoccupied feeder space was present, a maximum of 59.0±1.4% (average of 31.7±0.3%) hens fed simultaneously. No significant differences were detected among 12.0, 9.5 and 8.5 cm/hen in TS (293±10, 286±10 and 281±10 min/hen-day) and MPB (59.0±1.4, 57.3±1.4 and 53.3±1.4%) (P>0.05). The outcome of no significant differences also held true between 12.0 and 9.5 cm/hen in APB (31.7±0.3 v. 30.8±0.3%) and between 9.5 and 8.5 cm/hen in all response variables measured (P>0.05). However, there were significant differences in APB between 6.5 cm/hen and all other treatments; in TS and FV between 6.5 and 9.5 cm/hen; and in MPB between 6.5 and 12 cm/hen (P<0.05). Considerable inter-hen variability was observed in TS (CV varying from 28.0% to 32.1%) and FV (CV varying from 26.5% to 27.8%). All the feeder spaces tested showed no significant impact on FI, WU or HDEP (P>0.05). The results revealed that synchronous feeding of hens in the ECH did not increase with increasing feeder space. However, it is worth noting that lower feeder space may lead to aggression or frustration which was not quantified in the current study.

Production of Low-Sulfur High-Viscosity Marine Fuel by Hydrotreatment of Oil Residues

The article presents the results of tests of a system of catalysts developed for demetallation and desulfurization of oil residues to produce low-sulfur marine fuel. A fixed catalyst bed was used. The optimum feedstock hydrogenation conditions were chosen: pressure 15 MPa, process temperature 360-420°C, and feed space velocity 0.5/124. The prolonged tests of the developed catalysts system were conducted successfully.

CFD Investigation of the Effect of the Feed Spacer on Hydrodynamics in Spiral Wound Membrane Modules

Spacers are designed to create a feed channel, but they are also obstacles to the flow in spiral wound membrane modules. The geometry of the feed spacer influences the flow pattern, which was investigated by using a three-dimensional Computational Fluid Dynamics (CFD) model. For the conventional feed spacer, unavoidable disadvantages were caused by its line contact with the membrane. The pillar-like feed spacer was designed to achieve area contact, which made it possible to enhance the porosity and minimize the adverse effects from the dead zone caused by the transverse filament. Through reductions in the connecting filament’s diameter, the channel porosity reached 0.979. Regarding the maximum porosity, the dimensionless power number was reduced by 47.31% at Reynolds number 150 in comparison with a previously studied commercial spacer. Furthermore, a modified friction factor, as a dimensionless parameter, was employed to investigate the shear stress at the membrane’s surface. At dimensionless power number 106, the enhancement of the modified friction factor increased by approximately 22.27% in comparison with the results of a previous study. Based on the numerical prediction, the homogenization of shear stress distribution, which changed the flow profile near the membrane, was featured through contour plots.

Modification of a polypropylene feed spacer with metal oxide-thin film by chemical bath deposition for biofouling control in membrane filtration

Surface modification of polypropylene feed spacers typical of spiral wound membrane modules was studied by generation of crystalline ZnO nanorods. A seeding layer made by deposition of ZnO nanoparticles (20–40–60 nm diameter) from aqueous dispersions served as nucleation centers for crystallization. A uniform layer of ZnO nanorods was grown on the seeding layer by chemical bath deposition from a zinc acetate solution. Biocidal activity was estimated by antibacterial tests in static liquid culture against Escherichia coli and antibiofouling tests in flow-through/cross-flow mode against a mixture of Pseudomonas fluorescens and Bacillus subtilis. Best biocidal activity was displayed by 20 nm ZnO particles, suggesting a tradeoff between surface coverage, roughness and particle size. Although the seed layer itself displayed acceptable antibacterial activity, a marked improvement was achieved by the nanorods, proving that the morphology of the deposition layer was involved in the antibacterial mechanism. Antibiofouling activity was further improved by superhydrophobic over-coating of the nanorods with octadecyl-phosphonic acid. Modified spacers reduced permeate flux decay by at least 40% compared to controls. The enhanced antibiofouling activity of crystalline ZnO nanorods, compared with amorphous ZnO nanoparticles, can be explained by a combination of the abrasive surface of the crystalline nanorods, hydrophobic repulsion and cumulative oxidation.

Synthesis of Isobutylene from Ethanol in the Presence of Catalysts Containing Zinc Oxide and Zirconia

Synthesis of isobutylene from ethanol in the presence of ZnO/ZrO2 catalysts has been studied. The samples have been synthesized by incipient wetness impregnation of zirconium hydroxide derived from zirconyl chloride with zinc nitrate and subsequent calcination at 550°C. The synthesized samples have been studied by low-temperature nitrogen adsorption, SEM, XRD, IR spectroscopy of adsorbed CO, and TGA–DTA. Studies of the effect of the catalyst composition and the test conditions have revealed that, during the synthesis of isobutylene from ethanol, an optimum Zr : Zn molar ratio providing the production of isobutylene with a selectivity of 45–50% is 8–20 and optimum conditions for ethanol conversion to isobutylene are 500°C, a feed space velocity of 3 g/(g h), and a feedstock in the form of a 50% ethanol solution in water. According to thermogravimetric analysis, an increase in the zinc content in the samples leads to a decrease in the amount of coke deposits.

Available space in feeders for housed sheep: social behavior and performance

ABSTRACT This study was designed to assess the effects of feeding space availability on social behavior and performance of housed crossbreed sheep through the use of three different types of feeders. Thirty-six crossbreed ewes (Santa Ines × Dorper; 2-3 years old) with initial body weight of 34.99±4.28 kg were randomly assigned to a 3 × 3 (feeder type × available space at the feeder) factorial arrangement among nine pens. Pens had one of three feeder types (concrete bunk, plastic, or [...]

Studies into the mass transfer and energy consumption of commercial feed spacers for RO membrane modules using CFD: Effectiveness of performance measures

Different approaches have been reported in the literature that aim to improve the performance of reverse osmosis (RO) desalination plant operations, attempting to make the desalination process more efficient.This study investigates the performance of four commercial feed spacers for spiral wound reverse osmosis modules by considering energy consumption and production capacity, as well as their combination, through a previously proven approach to computational fluid dynamics (CFD) modelling.Among the performance measures studied, SCE (spacer configuration efficacy), SPC (specific power consumption) and Pn (power number) showed a high level of predictability (R2≥0.998, 0.994 and 0.994, respectively) through power law correlations of Re with two spacer-dependent parameters. Of the four commercial spacers investigated, the DelStar Technologies Naltex N05013_90HDPE-NAT (“90 HDPE”) spacer has been ranked as the best or second best based on multiple performance measures over the flow range Re=50–100. Furthermore, the very weak response to flowrate changes observed for 90 HDPE, based on pressure loss, SPC, Pn, Sh and SCE measures, indicates the prospects for energy savings. SPMP′, a modified definition of SPMP (Spacer Performance Ratio), shows no consistent response to flow variations for the spacers studied.

Impact of Modified Spacer on Flow Pattern in Narrow Spacer-Filled Channels for Spiral-Wound Membrane Modules

A modified spacer, which was constructed with arched filaments and zigzag filaments, was designed to improve vortex shedding and generate a directional change in flow patterns of membrane modules, especially in the vicinity of the feed spacer filament, which is most affected by fouling. A unit cell was investigated by using a three-dimensional computational fluid dynamics (CFD) model for hydrodynamic simulation. The results of CFD simulations were carried out for the fluid flow in order to understand the effect of the modified spacer on vortices to the performance of arched filaments at different distances. From 2D velocity vectors and shear stress contour mixing, the flow pattern and dead zone flushing were depicted. The ratio of low shear stress area to the total area increased with the inlet velocity closed to 20%. The energy consumption with respect to flow direction for the arched filament was 80% lower than that in the zigzag filament. Compared with previous commercial spacers’ simulation, the friction factor was lower when the main flow was normal to the arched filament and the modified friction factor was close to the commercial spacers. The homogenization was realized through the flow pattern created by the modified spacer.

Sensitivity analysis and gradient-based optimisation of feed spacer shape in reverse osmosis membrane processes using discrete adjoint approach

Spacers play a significant role in enhancing water permeation in membrane desalination processes but also increase pressure drop and specific energy consumption for freshwater production. The complex coupling of nonlinear channel flow along with mass transfer of water and salts across the membrane makes it challenging to determine an optimal spacer design. Conventional methods employ a design loop based on manual design and re-evaluation, which is time-consuming and typically will only find an improved, but not an optimal design. This paper presents an alternative approach that employs the gradient-based adjoint method to explore an optimal design in complex shapes with many design parameters. The novel design methodology provides an effective tool for designers to pursue advanced spacer designs. To elucidate the design method with sensitivities, the spacer in cavity, submerged and zigzag configurations are first analysed with the computed gradients of pressure loss and flow permeation with respect to the displacement of the grid nodes on spacer surface. Then, an optimisation case of cylinder spacers in the zigzag configuration finds an optimal spacer that has 24% pressure loss reduction and only 0.43% permeation drop as compared to a standard cylinder spacer, indicating the new method's potential in finding high-performance spacer designs.

Fouling minimization at membranes having a 3D surface topology with microgels as soft model colloids

Cross-flow ultrafiltration of colloidal suspensions is mainly limited by the accumulation of retained particles adjacent to the membrane surface. The hydrodynamic conditions in the feed channel strongly affect the mass transfer rate of colloids from the membrane surface to the bulk and is therefore an important control measure. A common approach for enhancing mass transfer through hydrodynamics is to modify the geometry of the feed channel. In flat-sheet membrane configurations, feed spacers are typically installed, which function as turbulence promoters. In tubular and hollow-fiber membranes implementation of feed spacers is difficult, thus different strategies are sought for. Here we study the effect of a spiralling surface pattern (Helix) on the hydrodynamics and flux performance of tubular ultrafiltration membrane operated in cross-flow mode at inside-out configuration. We apply flow Magnetic Resonance Imaging (MRI) to visualize the flow-field inside the lumen and asses the length dependency of the permeate flux. We combine this information with classical filtration experiments at a wider range of operational parameters. Microgel suspensions were used as a model for soft colloidal systems. The transmembrane flux for the Helix as compared to the reference tubular membrane only increases when non-laminar flow developed inside the lumen channel. Yet the onset of transient non-laminar flow conditions starts at much lower Reynolds numbers of above 1700 for the Helix, while the regular tube shows a transition at high velocities and Re>3150. In consecutive filtration experiments, the Helix shows less flux decline as well. This improved fouling resistance is based on less flux decline at the end of the Helix membrane. Flow-MRI proves that the helical corrugations impose swirling flow patterns with contributions normal to the membrane surface opposing the deposition of microgels onto the membrane surface.

Hydrofining of Oil Shale Pyrolysis Tar in the Presence of Ultradispersed Catalysts

The results of the catalytic hydroconversion of oil shale pyrolysis tar in the presence of in situ and ex situ synthesized ultradispersed and nanosized MoS2 particles in a flow reactor at a hydrogen pressure of 7MPa, a temperature of 430–450°C, a feed space velocity of 1–2.9 h–1, and an H2/feed flow ratio of 1000 L(NTP)/L with and without recycling the unconverted residue are reported. The optimum conditions of hydroconversion under which the yield of distillate fractions was 91.9 wt % on a raw material basis are proposed. It is shown that the quality of the refined synthetic oil makes it possible to use it in traditional petrochemical processes.

Development of anti-biofouling feed spacers to improve performance of reverse osmosis modules

This study investigates the biofouling resistance of modified reverse osmosis (RO) feed spacers. Control spacers (made of polypropylene) were functionalized with a biocidal coating (silver), hydrophilic (SiO2 nanoparticles) or superhydrophobic (TMPSi-TiO2 nanoparticles) anti-adhesive coatings, or a hybrid hydrophilic-biocidal coating (graphene oxide). Performance was measured by adhesion assays, viability tests, and permeate flow decline in a bench scale RO system. The control spacers proved to be one of the better performing materials based on bacterial deposition and dynamic RO fouling experiments. The good anti-adhesive properties of the control can be explained by its near ideal surface free energy (SFE). The only surface modification that significantly reduced biofouling compared to the control was the biocidal silver coating, which outperformed the other spacers by all measured indicators. Therefore, future efforts to improve spacer materials for biofouling control should focus on engineering biocidal coatings, rather than anti-adhesive ones.

CT scanning of membrane feed spacers – Impact of spacer model accuracy on hydrodynamic and solute transport modeling in membrane feed channels

This study evaluated the impact of precise representation of spacer geometry on numerical simulations of hydrodynamics and solute transport in feed channels of membrane processes. Three levels of increasing geometry accuracy were assessed: i) cylindrical filaments, ii) filaments with circular sections of variable diameter based on microscopic measurements, and iii) geometries obtained from X-ray computed tomography (CT scans) in three resolutions (22 µm, 11 µm, and 5.5 µm). The three-dimensional CT scans revealed quasi-elliptic, not circular, cross-sections of the filaments. Microscopic measurements fail to account for this ellipticity, resulting in overestimation of pressure drop calculated at industry-typical average velocities (0.07–0.15 m s−1) by a factor of 1.8 compared to CT-based geometries. On the other hand, the cylindrical spacer filaments representation overestimates concentration polarization at the membrane surface compared to CT-based geometries. Experimental results of pressure drop and particle deposition were in close agreement with simulations using CT scanned geometries. This work demonstrates that modeling results depend significantly on the spacer geometry accuracy. Within the investigated CT scan accuracies 20 µm was found sufficient for modeling hydrodynamics and solute transport in spacer-filled feed channels. The results may be useful for reliable investigation and development of novel spacer geometries.

Strategies to improve the growth and homogeneity of growing-finishing pigs: feeder space and feeding management

BackgroundThe aim was to test two strategies to improve the growth rate of the slow-growth pigs and to increase the batch’s homogeneity at slaughter. In Trial 1 a total of 264 weaned piglets were distributed into 24 pens (11 piglets/pen) according to sex and initial body weight (BW) for the transition period (T; 28 d to 64 d). During the T period, a commercial lidded feeder hopper was used (3.7 pigs/feeder space). When moving to the growing facilities, the 24 pens were maintained and split into two groups of 12 according to sex, feeder type (HD or 5.5 pigs/feeder space and LD or 2.2 pigs/feeder space). In Trial 2 a total of 1067 piglets were used and classified, when leaving the nursery at 63d of age, as Heavy (Hp, n = 524) and Light (Lp, n = 543) pigs. Along the growing period, Hp and half of the Lp pigs were fed with four consecutive feeds, following a standard feeding program (Std). Alternatively, the other half of the Lp pigs were fed according to a budget approach, changing the first three feeds on the basis of an equivalent feed consumption instead of age (Sp).ResultsIn Trial 1, higher BW (80.2 kg vs. 82.1 kg; P = 0.02), ADG (704 g/d vs. 725 g/d; P = 0.02) and lower number of lesions were observed for pigs raised in the LD treatment, compared to the HD treatment at d 154 (P < 0.05). The CV of the final BW was numerically lower for the LD treatment. In Trial 2, higher BW and ADG and lower CV were observed for the LSp pigs from 83 d until 163 d (P < 0.001) of age compared to LStd. Moreover, an interaction observed for carcass weight at slaughter (P = 0.016) showed that the Sp pigs had a higher carcass weight than did the Std pigs, and the difference increased as the emptying of the barn facility advanced.ConclusionIt is concluded that feeder space and feeding management may affect the growth of growing-finishing pigs and body-weight homogeneity at the end of the period.

3D printed triply periodic minimal surfaces as spacers for enhanced heat and mass transfer in membrane distillation

3D printing is utilized to create different feed channel spacer designs aimed at enhancing the spacer performance specifically for membrane distillation (MD) application. The novelty is the use of mathematically developed triply periodic minimal surface (TPMS) as feed spacers. Five different TPMS based spacer designs were evaluated and benchmarked against the conventionally used net type spacer. The best performing TPMS spacer topology exhibited 60% higher water flux and 63% higher overall film heat transfer coefficient than the commercial spacer. The TPMS spacer designs also had a significant advantage over the commercial spacer when treating feed with high fouling potential such as brine solution. The advantages of TPMS spacers were the high throughput combined with sustained flux performance over increasing TDS concentrations ranging from 75,000 ppm to 100,000 ppm. The best performing TPMS spacer design was identified to have the highest surface area to volume ratio along with a design structure that caused relatively higher turbulence by disrupting the feed flow. Particle deposition tests were done using microspheres to visualize the impact of TPMS spacer design on dead zone formation. Pearson correlation coefficient showed that particle deposition is strongly correlated to the spacer voidage and its membrane contact area.

Comparative Efficiency of Various Disinfectants Used in the Cattle Farm

Abstract The investigations were aimed to establish the comparative efficiency of four disinfectants (Aquadez, Ecocide S, Virocide and Na OH) used for the disinfection of cattle farm of State Agrarian University of Moldova. According to the classical methodology, the disinfectants have been used in concentrations which were recommended by the producers. Following this, lavages were collected from different supports and equipment of the cattle farm before sparing of the disinfectants and one hour after the contact of the disinfectants with the substrates. In this context samples were taken from places as the feeding space for animals and the rest area, cows’ milking rooms and the milk collection rooms. Afterwards, the samples have been inseminated in laboratory conditions for establishing the afterwards disinfecting effect on the farm. As a result, the microbiological investigation demonstrated that concentrations which were recommended by the producers and double concentrations of disinfectants don’t have satisfactory 100% of the anti-microbial and antifungal effect. For all disinfected places with the mentioned disinfectants colonies of microorganisms grew on nutrient media, especially bacterial forms as Streptococcus, Staphylococcus and microscopic fungal. Following comparisons, Ecocide S 3% and Na OH 3% had a higher efficiency than Aquadez 3%. The after application effect of Aquadez 3% established the presence of Salmonella, E. coli colonies grown on nutrient media as well as, Streptococcus and microscopic fungal.

Effects of wet/dry feeder and pen stocking density on grow-finish pig performance.

Three thousand one hundred and eighty-two terminal cross pigs (barrows and gilts) PIC line 359 sires × 1,050 dams were used from three consecutive grow-finish groups (initial BW of 21.51 ± 0.42 kg, 31.61 ± 1.18 kg, 29.41 ± 0.28 kg for replicates 1–3). Pigs were randomly assigned to each pen at the start of the trial and the research period continued for 106, 94, and 100 d for the first, second, and third replicates, respectively. The experimental treatments were designed as a two by three factorial (pen space of 0.65 or 0.78 m2/pig with 10, 13, or 16 pigs per feeder space), each pen had an equal number of barrows and gilts with 20, 26, and 32 pigs per pen for the 10, 13, and 16 pigs per feeder space pens. Each pen was equipped with one double-sided wet/dry feeder, 37.5 cm wide, with one nipple drinker. All pigs had ad libitum access to feed and water supply during the trial period. Pigs for all the three replicates were fed with the same series of diets. Pigs were weighed by pen at the start of trial and at the end of the trial to calculate ADG. Feed was removed from the feeders and weighed to determine ADFI and G:F. To express floor space allowance, the k value was estimated by the equation: . No interactions (P > 0.05) of floor space allowance with pigs per feeder were observed. Pigs with less floor space allowance had reduced BW (128.8 vs. 129.5 kg, P = 0.026), ADG (1.00 vs. 1.02 kg/d, P = 0.002), and ADFI (2.52 vs. 2.61 kg/d, P < 0.001). However, G:F was improved (0.402 vs. 0.397, P = 0.039) with less floor space allowance per pig. Increased pigs per feeder space reduced final BW (129.7, 129.4, 128.4 kg, linear; P = 0.001). However, ADG had a quadratic relationship (P = 0.005) with pigs per feeder space with means of 1.03, 1.01, and 1.01 kg/d for 10, 13, and 16 pigs per feeder space. Overall, ADFI had a quadratic relationship (P < 0.0001) with number of pigs per feeder space with means of 2.62, 2.52, and 2.55 kg/d for 10, 13, and 16 pigs per feeder space. Gain efficiency had a quadratic relationship (P = 0.005) with number of pigs per feeder space with means of 0.395, 0.404, and 0.400 for 10, 13, and 16 pigs per feeder space. In conclusion, a floor space allowance of 0.65 m2/pig in the grow-finish period reduced ADFI and ADG compared with 0.78 m2/pig. Overall, with the type of wet/dry feeder used in this study, 10 pigs per feeder had the greatest ADG and ADFI, compared with 13 or 16 pigs per feeder space. However, G:F improved as the number of pigs per feeder space increased.