Leland J. McKinney

Effect of crude glycerol on pellet mill production and nursery pig growth performance

The objective of this study was to determine the effects of diets containing crude glycerol on pellet mill production efficiency and nursery pig growth performance. In a pilot study, increasing crude glycerol (0, 3, 6, 9, 12, and 15%) in a corn-soybean meal diet was evaluated for pellet mill production efficiency. All diets were steam conditioned to 65.5 degrees C and pelleted through a pellet mill equipped with a die that had an effective thickness of 31.8 mm and holes 3.96 mm in diameter. Each diet was replicated by manufacturing a new batch of feed 3 times. Increasing crude glycerol increased both the standard (linear and quadratic, P < 0.01) and modified (linear, P < 0.01; quadratic, P </= 0.02) pellet durability indexes up to 9% with no further benefit thereafter. The addition of crude glycerol decreased (linear; P < 0.01) production rate (t/h) and production efficiency (kWh/t). In a 26-d growth assay, 182 pigs (initial BW, 11.0 +/- 1.3 kg; 5 or 6 pigs/pen) were fed 1 of 7 corn-soybean meal-based diets with no added soy oil or crude glycerol (control), the control diet with 3 or 6% added soy oil, 3 or 6% added crude glycerol, and 6 or 12% addition of a 50:50 (wt/wt) soy oil/crude glycerol blend with 5 pens/diet. The addition of crude glycerol lowered (P < 0. 01) delta temperature, amperage, motor load, and production efficiency. The addition of crude glycerol improved (P < 0.01) pellet durability compared with soy oil and the soy oil/crude glycerol blend treatments. Pigs fed increasing crude glycerol had increased (linear, P = 0.03) ADG. Average daily gain tended to increase with increasing soy oil (quadratic; P = 0.07) or the soy oil/crude glycerol blend (linear, P = 0.06). Adding crude glycerol to the diet did not affect G:F compared with the control. Gain:feed tended to increase with increasing soy oil (linear, P < 0.01; quadratic, P = 0.06) or the soy oil/crude glycerol blend (linear, P < 0.01; quadratic, P = 0.09). Nitrogen digestibility tended (P = 0.07) to decrease in pigs fed crude glycerol compared with pigs fed the soy oil treatments. Apparent digestibility of GE tended (P = 0.08) to be greater in the pigs fed soy oil compared with pigs fed the soy oil/crude glycerol blends. In conclusion, adding crude glycerol to the diet before pelleting increased pellet durability and improved feed mill production efficiency. The addition of 3 or 6% crude glycerol, soy oil, or a blend of soy oil and glycerol in diets for 11- to 27-kg pigs tended to increase ADG. For pigs fed crude glycerol, this was a result of increased ADFI, whereas, for pigs fed soy oil or the soy oil/crude glycerol, the response was a result of increased G:F.

Stored‐product insects carry antibiotic‐resistant and potentially virulent enterococci

A total of 154 enterococcal isolates from 95 stored-product insects collected from a feed mill, a grain storage silo, and a retail store were isolated and identified to the species level using PCR. Enterococcus casseliflavus represented 51% of the total isolates, followed by Enterococcus gallinarum (24%), Enterococcus faecium (14%), Enterococcus faecalis (7%), and Enterococcus hirae (5%). Many isolates were resistant to tetracycline (48%), followed by streptomycin (21%), erythromycin (14%), kanamycin (13%), ciprofloxacin (12%), ampicillin (4%), and chloramphenicol (<1%). Enterococci carried genes coding for virulence factors, including the gelatinase gene gelE (26% of isolates), an enterococcal surface protein gene esp (1%), and the cytolysin gene cylA (2%). An aggregation substance (asa1) gene was detected in six out of 10 E. faecalis isolates and five of these were positive for the aggregation substance. Enterococci were positive for hemolytic (57% of isolates) and gelatinolytic (23%) activity. The filter-mating assay showed that the tetracycline resistance gene, tetM, was transferable among E. faecalis by conjugation. These data demonstrated that stored-product insects can serve as potential vectors in disseminating antibiotic-resistant and potentially virulent enterococci.

Ultrasonic-Vibration Assisted Pelleting for Cellulosic Ethanol Manufacturing: An Experimental Investigation of Power Consumption

Ethanol produced from cellulosic biomass is an alternative to petroleum-based transportation fuels. However, its manufacturing costs are too high for cellulosic ethanol to be competitive. Cellulosic feedstocks have low density, causing their transportation and storage expensive, contributing to high manufacturing costs of cellulosic ethanol. Pelleting can increase the density of cellulosic feedstocks and reduce their transportation and storage costs. Ultrasonic vibration-assisted (UV-A) pelleting is a new pelleting method. Effects of input pelleting parameters (ultrasonic power, pelleting pressure, and particle size) on pellet quality and sugar yield have been studied. However, the effects of these parameters on power consumption in UV-A pelleting have not been studied. Since power consumption directly affects ethanol manufacturing costs, lower power consumption is desirable. The objective of this paper is to study effects of different input parameters (biomass material, particle size, ultrasonic power, and pelleting pressure) of UV-A pelleting on power consumption. Four types of biomass materials (big bluestem, corn stover, sorghum stalk, and wheat straw) were studied. Sorghum stalk consumed the least power. Pelleting pressure, particle size and ultrasonic power significantly affected power consumption of all four materials. Higher ultrasonic power and pelleting pressure resulted in lower power consumption. In addition, this paper also compares power consumption between UV-A pelleting and ring-die pelleting (a traditional pelleting method).© 2011 ASME

An Experimental Comparison of Two Pelleting Methods for Cellulosic Ethanol Manufacturing

Ethanol produced from cellulosic biomass is an alternative to petroleum-based transportation fuels. However, manufacturing costs of cellulosic ethanol are too high to be competitive. Low density of cellulosic feedstocks increases their handling and transportation costs, contributing to high overall costs of cellulosic ethanol manufacturing. Pelleting can increase density of cellulosic feedstocks, reduce transportation and storage costs, and make cellulosic ethanol production more competitive. UV-A (ultrasonic vibration-assisted) pelleting is a new pelleting method (available only in lab scale now). Preliminary research showed that UV-A pelleting could significantly increase pellet density and pellet durability but it has never been compared with other pelleting methods (e.g., using an extruder, a briquetting press or a ring-die pelleting). The objectives of this research are to compare UV-A pelleting with ring-die pelleting in terms of pellet density, pellet durability, energy consumptions of pelleting. The results will be useful to find a better pelleting method for cellulosic ethanol manufacturing.Copyright

The Effect of Moisture Content on Determining Corn Hardness from Grinding Time, Grinding Energy, and Near-Infrared Spectroscopy

The Stenvert hardness test was used to determine the energy-to-grind (ETG) and time-to-grind (TTG) of 107 food-grade corn hybrids at different moisture content (MC) levels. ETG and TTG were significantly affected by moisture content. Across hybrids, ETG displayed the most consistent response between 10% and 13% MC wet basis. An equation was developed to adjust ETG and TTG to a common MC level in order to minimize moisture effects on corn-hardness determination. ETG was considered to be the preferable method to measure corn hardness, considering ETG adjustments, based on MC, were more accurate using the developed equation. Results also supported grinding at MC levels between 10% and 13% MC to obtain the most accurate results, as opposed to higher MC levels. Grinder speed effects were also found to be significant but controllable, and the repeatability of ETG and TTG were about the same. Near-infrared reflectance spectroscopy was concurrently evaluated as a method to measure corn hardness in terms of ETG and TTG on whole-kernel and ground material from the grinder. Predictive models were poor using spectra (500 to 1700 nm) of whole-kernel and ground samples. Moisture-correction methods developed in this work allowed samples of corn to be tested over a broader range of MC. This provided more convenience and greater confidence in grinding parameters as a measurement of corn hardness.

Effects of feeding cracked corn to nursery and finishing pigs

Four experiments were conducted to determine the effects of supplementing cracked corn in nursery and finishing pig diets (PIC TR4 × 1050). In Exp. 1, 144 pigs (7.5 kg BW) were used in a 28-d experiment with 6 pigs per pen and 6 pens per treatment. Treatments were corn-soybean meal based in the form of mash, pellets (PCD), and pellets with 100% of the corn ground (PGr; 618 mm) or cracked (PCr; 3444 mm) and blended into the diet after the rest of the formulation had been pelleted. For d 0 to 28, pigs fed mash had increased (P = 0.042) ADFI compared with those fed the PCD diet. Pigs fed PCD had increased (P < 0.05) ADG and G:F compared with pigs fed PGr and PCr. Pigs fed PCr had decreased (P = 0.004) G:F compared with those fed PGr. For Exp. 2, 224 nursery pigs (7.4 kg BW) were used in a 28-d study with 7 pigs per pen and 8 pens per treatment. Treatments were similar to Exp. 1, with 50% of the corn either ground (445 mm) or cracked (2142 mm). For d 0 to 28, pigs fed mash had greater (P < 0.05) ADFI and G:F than pigs fed the PCD diet. Pigs fed the PCD diet had decreased (P = 0.001) ADFI and increased (P = 0.001) G:F compared to those fed PGr and PCr. For Exp. 3, 208 pigs (62.6 kg BW) were used in a 63-d experiment with 13 pigs per pen and 4 pens per treatment. Treatments were corn-soybean meal based with 0, 10, 20, and 40% cracked corn (3549 µm). All treatments were fed in mash form. For d 0 to 63, increasing cracked corn tended to decrease (linear, P = 0.093) G:F and decreased (linear, P = 0.047) carcass yield. Adding up to 40% of cracked corn to a mash diet decreased (P < 0.05) scores for keratinization and ulcers. For Exp. 4, 252 finishing pigs (40 kg BW) were used with 7 pigs per pen and 9 pens per treatment. The treatments were the same as described in Exp. 2. For the 80-d experiment, pigs fed mash had decreased (P < 0.05) ADG, stomach keratinization, and ulcer scores and increased (P < 0.05) yield and loin depth compared with pigs fed the PCD diet. Pigs fed PCD had increased (P < 0.05) ADG and G:F and decreased (P = 0.026) loin depth compared with pigs fed PGr and PCr diets. Pigs fed PCr had increased (P = 0.023) ADG and decreased (P = 0.001) yield compared with pigs fed PGr. Pigs fed PCr had decreased (P < 0.05) stomach keratinization and ulcer scores compared with pigs fed the PCD and PGr diets. In conclusion, pigs fed PCD had the greatest G:F, and PGr and PCr treatments had negative effects on G:F of pigs. Scores for stomach lesions were lowest for pigs fed PCr.

Effects of corn particle size, complete diet grinding, and diet form on finishing pig growth performance, caloric efficiency, carcass characteristics, and economics

A total of 855 pigs (PIC TR4 × Fast Genetics York × PIC Line 02), initially 56.54 lb BW) were used in a 111-d trial to evaluate the effects of corn particle size, complete diet grinding, and diet form (meal or pellet) on finishing pig growth performance, caloric efficiency, carcass characteristics, and economics. Pens of pigs were balanced by initial BW and randomly allotted to 1 of 5 dietary treatments with 9 replications per treatment. The same corn-soybean meal–based diets containing 30% dried distillers grains with solubles (DDGS) and 20% wheat middlings (midds) were used for all treatments. Diets were fed in four phases. Different processing techniques were used to create the 5 dietary treatments: (1) roller grinding the corn to approximately 650 μ with the diet fed in meal form; (2) hammer-mill grinding the corn to approximately 320 μ with the diet fed in meal form; (3) Treatment 2 but pelleted; (4) corn initially roller-mill ground to approximately 650 μ, then the complete mixed diet reground through a hammer mill to approximately 360 μ with the diet fed in meal form; and (5) Treatment 4 but pelleted.

Impact of pelleting and acid pretreatment on biomass structure and thermal properties of wheat straw, corn stover, big bluestem, and sorghum stalk.

Agricultural residues and energy crops are considered potential feedstocks for bioethanol production because of their high availability and energy potential as well as relatively low cost. Previous studies have shown that pelleting biomass feedstocks could increase their bulk density, thus increasing ease of handling and decreasing cost of handling and transportation. The pelleting process has also been shown to have a positive impact on the sugar yield of biomass. However, the effects of the pelleting process on biomass structure have not yet been studied. Therefore, the objective of this study was to investigate the impact of dilute acid pretreatment and the pelleting process on biomass structure of cellulosic materials, including crystallinity index (CrI,%) measured by the x-ray diffraction (XRD) method, structure of constituents and chemical changes determined by Fourier transform infrared spectroscopy (FTIR) and solid-state cross-polarization/magic angle spinning (CP/MAS) 13C NMR spectroscopy, morphological structure determined by scanning electron microscopy (SEM), and thermal properties determined by thermogravimetric analysis (TGA). Wheat straw, big bluestem, corn stover, and photoperiod-sensitive sorghum were used for this study. Pelleting did not have a significant effect on the pattern of FTIR spectra and solid-state 13C NMR spectra of biomass. XRD analysis showed that biomass crystallinity increased after dilute acid pretreatment and the pelleting process. Based on SEM analysis of biomass, dilute acid pretreatment and pelleting enhanced the removal of the softened surface region of biomass. TGA analysis showed that the decomposition temperature of pelleted biomass was slightly higher than that of corresponding unpelleted biomass, indicating that the pelleted biomass was more thermally stable than the unpelleted biomass.

The importance of defining the method in particle size analysis by sieving.

The American Society of Agricultural and Biological Engineers (ASABE) publishes a standard for identifying particle size by sieving (ASABE S319.4). However, this standard includes a number of options that allow the test to be conducted differently, and different laboratories may analyze a single sample with different results. Options include the type of sieve shaker used, the use of sieve agitators, the use of a dispersion agent, and the sieving time. A small study was conducted to examine the effect of varying these methods on the calculated geometric mean diameter by weight (dgw) and geometric standard deviation by weight (sgw). Results indicated that large differences existed depending on the methods used, with dgw varying by as much as 100 microns, and sgw varying by as much as 0.42 simply by altering one option. When compounding the differences in methods, the variations can be even larger. These discrepancies demonstrate that, for particle size analysis by sieving to be used as an effective tool, the same methodology must be used to compare samples. Additionally, the data demonstrate that unless the methods in the current standard are better defined, dgw and sgw should be used only as relative values for comparison.

Effect of glycerol on flow ability of swine diets

We conducted two experiments to determine the effect of added glycerol or a 50:50 soy oil/glycerol blend on the flow ability characteristics of ground corn or ground corn and 15 or 30% spray-dried whey. Experiments were conducted using corn ground by either a full circle, tear drop hammer mill or a threehigh roller mill at the Kansas State University Grain Science Feed Mill. Flow ability was determined by measuring angle of repose. In Exp. 1 we evaluated the effects of added soy oil, glycerol, or a 50:50 soy oil/glycerol blend on the flow ability of ground corn. Samples were ground through a roller mill (RM) or hammermill (HM). Particle size mean and standard deviations of the ground corn were 645 microns and 1.97 for the roller mill and 674 microns and 2.31 for the hammer mill. Soy oil, glycerol, or a 50:50 blend of soy oil/glycerol was added to the ground corn at 0, 2, 4, 6, or 8% for a total of 30 samples (1 RM sample, 1 HM sample, 3 liquid sources, and 5 levels of added liquid). In Exp. 2, we evaluated the effects of added soy oil, glycerol, or a 50:50 soy oil/glycerol blend on the flow ability of 85:15 or 70:30 blend of HM ground corn and spray-dried whey. Soy oil, glycerol, or a 50:50 blend of soy oil/glycerol was added to the ground corn and spray-dried wheybased diets at 0, 4, or 8% for a total of 18 samples (1 HM sample, 2 levels of added whey, 3 liquid sources, and 3 levels of added liquid). Angle of repose was then measured, and replicated 4 times on each sample. In Exp. 1 there was a three way interaction (P<0.05) between mill type, liquid source, and percent liquid added. Roller mill ground grain had decreased angle of repose (better flow ability) compared to HM ground grain. The addition of soy oil increased angle of repose, decreasing flow ability. The addition of glycerol or a 50:50 soy oil/glycerol blend decreased angle of repose, improving flow ability with HM ground corn. Addition of glycerol did not influence flow ability when added to RM corn ground. In Exp. 2 there was a three way interaction (P<0.05) between spray-dried whey level, added liquid source, and percent of liquid added. The addition of glycerol or the 50:50 soy oil/glycerol blend decreased angle of repose, improving flow ability. The addition of glycerol decreased angle of repose greater in the 15% spray-dried whey sample compared to the 30% spray-dried whey sample. The addition of soy oil increased angle of repose regardless of spray-dried whey concentration. These data suggest that the addition of glycerol to a meal diet containing HM ground corn will improve flow ability.