Mean Particle Length Research Articles

An easy decision-making graphic tool to improve herd level milk yield in a local scale dairy farming system

Several features prevent dairy farms from reaching their full potential milk yield levels. A plurality of methods are available to analyse a farm’s yield gap, but in practice, farmers rarely use them to understand their main constraints to production. We propose a simple and graphical approach to tune the limiting (feed-related) or reducing (management-related) factors to evaluate the likelihood of being a high-yielding farm. We gathered data from 32 farms within a local-scale dairy system in Northern Italy. Data regarded milk yield (MY), dry matter intake (DMI), feeding ration’s homogeneity index (Hi), feed sorting (Si) index, ration’s geometric mean particle length (GMPL), ration digestibility, income over feed cost (IOFC) and MY summer-winter ratio (SWR). Farms were classified according to their MY levels into high (H) and low or medium (L + M), with a 36.7 kg × cow−1 day−1 threshold. At an ANOVA model for MY class, H farms resulted in higher IOFC (p < 0.001), GMPL (p = 0.046), DMI (p = 0.006), digestible DM (DDM, p = 0.013), digestible crude protein (DCP, p = 0.011), digestible starch (Dstarch, p = 0.001), and feed efficiency (FE, p = 0.003). At a logistic AIC stepwise regression, the GMPL (odds = 6.528, 95% CI = 1.11-64.2) and DMI (odds = 3.889, 95% CI = 1.43-16.5) favoured farms being classified in the H production class. The nomogram was used to calculate a confusion matrix, achieving an overall accuracy of 0.70, demonstrating its ability to transform predictive models into a graphical, realisable tool.

Microplastics in human blood: Polymer types, concentrations and characterisation using μFTIR

Microplastics (MPs) are an everyday part of life, and are now ubiquitous in the environment. Crucially, MPs have not just been found within the environment, but also within human bodies, including the blood. We aimed to provide novel information on the range of MP polymer types present, as well as their size and shape characteristics, in human whole blood from 20 healthy volunteers. Twenty-four polymer types were identified from 18 out of 20 (90 %) donors and quantified in blood, with the majority observed for the first time. Using an LOQ approach, five polymer types met the threshold with a lower mean ± SD of 2466 ± 4174 MP/L. The concentrations of plastics analysed in blood samples ranged from 1.84 − 4.65 μg/mL. Polyethylene (32 %), ethylene propylene diene (14 %), and ethylene–vinyl-acetate/alcohol (12 %) fragments were the most abundant. MP particles that were identified within the blood samples had a mean particle length of 127.99 ± 293.26 µm (7–3000 µm), and a mean particle width of 57.88 ± 88.89 µm (5–800 µm). The MPs were predominantly categorised as fragments (88 %) and were white/clear (79 %). A variety of plastic additive chemicals were identified including endocrine disrupting-classed phthalates. The procedural blank samples comprised 7 polymer types, that were distinct from those identified in blood, mainly resin (25 %), polyethylene terephthalate (17 %), and polystyrene (17 %) with a mean ± SD of 4.80 ± 5.59 MP/L. This study adds to the growing evidence that MPs are taken up into the human body and are transported via the bloodstream. The shape and sizes of the particles raise important questions with respect to their presence and associated hazards in terms of potential detrimental impacts such as vascular inflammation, build up within major organs, and changes to either immune cell response, or haemostasis and thrombosis.

A review and analysis of particle size parameters and their relationships to physical properties of growing media

AbstractAn expanded description of particle morphology and the analysis of its relationships with physical properties may help to optimize the selection of raw materials and particle size fractions used as growing media constituents. Previous works have described the outlines of these relations based mostly on sieving procedures to characterize particle size distribution. They have shown limited and sometimes contradictory results due to the different methods used, size fractions selected, and physical properties measured. Also, sieve analysis, which separates particles based on their width, is less accurate for non‐spherical particles, which is the case for most growing media constituents. Recent works have promoted the use of dynamic image analysis (DIA) to precisely analyze both particle length and width. Five raw materials were chosen (white and black peats, coir, pine bark, and wood fiber) and sieved to obtain various particle size fractions. For each particle size fraction and the raw materials, the mean weight diameter (MWD), derived from sieving, was calculated, whereas mean particle length and width were determined using a DIA tool, the QicPic device. Also, physical properties were assessed from water retention curves established using Hyprop systems. The statement that the larger the particle size, the higher the air‐filled porosity (AFP), the lower the water holding capacity (WHC) was more precisely redefined. Large variations in WHC and AFP mainly occurred for finest particle size fractions, whereas changes were conversely very small or non‐existent for larger particle sizes. From data obtained for each particle size fractions, regression models were established to relate mean particle length and width (both determined using DIA) and MWD (determined from sieving) with WHC and AFP. Mean particle length was identified as the most relevant parameter for predicting WHC and AFP of the raw materials tested.

Strategies to Maximize Kernel Processing in a Brazilian Vitreous Endosperm Hybrid

Whole-plant corn silage (WPCS) is a major source of forage for dairy cattle in Brazil. Improved kernel processing may be especially advantageous when feeding corn hybrids with vitreous endosperms. Two experiments were conducted to evaluate the effects of the theoretical length of cut (TLOC) and ensiling time on WPCS particle size and kernel processing with two types of forage harvesters. In the first trial, the plant was harvested by a pull-type forage harvester (PTFH) at TLOCs of 3, 6 and 9 mm. In the second trial, the harvesting was performed by a self-propelled forage harvester (SPFH) at TLOCs of 6, 12 and 18 mm, with a roll gap of 3 mm. The WPCS were stored for 0, 35 and 140 days. In the PTFH trial, the TLOCs of 3 and 6 mm did not affect the WPCS particle size distribution and mean particle length (MPL). However, the TLOC of 9 mm increased the MPL. The increase in the TLOC with the SPFH led to a higher MPL and percentage of long particles. The ensiling time increased the MPL and long particles only for the WPCS harvested by the SPFH. The strategy of reducing the TLOC with the SPFH increased the percentage of kernels smaller than 4.75 mm. Furthermore, the TLOC of 6 mm led to the best kernel processing with the SPFH. The ensiling time reduced the particle size of the kernel fractions for both forage harvesters. The corn silage processing score was improved with 140 days of ensiling with the SPFH. These findings suggest that increasing the ensiling time and a low TLOC in SPFHs (6 mm) may be good strategies to increase kernel damage and starch digestibility in WPCS.

Effects of wheat straw particle size as a free-choice provision on growth performance and feeding behaviors of dairy calves

In the dairy calf feeding, supplementation of forage to the starter feed is commonly practiced. However, data are insufficient about how changes in particle size (PS) of forage affect calf performance and behavior in a free-choice forage provision system. This study aimed to assess the effects of supplementing wheat straw varying in PS on performance, skeletal growth characteristics, ruminal pH, nutritional behaviors, and blood metabolites of dairy calves. Forty-eight Holstein calves (43.8 ± 3.2 kg of BW) from d 15 of age were randomly assigned to one of the four treatments (n = 12/treatment; six males and six females): (1) starter without wheat straw supplementation (CON), (2) CON supplemented with wheat straw chopped at 1 mm geometrical mean particle length (GMPL) (fine PS), (3) CON supplemented with wheat straw at 4 mm GMPL (medium PS), and (4) CON supplemented with wheat straw at 7 mm GMPL (long PS). The calves were given ad libitum access to feed and water throughout the study. All calves were weaned on d 56 of age and continued the experiment until d 90. The starter, wheat straw, and total solid feed intakes were not affected by GMPL of wheat straw; however, CON calves had a lower solid feed-, total DM- and NDF-intake than calves offered wheat straw. Further, ADG, weaning, and final BWs as well as feed efficiency were similar between treatments. No difference was observed in growth rate of hip height, hip width, body barrel, wither height, and heart girth among treatments, however, wheat straw supplemented calves tended to have greater body length at weaning. Blood concentration of serum β-hydroxy butyrate was greater in wheat straw supplemented calves compared with CON calves on d 56 and 90. Calves supplemented with wheat straw spent more time eating starter and forage, lying and ruminating and less time for standing and non-nutritional behaviors compared with the CON calves on d 49 and 63 of the study. Moreover, calves offered wheat straw had greater ruminal pH than CON calves at 4 and 8 h after offering starter feed on d 35. In conclusion, supplementing wheat straw as a free-choice increased solid feed intake, rumen pH, and calves' welfare, however, PS of wheat straw had no effect.

Replacing soybean hulls with grass hay on growth, intake, total tract digestibility, and rumen microbial nitrogen production of weaned Holstein dairy calves from 8 to 16 weeks of age

The objective of this experiment was to determine the effects of replacing soybean hull (SBH) pellets with grass hay (GH) on growth, intake, total-tract digestibility, and rumen microbial nitrogen production of weaned dairy calves from 8 to 16 wk of age. Holstein calves (n = 16) were randomly assigned to 1 of 4 rations containing, on a dry matter (DM) basis, 76% grower with the remaining 24% being made up of different amounts of SBH pellets and GH [0% GH, 24% SBH (0GH); 8% GH, 16% SBH (8GH); 16% GH, 8% SBH (16GH); and 24% GH, 0% SBH (24GH)]. Calves were weaned at 6 wk, housed individually, and studied from 8 to 16 wk of age. From 8 to 9 wk of age calves were offered a ration consisting of 50% of texturized starter (20% CP and 35% starch), which was offered from 3 d of age, and 50% of their assigned ration. From 9 wk until the end of the study, calves were offered 100% of their assigned ration. Intake and body weight were measured weekly, and frame measurements were taken at the beginning and end of the study. Animal behavior observations were recorded every 5 min over a 24-h period at 10 and 14 wk of age. Total fecal and urine collection was conducted for 4 d consecutively at 11 and 15 wk of age. Feed and feces were evaluated for DM, N, neutral detergent fiber, acid detergent fiber, and starch to determine total-tract digestibility. Feces were evaluated for geometric mean particle length (Xgm) and particle size distribution. Urine was evaluated for N, creatinine, urea, and total purine derivatives to estimate microbial N yield. Calves offered 0GH and 8GH had a 20% increase in intake, average daily gain (1.23, 1.27, 0.89, and 0.71 kg/d for 0GH, 8GH, 16GH, and 24GH, respectively), and feed efficiency compared with 16GH and 24GH. Calves offered 8GH had the greatest levels of neutral detergent fiber and acid detergent fiber digestibility, as well as the greatest estimated microbial N yields. Inclusion of forage increased rumination time (2.75, 6.89, 7.18, and 8.16 h/d for 0GH, 8GH, 16GH, and 24GH, respectively) and decreased fecal Xgm by ~35% compared with calves offered 0GH. In the current study, increasing the replacement of SBH with GH beyond 8% was detrimental to weaned calf performance. These results indicate that when diets containing 8% GH and 16% SBH were fed to recently weaned calves, rumen functionality and feed efficiency were optimized compared with the other GH-SBH combinations.

Three-dimensional Phase-field simulation of γ″ precipitation kinetics in Inconel 625 during heat treatment

Metastable γ″ (D022-Ni3Nb) particles are strengthening precipitates for commercial Inconel 625 Ni-based superalloy. Understanding their morphological evolution is critical for evaluating its hardening effects and guiding heat treatments to improve its yield strength. Here we present a phase-field model to model and analyze the nucleation and growth kinetics of metastable γ″ in Inconel 625 during isothermal and non-isothermal aging conditions with thermodynamic properties, diffusion coefficients, and misfit strain data from both the literature and calibration to experimental results. We implemented the classical nucleation theory to introduce local nucleation taking into account local supersaturation. The simulated mean particle length and aspect ratio are in agreement with experimental data at 600 °C and 650 °C during isothermal aging. Utilizing the phase-field simulation results as input parameters, the coherency strengthening effect of γ″ as a function of aging temperature and time is predicted. A multistage aging strategy to optimize the γ″ strengthening effect and to reduce aging times using the developed phase-field model and coherency strengthening model is suggested.

Advanced imaging techniques to understand the impact of process variables on the particle morphology in a corn stover pellet

The objective of this study is to understand the impact of process variables on particle binding during corn stover pelleting. Initial particle attrition or percent fines <425 μm in 1/4-in. (6.35 mm) and 7/16-in. (11.11-mm) hammermill screen size was measured at 34.36% and 20.24%, respectively. A single pellet press was used to do the pelleting tests by varying the hammermill screen size (1/4-in. [6.35 mm] and 7/16-in. [11.11 mm]), corn stover moisture (10, 15, and 20%, w.b.), and residence time (45, 90, 120 and 150 s). The pellet properties measured were the particle dimensions (e.g., geometric mean particle length, d10, d50, and d90 [mm]), percent fines (e.g., <425μm), and unit density (e.g., kg/m3). Results indicated that both hammermill grind sizes impacted the pellet properties. Residence time, corn stover moisture content, and hammermill screen size all influenced the percent fines in the corn stover pellets. At 10% (w.b.) corn stover moisture content and a 150-s residence time, the maximum percentage of fines observed was about 26% for a 6.35-mm and about 16–17% for a 11.11 mm hammermill screen size grind. The pelleting process conditions also influenced the particle dimensions (e.g., geometric mean particle length, d10, d50, and d90 [mm]). At lower residence times of 45 s for both 1/4- and 7/16-in. (6.35 and 11.11 mm) hammermill screen size grind pellets, the fines in the corn stover pellets were minimized. In the case of corn stover moisture content, about 10–15% (w.b.) minimized percent fines and unit density was maximized at 150-s residence time for both the grind sizes that were tested. X-ray CT-scan analysis indicated that the agglomerate size, shape, and surface area are influenced by both corn stover moisture content and residence time. Focused ion beam tomography showed a lamellar structure with voids, which might have formed due to weak adhesion between the particles.

Biomass Grinding Process Optimization Using Response Surface Methodology and a Hybrid Genetic Algorithm.

Biomass could be a key source of renewable energy. Agricultural waste products, such as corn stover, provide a convenient means to replace fossil fuels, such as coal, and a large amount of feedstock is currently available for energy consumption in the U.S. This study has two main objectives: (1) to understand the impact of corn stover moisture content and grinder speed on grind physical properties; and (2) develop response surface models and optimize these models using a hybrid genetic algorithm. The response surface models developed were used to draw surface plots to understand the interaction effects of the corn stover grind moisture content and grinder speed on the grind physical properties and specific energy consumption. The surface plots indicated that a higher corn stover grind moisture content and grinder speed had a positive effect on the bulk and tapped density. The final grind moisture content was highly influenced by the initial moisture content of the corn stover grind. Optimization of the response surface models using the hybrid genetic algorithm indicated that moisture content in the range of 17 to 19% (w.b.) and a grinder speed of 47 to 49 Hz maximized the bulk and tapped density and minimized the geomantic mean particle length. The specific energy consumption was minimized when the grinder speed was about 20 Hz and the corn stover grind moisture content was about 10% (w.b.).

Analysis of breakage patterns in a sheared layer of elongated particles

Discrete Element Method (DEM) simulations of elongated (i.e. needle-shaped) particles breakage in a shear field confined between two parallel plates, in analogy with processes occurring in a powder shear cell tester, were carried out. Effects of particle strength, shear rate and the compressive stress were investigated. The breakage patterns occurring in a layer of particles due to compressive and shearing stress fields are analysed in detail and compared. The results of these computational experiments reveal that when the course of particle breakage is represented in the mean particle length vs. polydispersity diagram, the breakage patterns for slow shearing and compression follow the same path that is close to the path constructed for an idealized breakage scenario, while curves for fast shearing deviate from the scenario towards higher polydispersities.

Survey of mean particle length in whole-plant corn silage

ABSTRACT Theoretical length of cut (TLOC) settings on forage harvesters vary as dairy farmers attempt to increase the mean particle length (MPL) of whole-plant corn silage (WPCS). Our objective was to evaluate the MPL of WPCS using 2 methods of determination in whole-plant and stover-fraction samples. Eighty WPCS survey samples were collected and represented varied TLOC settings and processor types and settings. Particle size distributions for determining MPL were measured using either the Penn State Particle Size Separator (PSPS) or the Wisconsin Oscillating Particle Separator (WIOS). The MPL of WPCS samples determined by PSPS and WIOS, respectively, were 12.0 versus 11.8mm and for the stover-fraction samples were 11.8 versus 8.1 mm. The TLOC, indicated verbally by surveyed dairy farmers or their custom operator, was unrelated to MPL regardless of particle-separation method ( P > 0.10) for both whole-plant and stover-fraction samples. However, MPL measured by PSPS and WIOS were positively related in both as-fed whole-plant (R 2 = 0.62, P = 0.001) and dried stover-fraction samples (R 2 = 0.60, P = 0.001). The elimination of kernels through hydrodynamic separation did not improve the relationship between verbal TLOC and MPL. A relationship between MPL of as-fed whole-sample and MPL of the stover fraction was observed (PSPS, P = 0.001; WIOS, P = 0.001) but with poor R 2 values (PSPS, 0.25; WIOS, 0.18). The strong relationship between the 2 methods used to determine MPL in WPCS suggests that MPL may be measured adequately on farm by consultants using the PSPS.

Effects of replacing maize silage with lucerne silage and lucerne silage chop length on rumen function and milk fatty acid composition

The objective of this study was to investigate whether higher lucerne (Medicago sativa; alfalfa) silage inclusion rate and longer lucerne chop length improves rumen function through increased provision of physically effective fiber, when included in a maize and lucerne silage-based total mixed ration. Diets were formulated to contain a 50:50 forage:concentrate ratio [dry matter (DM) basis] and be isonitrogenous and contain equal levels of neutral detergent fiber (320 g/kg). The forage portion of the offered diets was composed of maize and lucerne silage DM in proportions (wt/wt) of either 25:75 (high lucerne; HL) or 75:25 (low lucerne; LL). Second-cut lucerne was harvested and conserved as silage at either a long (L) or a short (S) chop length (geometric mean particle lengths of 9.0 and 14.3 mm, respectively). These variables were combined in a 2 × 2 factorial arrangement to give 4 treatments (HLL, HLS, LLL, LLS), which were fed in a 4 × 4 Latin square design study to 4 rumen-cannulated, multiparous, Holstein dairy cows in mid lactation. Effects on DM intake, chewing behavior, rumen volatile fatty acid concentration, rumen pH, rumen and fecal particle size, milk production, and milk fatty acid profile were measured. Longer chop length increased rumination times per kilogram of DM intake (+2.8 min/kg) relative to the S chop length, with HLL diets resulting in the most rumination chews. Rumen concentrations of total volatile fatty acids, acetate, and n-valerate were higher for the HLS diet than the other 3 diets, whereas rumen propionate concentration was lowest for the HLL diet. Physically effective fiber (particles >4 mm) percentage in the rumen mat was increased when L chop length was fed regardless of lucerne inclusion rate. No effect of treatment was observed for milk yield, although milk protein concentration was increased by L for the LL diet (+1.6 g/kg) and decreased by L for the HLL diet (-1.4 g/kg). Milk fat concentrations of total cis-18:1 (+3.7 g/100 g of fatty acids) and 18:3 n-3 (+0.2 g/100 g of fatty acids) were greater with HL. In conclusion, longer lucerne silage chop length increased time spent ruminating per kilogram of DM intake, but had no effect on rumen pH in the present study. Increasing dietary lucerne inclusion rate had no effects on rumination activity or rumen pH, but decreased the ratio of n-6:n-3 polyunsaturated fatty acid concentrations in milk fat.

Evaluating the production cost and quality of feedstock produced by a sawdust machine

The utilization of forest residues as a woody biomass feedstock for the production of bioenergy and bioproducts requires processing (i.e., comminution) to meet feedstock specifications, such as moisture content and particle size. The objective of this study was to determine the effect of small diameter processed hardwood (SH) and small and large diameter processed softwood (SS and LS) stems had on the productivity and cost of a track mounted sawdust machine that produced sawdust. In addition, moisture content, particle size distribution, bulk density, and the effect of knife wear were evaluated. The sawdust machine's 298-kW engine was capable of comminuting all material types except the LH stems. The machine's productivity ranged between 18.3 and 26.7 bone-dry metric ton (BDmT)/productive machine hour (PMH) at a cost of US $5.3 and US $3.6/BDmT, respectively. The moisture content of material used in the study ranged between 26 and 36%. The geometric mean particle lengths for SH, SS, and LS were 4.7, 5.3, and 4.4 mm, respectively. The machine could not process LH materials due to limited power. The bulk density of feedstock produced ranged between 234 and 281 kg/m3. Analysis indicated that knife wear did not have a significant effect on comminution productivity and feedstock quality while comminuting 60 green metric tons (GmT) of forest residues. The results from this study suggest that this sawdust machine can be useful in producing feedstock for new biomass conversion technologies that require small, uniform particles.

Variation of TMR particle size and physical characteristics in commercial Iranian Holstein dairies and effects on eating behaviour, chewing activity, and milk production

Evidence is limited on the effect of physical form of total mixed rations (TMR) on management of group-housed dairy cows in commercial dairy herds. The objective of this study was to consider the variation of TMR particle size (PS) and physical characteristics in commercial dairies and its effects on eating behaviour, chewing activity, and milk production. Fifteen dairy herds, feeding TMR, were each studied for 7 consecutive days. In each herd, a group of multiparous (3.5±0.8 parity; mean±SD), high producing cows (47±4kg milk/d) in mid-lactation (109±12 DIM) was studied. Herds were visited for 7 consecutive days for sampling fresh and refusal feed from the test group to assess particle size distribution, dry matter, and chemical composition. Chewing activity and milk production were monitored for the group. The 15 herds were divided to 3 classes according to geometric mean particle size of TMR: short, medium, and coarse, with average lengths of 4.6, 5.4, and 6.7mm respectively. The classes were significantly different in geometric mean particle length (GMPL) and physically effective neutral detergent fibre1.18 (peNDF1.18) (P<0.01), but physically effective neutral detergent fibre8 (peNDF8) was similar between medium and coarse classes. Amount of TMR retained on the 19-mm sieve of Penn State Particle Separator was highest for dairy farms with medium GMPL (P<0.01). Diurnal changes in particle size of refusals and chewing activity were similar among classes; the only difference observed was that daily rumination activity in the medium class tended to be greater than for the short and coarse classes (P=0.10). Milk fat percentage and yield as well as fat-to-protein ratio (F:P) were higher in the classes with medium and coarse TMR PS (P<0.01). Although GMPL and peNDF1.18 of TMR were correlated (P<0.05) only with milk F:P (r=0.53 and 0.64, respectively), peNDF8 was correlated (P<0.05) with both milk F:P (r=0.56) and chewing activity (r=0.60). The 19-mm TMR fraction was the only variable that correlated (P<0.05) with milk fat percentage (r=0.51) along with a tendency to be correlated (P=0.09) with chewing time. Interestingly, grain percentage of TMR was negatively correlated (P<0.05) with both milk F:P (r=−0.58) and chewing time (r=−0.68). In conclusion, commercial dairy farms considered in this study had a high variation in TMR PS, and peNDF8 and the 19-mm fraction of the Penn State Particle Separator were good indicators for predicting bio-physical responses of cows.

Straw particle size in calf starters: Effects on digestive system development and rumen fermentation

Two trials were conducted to determine effects of straw particle size in calf starter on rumen fermentation and development in calves. Holstein calves (n=17 in trial 1; n=25 in trial 2) were housed in individual pens; bedding (wood shavings) was covered with landscape fabric to completely avoid consumption of bedding. Milk replacer was fed at 12% of birth body weight per day and water offered free choice. Calves were randomly assigned to 4 treatments differing in geometric mean particle length (Xgm) of straw comprising 5% of starter dry matter. Straw was provided within the pellet at manufacture (PS; 0.82mm Xgm) or mixed with the pellet at time of feeding at Xgm of 3.04 (SS), 7.10 (MS), or 12.7 (LS) mm. Calves (n=12; 3/treatment) in trial 1 were fitted with a rumen cannula by wk 2 of age. A fixed amount of starter that was adjusted with age and orts were fed through the cannula in cannulated calves. Calves were euthanized 6 wk after starter was offered (9 and 7 wk of age for trials 1 and 2, respectively). Rumen digesta pH linearly decreased with age, whereas volatile fatty acid concentration increased with age. Overall pH had a cubic trend with SS lower than that of PS and MS. Molar proportion of acetate decreased with age whereas propionate proportion increased. Overall molar proportions of volatile fatty acids were not affected by diet. Fecal Xgm was not different in spite of changes in diet particle size and rumen digesta of PS being greater than SS, MS, and LS at slaughter. Fecal pH and starch concentration were not affected by diet; however, pH decreased whereas starch content increased with age. Weight of stomach compartments, rumen papillae length and width, and rumen wall thickness did not differ between diets. Omasum weight as a percentage of body weight at harvest linearly decreased as straw particle size increased. Under the conditions of this study, modifying straw particle length in starter grain resulted in minimal rumen fermentation parameter changes and no changes in rumen development. Rumen pH and fermentation changes with age were likely effects of increasing starter intake.

Water Absorption Behavior of Hemp Hurds Composites

In this paper, water sorption behavior of 28 days hardened composites based on hemp hurds and inorganic binder was studied. Two kinds of absorption tests on dried cube specimens in deionized water bath at laboratory temperature were performed. Short-term (after one hour water immersion) and long-term (up to 180 days) water absorption tests were carried out to study their durability. Short-term water sorption behavior of original hemp hurds composites depends on mean particle length of hemp and on binder nature. The comparative study of long-term water sorption behavior of composites reinforced with original and chemically modified hemp hurds in three reagents confirmed that surface treatment of filler influences sorption process. Based on evaluation of sorption curves using a model for composites based on natural fibers, diffusion of water molecules in composite reinforced with original and chemically modified hemp hurds is anomalous in terms of the Fickian behavior. The most significant decrease in hydrophility of hemp hurds was found in case of hemp hurds modified by NaOH and it relates to change in the chemical composition of hemp hurds, especially to a decrease in average degree of cellulose polymerization as well as hemicellulose content.

Study of Low-Pressure Argon Adsorption on Synthetic Nontronite: Implications for Smectite Crystal Growth

AbstractBecause relatively little information about the crystal-growth process of smectite is available, the process was assessed here by studying the size and shape of nontronite particles synthesized at six different temperatures from 75 to 150°C over a period of 4 weeks.The morphology of nontronites was studied using low-pressure isotherms of argon adsorption at 77 K, a method which enables the measurement of the basal and edge surface areas of the nontronite particles and of their mean diameter and thickness. During the crystal growth of nontronite, the mean particle length increased whereas their thickness (and the number of stacked layers) did not vary significantly.A specific two-dimensional crystal-growth process was observed for smectite via the lateral extension of the layers. This process also appears to occur during the growth of neoformed natural smectite.

Effects of alfalfa hay particle size in high-concentrate diets supplemented with unsaturated fat: Chewing behavior, total-tract digestibility, and milk production of dairy cows

This study evaluated the effects of increasing the physically effective neutral detergent fiber (peNDF) intake of lactating dairy cows fed high-concentrate diets supplemented with unsaturated fat on intake, eating behavior, diet sorting, chewing activity, total-tract digestibility, and milk production and composition. Diets contained 24% alfalfa hay (AH), 16% corn silage, 58% concentrate, and 2% yellow grease [dry matter (DM) basis], and dietary peNDF content was increased by varying the particle size (PS) of the AH. Nine multiparous cows averaging 87.8±14.8d in milk and weighing 653±53kg were randomly assigned to a triplicate 3×3 Latin square. During each 21-d period, cows were offered 1 of 3 total mixed rations that varied in PS of AH: fine, medium, and long, with a geometric mean particle length of 3.00, 3.57 and 3.87mm, respectively. Increasing PS quadratically affected DM intake (DMI; 24.7, 25.4, and 23.7kg/d, for fine, medium, and long, respectively), but cumulative DMI at 2, 4, and 6h after feeding was similar across treatments, averaging 23.4, 35.6 and 46.4% of total DMI for the 3 time points, respectively. Increased peNDF intake did not affect feed sorting, but increased daily eating time, and eating and total chewing time per kilogram of DMI. Daily rumination time exhibited a quadratic response, with highest rumination time for the medium diet. Dietary PS had no effects on digestibility in the total tract, but we observed, for fine, medium, and long diets, quadratic responses in milk production (41.5, 43.3, and 40.4kg/d), 4% fat-corrected milk production, and milk protein yield. Milk fat content decreased linearly with increasing PS, but milk fat content and fat:protein ratio were low for all treatments, likely due to adding unsaturated fat to a diet containing a high level of nonfiber carbohydrates (42.2% of DM). The composition, degree of saturation, and total conjugated linoleic acid content of fatty acids in milk fat were not affected by the change in peNDF content of the diet. The study indicates that a moderate increase in the PS of AH in diets containing unsaturated fat elevates peNDF intake and increases chewing activity, DMI, milk yield and milk fat production. However, the effects of dietary PS were quadratic, with maximum DMI and milk production observed with diets supplying 24% dietary peNDF (measured as the proportion of the ration retained on sieves >1.18mm multiplied by dietary neutral detergent fiber content; DM basis).

Properties monitoring of fibrous composites based on hemp hurds with different mean particle size

In this paper, the effect of mean particle length of hemp hurds on compressive strength and other parameters of fibrous-composites is studied. Hemp hurds of various origin (Hungarohemp LTd, Nagylak, Hungary; Hempflax, Netherlands) with a wide particle size distribution were used in the experiments. Six samples of hemp hurds with various mean particle length (from 7.3 mm to 39.9 mm) were used for the preparation of fibrous composites based on MgO-cement as a binder. Bulk density, compressive strength, thermal conductivity and water absorbability of fibrous composites after 28 days of hardening were tested. The impact of men particle length of hemp hurds slices on values of bulk density, compressive strength and water absorbability of hardened composites was confirmed.

Chewing activities and particle size of rumen digesta and feces of precision-fed dairy heifers fed different forage levels with increasing levels of distillers grains

The objective of this study was to determine the effects of 2 differing forage to concentrate ratios (F:C) and various levels of corn dry distillers grain with solubles (DDGS) replacing canola meal in precision-fed dairy heifer rations on chewing behavior, rumen pH and fill, and particle size of rumen contents and feces. A split plot design with F:C as whole plot and DDGS inclusion level as subplot was administered in a 4-period 4 × 4 Latin square. Eight rumen-cannulated Holstein heifers (12.5±0.5 mo of age and 344±15kg of body weight, respectively) housed in individual stalls were allocated to F:C 50:50 (low forage) or 75:25 [high forage (HF); dry matter basis] and to a sequence of DDGS level (0, 7, 14, and 21%; dry matter basis). Forage was a mix of 50% corn silage and 50% grass hay (dry matter basis). Diets were fed once daily and formulated to provide equal amounts of nutrients and body weight gain. No differences were found for rumen pH between dietary treatments. Time spent eating tended to be longer for HF and was not affected by DDGS inclusion rate. Ruminating time did not differ by F:C, but linearly increased as DDGS increased (422 to 450±21 min/d). Total chewing time tended to be longer for HF and to increase linearly as DDGS increased (553 to 579±33 min/d). Wet rumen digesta weight and volume were greater for HF. Geometric mean particle length of rumen contents was greater for HF 2h prefeeding when analyzed with solubles (particles <0.15mm). Proportion of rumen solubles decreased as DDGS increased 5h postfeeding. Fecal geometric mean particle length and proportion of particles >1.18mm increased with increasing levels of DDGS and did not change with F:C. Total chewing time increased by the addition of DDGS and higher F:C. Heifers can compensate for lower physically effective neutral detergent fiber by modifying their chewing behavior. Rumen pH was never at a level that could induce acidosis, and lower eating time at lower F:C was somewhat compensated by time spent ruminating per unit of physically effective neutral detergent fiber intake. Dry distillers grains with solubles, when used in dairy heifer rations as a replacement for canola meal, yielded similar rumen digestion traits.