Unprocessed Mash Research Articles

The effects of steam conditioning and antimicrobial inclusion on feed manufacturing and inactivation of Enterococcus faecium, a Salmonella surrogate

SUMMARY Animal well-being, evolving feed manufacturing regulations, human health, and consumer perception drive the continued need to provide safe feed to food animals. Two experiments were conducted to determine the effects of antimicrobial inclusion and conditioning temperature variations on feed manufacturing metrics (EXP1) and the inactivation of Enterococcus faecium, a Salmonella surrogate (EXP2). Both short-term (ST) and long-term (LT) steam conditioning techniques were utilized in this split-plot design where ST (10 s) or LT (60 s) steam conditioning served as whole plot units. Whole plots contained either 2 × 3 (EXP1) or 2 × 4 (EXP2) factorial arrangements varying in mixer-added antimicrobial inclusion (with or without) and degree of thermal processing (unprocessed mash, 71°C, 82°C, and 88°C). Manufacturing of dietary treatments was replicated 3 times. A basal diet was used to obtain desired conditioning temperature before Salmonella surrogate-inoculated feed was exposed to either ST or LT conditioning. In EXP1, conditioning time and antimicrobial inclusion interacted (P = 0.03) by decreasing pellet durability when antimicrobial was included in diets subjected to ST conditioning. Pellet durability was not affected when LT conditioning was utilized. In EXP2, conditioning time, antimicrobial inclusion, and degree of thermal processing interacted (P

The Effects of Diet Formulation and Thermal Processes Associated With Pelleting on 18-day Broiler Performance and Digestible Amino Acid Concentration

SUMMARY The objectives of the study were to assess performance and digestible amino acid concentration of diets fed to broilers that differed in formulation and degree of thermal processing. Basal diets were corn, soybean meal (SBM), and dried distillers grains and solubles (DDGS) based and formulations were balanced to be similar in calculated metabolizable energy and digestible amino acids. Treatments were arranged in a 3 × 3 factorial that varied in diet formulation (basal, basal + meat and bone meal (MBM), and basal + bakery byproduct (BBP)) and degree of thermal processing (unprocessed mash, pellet, double pellet). All treatments were ground to similar particle size and fed to 10 replicate raised wire cages of 10 straight-run Hubbard x Cobb 500 broiler chicks for 18 d. Broilers provided a basal + MBM diet improved FCR (P = 0.0046). Pelleting and double pelleting improved FCR compared to unprocessed mash (P = 0.0003). Formulation and processing effects interacted to affect digestible lysine, methionine, threonine, and cysteine concentrations (P

The interactive influence of dietary nutrient density and feed form on the performance of broiler chickens

The present study investigates the interactions between dietary nutrient density and feed form on the growth performance, coefficient of apparent ileal digestibility (CAID) of dry matter (DM), nitrogen (N), starch, fat, calcium (Ca) and phosphorus (P), and N-corrected apparent metabolisable energy (AMEn) in broiler chickens to 21d post-hatch. Maize-soybean meal diets with five tiers of nutrient density were formulated and mixed. The diets were then divided into two equal batches; the first batch was offered as unprocessed mash and the second batch was steam-pelleted at a conditioning temperature of 75 °C. A 5 × 2 factorial array of ten dietary treatments were offered to a total of 480, day-old male broiler (Ross 308) chicks accommodated in 60 cages (eight birds per cage). Significant (P < 0.001) interactions between nutrient density and feed form were observed for weight gain, feed intake and feed per unit gain. While birds fed pelleted diets outperformed those fed mash diets at each nutrient density level, the pellet-associated benefits were more pronounced at the lowest nutrient density. Increasing nutrient density increased (P < 0.001) N digestibility from 0.772 to 0.811, but decreased (P < 0.001) that of starch from 0.969 in very low density diets to 0.943 in very high density diets. No significant (P > 0.05) effect of nutrient density on the CAID of DM and fat was found. Feeding pelleted diets, regardless of nutrient density, reduced (P < 0.001) the CAID of DM, N, starch and fat. Significant nutrient density × feed form interactions were observed for the CAID of Ca (P < 0.001) and P (P < 0.01). Pelleting enhanced (P < 0.05) the CAID of Ca and P in the diet with lowest nutrient density but reduced (P < 0.05) the digestibility of these minerals in all other nutrient density diets. Increasing dietary nutrient density progressively increased the AMEn, but feeding of pelleted diets, regardless of nutrient density, reduced (P < 0.001) the AMEn. Overall, the present data showed that the magnitude of pelleting-induced benefits on broiler performance varied depending on dietary nutrient density, with responses to pelleting decreasing with increasing dietary nutrient density. The present study highlights that dietary nutrient density must be taken into consideration if the full benefits associated with feeding pelleted diets are to be achieved.

Effect of pelleting on survival of porcine epidemic diarrhea virus-contaminated feed.

Porcine epidemic diarrhea virus (PEDV) is a heat-sensitive virus that has devastated the U.S. swine industry. Because of its heat sensitivity, we hypothesized that a steam conditioner and pellet mill mimicking traditional commercial thermal processing may mitigate PEDV infectivity. Pelleting, a common feed processing method, includes the use of steam and shear forces, resulting in increased temperature of the processed feed. Two thermal processing experiments were designed to determine if different pellet mill conditioner retention times and temperatures would impact PEDV quantity and infectivity by analysis of quantitative reverse transcription PCR and bioassay. In Exp. 1, a 3 · 3 · 2 factorial design was used with 3 pelleting temperatures (68.3, 79.4, and 90.6°C), 3 conditioning times (45, 90, or 180 s), and 2 doses of viral inoculation (low, 1 · 102 tissue culture infectious dose50 (the concentration used to see cytopathic effect in 50% of the cells)/g, or high, 1 · 104 tissue culture infectious dose50/g). Noninoculated and PEDV-inoculated unprocessed mash were used as controls. The low-dose PEDV–infected mash had 6.8 ± 1.8 cycle threshold (Ct) greater (P < 0.05) PEDV than the high-dose mash. Regardless of time or temperature, pelleting reduced (P < 0.05) the quantity of detectable viral PEDV RNA compared with the PEDV-inoculated unprocessed mash. Fecal swabs from pigs inoculated with the PEDV-positive unprocessed mash, regardless of dose, were clinically PEDV positive from 2 to 7 d (end of the trial) after inoculation. However, if either PEDV dose of inoculated feed was pelleted at any of the 9 tested conditioning time · temperature combinations, no PEDV RNA was detected in fecal swabs or cecum content. Based on Exp. 1 results, a second experiment was developed to determine the impact of lower processing temperatures on PEDV quantity and infectivity. In Exp. 2, PEDV-inoculated feed was pelleted at 1 of 5 conditioning temperatures (37.8, 46.1, 54.4, 62.8, and 71.1°C) for 30 s. The 5 increasing processing temperatures led to feed with respective mean Ct values of 32.5, 34.6, 37.0, 36.5, and 36.7, respectively. All samples had detectable PEDV RNA. However, infectivity was detected by bioassay only in pigs from the 37.8 and 46.1°C conditioning temperatures. Experiment 2 results suggest conditioning and pelleting temperatures above 54.4°C could be effective in reducing the quantity and infectivity of PEDV in swine feed. However, additional research is needed to prevent subsequent recontamination after pelleting as it is a point-in-time mitigation step.

Structural changes on a molecular basis of canola meal by conditioning temperature and time during pelleting process in relation to physiochemical (energy and protein) properties relevant to ruminants.

The objectives of this study were: (1) To investigate the effects of conditioning temperature (70, 80, 90°C), time (30, 60 sec), and interaction (temperature × time) during the pelleting process on internal protein molecular structure changes of the co-products; (2) To identify differences in protein molecular structures among pellets that were processed under different conditions, and between unprocessed mash and pellets; 3) To quantify protein molecular structure changes in relation to predicted energy and protein utilization in dairy cows. The final goal of this program was to show how processing conditions changed internal feed structure on a molecular basis and how molecular structure changes induced by feed processing affected feed milk value in dairy cows. The hypothesis in this study was that processing-induced protein inherent structure changes affected energy and protein availability in dairy cattle and the sensitivity and response of protein internal structure to the different pelleting process conditions could be detected by advanced molecular spectroscopy. The protein molecular structures, amides I and II, amide I to II ratios, α-helix structure, β-sheet structure, and α to β structure ratios, were determined using the advanced vibrational molecular spectroscopy (ATR-FT/IR). The energy values were determined using NRC2001 summary approach in terms of total digestible nutrients, metabolizable and net energy for lactation. The protein and carbohydrate subfactions that are related to rumen degradation characteristics and rumen undegraded protein supply were determined using updated CNCPS system. The experiment design was a RCBD and the treatment design was a 3x2 factorial design. The results showed that pelleting induced changes in protein molecular structure. The sensitivity and response of protein inherent structure to the pelleting depended on the conditioning temperature and time. The protein molecular structure changes were correlated (P < 0.05) with energy values and protein subfractions of the pelleted co-product. The results indicated that the protein internal molecular structure had significant roles in determining energy and protein nutritive values in dairy cows. Multi-regression study with model variables selection showed that the energy and protein profiles in pelleted co-products could be predicted with the protein molecular structure profiles. This approach provides us a relatively new way to estimate protein value in dairy cows based on internal protein molecular structure profile.

The effects of pelleting and glucanase supplementation in hulled barley based diets on feed manufacture, broiler performance, and digesta viscosity

Feeding broilers barley-based diets requires special consideration primarily due to effects on increased digesta viscosity and decreased nutrient digestion. Pelleting and glucanase supplementation are commonly performed prior to feeding broilers barley-based diets; however, the interaction of these practices is complex. The objective of this study was to establish a comprehensive evaluation of glucanase efficacy including: degree of processing, activity postpelleting, broiler performance, and digesta viscosity. Treatments were arranged in a 5 (diet formulation) × 2 (processing) factorial in a randomized complete block design with 8 replications/treatment. The 5 diet formulations consisted of positive control (PC), negative control (NC), glucanase A (GA) 125 or 1,000 β-Glu-U/kg feed, and glucanase B (GB) 1,000 β-Glu-U/kg feed. The PC and NC diets differed in metabolizable energy by 150 kcal/kg and enzymes were added to NC formulations. Diets were either fed as unprocessed mash or ground pellets. Diet formulation × processing did not interact for feed intake (FI), FCR, or total tract viscosity (P > 0.05); however, a trend was observed for ending bird weight, demonstrating that for ground pellets, GA 1,000 β-Glu-U/kg feed was improved relative to NC and similar to PC (P = 0.0903). Benefits associated with GB were not of similar magnitude, perhaps in part due to a 50% decrease in activity postpelleting. In addition, GA benefits were not suggested for unprocessed mash. The main effect processing was significant (P < 0.0001) demonstrating that broilers fed ground pellets resulted in greater pen ending bird weight, FI, and bird live weight gain (LWG) compared to birds fed unprocessed mash diets. Evaluations of glucanase should go beyond in vitro activity and include live bird performance using feed that has undergone pelleting.

Effect of Thermal Mitigation on Porcine Epidemic Diarrhea Virus (PEDV)- Contaminated Feed

Porcine Epidemic Diarrhea Virus (PEDV) is primarily transmitted by fecal-oral contamination. However, epidemiological evidence has shown that swine feed and ingredients may serve as potential vectors of transmission. Since it is known that PEDV is a heat-sensitive virus, we hypothesized that a conditioner and pellet mill mimicking commercial thermal processing would mitigate PEDV infectivity. To test this hypothesis, two experiments were designed to determine if different pellet mill conditioner retention times or temperatures would impact PEDV infectivity determined by polymerase chain reaction (PCR) analysis and bioassay. For the first study, a 3×3×2 factorial was utilized, with three pelleting temperatures (155, 175, or 195°F), three conditioning times (45, 90, or 180 s), and two levels of virus (low: 1×102 TCID50/g, or high: 1×104 TCID50/g). Non-inoculated and PEDV-inoculated unprocessed mash were used as controls. There was no PEDV RNA detected in the PEDV-free mash. The low-dose PEDV-infected mash was 6.8 ± 1.8 cycle threshold (Ct) greater (P < 0.01) than the high dose mash. Regardless of time or temperature, feed processing increased (P < 0.01) the Ct compared to the PEDV-inoculated unprocessed mash. As expected, fecal shedding of PEDV was not detected in rectal swabs from control pigs for the duration of the study. Fecal swabs from pigs fed the PEDV-inoculated unprocessed mash, regardless of dose, were PEDV-positive from 2 to 7 days post-inoculation, at which time the pigs were sacrificed. However, if either PEDV dose of inoculated feed was pelleted at any of the nine tested conditioning time × temperature combinations, no PEDV RNA was detected in fecal swabs or cecum content. Based on these results, a second experiment was developed to determine the impact of lower processing temperatures on PEDV infectivity. The pellet mill was heated for 1 hour at normal manufacturing conditions prior to simulating a plug by turning off the steam supply. This allowed the temperature of the mash feed to decrease below 100°F. The PEDV-inoculated feed was then pelleted at one of five conditioning temperatures (100, 115, 130, 145, or 160°F) for 30 s. This study was repeated three times on three separate days with complete decontamination between each experiment day. Again, non-inoculated and PEDV-inoculated mash were used as controls. The five increasing temperatures led to feed with respective mean Ct values of 32.5, 34.6, 37.0, 36.5, and 36.7. Even though all samples had detectable PEDV RNA in the feed, infectivity was only detected by bioassay in pigs from the 100 and 115°F conditioning treatments. In each of the other processing temperatures, no PEDV RNA was detected in fecal swabs or cecum contents. Our results suggest that processing feed through a conditioner and pellet mill similar to those used in commercial feed mills will be effective as a point-in-time mitigation step for PEDV as long as conditioning temperatures remain above 130°F. Any time feed is processed at temperatures below that level, such as during start-up or when the pellet mill die becomes plugged and the steam is consequently shut off, there is a risk that the feed can act as a vector for transferring infectious PEDV and lead to cross-contamination of post-pelleting handling equipment.

Influence of feed form on growth performance, ileal nutrient digestibility, and energy utilisation in broiler starters fed a sorghum-based diet

A broiler starter (1–21d) diet based on a finely ground red sorghum was used to develop 3 feed forms: (1) unprocessed mash, (2) pellets steam-conditioned at 70°C, and (3) re-ground pellets following steam-conditioning at 70°C. The influence of dietary treatments on the growth performance, coefficient of apparent ileal digestibility (CAID) of N, starch, fat, Ca, and P, and apparent metabolisable energy (AME) in broiler starters was evaluated. A total of 144 one-day-old male broilers (Ross 308) were individually weighed and allocated to 18 cages (8 broilers/cage), and cages were randomly assigned to 3 dietary treatments. Broilers fed the pelleted diet gained more (P<0.05) weight and had a greater (P<0.05) feed intake (FI) than those fed mash and re-ground pellet diets. Re-grinding the pellets resulted in similar weight gain and FI to the mash diet. Nitrogen digestibility tended (P=0.10) to be greater in broilers fed the mash diet compared to pellet and re-ground pellet diets. Pellet-feeding reduced (P<0.05) starch digestibility compared to the mash diet and re-ground pellet. Pellet feeding also reduced (P<0.05) CAID of fat compared to mash diet but re-grinding the pellets restored fat digestibility. Pelleting reduced (P<0.05) the CAID of Ca and re-grinding the pellets further decreased (P<0.05) Ca digestibility. Pelleting had no influence on the CAID of P, but re-grinding the pellets resulted in lower (P<0.05) P digestibility than that of the mash and pelleted diets. Feeding intact pellets reduced (P<0.05) the AME of the diet compared to the mash diet and the depression was maintained in re-ground pellets. Based on the greater nutrient intake of broilers offered intact pellets coupled with the lack of positive effect of pellet feeding on digestibility of nutrients, it can be suggested that an enhanced feed consumption was primarily responsible for the better performance of broilers fed sorghum-based pellets.

Steam-pelleting temperatures, grain variety, feed form and protease supplementation of mediumly ground, sorghum-based broiler diets: influences on growth performance, relative gizzard weights, nutrient utilisation, starch and nitrogen digestibility

A red sorghum was mediumly ground (3.2 mm) and incorporated into broiler diets that were steam-pelleted at conditioning temperatures of 65, 80 and 95°C and offered to male Ross 308 chicks from 7 to 28 days post hatch. This diet was also fed as unprocessed mash, reground mash following steam-pelleting at 95°C and diets steam-pelleted at 80°C were fed without and with exogenous protease. A nutritionally equivalent diet based on a mediumly ground white sorghum steam-pelleted at 95°C completed the seven dietary treatments each of which were offered to seven replicates of six birds per cage. The effects of treatment on growth performance, relative gizzard weights, nutrient utilisation [apparent metabolisable energy (AME), nitrogen (N) retention, and N-corrected AME] and apparent digestibility coefficients of starch and N in four segments of the small intestine (proximal and distal jejunum, proximal and distal ileum) were determined. Elevating conditioning temperatures at which the red sorghum-based diets were steam-pelleted reduced their protein solubilities and linearly reduced concentrations of free sulfydryl groups (P &lt; 0.02) and the two parameters were positively correlated (P &lt; 0.01). Elevating temperatures also linearly increased relative gizzard weights (P &lt; 0.02). However, increasing conditioning temperatures linearly depressed feed conversion efficiency (P &lt; 0.02), tended to depress weight gain (P &lt; 0.08) but did not influence nutrient utilisation parameters (P &gt; 0.50). Increasing conditioning temperatures influenced N digestibility coefficients in the distal jejunum (P &lt; 0.01) and distal ileum (P &lt; 0.05) in a quadratic manner. N coefficients varied from 0.565 to 0.538 and 0.638 in the distal jejunum with increasing conditioning temperatures; however, starch digestibility coefficients were not significantly influenced by conditioning temperatures. Birds offered the white sorghum-based pelleted diet conditioned at 95°C significantly outperformed (P &lt; 0.05) their red sorghum counterparts in terms of weight gain, feed per gain, AME, N retention, starch and N digestibility coefficients in the distal ileum. The differences in starch digestibility between the two sorghum varieties along the small intestine were pronounced and the possible contributing factors are considered. Diets fed as intact pellets generated greater feed intakes and weight gains than the average of the two mash diets. In red sorghum-based diets, distal ileal starch digestibility coefficients of intact pellets were inferior to the unprocessed and reground mash. However, the distal ileal N digestibility coefficient of the unprocessed mash diet was 3.5% higher than the reground mash diet and 8.3% higher than the intact pelleted diet. The inclusion of a Bacillus lichenformis-derived protease in red sorghum-based steam-pelleted at 80°C significantly (P &lt; 0.05) increased N digestibility coefficients in the distal jejunum, proximal ileum and distal ileum. Also, this protease significantly increased starch digestibility coefficients in the distal jejunum and proximal ileum. The implications of these findings in respect of feeding broiler chickens sorghum-based diets are discussed.

The kinetics of starch and nitrogen digestion regulate growth performance and nutrient utilisation of broilers fed coarsely ground, sorghum-based diets

A study was conducted to examine the effect of starch and nitrogen digestion kinetics on broiler performance using sorghum-based diets as a model. Three sorghum varieties with red, white and yellow pericarps and three feed forms, mash, intact pellets and reground pellets, constituted a 3 × 3 factorial array of dietary treatments. Starch and nitrogen digestion kinetics were determined using an exponential mathematical model to relate digestion coefficients in the proximal jejunum, proximal ileum and distal ileum with mean retention times in each segment. There were interactions between sorghum variety and feed form for starch and nitrogen digestion kinetics. Steam-pelleting at a conditioning temperature of 90°C (unprocessed mash versus reground pellets) substantially influenced starch digestion rate in red and yellow sorghum-based diets, but not in white sorghum-based diets. Alternatively, with nitrogen digestion rate, there were no significant differences in yellow sorghum-based diets between feed forms but there were in red and white sorghum-based diets. The digestion rate of starch was more rapid than nitrogen, especially in the proximal jejunum. Starch digestion rates were significantly correlated with nitrogen retention but this was not the case with nitrogen digestion rates. The rate of glucose absorption from predicted glycaemic indices was highly correlated with enhanced feed efficiency. Thus this study demonstrates that even under ad libitum feeding regimes, kinetics of starch and protein digestion regulated feed efficiency and nitrogen retention in broiler chickens. The dynamics of starch and protein digestion were more accurate indicators of feed efficiency and nitrogen retention than apparent ileal starch and nitrogen digestibility.

The Effect of Steam-Conditioning Practices on Pellet Quality and Growing Broiler Nutritional Value

ABSTRACT Feed currently constitutes 60 to 65% of the total cost of broiler production. Pellets are the primary feed form for commercially reared broilers. Understanding how to optimize pellet quality through precision thermo-mechanical processing may impact broiler performance and nutrient availability, and thus cost of production. Steam conditioning represents a manipulable thermo-mechanical processing variable. Corn-soybean meal-based diets were conditioned with 1 of 4 steam pressure × temperature combinations: 138 kPa at 82.2°C, 138 kPa at 93.3°C, 552 kPa at 82.2°C, or 552 kPa at 93.3°C. High steam pressure and temperature conditioning were shown to increase pellet quality. Three additional diets were prepared: unprocessed mash, the 552 kPa/93.3°C diet reground to mash, and a 50:50 combination of pellets and mash produced from the 552 kPa/93.3°C treatment to simulate a high fine percentage diet. All diets were fed to Cobb 500 broilers from 21 to 38 d, and nutrient availability was determined with Single Comb White Leghorn roosters. Broilers fed pellets conditioned with high steam temperature demonstrated decreased feed intake and feed conversion ratio. Amino acid and energy availability were not affected by variations in steam conditioning.