Feed Manufacture and Feeding of Rations with Graded Levels of Added Moisture Formulated to Different Energy Densities

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1 2003 Poultry Science Association, Inc. Feed Manufacture and Feeding of Rations with Graded Levels of Added Moisture Formulated to Different Energy Densities J. S. Moritz, 1 K. R. Cramer, K. J. Wilson, and R. S. Beyer 2 Department of Animal Science and Industry, Kansas State University, Manhattan, Kansas Primary Audience: Feed Mill Managers, Nutritionists, Broiler Producers, Researchers SUMMARY Graded levels of moisture were added to corn-soybean based formulations to create pelleted diets that differed in energy density. The pelleted diets were assessed using feed manufacturing parameters, pellet quality, performance, and energy metabolism of broilers during the growing phase. Treatments consisted of a factorial arrangement of three levels of added moisture (0, 2.5, and 5%) and two levels of energy density [NRC-recommended levels and 5% less than NRC recommended levels (low energy)]. NRC diets demonstrated increased pellet production rate, decreased pellet starch gelatinization, and decreased pellet durability compared to low energy diets during manufacture. Moisture addition, independent of dietary energy density, increased pellet production rate, decreased relative electrical energy usage, decreased pellet starch gelatinization, and increased pellet durability. These results suggest that moisture addition to broiler diets may increase economic returns of pellet manufacturing while simultaneously increasing pellet quality. In subsequent feeding experiments, broilers fed NRC diets in general demonstrated decreased feed intake and increased feed efficiency (FE) compared to broilers fed lower energy diets. However, broilers fed lower energy diets that included moisture additions demonstrated statistically similar FE compared to broilers fed NRC diets without added moisture. Broiler live weight gain and mortality were not affected by any treatment combination. In addition, broiler-derived true metabolizable energy values did not differ among treatments. These findings imply that feeding lower energy formulations that incorporate moisture can produce broiler FE equivalent to broilers fed NRC corn-soybean formulations, presumably due to benefits associated with improved pellet quality, which do not include increased metabolizable energy. Key words: broiler performance, feed manufacturing, moisture, nutrient density, pellet durability 2003 J. Appl. Poult. Res. 12: DESCRIPTION OF PROBLEM Addition of moisture to corn-soybean based broiler diets has been shown to significantly de- crease pellet mill relative electrical energy usage, as well as significantly increase pellet mill throughput and pellet quality [1, 2]. Furthermore, increased pellet quality has been associ- 1 Current address: West Virginia University, P.O. Box 6108, Morgantown, WV To whom correspondence should be addressed: sbeyer@oznet.ksu.edu.

2 372 ated with improved broiler feed efficiency (FE), likely resulting from increased productive energy [3, 4]. Moritz et al. [5] reported that improved pellet durability, gained through moisture additions to mash feed in the mixer, significantly increased 3-to-6-wk adjusted broiler feed efficiency [low moisture adjusted FE (0.515 g/ g) vs. high moisture adjusted FE (0.529 g/g)]. In that study, feed efficiency was adjusted to account for a nutrient dilution created by the addition of moisture. In a successive study the authors adjusted the nutrient density of diets prior to moisture addition in order to create nondiluted moisture-containing diets [2]. However, feeding these diets did not result in significant differences among 3-to-6-wk broiler FE [low moisture FE (0.625 g/g), high moisture FE (0.629 g/g)]. A contributing factor for these inconsistent FE results could be that the first study was conducted during considerably colder months of the year relative to the second study. Colder outside temperatures may increase bird maintenance requirements, creating a greater potential for feed-quality-derived productive energy to affect FE. Another explanation could be the second study s use of adjusted feed formulations and their resultant pellet qualities. In order to compensate for the energy diluting effects of added moisture, formulations utilized high amounts of soybean oil. High oil inclusion in broiler diets has been correlated with decreased pellet quality [6]. Accordingly, the increase in pellet durability from low moisture to high moisture treatments in the second study was 7% as compared to a 41% increase in the first study [2, 5]. Research has suggested that pellets of high quality can reduce broiler maintenance energy needs, creating the potential to reduce dietary metabolizable energy (ME) while maintaining performance [4]. It seems plausible that low oil, high moisture formulation may create pellets of a high enough quality to offset energy dilutions. The objectives of the current study were to evaluate the addition of moisture to diets that differed in energy density at the expense of soybean oil, and to assess low-level graded moisture additions, because moisture additions of this kind have not been explored. The impact of these various feed formulations was measured in terms of feed manufacturing efficiency, pellet quality, JAPR: Research Report 3-to-6-wk male broiler performance and broiler metabolism. Feeding trials were conducted during cold months of the year to maximize any potential benefits of feed-quality-derived productive energy on broiler performance. MATERIALS AND METHODS Diet Compositions and Feed Manufacture (Experiment 1) Experimental grower diets were formulated with three levels of added moisture (0, 2.5 and 5%) to aid in creating diets that varied in energy density [NRC-recommended levels [7] and 5% less than NRC recommended levels (low energy)]. The energy densities were established primarily through manipulating soybean oil percentages. Other ingredients were adjusted to compensate for nutrient dilutions created by moisture additions. In total, six different diets were formulated in a moisture level energy density factorial structure (Table 1). Wheat middlings were used in low energy basal diets (8.75%) to decrease ME and maintain amino acid percentages. Accordingly, all six formulations of diet contained wheat middlings to maintain similar ingredient profiles. As a means for comparison, a low energy basal diet without wheat middlings was manufactured as was an NRC basal diet that did not include soybean oil. Thus, any manufacturing or pellet quality effects produced from wheat middling or soybean oil inclusion could be estimated. Moisture additions were made at the mixer [8] using tap water. Immediately after moisture addition, the mash diets were mixed for 3 min followed by soybean oil addition and another 3 min mix cycle. The mash was conveyed to the pellet mill and subsequently steam conditioned using a short-term conditioner (1 3 ft ( m), 10 s retention time) set at a constant temperature of 180 F (82.2 C). Pellets were formed using a California Pellet Mill [9] with a 5/ in ( mm) die. All diets were pelleted at the same pellet mill motor load and then conveyed through a horizontal double pass cooler with an 8-min retention time. The six experimental diet formulations were manufactured in four replicates, in a randomized complete block design. Blocking criterion was time of manufacturing, and the experimental unit was

3 MORITZ ET AL.: GRADED MOISTURE ADDITION TO FEED 373 TABLE 1. Ingredient percentages of diets formulated to NRC specifications or low energy (LE), i.e., 5% less NRCrecommended energy A Ingredient NRC NRC (+2.5) NRC (+5) LE LE (+2.5) LE (+5) Yellow corn Soybean meal (47.5%) Wheat middlings Meat and bone meal (47.9%) Soybean oil Limestone Salt Methionine Poultry premix B Defluorinated phosphate Monensin C BMD D Nitro E Calculated analysis before moisture addition ME (kcal/kg) 3,143 3,222 3,300 2,986 3,061 3,135 Crude protein (%) Crude fat (%) A All diets were adjusted in nutrient density for the percentage of added moisture; see numbers in parentheses in column heads. B Supplied per kilogram of diet: manganese, 0.02%; zinc, 0.02%; iron, 0.01%; copper, %; iodine, %; selenium, %; folic acid, 0.69 mg; choline, 386 mg; riboflavin, 6.61 mg; biotin, 0.03 mg; vitamin B 6, 1.38 mg; niacin, mg; panthothenic acid, 6.61 mg; thiamine, 2.20 mg; menadione, 0.83 mg; vitamin B 12, 0.01 mg; vitamin E, IU; vitamin D 3, 2,133 ICU; vitamin A, 7,716 IU. C Monensin sodium (110 g/ton inclusion), Elanco Animal Health, Indianapolis, IN. D Bacitracin methylene disalicylate (50 g/ton inclusion), Alpharma ( E Roxarsone (45.4 g/ton inclusion), Alpharma. a single 1,000 lb (454 kg) batch of feed. Feed manufacture was conducted over 2 consecutive d. During the manufacture of each grower diet, measurements of pellet mill relative electrical energy usage [10], production rate [11], and hot pellet temperature [12] were collected. Immediately after each diet was manufactured, a representative sample of the run was collected and analyzed for bulk density [13] and pellet durability [13]. These same samples were also analyzed for their percentage moisture [14], starch gelatinization [15] and protein denaturation [15]. The samples were analyzed in duplicate and averaged, providing a mean for each formulation in each replicate. All diets were bagged in 50-lb allotments (22.68 kg) and stored for 1 wk prior to use as feeding treatments in experiments 2 and 3. Broiler Performance (Experiment 2) Commercial broilers were reared on the floor in a curtain-sided positive-pressure ventilated house. Day-old male chicks [16] were allotted to each floor pen [ ft ( m)], which was defined as the experimental unit. Each pen contained fresh wood shavings, nipple drinkers and a Choretime feed pan adapted to a hopper. All pens received the same mash starter diet for the first 3 wk. At the end of the third week, 45 birds were randomly assigned to each pen. From wk 3 through 6, each of the six grower diets was fed to 10 replicate pens (450 birds/ diet). Diets were randomly assigned to pens in each block, and blocks consisted of groupings of six pens within the house. At the conclusion of wk 6, pen body weight and feed consumption were recorded and live weight gain (LWG), feed intake, FE and percentage mortality were determined for the 3-to-6-wk period. All FE values were calculated using mortality weights [(ending pen weight + pen mortality weight starting pen weight)/total feed consumed by pen]. Throughout the experiment, feed and water were provided ad libitum. All animals were reared according to protocols established by the Kansas State University

4 374 Animal Care and Use Committee. The study was conducted during the months of November and December Throughout the experiment, temperature was regulated thermostatically by starting chicks at 95 F (35 C) and decreasing the temperature by 5 F (2.8 C) each subsequent week in order to maximize bird comfort. Broiler Metabolism (Experiment 3) Experiment 3 utilized male broilers [16] from the same lot of birds obtained for the floor pen experiment. Experimental methods were similar to those reported by Sibbald [17], with the main exceptions being the use of broiler chickens and timed ad libitum feeding. This procedure was thought to provide metabolism data more indicative of commercially reared birds. Three-week-old broilers were individually placed in raised wire grower cages [23 30 in ( cm)] equipped with nipple drinkers and trough type feeders. Four groups of seven adjacently caged birds constituted blocks for a randomized complete block design. An individually caged broiler was defined as the experimental unit. The six experimental pelleted grower diets were randomly assigned to each group of caged birds, with one bird as a control. Birds were fed experimental diets for an 11-d adaptation period, restricted feed for 24 h, and then given a 20-min ad libitum refeeding period. Control birds were not refed. Total fecal/uric acid excretion was collected for a 48-h period following refeeding. Feed samples and fecal samples were analyzed for gross energy using a nonadiabatic bomb calorimeter [18]. TME values were calculated using equations derived from Sibbald [17]. Throughout the experiment, temperature was regulated to maximize bird comfort. Statistical Analysis Pearson correlation coefficients were calculated for numerous variables in both NRC and low energy diet series. For specific correlations of interest, relationships were modeled using linear regression. Additionally, a moisture level energy density factorial analysis was performed in order to explore main effects and their interaction. Significant effects were further evaluated using Fisher s least significant difference test to determine differences among treatment means. JAPR: Research Report Statistics were computed using a combination of the PLOT, CORR, REG and GLM procedures of the Statistical Analysis System [19]. In all cases α was RESULTS AND DISCUSSION Experiment 1 The main effects and interactions for milling parameters and pellet qualities of the six experimental treatments and the two control formulations are presented in Table 2. Graded moisture additions did not influence the final pellet moisture percentage as would be expected. NRC diets without added moisture had final pellet moisture content of 12.33%, yet when 5% moisture was added to NRC formulations a final pellet moisture of 15.16% resulted as opposed to an expected 17.33% (Table 2). A similar trend was apparent for low energy formulations (Table 2). One explanation for these lower moisture percentages could be that additions were made to diets already balanced to 100% (Tables 1 and 2). Nutrients in low energy diets were increased by either 2.5 or 5% prior to moisture addition and water per se was not incorporated in the feed formulation program as a nutrient. In this case, moisture additions shown to be 2.5 and 5% are calculated to be 2.44 and 4.76% respectively. Another possibility would be that high amounts of free moisture might be more efficiently flashed off at the pellet die or driven off during cooling. Nevertheless, moisture addition did increase final pellet moisture percentages (P = , Table 2). The NRC treatments in general demonstrated increased pellet mill production rates compared to low energy treatments (P = ). The NRC control, which did not include soybean oil, had the lowest numerical production rate of all treatments. These findings may be attributed to the lubricating effect of soybean oil on the mash die interface, as mentioned in other reports [2, 20]. Increasing moisture addition to diets of either energy density also improved pellet mill production rates (P = ). These findings could be related to the lubricating effects of added moisture, as well as the increased oil percentages that accompanied moisture addition (Tables 1 and 2). Similarly, lubricating effects of increased levels of added moisture and soy-

5 MORITZ ET AL.: GRADED MOISTURE ADDITION TO FEED 375 TABLE 2. Influence of energy density and moisture level on milling parameters and pellet quality (experiment 1) A Protein Pellet P-rate B REE C HPT D PGT E SG F PDT G denaturation H PDI I M-PDI J BD K Diet H 2 O (%) (MT/h) (kwh/mt) ( C) ( C) (%) ( C) (%) (%) (%) (kg/m 3 ) NRC d 2.08 c 3.97 ab ab ab b b ab NRC + 2.5% water b 2.57 b 3.40 bc ab bc b b bc NRC + 5% water a 3.13 a 3.22 c b 6.09 c b b c Low energy d 1.71 d 4.06 a a a a a a Low energy + 2.5% water c 2.13 c 3.86 ab ab ab a a ab Low energy + 5% water a 2.24 c 3.42 bc b abc a a b LSD L Low energy no midds L NRC no oil M P-values generated for the main effects and the interaction Energy density Moisture level Interaction a c Means within a column with no common superscript differ significantly (P 0.05). A Treatment means among milling parameters and pellet qualities. B Production rate of the pellet mill; MT = tonnes. C Relative electrical energy (pellet mill). D Hot pellet temperature. E Peak temperature of starch gelatinization determined by differential scanning calorimetry (DSC). F Starch gelatinization determined by DSC and calculated on a dry matter basis. G Peak temperature of protein denaturation determined by DSC. H Protein denaturation determined by DSC and calculated on a dry-matter basis. I Pellet durability index. J Modified pellet durability index (utilizing five 13-mm hex nuts for added pressure on pellets). K Bulk density. L Fisher s least significant difference value. M Negative control treatments that were not replicated and not included in the statistical analysis.

6 376 JAPR: Research Report bean oil likely decreased pellet mill relative electrical energy usage of moisture-containing diets (P = ). Frictional heat, created when mash feeds are extruded through the pellet die, has a large influence on the chemical and physical properties of pellets produced. Pellet mill production rate and energy usage provide insight as to how much frictional heat may be generated during pelleting. Hot pellet temperatures in the current study suggest a trend, though not statistically significant, of decreased frictional heat production as moisture and oil levels were increased in each series (P = , Table 2). This trend may have contributed to decreased starch gelatinization (P = ) that accompanied increased moisture addition in each series. The gelatinization of starch occurs when granules are heated above a characteristic temperature in the presence of water. Moreover, full gelatinization of a population of starch granules requires heating over a range of temperatures [21]. In addition to potential decreases in the range of frictional heat produced, increased production rates would decrease the amount of time starches are held at their gelatinization temperatures. This may curtail gelatinization, as indicated with the marked difference in starch gelatinization percentages between NRC treatments and the more slowly produced low energy treatments (P = ). Furthermore, NRC treatments contained much higher levels of soybean oil compared to low energy treatments, which may repress the swelling and solubilization of starch [22]. The NRC control diet, which did not contain soybean oil, demonstrated the highest starch gelatinization percentage of all treatments (Table 2). Moritz et al. [2] reported a 10% decrease in starch gelatinization when soybean oil was increased 3.5% in corn-soybean based rations. Several authors have attempted to explain relationships between conformational ingredient changes and pellet quality [2, 4, 5, 20, 23]. Typically, moisture additions to corn-soybean based diets result in increased starch gelatinization, which coincides with increased pellet durability [2, 5]. However, data from the current study illustrate that moisture addition to diets of either energy density decreased starch gelatinization (P = ) and increased pellet durability (P = , Table 2). Improvements in pellet durability for the low energy series of diets were additive to benefits from wheat middling inclusions. Protein denaturation was not significantly affected by any treatment combination (Table 2). The true relationship between starch gelatinization and pellet durability may depend on the location of the gelatinized starch, e.g., pellet surface or pellet center, as opposed to the total percentage of pellet gelatinization [24, 25]. Additionally, the uniformity of gelatinization throughout the pellet may be of importance. In this scenario, a small amount of gelatinization evenly distributed throughout the pellet may be more effective in binding feed particles than high amounts of localized gelatinization. Bulk density was significantly affected by both energy density and moisture level (Table 2). As moisture addition increased in each series, the bulk density of the feed decreased accordingly (P = ). It has been documented that bulk densities of corn-soybean and sorghum based diets decrease as pellet quality increases [2, 26]. This relationship is most likely due to an increase in bulk air space, created by more intact pellets and fewer fines. Conversely, NRC treatments demonstrated decreased bulk density compared to low energy treatments (P = ), despite corresponding improvements in pellet durability (P = ). This finding may be explained by variations in ingredient density and inclusion in each diet, which may also confound moisture level effects on bulk density. Experiment 2 The 3-to-6-wk phase of growth was chosen because past research indicated significant moisture addition effects on broiler performance during this period [2, 5]. Performance data are presented in Table 3. Broiler weight gain did not significantly differ among treatments. Broiler feed intake and efficiency were, however, significantly affected by differences in dietary energy density (Table 3). Broilers fed low energy treatments consumed more feed than broilers fed NRC treatments (P = ) and consequently had lower feed efficiency (P = ). Broilers fed low energy treatments ate more feed, presumably to meet their energy requirements. However, broilers fed low energy treatments that contained either 2.5 or 5% added moisture showed a statistically similar feed intake and

7 MORITZ ET AL.: GRADED MOISTURE ADDITION TO FEED 377 TABLE 3. Influence of energy density and moisture level on broiler performance, 3 to 6 wk data (experiment 2) A Broiler Broiler Broiler live weight feed intake feed Broiler gain (pen) efficiency B mortality Diet (g) (kg) (g/g) (%) NRC 1, a ab 2.0 NRC + 2.5% water 1, b a 2.9 NRC + 5% water 1, ab a 3.6 Low energy 1, a c 4.2 Low energy + 2.5% water 1, a bc 4.0 Low energy + 5% water 1, a bc 3.3 LSD C P-values generated for main effects and the interaction Energy density Moisture level Interaction a c Means within a column with no common superscript differ significantly (P 0.05). A Treatment means among performance parameters. B Body weight gain/feed intake. C Fisher s least significant difference value. feeding efficiency as broilers fed the NRC treatment without added moisture (Table 3). These findings may relate to differences among treatment pellet quality. Past research has suggested that broilers fed higher quality pellets may improve their performance due to increases in productive energy and/or decreased feed waste [3, 4, 5, 27]. Productive energy can be defined as metabolizable feed energy less bird heat loss [28]. Broilers typically lose energy in the form of heat through activity, thermal regulation, digestion, tissue synthesis/degradation and excretion. Low energy treatments that contained added moisture had an average pellet durability 27.4% higher than that of the NRC treatment without added moisture (Table 2). This difference in pellet quality could have generated a reduction in bird activity related to feed prehension. If broilers did expend substantially less energy in apprehending pellets of higher quality, then it is probable that the energy dilution in the low energy treatments could have been partially offset. Broiler mortality was not affected by any treatment combination. The results of experiments 1 and 2 demonstrate that adding moisture to corn-soybean based diets may improve pellet quality, feed manufacturing and cost of dietary formulation. Relationships involving moisture addition were further explained using correlation analyses (Tables 4 and 5). For correlation coefficients that were thought pertinent, linear regressions were performed. These regression equations are restricted to the specific manufacturing equipment used in the study. Concerning NRC diets, for every 1% increase in moisture addition, pellet mill production rates increased by 0.21 tonnes/ h on average. For low energy diets, every 1% increase in moisture addition decreased relative electrical energy of the pellet mill by 0.13 kwh/ tonne on average. Other significant relationships in the low energy series included increased starch gelatinization associated with decreased rates of production and increased bulk density (Table 5). Starch gelatinization in the NRC series, however, was correlated with decreased pellet moisture percentage and increased hot pellet temperature (Table 4). Pellet durability in this series was correlated with decreased hot pellet temperature and starch gelatinization (Table 4). Despite inconsistencies between series, the data support speculations that were described in the discussion of the factorial analysis. Significant correlations between broiler FE and pellet qualities were not found. Experiment 3 Experiment 3 explored differences in nutrient availability of the low energy and NRC treatments, as well as effects of added moisture. In-

8 378 JAPR: Research Report TABLE 4. Pearson correlation coefficients among milling parameters, pellet qualities and broiler performance values for NRC diets Pellet Protein 2 H O P-rate A REE B HPT C PGT D SG E PDT F denaturation G PDI H M-PDI I BD J LWG K FI L FE M Mort N Item (%) (MT/h) (kwh/mt) ( C) ( C) (%) ( C) (%) (%) (%) (kg/m 3 ) (g) (g) (g/g) (%) Pellet H 2 O (%) 0.90 NS O 0.70 NS 0.70 NS NS NS NS 0.74 NS NS NS NS P-rate A (MT/h) 0.65 NS NS NS NS NS NS NS 0.80 NS NS 0.66 NS REE B (kwh/mt) NS NS NS NS NS NS NS 0.65 NS NS NS NS HPT C ( C) NS 0.73 NS NS 0.68 NS NS NS NS NS NS PGT D ( C) NS 0.65 NS NS NS NS NS NS NS NS SG E (%) NS NS 0.73 NS NS NS NS NS NS PDT F ( C) NS NS NS NS NS NS Protein denaturation G (%) NS NS NS NS NS NS NS PDI H (%) 0.84 NS NS NS NS NS M-PDI I (%) NS NS NS NS NS BD J (kg/m 3 ) NS NS NS NS LWG K (g) FI L (g) 0.41 NS FE M (g/g) NS A Production rate of the pellet mill; MT = tonnes. B Relative electrical energy (pellet mill). C Hot pellet temperature. D Peak temperature of starch gelatinization determined by differential scanning calorimetry (DSC). E Starch gelatinization determined by DSC and calculated on a dry-matter basis. F Peak temperature of protein denaturation determined by DSC. G Protein denaturation determined by DSC and calculated on a dry-matter basis. H Pellet durability index. I Modified pellet durability index (utilizing five 13-mm hex nuts for added pressure on pellets). J Bulk density. K Live weight gain. L Feed intake. M Feed efficiency. N Mortality. O Not significant at the 0.05 level to reject the null hypothesis of the slope of the regression line being equivalent to zero.

9 MORITZ ET AL.: GRADED MOISTURE ADDITION TO FEED 379 TABLE 5. Pearson correlation coefficients among milling parameters, pellet qualities and broiler performance values for Low energy diets Pellet Protein Mod 2 H O P-rate A REE B HPT C PGT D SG E PDT F denaturation G PDI H PDI I BD J LWG K FI L FE M Mort N Item (%) (MT/h) (kwh/mt) ( C) ( C) (%) ( C) (%) (%) (%) (kg/m 3 ) (g) (g) (g/g) (%) Pellet H 2 O (%) NS 0.72 NS NS NS NS NS NS NS NS NS NS P-rate A (MT/h) NS O NS NS 0.73 NS NS NS NS 0.71 NS NS NS NS REE B (kwh/mt) NS NS NS NS NS NS NS 0.60 NS NS NS NS HPT C ( C) NS NS NS NS NS NS 0.69 NS NS NS NS PGT D ( C) NS 0.67 NS NS NS 0.72 NS NS NS NS SG E (%) NS NS NS NS 0.69 NS NS NS NS PDT F ( C) NS NS NS 0.61 NS NS NS NS Protein denaturation G (%) NS NS NS NS NS NS NS PDI H (%) 0.95 NS NS NS NS NS M-PDI I (%) NS NS NS NS NS BD J (kg/m 3 ) NS NS NS NS LWG K (g) NS FI L (g) NS NS FE M (g/g) NS A Production rate of the pellet mill; MT = tonnes. B Relative electrical energy (pellet mill). C Hot pellet temperature. D Peak temperature of starch gelatinization determined by differential scanning calorimetry (DSC). E Starch gelatinization determined by DSC and calculated on a dry-matter basis. F Peak temperature of protein denaturation determined by DSC. G Protein denaturation determined by DSC and calculated on a dry-matter basis. H Pellet durability index. I Modified pellet durability index (utilizing five 13-mm hex nuts for added pressure on pellets). J Bulk density. K Live weight gain. L Feed intake. M Feed efficiency. N Mortality. O Not significant at the 0.05 level to reject the null hypothesis of the slope of the regression line being equivalent to zero.

10 380 JAPR: Research Report TABLE 6. Influence of energy density and moisture level on gross energy and broiler TME (experiment 3) A Feed gross energy A Broiler TME B Diet (kcal/kg) (kcal/kg) NRC 4,105.2 ab (24.26) 3,531.7 (272.67) NRC + 2.5% water 4,084.2 b (29.54) 3,396.5 (379.81) NRC + 5% water 4,116.9 a (11.54) 3,583.9 (98.38) Low energy 3,978.4 c (17.07) 3,316.1 (223.44) Low energy + 2.5% water 4,001.6 c (46.32) 3,229.4 (218.31) Low energy + 5% water 3,934.8 d (19.44) 3,441.0 (283.14) LSD C 29.5 P-values generated for main effects and the interaction Energy density Moisture level Interaction a c Means within a column with no common superscript differ significantly (P 0.05). A Treatment means among performance parameters with standard deviations in parentheses. B Gross energy measurements were obtained using a nonadiabatic bomb calorimeter and air dried samples. C True metabolizable energy was determined using a procedure modified from Sibbald [17]. D Fisher s least significant difference value. vestigators have speculated that moisture addition to broiler feeds may improve productive energy by increasing pellet quality, and may also improve broiler metabolism through chemical alteration of ingredients [5]. For example, adding moisture to corn-soybean based diets may increase the percentage of gelatinized starch, which may increase starch availability. Table 6 presents gross and true metabolizable energy values for each of the six experimental treatments. Gross energy, as anticipated, was significantly affected by calculated energy density. By design NRC treatments possessed higher energy contents than low energy treatments (P = ). Moisture level did not affect gross energy (P = ), however, a moisture level energy density effect was observed (P = ). This interaction effect is difficult to explain, and perhaps more a result of low standard deviations than moisture contributing effects (Table 6). Broiler TME values were not significantly affected by either main effect or their interaction (Table 6). Moisture-containing low energy treatments averaged 197 kcal/kg TME less than the NRC treatment without added moisture, but this difference was not statistically significant (P = ). The moisture level effect on TME was not significant among treatments nor was any trend apparent (Table 6). It appears that variations in starch gelatinization and protein denaturation produced from pelleting did not affect broiler metabolism. It is also possible that the broilers used in this specific design were not sensitive enough models to ascertain these differences. The data support that broilers fed low energy moisture-containing treatments have feed efficiencies equivalent to that of broilers fed NRC treatments without added moisture, likely due to improvements obtained from pellet quality. However, altering moisture did not result in elevations in metabolizable energy. The current manuscript did not explore potential problems of mycotoxin production or moisture migration resulting from diets containing added moisture. Although at no time during the study did feed show outward signs of mold. CONCLUSIONS AND APPLICATIONS 1. Addition of moisture to NRC or low energy diets improved pellet mill production rate and the quality of pellets produced while reducing the amount of electrical energy required for pelleting.

11 MORITZ ET AL.: GRADED MOISTURE ADDITION TO FEED Improved pellet quality in corn-soybean based diets may not always be associated with increased starch gelatinization of the total pellet. 3. Feeding nutritionally balanced, low energy diets that contain added moisture of 2.5%, produced broiler 3-to-6-wk performances equivalent to that of broilers fed NRC corn-soybean formulations. 4. Associations between improved broiler performance and increased pellet quality were more likely derived from increased productive energy rather than improved ingredient metabolism. REFERENCES AND NOTES 1. Fairchild, F., and D. Greer Pelleting with precise mixer moisture control. Feed Int. 20(8): Moritz, J. S., K. J. Wilson, K. R. Cramer, R. S. Beyer, L. J. McKinney, W. B. Cavalcanti, and X. Mo Effect of formulation density, moisture and surfactant on feed manufacturing, pellet quality and broiler performance. J. Appl. Poult. Res. 11: Nir, I., Y. Twina, E. Grossman, and Z. Nitsan Quantitative effects of pelleting on performance, gastrointestinal tract and behavior of meat-type chickens. Br. Poult. Sci. 35: Moran, E. T., Jr Effect of pellet quality on the performance of meat birds. Pages in Recent Advances in Animal Nutrition. W. Haresign and D. J. A. Cole, ed. Butterworths, London. 5. Moritz, J. S., R. S. Beyer, K. J. Wilson, K. R. Cramer, L. J. McKinney, and F. J. Fairchild Effect of moisture addition at the mixer to a corn-soybean based diet on broiler performance. J. Appl. Poult. Res. 10: Richardson, W., and E. J. Day Effect of varying levels of added fat in broiler diets on pellet quality. Feedstuffs (May 17): National Research Council Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. 8. Sprout Waldron Model B-37, double ribbon mixer with a shaft speed of 34 rotations per minute and a capacity of 454 kg (1,000 lb). Sprout-Waldron Manufacturing Engineers, Muncy, PA. 9. California Pellet Mill Master Model HD Series CPM Co., Crawfordsville, IN. 10. Relative electrical energy was measured specifically on the pellet mill (Amprobe Instrument model DMI, Core Industries Inc. Lynbrook, NY). 11. Production rate was calculated by dividing the metric tons of pellets produced by the total production time in hours. 12. Hot pellet temperature was taken on a sample of pellets collected directly after pellets were purged from the die. 13. American Society of Agricultural Engineers ASAE S269.4, Cubes, pellets, and crumbles Definitions and methods for determining density, durability, and moisture. Standards Am. Soc. Agric. Eng., St. Joseph, MI. Due to the use of a 5/ in. die, pellets were sifted in a No. 6 American Society for Testing and Materials (ASTM) screen. Five hundred grams of sifted pellets were placed in a dust-tight enclosure and tumbled for 10 min at 50 rpm. The enclosure was of the dimensions in., with a 2 9 in. plate affixed diagonally along one of the in. sides. The tumbled samples were then sifted again [No. 6 (ASTM)] and weighed. The pellet durability index was calculated by dividing the weight of pellets after tumbling by the weight of pellets before tumbling then multiplying by 100. The modified pellet durability index was determined in a similar manner with the exception of adding five 13-mm hex nuts to the pretumbled sample in order to obtain added pellet pressure 14. American Association of Cereal Chemists Moisture Air-Oven Method. AACC Method 44-15A. Approved Methods of the American Association of Analytical Chemists Vol II. Am. Assoc. Cereal Chem., St. Paul, MN. 15. Starch gelatinization was determined by differential scanning calorimetry (DSC) (DSC7, Perkin-Elmer, Norwalk, CT) and calculated on a dry matter basis. Enthalpy values were determined by a computer integrator for peaks in the approximate temperature range for cornstarch. The percentage of starch gelatinization was determined by subtracting the enthalpy of the unprocessed mash sample from the enthalpy of processed pellet sample and dividing the difference by the enthalpy of the unprocessed mash sample. The method used for this analysis included holding the sample for 1 min at 30 C then heating from 30 to 130 C with increases of 10 C per min. Protein denaturation was determined in the same analysis with peaks occurring at higher temperatures typical of soy proteins. 16. Cobb-Vantress, Inc., Siloam Springs, AR. 17. Sibbald, I. R A bioassay for true metabolizable energy in feedingstuffs. Poult. Sci. 55: Oxygen bomb calorimeter model 1341EB with precision thermometer model 1672, Parr Instrument Company, Moline, IL. 19. SAS Institute The SAS System for Windows Release 8.1. SAS Institute Inc., Cary, NC. 20. Thomas, M., T. van Vliet, and A. F. B. van der Poel Physical quality of pelleted animal feed 3. Contribution of feedstuff components. Anim. Feed Sci. Technol. 70: Parker, R., and S. G. Ring Aspects of the physical chemistry of starch. J. Cereal Sci. 34: Lund, D Influence of time, temperature, moisture, ingredients and processing conditions on starch gelatinization. CRC Crit. Rev. Food Sci. Nutr. 20: Wood, J. F The functional properties of feed raw materials and their effect on the production and quality of feed pellets. Anim. Feed Sci. Technol. 18: Stevens, C. A Starch gelatinization and the influence of particle size, steam pressure and die speed on the pelleting process. Ph.D. Dissertation. Kansas State University, Manhattan, KS. 25. Behnke, K. C Factors influencing pellet quality. Feedtech 5(4): Cramer, K. C., K. J. Wilson, R. S. Beyer, L. J. McKinney, and K. C. Behnke Effect of a sorghum-based diet subjected to various feed manufacturing processes on subsequent broiler performance. Poult. Sci. 78(Suppl. 1):45. (Abstr.) 27. Jensen, L. S., L. H. Merill, C. V. Reddy, and J. McGinnis Observations on eating patterns and rate of food passage of birds fed pelleted and unpelleted diets. Poult. Sci. 41: Farrell, D. J General principles and assumptions of calorimetry. Pages 1 24 in Energy Requirements of Poultry. T. R. Morris and B. M. Freeman, ed. British Poultry Science, Ltd., Longman Group, Ltd., London. Acknowledgments This study was financed in part by state and Hatch funds allocated to Kansas State University. The authors acknowledge Allen Baldridge, Myron Lawson, and Robert Resser for their assistance with animal husbandry. Contribution no J from the Kansas Agricultural Experiment Station.