SUMMARY. This is Journal Article Number J12279 from the Mississippi Agricultural and Forestry Experiment Station. 2

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1 2014 Poultry Science Association, Inc. Effects of varying conditioning temperature and mixer-added fat on feed manufacturing efficiency, 28- to 42-day broiler performance, early skeletal effect, and true amino acid digestibility 1 R. E. Loar II,* 2 K. G. S. Wamsley,* A. Evans, J. S. Moritz, and A. Corzo * 3 * Department of Poultry Science, Mississippi State University, Mississippi State; and Department of Animal and Nutritional Science, West Virginia University, Morgantown Primary Audience: Feed Mill Managers, Nutritionists, Researchers, Production Managers SUMMARY Three experiments (EXP) were conducted with the objective of evaluating the effects of varying steam conditioning temperatures (CT) and mixer-added fat (MAF) on a practical broiler finisher diet on feed manufacture variables (EXP 1), 28- to 42-d broiler performance (EXP 2), and early skeletal effect using 3-to 21-d broiler performance and tibiae ash measurements and true amino acid digestibility using cecectomized roosters (EXP 3). For all EXP, we used a 3 CT (74, 85, or 96 C) by 2 MAF (low or high) factorial arrangement, resulting in 6 experimental diets. Prior to EXP 2 and 3, all diets were ground to a common crumble size. In EXP 1, increasing both CT and MAF decreased relative electrical energy use at the pellet mill. In EXP 2, feeding finisher diets manufactured utilizing increased CT and decreased MAF to broilers from 28 to 42 d resulted in increased FCR. Also, CT by MAF interactions demonstrated the highest BW gain when birds were fed diets with high MAF, conditioned at 85 C. In EXP 3, feeding diets manufactured in EXP 1 to broilers from 3 to 21 d resulted in no significant effects on live performance variables. However, a significant CT by MAF interaction was observed, where chicks fed diets using low MAF conditioned at 85 and 96 C resulted in incrementally increased percent tibia ash over those with high MAF. In addition, based on true amino acid digestibility data, altering MAF and especially CT can affect the digestibility of several amino acids. Key words: conditioning temperature, mixer-added fat, feed manufacture, pellet durability index, true amino acid digestibility, tibia ash 2014 J. Appl. Poult. Res. 23 : DESCRIPTION OF PROBLEM In response to increased costs associated with feed ingredients, many nutritionists are using less supplemental fat. In addition, a practice becoming more popular in feed manufacture is the application of supplemental fat via postpellet application. Both of these strategies lead to a decrease in supplemental fat added at the mixer (mixer-added fat; MAF). Some manufac- 1 This is Journal Article Number J12279 from the Mississippi Agricultural and Forestry Experiment Station. 2 Present address: Ridley Feed Ingredients, Lost Creek Rd., Warrenton, MO Corresponding author: corzo_alejandro@elanco.com

2 Loar et al.: TEMPERATURE AND FAT EFFECTS 445 turers are also utilizing increased conditioning temperatures (CT) to compensate for lost feed through-put (caused by decreased MAF) or to improve pellet quality. Recently, researchers, via published literature, have suggested that the practice of increasing CT and decreasing MAF ( 1%) may decrease bird performance [1, 2] via decreased enzyme efficacy [3] or amino acid digestibility [4]. Therefore, the current study was designed with a comprehensive approach (3 experiments with 3 objectives) to determine the effects of varying CT (74, 85, or 96 C) and MAF (low or high) on an industry standard diet containing commercially available feed ingredients, including corn distillers dried grains with solubles (DDGS) and a thermally stable phytase enzyme, added at the mixer. In experiment (EXP) 1, the objective was to alter CT and MAF to determine their effect on the feed manufacturing variables. In EXP 2, the objective was to feed diets manufactured in EXP 1 to broilers from 28 to 42 d to determine if altering CT and MAF had a detrimental effect on nutrients in the feed that would be realized via 28- to 42-d growth performance and 43-d processing yields. Results from EXP 2 prompted the design of EXP 3, which had the objective of investigating the nutritional consequences of varying CT and MAF on the characteristics of 2 critically limiting and important nutrient types: phosphorus availability via early skeletal effect and true amino acid digestibility (TAAD) using cecectomized roosters. MATERIALS AND METHODS EXP 1: Feed Manufacture All diets used for the current experiment were identical in formulation (Table 1). To ensure accurate formulation of the experimental diets, samples of corn, soybean meal, DDGS, and meat-and-bone meal (porcine) were analyzed for total amino acids and CP composition [5]. These analyses were used to update the nutrient matrices for their respective ingredients. Digestible amino acid values were calculated from published digestible coefficients [6] by using the analyzed total amino acid content of the ingredients. Crude protein was not assigned a minimum value during formulation, and essential digestible amino acids were maintained in all dietary treatments by setting minimum formulation ratios relative to digestible Lys as TSAA 75, Thr 65, Val 78, Ile 68, Trp 17, and Arg 105, and following previously published recommendations [7]. All other essential nutrients were formulated to meet or exceed nutrient recommendations [8]. Diets were batched and pelleted over a 6-d period at the West Virginia University pilot feed mill. A 3 2 factorial arrangement was used, resulting in 6 treatments, with variations in CT (74, 85, and 96 C) and MAF [low (1%) or high (2.18%)]. Batching was accomplished daily by creating two kg batches of the basal diet (Table 1) that contained only 1% of the fat required by formulation. Batches were mixed for 15 min in a single-screw vertical mixer [9]. Each batch was equally distributed and assigned to 1 of 6 treatments, creating a total of kg as the experimental unit to be pelleted for each treatment replicate. For high-maf experimental diets, the remaining 1.18% supplemental fat was added to each respective experimental unit at the mixer and then the complete diet was mixed for 15 min before being conveyed to the conditionerpellet mill. For diets requiring low MAF, the experimental unit to be pelleted was placed in the mixer and mixed for 15 min to ensure sufficient blending of the 2 large basal diet batches from which the treatments were made. For these low- MAF diets, the remaining 1.18% fat was added after manufacture via pouring the pelleted diets back into the vertical mixer and adding the appropriate volume of liquid fat through a microingredient chute on the mixer. We recognize that this method does not mimic industry practice for postpellet fat application; however, it provided a means to accurately apply and mix fat for small replicated batches of feed. Mash was conditioned for 10 s at either 74, 85, or 96 C, depending on treatment. Steam pressure measured at the gauge was adjusted to 262 kpa (38 psi) through use of a globe valve. Feed temperature was monitored with a digital thermometer inserted directly into the stream of conditioned mash, and was controlled by throttling steam into the conditioner using a ball valve. Rate of feed entering the conditioner was held constant across all treatments. Mash was conditioned utilizing a short-term CPM conditioner then extruded through the pellet die [10].

3 446 JAPR: Research Report Table 1. Composition of practical diets used in experiments 1 to 3 1 that were formulated to meet 28- to 42-d broiler requirements Item (% as-is, unless otherwise noted) Finisher diet (28 42 d) Ingredient Corn Soybean meal (48% CP) DDGS Meat and bone meal (Porcine) 4.00 Fat Calcium carbonate Premix NaCl dl-met l-lys HCl l-thr Coccidiostat Choline chloride (60%) Phytase enzyme Dicalcium phosphate Calculated composition AME (kcal/kg) 3,150 CP 19.1 Digestible Lys 1.0 Digestible TSAA 0.75 Digestible Thr 0.65 Available P 0.41 Ca 0.82 Na Diets were manufactured in experiment 1, fed from 28 to 42 d to female Ross Ross 708 broilers in experiment 2 to measure live performance and processing characteristics, and then fed from 3 to 21 d to male Hubbard Cobb 500 broilers, as well as precision fed to cecectomized roosters to indicate early skeletal development and true amino acid digestibility, respectively (experiment 3). 2 Distillers dried grains with solubles. 3 Animal-vegetable oil blend; diets either had 1% fat added at the mixer and the remainder of the fat (1.18%) added postpellet [low mixer-added fat (MAF)] or all of the fat (2.18%) was added at the mixer (high MAF). 4 The vitamin and mineral premix provided per kilogram of diet: retinyl acetate, 2,654 µg; cholecalciferol, 110 µg; dl-αtocopherol acetate, 9.9 mg; menadione, 0.9 mg; vitamin B 12, 0.01 mg; folic acid, 0.6 µg; choline, 379 mg; d-pantothenic acid, 8.8 mg; riboflavin, 5.0 mg; niacin, 33 mg; thiamin, 1.0 mg; d-biotin, 0.1 mg; pyridoxine, 0.9 mg; ethoxiquin, 28 mg; manganese, 55 mg; zinc, 50 mg; iron, 28 mg; copper, 4 mg; iodine, 0.5 mg; and selenium, 0.3 mg. 5 Dietary inclusion of coccidiostat provided 60 g of salinomycin sodium per kg of feed. 6 DSM Nutritional Products (Parsippany, NJ). After extrusion, pellets were cooled on a horizontal belt cooler using forced ambient air [11]. Measured variables for each treatment included relative electrical energy use (REEU) at both the conditioner and pellet mill [12], production rate, and percentage of fines and bulk density. In addition, 1 representative bag from each replication was reserved for determination of pellet quality, as measured by pellet durability index (PDI) and modified pellet durability index (MPDI). Pellet quality was assessed on the day of manufacture using the Pfost tumbling can method [13]. EXP 2: 28- to 42-d Broiler Performance Broiler Performance. The experimental diets were transported to the Poultry Research Farm of Mississippi State University. The grow-out component of the current research encompassed the period between 28 and 42 d and used Ross Ross 708 [14] females obtained from a commercial hatchery. One-day-old female chicks were randomly placed in each of 60 floor pens (13 birds/pen; 780 birds total; 0.08m 2 /bird). The close-sided house had thermostatically controlled heating, cool cells, and cross ventilation. Each pen contained built-up litter, a hanging feeder (22.5 kg capacity), and nipple drinkers (3 nipples/pen). The lighting program consisted of 23 h of light and 1 h of dark; and ventilation was accomplished by negative air pressure. Chicks were vaccinated for Marek s disease (via in ovo administration at d 18), as well as Newcastle disease and infectious bronchitis (via coarse spray at hatch). All birds were fed a common starter (formulated to contain 3,075 kcal/kg of AME; 23.06% CP; 1.25% Lys; 0.90% TSAA; 0.81% Thr; and 0.45% available P) and grower (formulated to contain 3,100 kcal/kg of AME; 20.75% CP; 1.14% Lys; 0.82% TSAA; 0.74% Thr; and 0.42% available P) ration from 0 to 28 d. The feed was provided to the birds from 0 to 14 d of age in crumbles, and from 14 to 28 d as pellets. On d 28, the grower phase feed was removed, all pens were equalized (12 birds/pen; 720 birds total; 0.09 m 2 /bird), and feeding of the 6 experimental finisher diets (3 CT 2 MAF) commenced. The experimental diets were fed from 28 to 42 d and provided to the birds in crumble form so as to eliminate feed form effects on bird performance. Each treatment was replicated 10 times for a total of 60 experimental units. Treatments were blocked according to location within the house. Feed and water were provided for ad libitum consumption.

4 Loar et al.: TEMPERATURE AND FAT EFFECTS 447 All birds in each pen were weighed collectively at the beginning (d 28) and end of the finisher phase (d 42). Feed consumption and mortality were monitored throughout the experiment and FCR was corrected for the weight of mortality birds. All procedures were approved by the Mississippi State University Institutional Animal Care and Use Committee. Processing Measurements. On d 42, 5 birds per pen (300 total) were randomly selected, tagged, individually weighed, and cooped 12 h before processing. Birds were processed at a pilot processing plant. Electrical stunning was performed by applying 11.5 V (<0.05 ma, AC to DC current) for 5 s to each bird; birds were then exsanguinated for 140 s. Next, carcasses were scalded, picked, and eviscerated automatically using commercial prototype equipment [15]. Carcass and abdominal fat weights were obtained as birds were manually removed from the line. Birds were then chilled for 4 h, and then manually deboned to obtain weights for breasts, wings, and back halves of all birds. Absolute and relative weights (% of live weight) were determined for carcass yield, abdominal fat, back half, wings, and boneless-skinless breast meat. EXP 3: Early Skeletal Effect and TAAD Experiment 3 was conducted at West Virginia University and designed to potentially explain bird performance differences established in EXP 2 due to varying feed manufacturing techniques by exploring the availability of 2 limiting and important types of nutrients: phosphorus and amino acids. Therefore, all 6 experimental diets manufactured in EXP 1 were used in the current experiment. Early Skeletal Effect. Once again, diets from EXP 1 were ground to a common feed form through the use of a roller mill to eliminate potentially confounding effects of variations in feed form. For this experiment, male Hubbard Cobb 500 chicks [16, 17] were obtained from a commercial hatchery on d of hatch, placed in floor pens, and fed a common diet for 3 d. On d 3, chicks were weighed, randomly assigned to treatment, and placed in raised wire cages for the duration of the trial until 21 d of age. Experiment 3 used 8 replications per treatment, resulting in 48 total pens with 5 birds per pen (240 birds total). Temperature and lighting was held constant for all pens of birds. On d 21, feed and birds were weighed, for calculations of BW gain and FCR, and then birds were euthanized via cervical dislocation. The left tibia was excised from each bird and adhering tissue was removed. Bones were dried [18] and ashed [19] to obtain tibia ash (mg per chick) and percent tibia ash. TAAD. Precision feeding methods were followed as described in previous publications [4, 20, 21]. Briefly, feed samples retained from EXP 1 were weighed into 30-g samples and randomly assigned or precision fed to 1 of 24 cecectomized roosters. Cornstarch (30 g) was precision fed to an additional 4 cecectomized roosters to serve as a nitrogen-free control. For 48 h after precision feeding, excreta were collected, dried, weighed, and ground before being submitted with feed samples to a laboratory [22] for amino acid [23] and nitrogen determination [23]. Statistical Analysis For EXP 1, diets in all treatments were manufactured using Latin square design over a 6-d period, resulting in 6 replications for each treatment, with kg of feed representing the experimental unit. Treatments were blocked by day of production and run order. All data were analyzed using a 3 (CT) by 2 (MAF) factorial arrangement within the Latin square design. Data from EXP 1 can be found in Table 2. Data generated from EXP 2 (28- to 42-d broiler performance and d 43 processing; Tables 2 and 3) and EXP 3 (early skeletal effect and TAAD; Tables 4 and 5, respectively) were evaluated as a randomized complete block design with pen representing an experimental unit. All data were analyzed using the GLM procedure of SAS software [24] with P < 0.05 indicating significance. When differences (P < 0.05) existed, Fisher s least significant difference option of SAS was used to separate treatment means [24]. RESULTS AND DISCUSSION EXP 1: Feed Manufacture All data pertaining to the feed manufacture portion of our experiment are presented in Table 2. Treatment responses were observed for

5 448 JAPR: Research Report all feed milling parameters with the exception of production rate and conditioner REEU. Production rate and conditioner energy usage were likely unaffected due to the mill operator keeping the rate at which feed enters the conditioner constant. Conditioning at 85 and 96 C significantly decreased REEU at the pellet mill by 15 and 16%, respectively, as compared with the 74 C temperature (P < ; Table 2). This is most likely due to the increased steam volume necessary to increase temperature producing a lubricating action at the die, thus reducing the energy needed to extrude mash [25]. A significant decrease in REEU at the pellet mill of 9.6% was also observed for diets manufactured using high MAF (P < ) as compared with diets manufactured utilizing low MAF (Table 2), and likely is attributed to increased lubrication, which is supported by past research [3, 26, 27]. A significant CT by MAF interaction was observed for both PDI and MPDI (P < ; Table 2) and was similar for both parameters. In both instances, at each CT for treatments that required low MAF, PDI and MPDI was significantly greater (P < 0.001) as compared with diets with high MAF at the same CT. However, as CT increased, the difference in pellet quality between diets differing in MAF became less dramatic. Based on these data, the authors suggest that low MAF provides for greater pellet durability; however, as steam conditioning temperature increases, the effect is diminished. These results are in agreement with previous research, that increased MAF results in a decreased in pellet quality [3, 4, 28] and that increased steam conditioning temperature increases pellet quality [2, 29]. Based on data for bulk density (Table 2), diets conditioned at 96 C had significantly greater bulk density when compared with those conditioned at 85 C (P = 0.01), whereas diets conditioned at 74 C were not different. These results conflict with previous research conducted by Moritz et al. [30], who determined that highquality pellets result in more air space in a bulk density sample as a result of more whole pellets and decreased fines, thus resulting in a lower bulk density. However, Wamsley and Moritz [4] reported that bulk density may be improved in diets with high pellet quality (low percentage of fines) to a certain extent before the effects of air space decrease bulk density. It was also observed that the diets requiring low MAF resulted in significantly greater bulk density (P < ) compared with diets manufactured utilizing high MAF (Table 2). This result can be attributed to the fact that the bulk density of the dietary treatments with low MAF was measured after the fat was added postpellet, via placing the pelleted feed back into the mixer and adding the fat through a microingredient chute. As a result, pellets from low-maf treatments underwent significantly more stress and handling than pellets from high-maf treatments, and thus had more physical damage. Consequently, these were pellets of decreased length and thus had less air space in each bulk density sample, resulting in a heavier sample. Results for total fines (Table 2) were as expected based on the previous explanation for the bulk density results where fat application was concerned. Diets manufactured using low MAF resulted in significantly more fines (P < ) than diets manufactured with high MAF. Once again, we attribute this result to the increased handling and stress associated with the postpellet fat application for diets manufactured with low MAF. In agreement with Cutlip et al. [29], that increased steam temperature will increase pellet quality, the 85 C treatment had significantly less fines (P < ) than the 74 C treatment, whereas the 96 C treatment had significantly less fines than the 85 C treatment. EXP 2: 28- to 42-d Broiler Performance It is important to remember that all feed was crumbled to a common feed form before being fed to broilers in this experiment, with the aim of revealing nutritional effects associated with CT and MAF rather than feed form. Consequently, if feed form would have been maintained, it is likely that new or more pronounced responses would have been observed. Significance was established for the main effects of CT (P < ) and MAF (P = 0.05) for the measured variable of FCR. Increasing CT and decreasing MAF proved detrimental to FCR (Table 2). More specifically, birds fed diets conditioned at 74 C had an average 28- to 42-d FCR of 1.96, which is 3 and 8 points lower than the average FCR estab-

6 Loar et al.: TEMPERATURE AND FAT EFFECTS 449 Table 2. Effects of varying conditioning temperature and mixer-added fat of practical finisher-phase broiler diets on feed mill efficiency and pellet quality (experiment 1), as well as d female Ross x Ross 708 live production measurements (experiment 2) CT 1 ( C) MAF 2 Production rate (t/h) Conditioner REEU 3 (kwh/t) Pellet mill REEU 3 (kwh/t) PDI 4 (%) MPDI 5 (%) Bulk density 6 (kg/m 3 ) Total fines 7 (%) Average BWG 8 (kg) Average feed intake/ bird Mortality (kg) FCR 9 (%) Main effect 74 Low c 69.8 d ab High e 49.6 f ab Low b 81.8 c b High d 62.9 e a Low a 92.9 a b High b 87.8 b b SEM Marginal mean a 73.3 c 59.7 c ab 38.5 a c b 82.7 b 72.4 b b 30.1 b b b 93.8 a 90.4 a a 17.3 c a 0.42 SEM Low a 89.7 a 81.5 a a 34.0 a a 0.28 High b 76.7 b 66.8 b b 23.3 b b 0.56 SEM Main effect and interaction probability CT < < < < < MAF < < < < < CT MAF < < a- f Means within a column not sharing a common superscript differ (P 0.05). 1 CT = conditioning temperature; Diets were either manufactured at 74, 85, or 96 ( C). 2 MAF = Mixer-added fat; either 1(Low) or 2.18% (High) fat was added at the mixer before pelleting; Diets containing Low MAF (1%) had the remaining 1.18% fat added via post-pellet application so that all complete diets contained the same percentage of fat. 3 REEU = relative electrical energy use; equations used to determine REEU used the production rate (t/h) and electrical energy usage of the conditioner and pellet mill. Additionally, the amount of energy required by the conditioner and pellet mill to run without feed is used as a correction factor. 4 PDI = pellet durability index; determined by placing 500 g of sifted pellets into a Pfost tumbler (Gamet Manufacturing Inc., Saint Paul, MN). Samples were tumbled for 10 min at 50 rpm. The sample was then sifted again and weighed. Pellet durability index was calculated as the percent of sifted pellets retained after tumbling. 5 MPDI = modified pellet durability index; assessed similarly to the previous description, with the exception of the addition of five 13-mm hexagonal nuts to the 500-g sample before tumbling. 6 Bulk density was calculated using a box ( cm) that was tared of its weight on a scale. A 22.7-kg representative feed sample from each treatment replicate (obtained after postpellet fat application) was poured into the box until it reached maximum capacity and the top was leveled off using a ruler. The weight of the amount of feed that exactly filled the box was used to determine the bulk density. 7 Percent of total feed produced that was fines. 8 BWG = body weight gain; n = 12 birds per pen. 9 Feed conversion was adjusted with mortality weight.

7 450 JAPR: Research Report Table 3. The effect of feeding finisher diets (28 42 d) manufactured utilizing 3 conditioning temperatures (CT) and 2 levels of mixer-added fat (MAF) on 43-d female Ross x Ross 708 processing characteristics (experiment 2) Carcass Breast 5 Wing Back Abdominal fat CT ( C) 1 MAF 2 Weight 3 (kg) Yield 4 (%) Weight (kg) Yield (%) Weight (kg) Yield (%) Weight (kg) Yield (%) Weight (kg) Yield (%) Main effect 74 Low High Low High Low High SEM Marginal mean SEM Low High SEM Main effect and interaction probability CT MAF CT MAF CT = conditioning temperature; diets were either manufactured at 74, 85, or 96 ( C). 2 MAF = mixer-added fat; either 1(low) or 2.18% (high) fat was added at the mixer before pelleting; diets containing low MAF (1%) had the remaining 1.18% fat added via postpellet application so that all complete diets contained the same percentage of fat. 3 Carcass weight was the average of 5 birds that were randomly selected by pen at d Percent of live weight was calculated by part weight/live BW 100%. 5 Pectoralis major and minor.

8 Loar et al.: TEMPERATURE AND FAT EFFECTS 451 Table 4. Early skeletal effect of diets manufactured at varying conditioning temperature and mixer-added fat as determined with 3- to 21-d broiler chick performance and 21-d tibia ash measurements (experiment 3) CT ( C) 1 MAF 2 weight 3 (kg) Starting pen BWG 4 Tibia ash 6 Tibia ash/bird (kg) FCR 5 (%) (mg) Main effect 74 Low c 627 High c Low b 691 High c Low a 661 High c 606 SEM Marginal mean SEM Low High SEM Main effect and interaction probabilities CT MAF CT MAF a c Means within a column not sharing a common superscript differ (P 0.05). 1 CT = conditioning temperature; diets were either manufactured at 74, 85, or 96 ( C). 2 MAF = mixer-added fat; either 1 (low) or 2.18% (high) fat was added at the mixer before pelleting; diets containing low MAF (1%) had the remaining 1.18% fat added via postpellet application so that all complete diets contained the same percentage of fat. 3 At 3 d of age, n = 5 birds / pen. 4 Average body weight gain (BWG) from d 3 to Adjusted with mortality weight. 6 The left tibia was excised from each bird from each pen on d 21; percent bone ash was determined utilizing tibia ash/live BW 100%. lished for birds fed diets conditioned at 85 and 96 C, respectively (Table 2). In addition, birds fed diets with high MAF demonstrated an average FCR of 1.99, whereas birds fed diets manufactured using low MAF had an average FCR of 2.01 (Table 2). Also, a significant CT MAF interaction was established for average 28- to 42-d BW gain, demonstrating the highest BW gain for birds fed diets manufactured utilizing high MAF and conditioned at 85 C (P = 0.05; Table 2). Birds fed these diets demonstrated similar gain to that of birds fed diets conditioned at 74 C, regardless of MAF. The authors feel that this result indicates increased MAF may play an important role in preserving heat-sensitive nutrients at certain conditioning temperatures (i.e., at 85 C) for the current study. The aforementioned observation is of practical importance considering that most commercial feed mills in the United States aim to condition feed at least at the intermediate value used in the present study (85 C). In addition, many mills are utilizing decreased MAF. A possible explanation to observed differences in the current experiment could be that when utilizing a CT of 74 C or 85 C with high MAF, the heat exposure that nutrients in the diet endure is minimal, thus resulting in no negative performance effects. It is likely that as conditioning temperature is increased to 85 (low MAF) and 96 C, the heat exposure is so great that some nutrients likely suffer digestibility and bioavailability changes. This is in agreement with a trend found for FCR for the CT MAF interaction (P = 0.06; Table 2). Based on these data, we suggest that the thermal exposure that nutrients endured was ameliorated via the use of high MAF. Reducing MAF

9 452 JAPR: Research Report Table 5. The effects of using increasing conditioning temperatures and varying levels of mixer-added fat (MAF) on true amino acid digestibility 1 (experiment 3) CT 2 ( C) MAF 3 Met (%) Cys (%) Lys (%) Thr (%) Ile (%) Val (%) Glu (%) Leu (%) Pro (%) Ala (%) Main effect 74 Low High Low High Low High SEM Marginal mean a a a b b b b b b 74.3 SEM Low b High a SEM Main effect and interaction probabilities CT MAF CT MAF a,b Means within a column not sharing a common superscript differ (P 0.05). 1 Cecectomized roosters. 2 CT = conditioning temperature; diets were either manufactured at 74, 85, or 96 ( C). 3 MAF = mixer-added fat; either 1(low) or 2.18% (high) fat was added at the mixer before pelleting; diets containing low MAF (1%) had the remaining 1.18% fat added via postpellet application so that all complete diets contained the same percentage of fat.

10 Loar et al.: TEMPERATURE AND FAT EFFECTS 453 has been suggested as a cause of nutrient degradation via an increase in frictional heat at the mash die interface [2 4]. No significant responses were established for either CT or MAF for any of the processing parameters measured (Table 3). Therefore, based on the grow-out data, BW gain and FCR seem to be the only effects translated into production responses from steam conditioning temperature and fat application methods employed herein. However, male broilers will grow faster than females and thus require more feed [31]. It is possible that if male birds would have been used in the current study they may have been more sensitive to the treatments employed, demonstrating more pronounced results for some of the parameters measured. In addition, if feed form would have been maintained it is likely that new or more pronounced responses would have been observed. EXP 3: Early Skeletal Effect and TAAD Early Skeletal Effect. Results for the early skeletal effect portion of the current study are displayed in Table 4. A trend was demonstrated for the interaction of CT MAF for the parameter of BW gain (P = 0.064), and significance for this interaction was established for percent tibia ash (P = 0.006). The interaction for BW gain demonstrates no differences in weight gain, regardless of MAF, at either 74 or 85 C; however, a tendency for birds fed diets conditioned at 96 C with high MAF to maintain their BW gain was observed, whereas those fed diets with low MAF had decreased BW gain. Therefore, thermal processing, via high-conditioning temperature (96 C) and increased friction at the mashdie interface as a result of low MAF, could have caused a reduction in nutrient availability and, in turn, BW gain. The significant (P < 0.01) CT MAF interaction observed for percent tibia ash does not necessarily support the interaction trend obtained for BW gain. The interaction seen was such that, at 74 C CT, no differences in tibia ash were noted regardless of MAF; as CT increased, a higher percent tibia ash value was observed in those birds fed diets manufactured with low MAF, whereas birds fed diets manufactured with high MAF had similar percent tibia ash values to those from the lower CT treatments. Based on these data, mixer-added phytase was likely not degraded at any of the tested CT, regardless of MAF; however, it is also plausible that increased CT enhanced the digestibility of P [32]. TAAD. Based on these data, MAF and CT affected the digestibility of many of the tested amino acids (Table 5). Conditioning at 85 and 96 C significantly reduced the digestibility of Met (P = 0.002), Ile (P = 0.037), and Pro (P = 0.026) as compared with diets conditioned at 74 C. Similarly, though not significant, conditioning at increased CT tended to decrease the digestibility of Lys (P = 0.059), Val (P = 0.061), and Leu (P = 0.052). In general, increased CT decreased TAAD of Met, Ile, and Pro by 3 to 5% (P < 0.05) and tended to decrease the digestibility of Lys, Val, and Leu by 3 to 6% (Table 5; P < 0.10). A significant response for MAF was established for Thr, resulting in higher digestibility for diets manufactured with high MAF (P = 0.021). Cysteine and Pro exhibited a similar, although not significant, response to that of Thr, where the digestibility values tended to be higher when diets were manufactured with high MAF (P = and 0.072, respectively). Therefore, utilizing low MAF (1%) significantly decreased the digestibility of Thr by 6.3% and tended to decrease the digestibility of Pro and Cys by 3 and 6%, respectively. This is supported by previous research, where a 4 to 7% decrease in TAAD was observed when commercial turkey diets were manufactured with 1% MAF and natural binders, as compared with diets manufactured utilizing 3% MAF and lignosulfonate binder [4]. It is clear from the data generated in the current study that CT and MAF have marked effects on feed manufacture, nutrient utilization, and bird performance. In feed manufacturing, increasing CT and MAF can decrease the amount of electrical energy necessary to run the mill, whereas increased CT and decreased MAF can also yield a more durable pellet (EXP 1; Table 2). However, manufacturing techniques that increased pellet quality (increased CT and decreased MAF) increased 28- to 42-d FCR by 8 and 3 points, respectively (EXP 2; Table 2). These data suggest that at certain intermediate steam conditioning temperatures, increasing

11 454 JAPR: Research Report MAF appears to aid in nutritional preservation and possibly prevent the degradation of some nutrients, as proposed in previously mentioned research [2 4]. This theory is further supported by the results obtained for BW gain in the broiler performance experiment (EXP 2; Table 2), where birds fed diets that were conditioned at 85 C with high MAF yielded the highest BW gain. In addition, based on TAAD responses from many of the primary limiting amino acids, such as Met, Cys, Lys, Thr, Ile, and Val (EXP 3; Table 5), it is clear that CT, and to a lesser extent MAF, can play a role in the availability these amino acids, and ultimately bird performance. In conclusion, based on the current study, we have established that certain feed manufacturing techniques typically employed in commercial feed mills to conserve or improve pellet quality or feed through-put can be detrimental to TAAD and, ultimately, bird performance. CONCLUSIONS AND APPLICATIONS 1. In EXP 1, manufacturing practical diets using increased CT from 74 to 85 and 74 to 96 C decreased pellet mill REEU by 15 and 16%, respectively. Also, increasing MAF from 1 to 2.18% decreased pellet mill REEU by 9.6%. Pellet quality was improved with increased CT; however, the magnitude of improvement was less when high MAF was incorporated compared with low MAF. 2. Based on data from EXP 2, manufacturing feed with increased CT increased 28- to 42-d cumulative FCR by up to 8 points (1.96 vs. 2.04), for 74 and 96 C, respectively. Also, decreasing MAF in diets (from 2.18 to 1%) increased FCR by 3 points (1.99 vs. 2.01). 3. In EXP 3, CT and MAF had little effect on early skeletal development, but did affect TAAD. Increased CT decreased TAAD of Met, Ile, and Pro by 3 to 5%, whereas low MAF decreased the digestibility of Thr by 6.3%. REFERENCES AND NOTES 1. Buchanan, N. P., K. G. S. Lilly, and J. S. Moritz The effects of altering diet formulation and manufacturing technique on pellet quality. J. Appl. Poult. Res. 19: Lilly, K. G. S., C. K. Gehring, K. R. Beaman, P. J. Turk, M. Sperow, and J. S. Moritz Examining the relationships between pellet quality, broiler performance, and bird sex. J. Appl. Poult. Res. 20: Gehring, C. K., K. G. S. Lilly, L. K. Shires, K. R. Beaman, S. A. Loop, and J. S. Moritz Increasing mixer-added fat reduces the electrical energy required for pelleting and improves exogenous enzyme efficacy for broilers. J. Appl. Poult. Res. 20: Wamsley, K. G. S., and J. S. Moritz Resolving poor pellet quality and maintaining amino acid digestibility in commercial turkey diet feed manufacture. J. Appl. Poult. Res. 22: AOAC International Official Methods of Analysis (985.28, , and ). 18th ed. Association of Official Analytical Chemists International, Arlington, VA. 6. Ajinomoto Heartland, LLC True Digestibility of Essential Amino Acids for Poultry. rev. 7. Ajinomoto Heartland LLC, Chicago, IL. 7. Lemme, A., V. Ravindran, and W. L. Bryden Standardized ileal amino acid digestibility of raw materials in broilers. Proc. Multi-State Poult. Feed. Nutr. Health Manag. Conf. Degussa Corp. Tech. Symp. Indianapolis, IN. 8. NRC Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Press, Washington, DC. 9. Vertical mixer, Avery Weigh-Tronix, Fairmont, MN. 10. Master Model Pellet Mill, California Pellet Mill Company, Crawfordsville, IN; A 4.25-ft length, 1.02-ft diameter short-term California pellet mill conditioner (3 steam inlet ports), 429 rpm shaft speed; 21 picks; 10-s feed retention time. CPM 2288A master model pellet mill with a 40-horsepower main drive motor, 12 in diameter, mm die, and 25 boiler house power Columbia boiler (Columbia Boiler Company, Pottstown, PA). 11. Horizontal cooler, Pyramid Processing Equipment LLC, Stilwell, KS. 12. Powerlogic power meters attached to the 3-phase leads of the pellet mill main drive and conditioner motor; Square D, Palatine, IL. 13. American Society of Agricultural Engineers ASAE S 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 in. die pellets were sifted in a No. 6 American Society for Testing and Materials (ASTM) screen (W. S. Tyler Industrial Group, Mentor, OH). Five hundred grams of sifted pellets were placed in a dust-tight enclosure and tumbled for 10 min at 50 rpm. The enclosure dimensions were 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 to obtain added pellet agitation. 14. Aviagen Group, Huntsville, AL. 15. Baader-Johnson, Kansas City, KS. 16. Hubbard LLC, Walpole, NH. 17. Cobb-Vantress Inc., Siloam Springs, AR.

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