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Effects of feed form on growth performance and processing yields of broiler chickens during a 42-day production period1
©2010 Poultry Science Association, Inc.
Effects of feed form on growth performance and processing yields of broiler chickens during a 42-day production period1 W. A. Dozier III,*2,3 K. C. Behnke,† C. K. Gehring,‡ and S. L. Branton*
Primary Audience: Feed Mill Managers, Live Production Personnel, Nutritionists SUMMARY Meat birds fed high-quality pellets exhibit advantages in rate and efficiency of growth over birds fed poorer quality pellets. However, the associated feed manufacturing cost and reduced production rates to obtain high-quality pellets are viewed by the industry as offsetting the benefits in broiler performance provided by high-quality pellets. With the combination of increased costs for utilities in the feed mill and for feed ingredients, strategies are needed to conserve milling costs while optimizing the efficiency of broiler growth. In this study, we evaluated the effects of feed form on live performance and meat yield of broiler chickens during a 42-d production period. Four treatments were provided from 18 to 42 d of age: 1) high-quality pellets (88% pellet durability index), 2) low-quality pellets (66% pellet durability index), 3) a proportion of the formulated corn added post-pellet (89% pellet durability index), and 4) mash (corn was ground via a roller mill). Broilers fed the high-quality pellets had higher cumulative BW gain and consumed more feed than birds fed low-quality pellets. Mash-fed broilers had poorer growth performance and less meat recovery than birds in the other treatments. Adding corn post-pellet resulted in broilers having similar performance and meat yields compared with those fed high-quality pellets. In this study, we confirm that adding corn post-pellet does not negatively affect growth performance and meat yield. Feeding broilers high-quality pellets provides a benefit in growth rate over feeding low-quality pellets by increasing feed consumption. Key words: broiler, corn, feed manufacturing, grinding, particle size 2010 J. Appl. Poult. Res. 19:219–226 doi:10.3382/japr.2010-00156
DESCRIPTION OF PROBLEM Because of the demand for corn and oils for biofuel production, feed ingredients recently have reached unprecedented prices, translating 1
to increased live production costs for broilers [1]. Therefore, optimizing feed conversion at effective costs is of utmost importance. Providing meat birds diets in whole pellet form improves the rate and efficiency of growth [2–5]. Cutlip
Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA and Kansas State University. 2 Corresponding author: [email protected] 3 Current address: Auburn University, Department of Poultry Science, 201 Poultry Science Building, 260 Lem Morrison Drive, Auburn, AL 36849-5416.
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*USDA, Agricultural Research Service, Poultry Research Unit, Mississippi State, MS 39762; †Department of Grain Science and Industry, Kansas State University, Manhattan 66506; and ‡Department of Poultry Science, Auburn University, Auburn, AL 36849
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MATERIALS AND METHODS Dietary Treatments Broilers were fed a 3-phase feeding program during a 42-d production period. Diets were identical in nutrient specifications during the same age period (Table 1). The common start-
er feed was provided as crumbles until 15 d of age. Four treatments differing in feed form were evaluated from 15 to 42 d of age (Table 2). The 4 treatments were 1) high-quality pellets, 2) lowquality pellets, 3) 20 and 30% of the formulated corn added post-pellet from 15 to 28 d and 29 to 42 d of age, respectively, and D) mash using roller mill ground corn. Feed Manufacturing Experimental diets (grower and finisher) were manufactured at the Grain Science Department at Kansas State University (Table 1). Yellow dent corn was ground through a 22.4-kW Jacobson hammer mill [14] using a screen with 4.0-mm holes or was cracked on a Roskamp [15] 3-high roller mill. Roll gaps for the coarse rolled corn were set at 2.46 mm for the top rolls, with the bottom 2-roll sets being left open. The average particle size of the coarse rolled corn was approximately 2,600 μm for treatment 3 and 1,200 μm for treatment 4. After grinding, the rolled corn for treatment 3 was sifted over a number 10 wire to remove fines. Fines were diverted to the hammer mill ground corn bin so that the sifted fines from the rolled corn were returned to the diet as a part of the corn fraction in the mixer. After the grinding process, ingredients were batched and mixed in a horizontal double ribbon mixer [16] for 120 s of dry mixing, followed by 180 s of wet mixing. Fat was added at 0.5% in the mixer for treatments 1 and 3, and the remaining fat was added post-pellet. Conversely, all the fat was added in the mixer for treatments 2 and 4. The complete mash diets and incomplete mash diets of treatments 1 and 3 (without rolled corn added post-pellet) were conditioned and pelleted with a CPM pellet mill [17]. The pellet mill was equipped with a 31.8-mm-thick die and with 4.8-mm-diameter holes. In addition, treatments 1 and 3 were conditioned at 85°C, whereas conditioning temperature was reduced to 71°C with treatment 2. The combination of using a lower conditioning temperature and additional fat in the mixer facilitated the production of lower quality pellets for treatment 2. After pelleting, all pellets were placed in the mixer for 30 s for the following steps: 1) add fat to treatment 1; 2) subject treatment 2 to the same mixing conditions as treatments 1 and 3; and 3) mix incomplete pelleted diets for treatment 4
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et al. [6] examined the performance of broilers fed diets differing in pellet quality. Those fed diets having a better modified pellet durability index (PDI; 90 vs. 80%) had lower cumulative feed conversion (1.99 vs. 2.16) and higher breast meat yields (21.32 vs. 20.23%). Moritz et al. [7] reported that broilers fed diets having a high pellet quality (87% PDI) had improved FE (standardized at 12.5% moisture; 0.579 vs. 0.572 kg/ kg) compared with birds provided feed having a lower pellet quality (62% PDI). Conditioning and pelleting increase the cost of manufacturing diets ($4 to $6 per ton). Strategies are needed to reduce the utility cost of manufacturing and enhance the pelleting production rate while not adversely affecting broiler performance. Clarke and Behnke [8] determined that adding 30% of the formula corn (as coarse rolled corn) post-pellet resulted in decreased manufacturing cost and increased pelleting output. Pelleting production rate was increased by 20% when 30% of the formulated corn was added post-pellet. Adding 20 to 35% of the formulated corn post-pellet during the grower and finisher periods has not limited broiler growth or meat yield [9–11]. Another strategy for improving manufacturing cost may be to provide the diets in mash form, using roller mill ground corn to control flow problems. Broilers fed mash diets ground through a hammer mill exhibit poorer growth than birds fed pelleted diets [3, 12]. Mash diets are known to have poor flowability with mechanical feeding equipment, resulting in poor growth performance of meat birds [13]. Grinding corn via roller mill results in a more uniform grind size, and using a relatively larger particle size may improve feed flowability and broiler performance without the higher utility cost associated with feed manufacturing. In this study, we examined live production and meat yield responses of mixed-sexed broilers fed diets provided as 4 feed forms from 15 to 42 d of age.
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Table 1. Ingredient and nutrient composition of the experimental diets Item
Grower, 15 to 28 d 63.00 26.21 5.00 3.10 1.27 0.56 0.30 0.25 0.17 0.08 0.08
66.88 22.44 5.00 3.21 1.02 0.61 0.33 0.25 0.14 0.05 0.08
3,150 20.0 0.85 1.15 0.82 0.85 0.43 0.22
3,200 18.5 0.78 1.02 0.76 0.78 0.38 0.22
1
Vitamin and mineral premix supplied per kilogram of diet: selenium, 0.15 mg; manganese, 100 mg; iron, 50 mg; iodine, 1.5 mg; zinc, 100 mg; retinyl acetate, 7,715 IU; cholecalciferol, 2,756 IU; α-tocopherol acetate,17 IU; menadione sodium bisulfate, 0.8 mg; cyanocobalamin, 0.01 mg; thiamine mononitrate, 1.1 mg; riboflavin, 6.6 mg; pyridoxine hydrochloride, 1.4 mg; nicotinic acid amine, 28 mg; d-calcium pantothenate, 6.6 mg; folic acid, 0.69 mg; d-biotin, 0.044 mg; choline chloride, 386 mg. 2 Coban 60 (Elanco, Indianapolis, IN) provided 90 g of monensin sodium per 907.2 kg of diet.
experimental facility was solid-sided, with a negative-pressure ventilation system equipped with exhaust fans and evaporative cooling pads. The temperature regimen and lighting schedule were similar to those used in commercial practice [20, 21]. Each pen had new pine shavings, a tube feeder [22], and a nipple drinker line having 9 nipples. Birds were offered feed and water ad libitum. Birds and feed were weighed on a pen basis at 1, 15, 28, and 42 d of age for the determination of growth rate, feed intake, and feed conversion. Mortality was recorded daily. On d 43, 12 birds per pen (6 males and 6 females) were randomly selected for processing, weighed, placed in coops, and transported to the Mississippi State University Poultry Processing
with rolled corn and the remaining supplemental fat. Representative samples were collected to assess pellet integrity using standard procedures [18]. After mixing, all diets were bagged and transported to the USDA-Agricultural Research Service Poultry Research Unit at Mississippi State, Mississippi. Bird Management and Processing Yields Sixteen hundred Ross × Ross 708 [19] broiler chicks were obtained from a commercial hatchery and randomly distributed to 32 floor pens (25 males and 25 females; 0.07 m2) 4 h after hatching. At the hatchery, chicks were administered vaccinations for Marek’s disease, Newcastle disease, and infectious bronchitis. The
Table 2. Pellet durability index (PDI) of diets differing in feed form from 15 to 42 d of age1 Grower Treatment High-quality pellets Low-quality pellets Added rolled corn post-pellet 1
Values are duplicate averages.
Finisher
PDI, %
Modified PDI, %
PDI, %
Modified PDI, %
88.92 66.04 89.48
85.02 50.63 87.00
89.55 67.05 90.01
86.26 54.65 87.82
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Ingredient, % (as-is basis) Corn Soybean meal (47.5% CP) Poultry by-product meal (58.0% CP) Poultry oil Defluorinated phosphate Calcium carbonate Sodium chloride Mineral and vitamin premix1 dl-Methionine l-Lysine hydrochloride Monensin sodium2 Calculated composition AMEn, kcal/kg CP, % Methionine + cysteine, % Lysine, % Threonine, % Calcium, % Nonphytate phosphorus, % Sodium, %
Finisher, 29 to 42 d
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Statistics Data were statistically evaluated using the ANOVA procedure of SAS [23]. The experimental design consisted of a 1-way treatment structure using a randomized complete block design, with pen location being the blocking factor. Means were separated by Tukey’s honestly significant differences procedure [23] when the overall F-test was P ≤ 0.05. Preplanned orthogonal contrasts were used to divide treatment effects with 3 df into 1) pellets vs. mash, 2) highquality pellets vs. low-quality pellets, and 3) high-quality pellets vs. added corn post-pellet. Statistical significance was established at P ≤ 0.05.
RESULTS Live Performance Broilers fed pelleted diets grew faster (P ≤ 0.001) and consumed more (P ≤ 0.001) feed from 15 to 28 d, 15 to 42 d, and 1 to 42 d of age than mash-fed broilers (Tables 3, 4, and 5). Feeding higher quality pellets to broilers increased growth rate and feed consumption during the grower, finisher, and cumulative periods over birds fed diets having lower quality pellets. Broilers fed lower quality pellets had marginally superior cumulative feed conversion compared with birds fed higher quality pellets (1.694 vs. 1.712). From 15 to 28 d of age, broilers fed highquality pellets had superior feed conversion (P ≤ 0.022) compared with birds provided feeds having rolled corn post-pellet, but no differences in feed conversion were noted in subsequent periods. In addition, BW gain was similar for broil-
ers fed diets presented as high-quality pellets or rolled corn post-pellet throughout experimentation. No treatment differences (P = 0.24) were observed for the incidence of mortality. Processing Yields Broilers fed diets in pelleted form had advantages (P ≤ 0.05) in carcass weight, carcass yield, total breast meat weight, and total meat yield. Feeding broilers diets as low-quality pellets and rolled corn post-pellet produced similar (P < 0.05) carcass and breast meat yields as birds provided diets as high-quality pellets (Table 6).
DISCUSSION In the United States, feeding broiler chickens diets in crumble or whole pellet form is practiced exclusively. Advantages of feeding pelleted diets are improved flowability with mechanical feeding systems, decreased feed wastage, and an enhanced rate and efficiency of growth [2–4, 13]. The improvement in broiler performance due to pelleting relates to less time devoted to eating translating to reduced energy spent for prehension [24, 25]. However, pelleting is a costly process and the benefits of high-quality pellets have been a subject of debate. Alternatives are needed to reduce feed manufacturing costs without compromising the growth performance and meat yield of broilers. In the present research, broilers provided mash diets exhibited similar BW gain, feed conversion, and breast meat weight as broilers fed low-quality pellets. This may have occurred because the corn was ground via a roller mill, which had larger and more uniform particle sizes, potentially allowing for improved flowability in the feeders compared with when corn was ground via hammer mill. Moreover, previously, researchers may have used a higher quality pellet that accentuated the performance differences of broilers fed pellets vs. mash diets. Broilers fed the high-quality pellets grew 2.7 and 4.7% faster and consumed 3.7 and 5.6% more feed, respectively, compared with birds fed diets as low-quality pellets or as mash from 15 to 49 d of age. The improvement in BW gain was commensurate with increased feed intake. In parallel 15- to 42-d data, feeding broilers diets as high-quality pellets increased BW gain
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Plant. Feed was removed 12 h before processing. Birds were electrically stunned (5 s), exsanguinated (80 s), scalded (150 s, 53°C, and 12.5 V), mechanically picked (35 s), and mechanically eviscerated. Whole carcass (without abdominal fat) and abdominal fat were weighed. Carcasses were split into front and back halves and placed on ice for 18 h. The front halves were then deboned to obtain weights of the pectoralis major and minor muscles. Carcass, abdominal fat, and total breast meat (pectoralis major and minor muscles) yields were determined from 43-d BW of the broilers selected for processing.
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Table 3. Growth performance of Ross × Ross 708 male broilers fed diets differing in feed form from 15 to 28 d of age1 Item
BW, kg
BW gain, kg
Response criterion High-quality pellets (1) Low-quality pellets (2) Added rolled corn post-pellet (3) Mash (4) SEM
1.311a 1.273ab 1.289ab 1.247b 0.011
0.828a 0.793ab 0.801a 0.756b 0.009
Feed intake, kg 1.232a 1.178b 1.224a 1.143b 0.010
FCR2
Mortality, %
1.486ab 1.480b 1.522a 1.503ab 0.010
0.5 0.2 0.7 0.2 0.3
0.144 0.735 0.022
0.741 0.568 0.568
P-value 0.005 0.035 0.205
0.0001 0.016 0.053
<0.0001 0.001 0.576
a,b
Means within a column without a common superscript differ (P < 0.05). Values are least squares means of 8 replicate pens with 50 broilers per pen at 1 d of age. 2 Corrected for mortality. 1
by 72 and 123 g, respectively, compared with birds fed diets in the forms of low-quality pellets or mash. Cumulative feed conversion was 1% higher for broilers fed diets as high-quality pellets compared with those fed low-quality pellets. This difference probably resulted from increased maintenance requirements associated with higher BW. No differences were observed for processing parameters for broilers fed highand low-quality pellets. However, total breast meat weight was reduced by 43 g when mash diets were fed relative to broilers provided diets as high-quality pellets. Manufacturing highquality pellets resulted in superior growth rate,
and this improvement could potentially translate to a decreased number of grow-out days. The current study was conducted during winter months, when growth rate and feed intake were favorable, so the magnitude of the differences observed between treatments might have varied if this research had been conducted during summer production, when feed intake is limited. In agreement with the current research, Proudfoot and Sefton [2] evaluated growth and meat yield responses of broilers fed diets containing varying proportions of fines from 28 to 49 d of age. Broilers fed pelleted diets with 0% fines had the highest 49-d BW, whereas cumulative
Table 4. Growth performance of Ross × Ross 708 male broilers fed diets differing in feed form from 15 to 42 d of age1 Item Response criterion High-quality pellets (1) Low-quality pellets (2) Added rolled corn post-pellet (3) Mash (4) SEM
BW, kg 2.684a 2.612bc 2.653ab 2.562c 0.017
BW gain, kg 2.202a 2.132bc 2.165ab 2.071c 0.017
Feed intake, kg 3.899a 3.737b 3.862a 3.656b 0.025
FCR2
Mortality, %
1.761 1.745 1.769 1.751 0.007
1.2 0.9 2.1 1.2 0.5
0.834 0.161 0.437
0.854 0.726 0.246
P-value Planned orthogonal contrast 1 and 2 vs. 4 1 vs. 2 1 vs. 3 a–c
<0.001 0.009 0.234
<0.001 0.009 0.146
<0.0001 <0.001 0.328
Means within a column without a common superscript differ (P < 0.05). Values are least squares means of 8 replicate pens with 50 broilers per pen at 1 d of age. 2 Corrected for mortality. 1
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Planned orthogonal contrast 1 and 2 vs. 4 1 vs. 2 1 vs. 3
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Table 5. Growth performance of Ross × Ross 708 male broilers fed diets differing in feed form from 1 to 42 d of age1 Item
BW, kg
Response criterion High-quality pellets (1) Low-quality pellets (2) Added rolled corn post-pellet (3) Mash (4) SEM
3.167a 3.093ab 3.141a 3.053b 0.020
BW gain, kg
Feed intake, kg
2.641a 2.569bc 2.610ab 2.518c 0.017
4.523a 4.355b 4.477a 4.270b 0.028
FCR2
Mortality, %
1.712ab 1.694b 1.715a 1.695b 0.004
2.0 1.3 1.6 1.5 0.5
0.183 0.016 0.675
0.857 0.311 0.616
P-value 0.005 0.017 0.383
<0.001 0.010 0.236
<0.0001 <0.001 0.259
a–c
Means within a column without a common superscript differ (P < 0.05). Values are least squares means of 8 replicate pens with 25 broilers per pen at 1 d of age. 2 Corrected for mortality. 1
feed conversion was optimized with 15% fines. Feeding mash diets and pelleted diets containing 100% fines produced similar results, with an 8% reduction in BW gain and the FCR increased by 4% when compared with the pelleted treatments, providing the best responses for growth rate and feed conversion. Choi et al. [3] reported increases in BW gain and feed intake of 11 and 10%, respectively, for broilers fed pelleted vs. mash fed diets from 28 to 56 d of age. No difference in feed conversion was noted between birds fed pelleted and mash diets.
Adding a proportion of the formulated corn post-pellet is potentially a strategy to reduce milling costs without compromising broiler performance [9–11]. In the current research, broilers fed diets having a proportion of the formulated corn added post-pellet resulted in cumulative growth rate, feed intake, feed conversion, carcass weight and yield, and total breast weight and yield similar to birds fed high-quality pellets. In addition, feeding broilers diets having added corn post-pellet increased the cumulative feed intake by 122 g compared with broilers fed
Table 6. Processing weights and yields of 43-d-old Ross × Ross 708 male broilers fed diets differing in feed form from 1 to 42 d of age1 Carcass Item Response criterion High-quality pellets (1) Low-quality pellets (2) Added rolled corn post-pellet (3) Mash (4) SEM
Abdominal fat
Total breast
Weight, kg
Yield,2 %
Weight, kg
Yield, %
Weight, kg
Yield, %
1.949a 1.891ab 1.893ab 1.813b 0.028
70.61 70.67 70.05 69.45 0.42
0.057 0.051 0.053 0.052 0.001
2.09 1.92 1.96 2.00 0.07
0.570a 0.559ab 0.558ab 0.527b 0.009
20.65 20.92 20.63 20.18 0.23
0.999 0.106 0.214
0.003 0.443 0.372
P-value Planned orthogonal contrast 1 and 2 vs. 4 1 vs. 2 1 vs. 3 a,b
0.006 0.166 0.182
0.032 0.929 0.354
0.446 0.030 0.121
Means within a column without a common superscript differ (P < 0.05). Values are least squares means of 8 replicate pens with 12 broilers per pen. 2 Yields are defined as grams of tissue/100 g of BW. 1
0.043 0.412 0.966
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Planned orthogonal contrast 1 and 2 vs. 4 1 vs. 2 1 vs. 3
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CONCLUSIONS AND APPLICATIONS
1. Feeding broilers diets in mash form ground via roller mill adversely affected cumulative feed intake, BW gain, carcass weight, and total breast meat weight when compared with feeding broilers high-quality pellets, but not low-quality pellets. 2. Feeding broilers diets having added rolled corn post-pellet resulted in growth performance and meat yield similar to broilers provided diets as high-quality pellets. 3. Broilers fed diets as high-quality pellets exhibited BW gain and feed intake advantages from 15 to 42 d and 1 to 42 d of age compared with birds in the other treatments.
REFERENCES AND NOTES 1. Donohue, M., and D. L. Cunningham. 2009. Effects of grain and oilseed meals on the cost of US poultry production. J. Appl. Poult. Res. 18:325–337. 2. Proudfoot, F. G., and A. E. Sefton. 1978. Feed texture and light treatment effects on the performance of broiler chickens. Poult. Sci. 57:408–416. 3. Choi, J. H., B. S. So, K. S. Ryu, and S. L. Kang. 1986. Effects of pelleted or crumbled diets on the performance and development of the digestive organs of broilers. Poult. Sci. 65:594–597. 4. McKinney, L. J., and R. G. Teeter. 2004. Predicting effective caloric value of nonnutritive factors: I. Pellet
quality and II. Prediction of consequential formulation dead zones. Poult. Sci. 83:1165–1174. 5. Proudfoot, F. G., and H. W. Hulan. 1982. Feed texture effects on the performance of turkey broilers. Poult. Sci. 57:408–416. 6. Cutlip, S. E., J. M. Hott, N. P. Buchanan, A. L. Rack, J. D. Latshaw, and J. S. Moritz. 2008. The effect of steamconditioning practices on pellet quality and growing broiler nutritional value. J. Appl. Poult. Res. 17:249–261. 7. Moritz, J. S., R. S. Beyer, K. J. Wilson, and K. R. Cramer. 2001. Effect of moisture at the feed mixer to a cornsoybean-based diet on broiler performance. J. Appl. Poult. Res. 10:347–353. 8. Clark, P. M., and K. C. Behnke. 2004. Effects of pelleting protein concentrate pellets on feed mill throughout and electrical efficiency. Poult. Sci. 83(Suppl. 1):170. (Abstr.) 9. Clark, P. M., K. C. Behnke, and A. C. Fahrenholz. 2009. Effects of feeding cracked corn and concentrate protein pellets on broiler growth performance. J. Appl. Poult. Res. 18:259–268. 10. Dozier, W. A., III, K. Behnke, M. T. Kidd, and S. L. Branton. 2006. Effects of the addition of roller mill ground corn to pelleted feed on pelleting parameters, broiler performance, and intestinal strength. J. Appl. Poult. Res. 15:236– 244. 11. Dozier, W. A., III, K. Behnke, P. Twining, and S. L. Branton. 2009. Effects of the addition of roller mill ground corn to pelleted feed during a fifty-six-day production period on growth performance and processing yields of broiler chickens. J. Appl. Poult. Res. 18:310–317. 12. Nir, I., Y. Twina, E. Grossman, and Z. Nitsan. 1994. Quantitative effects of pelleting on performance, gastrointestinal tract and behavior of meat-type chickens. Br. Poult. Sci. 35:589–602. 13. Briggs, J. L., D. E. Maier, B. A. Watkins, and K. C. Behnke. 1999. Effects of ingredients and processing parameters on pellet quality. Poult. Sci. 78:1464–1471. 14. Jacobson Mfg. Co., Minneapolis, MN. 15. Roskamp Champion, Roskamp, Waterloo, IA. 16. Sprout-Waldron, Muncie, PA. 17. California Pellet Mill Master Model HD Series 1000, CPM Co., Crawfordville, IN. 18. American Society of Agricultural Engineers. 1993. Cubes, pellets, and crumbles—Definitions and method for determining density, durability, and moisture. Method S269.4 in Am. Soc. Agric. Eng. Yearb. of Stand. Am. Soc. Agric. Eng., St. Joseph, MI. 19. Aviagen Inc., Huntsville, AL. 20. Temperature set points consisted of 34°C from placement to 4 d, 32°C from 5 to 9 d, 29°C from 10 to 14 d, 28°C from 15 to 19 d, 27°C from 20 to 24 d, 26°C from 25 to 29 d, 24°C from 30 to 34 d, 22°C from 35 to 39 d, and 21°C from 40 to 42 d. 21. A continuous lighting program was used throughout production, with a light intensity of 30 lux being implemented from placement until 7 d of age, an intensity of 5 lux from 8 to 22 d, and an intensity of 3 lux from 23 to 42 d of age. Light intensity settings were verified at the bird level (30 cm) by using a photometric sensor with National Institute of Standards and Technology-traceable calibration (403125, Extech Instruments, Waltham, MA) for each intensity adjustment.
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low-quality pellets. In agreement, Dozier et al. [11] reported that broilers fed diets having 20, 30, and 40% of the formulated corn post-pellet from 18 to 35 d, 36 to 46 d, and 47 to 56 d of age, respectively, had cumulative BW gain, feed intake, feed conversion, carcass weight and yield, and total breast meat weight and yield similar to birds fed pelleted feeds with no added corn postpellet. In addition, Dozier et al. [10] determined that 25 and 35% of formulated corn post-pellet could be added from 18 to 29 d and 30 to 42 d of age without adverse effects on BW gain and feed conversion. From 18 to 29 d of age, BW gain and feed conversion were adversely affected when added corn post-pellet was increased to 35%, inferring that the proportion of added corn post-pellet should be limited during the grower period and should increase as the broiler advances in age [11].
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226 22. Model C2M, Chore Time/Brock International, Milford, IN. 23. SAS Institute. 2004. SAS User’s Guide: Statistics. Version 9.1 Edition. SAS Inst. Inc., Cary, NC. 24. Jensen, L. S., L. H. Merrill, C. V. Reddy, and J. McGinnis. 1962. Observations on eating patterns and rate of
JAPR: Research Report passage of birds fed pellets and unpelleted diets. Poult. Sci. 41:1414–1419. 25. Moran, E. T., Jr. 1989. Effect of pellet quality on the performance of meat birds. Pages 87–108 in Recent Advances in Animal Nutrition. W. Harasign and D. J. A. Cole, ed. Butterworths, London, UK.
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Effects of feed form on growth performance and processing yields of broiler chickens during a 42-day production period1 W. A. Dozier III,*2,3 K. C. Behnke,† C. K. Gehring,‡ and S. L. Branton*
Primary Audience: Feed Mill Managers, Live Production Personnel, Nutritionists SUMMARY Meat birds fed high-quality pellets exhibit advantages in rate and efficiency of growth over birds fed poorer quality pellets. However, the associated feed manufacturing cost and reduced production rates to obtain high-quality pellets are viewed by the industry as offsetting the benefits in broiler performance provided by high-quality pellets. With the combination of increased costs for utilities in the feed mill and for feed ingredients, strategies are needed to conserve milling costs while optimizing the efficiency of broiler growth. In this study, we evaluated the effects of feed form on live performance and meat yield of broiler chickens during a 42-d production period. Four treatments were provided from 18 to 42 d of age: 1) high-quality pellets (88% pellet durability index), 2) low-quality pellets (66% pellet durability index), 3) a proportion of the formulated corn added post-pellet (89% pellet durability index), and 4) mash (corn was ground via a roller mill). Broilers fed the high-quality pellets had higher cumulative BW gain and consumed more feed than birds fed low-quality pellets. Mash-fed broilers had poorer growth performance and less meat recovery than birds in the other treatments. Adding corn post-pellet resulted in broilers having similar performance and meat yields compared with those fed high-quality pellets. In this study, we confirm that adding corn post-pellet does not negatively affect growth performance and meat yield. Feeding broilers high-quality pellets provides a benefit in growth rate over feeding low-quality pellets by increasing feed consumption. Key words: broiler, corn, feed manufacturing, grinding, particle size 2010 J. Appl. Poult. Res. 19:219–226 doi:10.3382/japr.2010-00156
DESCRIPTION OF PROBLEM Because of the demand for corn and oils for biofuel production, feed ingredients recently have reached unprecedented prices, translating 1
to increased live production costs for broilers [1]. Therefore, optimizing feed conversion at effective costs is of utmost importance. Providing meat birds diets in whole pellet form improves the rate and efficiency of growth [2–5]. Cutlip
Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA and Kansas State University. 2 Corresponding author: [email protected] 3 Current address: Auburn University, Department of Poultry Science, 201 Poultry Science Building, 260 Lem Morrison Drive, Auburn, AL 36849-5416.
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*USDA, Agricultural Research Service, Poultry Research Unit, Mississippi State, MS 39762; †Department of Grain Science and Industry, Kansas State University, Manhattan 66506; and ‡Department of Poultry Science, Auburn University, Auburn, AL 36849
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MATERIALS AND METHODS Dietary Treatments Broilers were fed a 3-phase feeding program during a 42-d production period. Diets were identical in nutrient specifications during the same age period (Table 1). The common start-
er feed was provided as crumbles until 15 d of age. Four treatments differing in feed form were evaluated from 15 to 42 d of age (Table 2). The 4 treatments were 1) high-quality pellets, 2) lowquality pellets, 3) 20 and 30% of the formulated corn added post-pellet from 15 to 28 d and 29 to 42 d of age, respectively, and D) mash using roller mill ground corn. Feed Manufacturing Experimental diets (grower and finisher) were manufactured at the Grain Science Department at Kansas State University (Table 1). Yellow dent corn was ground through a 22.4-kW Jacobson hammer mill [14] using a screen with 4.0-mm holes or was cracked on a Roskamp [15] 3-high roller mill. Roll gaps for the coarse rolled corn were set at 2.46 mm for the top rolls, with the bottom 2-roll sets being left open. The average particle size of the coarse rolled corn was approximately 2,600 μm for treatment 3 and 1,200 μm for treatment 4. After grinding, the rolled corn for treatment 3 was sifted over a number 10 wire to remove fines. Fines were diverted to the hammer mill ground corn bin so that the sifted fines from the rolled corn were returned to the diet as a part of the corn fraction in the mixer. After the grinding process, ingredients were batched and mixed in a horizontal double ribbon mixer [16] for 120 s of dry mixing, followed by 180 s of wet mixing. Fat was added at 0.5% in the mixer for treatments 1 and 3, and the remaining fat was added post-pellet. Conversely, all the fat was added in the mixer for treatments 2 and 4. The complete mash diets and incomplete mash diets of treatments 1 and 3 (without rolled corn added post-pellet) were conditioned and pelleted with a CPM pellet mill [17]. The pellet mill was equipped with a 31.8-mm-thick die and with 4.8-mm-diameter holes. In addition, treatments 1 and 3 were conditioned at 85°C, whereas conditioning temperature was reduced to 71°C with treatment 2. The combination of using a lower conditioning temperature and additional fat in the mixer facilitated the production of lower quality pellets for treatment 2. After pelleting, all pellets were placed in the mixer for 30 s for the following steps: 1) add fat to treatment 1; 2) subject treatment 2 to the same mixing conditions as treatments 1 and 3; and 3) mix incomplete pelleted diets for treatment 4
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et al. [6] examined the performance of broilers fed diets differing in pellet quality. Those fed diets having a better modified pellet durability index (PDI; 90 vs. 80%) had lower cumulative feed conversion (1.99 vs. 2.16) and higher breast meat yields (21.32 vs. 20.23%). Moritz et al. [7] reported that broilers fed diets having a high pellet quality (87% PDI) had improved FE (standardized at 12.5% moisture; 0.579 vs. 0.572 kg/ kg) compared with birds provided feed having a lower pellet quality (62% PDI). Conditioning and pelleting increase the cost of manufacturing diets ($4 to $6 per ton). Strategies are needed to reduce the utility cost of manufacturing and enhance the pelleting production rate while not adversely affecting broiler performance. Clarke and Behnke [8] determined that adding 30% of the formula corn (as coarse rolled corn) post-pellet resulted in decreased manufacturing cost and increased pelleting output. Pelleting production rate was increased by 20% when 30% of the formulated corn was added post-pellet. Adding 20 to 35% of the formulated corn post-pellet during the grower and finisher periods has not limited broiler growth or meat yield [9–11]. Another strategy for improving manufacturing cost may be to provide the diets in mash form, using roller mill ground corn to control flow problems. Broilers fed mash diets ground through a hammer mill exhibit poorer growth than birds fed pelleted diets [3, 12]. Mash diets are known to have poor flowability with mechanical feeding equipment, resulting in poor growth performance of meat birds [13]. Grinding corn via roller mill results in a more uniform grind size, and using a relatively larger particle size may improve feed flowability and broiler performance without the higher utility cost associated with feed manufacturing. In this study, we examined live production and meat yield responses of mixed-sexed broilers fed diets provided as 4 feed forms from 15 to 42 d of age.
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Table 1. Ingredient and nutrient composition of the experimental diets Item
Grower, 15 to 28 d 63.00 26.21 5.00 3.10 1.27 0.56 0.30 0.25 0.17 0.08 0.08
66.88 22.44 5.00 3.21 1.02 0.61 0.33 0.25 0.14 0.05 0.08
3,150 20.0 0.85 1.15 0.82 0.85 0.43 0.22
3,200 18.5 0.78 1.02 0.76 0.78 0.38 0.22
1
Vitamin and mineral premix supplied per kilogram of diet: selenium, 0.15 mg; manganese, 100 mg; iron, 50 mg; iodine, 1.5 mg; zinc, 100 mg; retinyl acetate, 7,715 IU; cholecalciferol, 2,756 IU; α-tocopherol acetate,17 IU; menadione sodium bisulfate, 0.8 mg; cyanocobalamin, 0.01 mg; thiamine mononitrate, 1.1 mg; riboflavin, 6.6 mg; pyridoxine hydrochloride, 1.4 mg; nicotinic acid amine, 28 mg; d-calcium pantothenate, 6.6 mg; folic acid, 0.69 mg; d-biotin, 0.044 mg; choline chloride, 386 mg. 2 Coban 60 (Elanco, Indianapolis, IN) provided 90 g of monensin sodium per 907.2 kg of diet.
experimental facility was solid-sided, with a negative-pressure ventilation system equipped with exhaust fans and evaporative cooling pads. The temperature regimen and lighting schedule were similar to those used in commercial practice [20, 21]. Each pen had new pine shavings, a tube feeder [22], and a nipple drinker line having 9 nipples. Birds were offered feed and water ad libitum. Birds and feed were weighed on a pen basis at 1, 15, 28, and 42 d of age for the determination of growth rate, feed intake, and feed conversion. Mortality was recorded daily. On d 43, 12 birds per pen (6 males and 6 females) were randomly selected for processing, weighed, placed in coops, and transported to the Mississippi State University Poultry Processing
with rolled corn and the remaining supplemental fat. Representative samples were collected to assess pellet integrity using standard procedures [18]. After mixing, all diets were bagged and transported to the USDA-Agricultural Research Service Poultry Research Unit at Mississippi State, Mississippi. Bird Management and Processing Yields Sixteen hundred Ross × Ross 708 [19] broiler chicks were obtained from a commercial hatchery and randomly distributed to 32 floor pens (25 males and 25 females; 0.07 m2) 4 h after hatching. At the hatchery, chicks were administered vaccinations for Marek’s disease, Newcastle disease, and infectious bronchitis. The
Table 2. Pellet durability index (PDI) of diets differing in feed form from 15 to 42 d of age1 Grower Treatment High-quality pellets Low-quality pellets Added rolled corn post-pellet 1
Values are duplicate averages.
Finisher
PDI, %
Modified PDI, %
PDI, %
Modified PDI, %
88.92 66.04 89.48
85.02 50.63 87.00
89.55 67.05 90.01
86.26 54.65 87.82
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Ingredient, % (as-is basis) Corn Soybean meal (47.5% CP) Poultry by-product meal (58.0% CP) Poultry oil Defluorinated phosphate Calcium carbonate Sodium chloride Mineral and vitamin premix1 dl-Methionine l-Lysine hydrochloride Monensin sodium2 Calculated composition AMEn, kcal/kg CP, % Methionine + cysteine, % Lysine, % Threonine, % Calcium, % Nonphytate phosphorus, % Sodium, %
Finisher, 29 to 42 d
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Statistics Data were statistically evaluated using the ANOVA procedure of SAS [23]. The experimental design consisted of a 1-way treatment structure using a randomized complete block design, with pen location being the blocking factor. Means were separated by Tukey’s honestly significant differences procedure [23] when the overall F-test was P ≤ 0.05. Preplanned orthogonal contrasts were used to divide treatment effects with 3 df into 1) pellets vs. mash, 2) highquality pellets vs. low-quality pellets, and 3) high-quality pellets vs. added corn post-pellet. Statistical significance was established at P ≤ 0.05.
RESULTS Live Performance Broilers fed pelleted diets grew faster (P ≤ 0.001) and consumed more (P ≤ 0.001) feed from 15 to 28 d, 15 to 42 d, and 1 to 42 d of age than mash-fed broilers (Tables 3, 4, and 5). Feeding higher quality pellets to broilers increased growth rate and feed consumption during the grower, finisher, and cumulative periods over birds fed diets having lower quality pellets. Broilers fed lower quality pellets had marginally superior cumulative feed conversion compared with birds fed higher quality pellets (1.694 vs. 1.712). From 15 to 28 d of age, broilers fed highquality pellets had superior feed conversion (P ≤ 0.022) compared with birds provided feeds having rolled corn post-pellet, but no differences in feed conversion were noted in subsequent periods. In addition, BW gain was similar for broil-
ers fed diets presented as high-quality pellets or rolled corn post-pellet throughout experimentation. No treatment differences (P = 0.24) were observed for the incidence of mortality. Processing Yields Broilers fed diets in pelleted form had advantages (P ≤ 0.05) in carcass weight, carcass yield, total breast meat weight, and total meat yield. Feeding broilers diets as low-quality pellets and rolled corn post-pellet produced similar (P < 0.05) carcass and breast meat yields as birds provided diets as high-quality pellets (Table 6).
DISCUSSION In the United States, feeding broiler chickens diets in crumble or whole pellet form is practiced exclusively. Advantages of feeding pelleted diets are improved flowability with mechanical feeding systems, decreased feed wastage, and an enhanced rate and efficiency of growth [2–4, 13]. The improvement in broiler performance due to pelleting relates to less time devoted to eating translating to reduced energy spent for prehension [24, 25]. However, pelleting is a costly process and the benefits of high-quality pellets have been a subject of debate. Alternatives are needed to reduce feed manufacturing costs without compromising the growth performance and meat yield of broilers. In the present research, broilers provided mash diets exhibited similar BW gain, feed conversion, and breast meat weight as broilers fed low-quality pellets. This may have occurred because the corn was ground via a roller mill, which had larger and more uniform particle sizes, potentially allowing for improved flowability in the feeders compared with when corn was ground via hammer mill. Moreover, previously, researchers may have used a higher quality pellet that accentuated the performance differences of broilers fed pellets vs. mash diets. Broilers fed the high-quality pellets grew 2.7 and 4.7% faster and consumed 3.7 and 5.6% more feed, respectively, compared with birds fed diets as low-quality pellets or as mash from 15 to 49 d of age. The improvement in BW gain was commensurate with increased feed intake. In parallel 15- to 42-d data, feeding broilers diets as high-quality pellets increased BW gain
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Plant. Feed was removed 12 h before processing. Birds were electrically stunned (5 s), exsanguinated (80 s), scalded (150 s, 53°C, and 12.5 V), mechanically picked (35 s), and mechanically eviscerated. Whole carcass (without abdominal fat) and abdominal fat were weighed. Carcasses were split into front and back halves and placed on ice for 18 h. The front halves were then deboned to obtain weights of the pectoralis major and minor muscles. Carcass, abdominal fat, and total breast meat (pectoralis major and minor muscles) yields were determined from 43-d BW of the broilers selected for processing.
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Table 3. Growth performance of Ross × Ross 708 male broilers fed diets differing in feed form from 15 to 28 d of age1 Item
BW, kg
BW gain, kg
Response criterion High-quality pellets (1) Low-quality pellets (2) Added rolled corn post-pellet (3) Mash (4) SEM
1.311a 1.273ab 1.289ab 1.247b 0.011
0.828a 0.793ab 0.801a 0.756b 0.009
Feed intake, kg 1.232a 1.178b 1.224a 1.143b 0.010
FCR2
Mortality, %
1.486ab 1.480b 1.522a 1.503ab 0.010
0.5 0.2 0.7 0.2 0.3
0.144 0.735 0.022
0.741 0.568 0.568
P-value 0.005 0.035 0.205
0.0001 0.016 0.053
<0.0001 0.001 0.576
a,b
Means within a column without a common superscript differ (P < 0.05). Values are least squares means of 8 replicate pens with 50 broilers per pen at 1 d of age. 2 Corrected for mortality. 1
by 72 and 123 g, respectively, compared with birds fed diets in the forms of low-quality pellets or mash. Cumulative feed conversion was 1% higher for broilers fed diets as high-quality pellets compared with those fed low-quality pellets. This difference probably resulted from increased maintenance requirements associated with higher BW. No differences were observed for processing parameters for broilers fed highand low-quality pellets. However, total breast meat weight was reduced by 43 g when mash diets were fed relative to broilers provided diets as high-quality pellets. Manufacturing highquality pellets resulted in superior growth rate,
and this improvement could potentially translate to a decreased number of grow-out days. The current study was conducted during winter months, when growth rate and feed intake were favorable, so the magnitude of the differences observed between treatments might have varied if this research had been conducted during summer production, when feed intake is limited. In agreement with the current research, Proudfoot and Sefton [2] evaluated growth and meat yield responses of broilers fed diets containing varying proportions of fines from 28 to 49 d of age. Broilers fed pelleted diets with 0% fines had the highest 49-d BW, whereas cumulative
Table 4. Growth performance of Ross × Ross 708 male broilers fed diets differing in feed form from 15 to 42 d of age1 Item Response criterion High-quality pellets (1) Low-quality pellets (2) Added rolled corn post-pellet (3) Mash (4) SEM
BW, kg 2.684a 2.612bc 2.653ab 2.562c 0.017
BW gain, kg 2.202a 2.132bc 2.165ab 2.071c 0.017
Feed intake, kg 3.899a 3.737b 3.862a 3.656b 0.025
FCR2
Mortality, %
1.761 1.745 1.769 1.751 0.007
1.2 0.9 2.1 1.2 0.5
0.834 0.161 0.437
0.854 0.726 0.246
P-value Planned orthogonal contrast 1 and 2 vs. 4 1 vs. 2 1 vs. 3 a–c
<0.001 0.009 0.234
<0.001 0.009 0.146
<0.0001 <0.001 0.328
Means within a column without a common superscript differ (P < 0.05). Values are least squares means of 8 replicate pens with 50 broilers per pen at 1 d of age. 2 Corrected for mortality. 1
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Planned orthogonal contrast 1 and 2 vs. 4 1 vs. 2 1 vs. 3
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Table 5. Growth performance of Ross × Ross 708 male broilers fed diets differing in feed form from 1 to 42 d of age1 Item
BW, kg
Response criterion High-quality pellets (1) Low-quality pellets (2) Added rolled corn post-pellet (3) Mash (4) SEM
3.167a 3.093ab 3.141a 3.053b 0.020
BW gain, kg
Feed intake, kg
2.641a 2.569bc 2.610ab 2.518c 0.017
4.523a 4.355b 4.477a 4.270b 0.028
FCR2
Mortality, %
1.712ab 1.694b 1.715a 1.695b 0.004
2.0 1.3 1.6 1.5 0.5
0.183 0.016 0.675
0.857 0.311 0.616
P-value 0.005 0.017 0.383
<0.001 0.010 0.236
<0.0001 <0.001 0.259
a–c
Means within a column without a common superscript differ (P < 0.05). Values are least squares means of 8 replicate pens with 25 broilers per pen at 1 d of age. 2 Corrected for mortality. 1
feed conversion was optimized with 15% fines. Feeding mash diets and pelleted diets containing 100% fines produced similar results, with an 8% reduction in BW gain and the FCR increased by 4% when compared with the pelleted treatments, providing the best responses for growth rate and feed conversion. Choi et al. [3] reported increases in BW gain and feed intake of 11 and 10%, respectively, for broilers fed pelleted vs. mash fed diets from 28 to 56 d of age. No difference in feed conversion was noted between birds fed pelleted and mash diets.
Adding a proportion of the formulated corn post-pellet is potentially a strategy to reduce milling costs without compromising broiler performance [9–11]. In the current research, broilers fed diets having a proportion of the formulated corn added post-pellet resulted in cumulative growth rate, feed intake, feed conversion, carcass weight and yield, and total breast weight and yield similar to birds fed high-quality pellets. In addition, feeding broilers diets having added corn post-pellet increased the cumulative feed intake by 122 g compared with broilers fed
Table 6. Processing weights and yields of 43-d-old Ross × Ross 708 male broilers fed diets differing in feed form from 1 to 42 d of age1 Carcass Item Response criterion High-quality pellets (1) Low-quality pellets (2) Added rolled corn post-pellet (3) Mash (4) SEM
Abdominal fat
Total breast
Weight, kg
Yield,2 %
Weight, kg
Yield, %
Weight, kg
Yield, %
1.949a 1.891ab 1.893ab 1.813b 0.028
70.61 70.67 70.05 69.45 0.42
0.057 0.051 0.053 0.052 0.001
2.09 1.92 1.96 2.00 0.07
0.570a 0.559ab 0.558ab 0.527b 0.009
20.65 20.92 20.63 20.18 0.23
0.999 0.106 0.214
0.003 0.443 0.372
P-value Planned orthogonal contrast 1 and 2 vs. 4 1 vs. 2 1 vs. 3 a,b
0.006 0.166 0.182
0.032 0.929 0.354
0.446 0.030 0.121
Means within a column without a common superscript differ (P < 0.05). Values are least squares means of 8 replicate pens with 12 broilers per pen. 2 Yields are defined as grams of tissue/100 g of BW. 1
0.043 0.412 0.966
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Planned orthogonal contrast 1 and 2 vs. 4 1 vs. 2 1 vs. 3
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CONCLUSIONS AND APPLICATIONS
1. Feeding broilers diets in mash form ground via roller mill adversely affected cumulative feed intake, BW gain, carcass weight, and total breast meat weight when compared with feeding broilers high-quality pellets, but not low-quality pellets. 2. Feeding broilers diets having added rolled corn post-pellet resulted in growth performance and meat yield similar to broilers provided diets as high-quality pellets. 3. Broilers fed diets as high-quality pellets exhibited BW gain and feed intake advantages from 15 to 42 d and 1 to 42 d of age compared with birds in the other treatments.
REFERENCES AND NOTES 1. Donohue, M., and D. L. Cunningham. 2009. Effects of grain and oilseed meals on the cost of US poultry production. J. Appl. Poult. Res. 18:325–337. 2. Proudfoot, F. G., and A. E. Sefton. 1978. Feed texture and light treatment effects on the performance of broiler chickens. Poult. Sci. 57:408–416. 3. Choi, J. H., B. S. So, K. S. Ryu, and S. L. Kang. 1986. Effects of pelleted or crumbled diets on the performance and development of the digestive organs of broilers. Poult. Sci. 65:594–597. 4. McKinney, L. J., and R. G. Teeter. 2004. Predicting effective caloric value of nonnutritive factors: I. Pellet
quality and II. Prediction of consequential formulation dead zones. Poult. Sci. 83:1165–1174. 5. Proudfoot, F. G., and H. W. Hulan. 1982. Feed texture effects on the performance of turkey broilers. Poult. Sci. 57:408–416. 6. Cutlip, S. E., J. M. Hott, N. P. Buchanan, A. L. Rack, J. D. Latshaw, and J. S. Moritz. 2008. The effect of steamconditioning practices on pellet quality and growing broiler nutritional value. J. Appl. Poult. Res. 17:249–261. 7. Moritz, J. S., R. S. Beyer, K. J. Wilson, and K. R. Cramer. 2001. Effect of moisture at the feed mixer to a cornsoybean-based diet on broiler performance. J. Appl. Poult. Res. 10:347–353. 8. Clark, P. M., and K. C. Behnke. 2004. Effects of pelleting protein concentrate pellets on feed mill throughout and electrical efficiency. Poult. Sci. 83(Suppl. 1):170. (Abstr.) 9. Clark, P. M., K. C. Behnke, and A. C. Fahrenholz. 2009. Effects of feeding cracked corn and concentrate protein pellets on broiler growth performance. J. Appl. Poult. Res. 18:259–268. 10. Dozier, W. A., III, K. Behnke, M. T. Kidd, and S. L. Branton. 2006. Effects of the addition of roller mill ground corn to pelleted feed on pelleting parameters, broiler performance, and intestinal strength. J. Appl. Poult. Res. 15:236– 244. 11. Dozier, W. A., III, K. Behnke, P. Twining, and S. L. Branton. 2009. Effects of the addition of roller mill ground corn to pelleted feed during a fifty-six-day production period on growth performance and processing yields of broiler chickens. J. Appl. Poult. Res. 18:310–317. 12. Nir, I., Y. Twina, E. Grossman, and Z. Nitsan. 1994. Quantitative effects of pelleting on performance, gastrointestinal tract and behavior of meat-type chickens. Br. Poult. Sci. 35:589–602. 13. Briggs, J. L., D. E. Maier, B. A. Watkins, and K. C. Behnke. 1999. Effects of ingredients and processing parameters on pellet quality. Poult. Sci. 78:1464–1471. 14. Jacobson Mfg. Co., Minneapolis, MN. 15. Roskamp Champion, Roskamp, Waterloo, IA. 16. Sprout-Waldron, Muncie, PA. 17. California Pellet Mill Master Model HD Series 1000, CPM Co., Crawfordville, IN. 18. American Society of Agricultural Engineers. 1993. Cubes, pellets, and crumbles—Definitions and method for determining density, durability, and moisture. Method S269.4 in Am. Soc. Agric. Eng. Yearb. of Stand. Am. Soc. Agric. Eng., St. Joseph, MI. 19. Aviagen Inc., Huntsville, AL. 20. Temperature set points consisted of 34°C from placement to 4 d, 32°C from 5 to 9 d, 29°C from 10 to 14 d, 28°C from 15 to 19 d, 27°C from 20 to 24 d, 26°C from 25 to 29 d, 24°C from 30 to 34 d, 22°C from 35 to 39 d, and 21°C from 40 to 42 d. 21. A continuous lighting program was used throughout production, with a light intensity of 30 lux being implemented from placement until 7 d of age, an intensity of 5 lux from 8 to 22 d, and an intensity of 3 lux from 23 to 42 d of age. Light intensity settings were verified at the bird level (30 cm) by using a photometric sensor with National Institute of Standards and Technology-traceable calibration (403125, Extech Instruments, Waltham, MA) for each intensity adjustment.
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low-quality pellets. In agreement, Dozier et al. [11] reported that broilers fed diets having 20, 30, and 40% of the formulated corn post-pellet from 18 to 35 d, 36 to 46 d, and 47 to 56 d of age, respectively, had cumulative BW gain, feed intake, feed conversion, carcass weight and yield, and total breast meat weight and yield similar to birds fed pelleted feeds with no added corn postpellet. In addition, Dozier et al. [10] determined that 25 and 35% of formulated corn post-pellet could be added from 18 to 29 d and 30 to 42 d of age without adverse effects on BW gain and feed conversion. From 18 to 29 d of age, BW gain and feed conversion were adversely affected when added corn post-pellet was increased to 35%, inferring that the proportion of added corn post-pellet should be limited during the grower period and should increase as the broiler advances in age [11].
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226 22. Model C2M, Chore Time/Brock International, Milford, IN. 23. SAS Institute. 2004. SAS User’s Guide: Statistics. Version 9.1 Edition. SAS Inst. Inc., Cary, NC. 24. Jensen, L. S., L. H. Merrill, C. V. Reddy, and J. McGinnis. 1962. Observations on eating patterns and rate of
JAPR: Research Report passage of birds fed pellets and unpelleted diets. Poult. Sci. 41:1414–1419. 25. Moran, E. T., Jr. 1989. Effect of pellet quality on the performance of meat birds. Pages 87–108 in Recent Advances in Animal Nutrition. W. Harasign and D. J. A. Cole, ed. Butterworths, London, UK.
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