J. Appl. Poult. Res.
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J APPL POULT RES 2006. 15:236-244
© 2006 Poultry Science Association
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Research Reports

Effects of the Addition of Roller Mill Ground Corn to Pelleted Feed on Pelleting Parameters, Broiler Performance, and Intestinal Strength1

W. A. Dozier, III*,2, K. Behnke{dagger}, M. T. Kidd{ddagger} and S. L. Branton*

* United States Department of Agriculture, Agriculture Research Service, Poultry Research Unit PO Box 5367, Mississippi State 39762-5367; {dagger} Department of Grain Science and Industry, Kansas State University, Manhattan 66506; and{ddagger} Department of Poultry Science, Mississippi State University, Mississippi State 39762

Correspondence: 2 Corresponding author: bdozier{at}msa-msstate.ars.usda.gov


   SUMMARY
TOP
 SUMMARY
DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Maintaining an optimal pelleting production rate can be difficult when manufacturing feeds for meat birds. Increased production time may be required to fill feed demand and feed outages occur if demand is not met. Identifying management strategies to enhance overall feed production rate without compromising broiler performance is warranted. This study examined the effects of adding varying amounts of corn, ground through a roller mill, to pelleted supplements on feed production parameters, growth performance, and intestinal strength of broiler chickens. Four treatments were used from 18 to 41 d, which included a control (total diet pelleted), and addition of rolled corn to pelleted supplements at 15, 25, and 35% of the corn required in diet formulation. The final diets fed were identical in nutrient composition. Decreasing the amount of ground corn in the pelleted supplement did not affect pellet durability index in the grower diet, but pellet quality declined in the finisher diet. The dietary treatments did not adversely affect final BW gain or feed conversion. Progressive additions of ground corn to pelleted supplement did not affect gizzard weight or peak force intestinal strength. These data indicate that 35% of the formula corn can be added postpellet to reduce electrical cost for grinding and pelleting and improve overall production rate without adversely affecting cumulative growth performance of broilers.

Key Words: broiler • corn • grinding • particle size • pellet quality


   DESCRIPTION OF PROBLEM
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Due to the demand for breast fillets and value-added products, market weights of broiler chickens have been increased. Because of this increase, some older feed mills may be faced with challenges to meet increased feed demand. Many of these facilities were designed for less production capacity based on market demand for smaller broilers. This has led to increased production and increased employee workloads to meet feed demands. In addition, increased feed production schedules require more total energy usage for feed manufacturing. Utility usage comprises approximately 25 to 30% of the feed manufacturing cost [1] with labor also representing a significant portion of the cost.

In Europe and Canada whole wheat has been added to pelleted feed to increase usage of locally grown grain [2]. Broiler growers can blend whole wheat (15 to 20%) with pelleted supplements without adversely affecting growth responses [3]. This, in turn, reduces energy usage associated with grinding and pelleting at the feed mill. Supplementing whole wheat (20%) to pelleted feed did not alter the BW of broiler chickens provided that diet density was not reduced [4, 5, 6]. However, feed conversion of broiler chickens or turkeys was adversely affected with progressive additions of whole wheat or barley compared with the control group [4, 6, 7]. Other research found no differences in feed conversion with birds fed diets supplemented with whole grains [5, 8].

Clark and Behnke [9] showed that pelleting a protein concentrate and adding cracked corn, postpellet, at 13 and 28% of its formulated amount improved pelleting production rate without affecting pellet durability index (PDI). Moreover, the addition of 13 and 28% cracked grain postpellet decreased total feed mill energy usage by 11 and 22%, respectively. However, growth performance of broiler chicks was not evaluated. Broilers are known to undergo reverse intestinal peristalsis [10]; providing feeds with larger particles may lead to increased intestinal strength.

This study examined the effects of adding increased amounts of rolled corn to a pelleted feed supplement on pellet quality, growth performance, and intestinal strength of male broilers.


   MATERIALS AND METHODS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Husbandry Practices
One thousand, six hundred Ross [11] x Cobb [12] male broiler chicks were obtained from a commercial hatchery and randomly distributed to 32 floor pens (50 birds per pen; 0.07 m2/bird) of a solid-sided facility at 1 d of age. Vaccinations for Marek’s disease, Newcastle disease, and infectious bronchitis were administered at the hatchery. Each pen was equipped with fresh pine shavings, a tube feeder [13], and nipple watering system. The temperature regimen and lighting schedule were similar to those used in commercial practice [14, 15]. The experimental facility had a negative-pressure ventilation system equipped with exhaust fans and evaporative cooling pads. All birds were offered feed and water ad libitum. Average BW and feed weight on a pen basis were collected at 17, 29, and 41 d of age for the calculation of feed disappearance, growth rate, and feed conversion. Mortality was recorded daily.

Feed Manufacturing
A 3-phase feeding program was used (Table 1Go) and all feed treatments in a phase were formulated to be isocaloric and isonitrogenous. The starter feed was provided as crumbles and subsequent feeds were fed as whole pellets (4,746 µm). The corn used in the pelleted feed was ground through a hammer mill (800 µm) [16], whereas the corn added postpellet was ground through a roller mill (1,500 µm) [17]. The average particle sizes of the corn ground via hammer mill and roller mill were determined using methodology previously published [18]. Ingredients for pelleted feed were batched and mixed in a 1-ton mixer for 300 s, and then conditioned and pelleted [19]. Supplemental fat was added in the mixer before feeds were conditioned and pelleted. Three samples from each feed treatment were collected to evaluate percentage of pellets and PDI [20], and pelleting production rate was determined. For PDI determination, each sample consisting of 250 g of whole pellets was placed in a pellet tumbler [21]. The pellet tumbler was operated for 5 min. Then, each sample was placed in a Ro-Tap Shaker [22] for 5 min and the amount of pellets retained on US sieves #4 (4,746 µm) and #8 (2,380 µm) were weighed. The amount of whole pellets obtained after tumbling was divided by the amount of whole pellets placed in the tumbler and multiplied by 100. Both the pelleted feed and rolled corn were placed in the mixer, mixed for 30 s, bagged, identified, and transported to the experimental facility.


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  		Table 1. Diet formulation of the feeds provided from placement until 41 d of age
 
Dietary Treatments
Four dietary treatments were used from 18 to 41 d of age. The 4 treatments consisted of 1) control—no added corn; 2) 15% rolled corn added to pelleted feed; 3) 25% rolled corn added to pelleted feed; and 4) 35% rolled corn added to pelleted feed. The amount of rolled corn added to pelleted feed was determined as a percentage of formulated corn (Table 2Go).


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  		Table 2. Amount of corn in the pelleted feeds and the added rolled corn postpelleting in the experimental feeds
 
Intestinal Strength
At 41 d of age, 10 birds from each pen were randomly selected, and killed by cervical dislocation. The viscera were removed and 2 sections of the small intestine (foregut and hindgut) were excised for the determination of intestinal strength. The intestinal sections were characterized as the foregut (from the duodenum loop to Meckel’s diverticulum) and the hindgut (from Meckel’s diverticulum to the ileo-cecal junction). Each section was approximately 25 cm long. The contents were gently discarded and adhering fat and connective tissue were removed before intestinal strength measurement. Peak force strength was measured by securing intestinal segments to the fasteners of a Texture Analyzer [23].

Statistical Analysis
Data were statistically evaluated by the ANOVA in a 1-way treatment structure in a randomized complete block design [24]. Orthogonal contrasts were established and treatment means were separated by Tukey’s honestly significant different procedure [25]. Orthogonal contrasts were used to divide treatment effects with 3 df into: 1) control vs. average addition of corn postpelleting (1 df), 2) linear effect of addition of corn postpelleting (1 df), and 3) lack of fit (differences in 3 amounts of added corn postpel-leting not explained by linear effect; 1 df). Statistical significance was established at P ≤ 0.05.


   RESULTS AND DISCUSSION
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Supplementing pelleted feed with rolled corn improved pelleting production rate (Figure 1Go). This measurement did not account for the amount of ground corn added postpellet; thus, added corn would accentuate these differences in pelleting production rate. Adding increasing amounts of rolled corn postpellet in the grower feed did not alter PDI, whereas percentage of pellets declined (P ≤ 0.0001) linearly (Table 3Go). Conversely, both PDI (P ≤ 0.006) and percentage of pellets (P ≤0.009) were reduced as rolled corn was added postpelleting in the finisher feeds (Table 3Go). However, the lack of fit for percentage pellets in the grower feed, and PDI and percentage of pellets in the finisher feed were P ≤0.0001, P ≤0.002, and P ≤0.004, respectively. This implies that a linear response did not adequately explain the differences among the treatment means. Other research has reported a 20% increase in pelleting production rate with adding ground corn postpelleting, but pellet quality was similar compared with the control feed [9]. In contrast to our research, supplemental fat was added as 1% in the mixer and the remaining amount of added fat was provided postpel-leting [9].


Figure 1
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  		Figure 1. Effects of added roller mill ground corn to pelleted feeds on pelleting production rate.

 

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  		Table 3. Effects of the reductions of corn prepellet on pellet quality1
 
In the present study, pellet quality decreased with the progressive addition of rolled corn post-pellet in the finisher feed. The amount of fat added in the mixer was approximately 4.0% of the diet. Pellet quality was not affected by the feed treatments during the grower period. The difference in PDI response between the grower and finisher periods may be explained by increasing dietary fat in the finisher period, but the difference in supplemental fat inclusion between the grower and finisher diets was only 0.19%. Increasing added fat above 1% has been shown to exponentially decrease pellet quality [26]. Even though the fat addition was equal across the treatments, in the final diets, the proportion of fat differed, relative to the other ingredients, as varying amounts of corn were omitted from the diets before pelleting. The amount of added fat on a weight basis was similar across the treatments to ensure that all diets were isocaloric when the rolled corn was added postpellet. If the amount of fat was not equalized in the pelleted feed, the energy content of the feeds after the addition of ground corn would have differed resulting in a confounding effect due to differences in ME content.

From 18 to 29 d of age, increasing rolled corn to 25% postpellet did not alter live performance, but increasing rolled corn to 35% adversely affected growth rate and feed conversion (Table 4Go). The increase in feed conversion because of the addition of 35% rolled corn postpel-let was only a 2-point difference indicating that the level of significance was partially due to a small amount of variation (SEM = 0.006) between the treatments. This reduction in performance was not apparent with the addition of rolled corn to pelleted feed from 30 to 41 d of age (Table 5Go) leading to no differences in cumulative live performance between the treatments (Table 6Go).


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  		Table 4. Growth performance responses of male broilers provided pelleted feeds having varying amounts of roller mill ground corn added from 18 to 29 d of age1
 

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  		Table 5. Growth performance responses of male broilers provided pelleted feeds having varying amounts of roller mill ground corn added from 30 to 41 d of age1
 

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  		Table 6. Cumulative growth performance of male broilers provided pelleted feeds having varying amounts of roller mill ground corn added from placement to 41 d of age1
 
Adding whole wheat to pelleted feeds adversely affected feed conversion but not BW of broiler chickens [4, 6]. Other published research demonstrated no reductions in growth rate or feed conversion by adding whole wheat at 15 and 30% from 24 to 33 and 34 to 42 d, respectively [5]. Bird age appeared to influence the response of adding whole grain to pelleted feed. In the present study, the addition of 35% rolled corn to the pelleted feed reduced growth rate and feed conversion compared with the control-fed birds from 18 to 30 d. However, these differences were not apparent from 30 to 41 and 0 to 41 d of age. In agreement, Bennett et al. [6] reported poor feed conversion with the addition of 20% whole wheat to the diet from 13 to 27 d of age, but feed conversion was similar to the control fed birds from 28 to 48 d as the whole-wheat addition was extended to 35%. The reduction in performance from d 13 to 27 may have been partially attributed to nutrient dilution. Bennett and Classen [7] determined with turkeys that adding crystalline and synthetic amino acids can alleviate reductions in BW and meat yield when turkeys were provided relatively high additions of whole wheat. The diets used in the current study were formulated to a moderate CP and amino acid nutrient density; therefore, cumulative reductions were not apparent but may have occurred if the diets were formulated to a suboptimal nutrient basis.

Intestinal strength and gizzard yield were not affected by the dietary treatments (data not shown). Adding whole wheat and barley to pelleted feed has been shown to increase gizzard weight relative to BW [6, 8, 27]. In the current study, adding rolled corn to pelleted feed probably did not induce increased gizzard activity to any great extent as other research has reported with supplementing diets with whole cereal grains [6, 8, 27, 28].

To reduce processing costs and increase the production potential of any given feed mill, a companion study to that presented herein was conducted in which either 13 or 28% of the rolled corn fraction was eliminated from a broiler formula (corn-soy—based diet) and replaced, postpellet, with coarsely ground (rolled) corn mixed with the pellet before fat-coating [9]. To keep the "fines" content of the final blend as low as possible and improve overall grinding, the roller mill ground corn was sieved across a 10-mesh screen (2.0 mm) with the –10-mesh fraction being added to the hammer mill ground grain and the +10 fraction isolated to be blended with the pellets to produce the complete feed. For this study, the actual throughput (ton/h) by cost center was used at an energy cost of $0.07/kWh. The energy cost for pelleting ($1.044/ton) was more than twice the cost of hammer mill grinding ($0.497/ton), and nearly 4 times the cost of roller mill grinding ($0.257/ton). When these values are used to calculate the unit cost for each cost center for the control, 13% grain removal, and 28% grain removal, the savings can be dramatic. Removing 28% of the grain prepellet and adding it postpellet increased production potential by 27% and decreased energy cost per ton of complete feed by an estimated 22%. Because 13% of the grain was removed prepel-let and added postpellet, production rate increased 12% and energy cost per ton decreased by 11%.

To project the potential savings to an integrated broiler feed mill, calculated estimates are shown in Table 7Go. Because of larger and more efficient equipment, the cost savings can be even greater than those found by Clark and Behnke [9]. By removing a fraction of the grain from the pellet mash, total production for a single line was increased from 41.1 ton/h (control) to 46.6 ton/h (13% removal) and 56.3 ton/h (28% removal). Electrical cost decreased from $0.88/ton (control) to $0.74/ton at 13% removal and $0.56/ton at 28% removal.


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  		Table 7. Electrical costs, monetary, and production responses for a single pelleting line (vertically integrated feed mill)
 
The implementation of this strategy can provide substantial economic benefits by reducing weekly operating time of the feed mill and decreasing cost for labor overtime. The capital investment ($75,000 to $100,000) to purchase and install a roller mill, sieve, and feeder to route the rolled corn to be mixed with the pelleted feed downstream would be required. In a commercial feed mill scenario, an integrated feed mill is operating 132 h (5 d/wk x 24 h + Saturday for 12 h) to produce 10,000 tons/wk [29]. The cost to operate the feed mill is about $300/h [29]. By adding part of the corn via postpellet would reduce operating time by 36 h resulting in a weekly savings of $10,800 (as well as improved employee morale by not operating the feed mill on weekends). With savings of this magnitude, the capital investment should be recovered within 1 yr.


   CONCLUSIONS AND APPLICATIONS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
REFERENCES AND NOTES
 

  1. Progressive additions of rolled corn to pelleted feed improved pelleting production rate. The PDI was not affected in the grower feed, but pellet quality declined in the finisher feed with the addition of rolled corn.
  2. Cumulative growth rate and feed conversion were not influenced by the addition of rolled corn postpellet.
  3. The addition of 35% rolled corn postpellet can decrease electrical cost for grinding and pelleting and increase production rate without compromising broiler performance.


   FOOTNOTES
 
1 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 U.S. Department of Agriculture. Back


   REFERENCES AND NOTES
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 

  1. Dozier, W. A., III. 2002. Reducing utility cost in the feed mill. Watt Poultry USA 53:40–44.
  2. Cumming, R. B. 1994. Opportunities in whole grain feeding. Pages 219–222 in Proc. 9th Eur. Poult. Conf. Vol. 2. WSPA (United Kingdom Branch), Glasgow, UK.
  3. Forbes, J. M., and M. Covasa. 1995. Application of diet selection by poultry with particular reference to whole cereals. Worlds Poult. Sci. J. 51:149–165.
  4. Bennett, C. D., H. L. Classen, and C. Riddell. 1995. Live performance and health of broiler chickens fed diets diluted with whole or crumbled wheat. Can. J. Anim. Sci. 75:611–614.
  5. Salah Uddin, M., S. P. Rose, T. A. Hiscock, and S. Bonnet. 1996. A comparison of the energy availability for chickens of ground and whole grain samples of two wheat varieties. Br. Poult. Sci. 37:347–357.[ISI][Medline]
  6. Bennett, C. D., H. L. Classen, and C. Riddell. 2002. Feeding broiler chickens wheat and barley diets containing whole, ground and pelleted grain. Poult. Sci. 81:995–1003.[Abstract/Free Full Text]
  7. Bennett, C. D., and H. L. Classen. 2003. Effect of whole wheat dilution on performance and carcass characteristics of male turkeys. J. Appl. Poult. Res. 12:468–475.[Abstract/Free Full Text]
  8. Svihus, B., O. Herstad, C. W. Newman, and R. K. Newman. 1997. Comparison of performance and intestinal characteristics of broilers fed on diets containing whole, rolled or ground barley. Br. Poult. Sci. 38:524–529.[ISI][Medline]
  9. Clark, P. M., and K. C. Behnke. 2004. Effects of pelleting protein concentrate pellets on feed mill throughput and electrical efficiency. Poult. Sci. 83(Suppl. 1):170. (Abstr.)
  10. Savage, S. I. 1995. Preparing broilers to minimize reprocessing. Pages 109–112 in Proc. 30th Natl. Mtg. Poult. Health and Processing, Ocean City, MD.
  11. Aviagen, Inc., Huntsville, AL.
  12. Cobb-Vantress, Inc., Siloam Springs, AR.
  13. Model C2MTM, Chore Time/Brock International, Mil-ford, IN.
  14. Temperature set points consisted of 33.3°C from placement to 4 d, 32.2°C from 5 to 9 d, 28.9°C from 10 to 14 d, 27.8°C from 15 to 19 d, 26.7°C from 20 to 24 d, 25.6°C from 25 to 29 d, 23.9°C from 30 to 34 d, 22.2°C from 35 to 39 d, and 21.1°C from 40 to 41 d.
  15. A continuous lighting program consisting of 23 h light with an intensity of 20 lx was implemented from placement until 7 d of age, 16 h light with an intensity of 5 lx from 8 to 23 d, and 24 h light with an intensity of 5 lx from 24 to 41 d of age.
  16. Jacobson Mfg. Co., Minneapolis, MN.
  17. Roskamp Champion, Waterloo, IA.
  18. Canada Committee on Agriculture Engineering. 1971. Size characteristics. Pages 2–10 in Agricultural Materials Handling Manual. Part 3: Processing Equipment. Section 3.2: Size Reduction and Mixing. Information Canada Publ. Div., Ottawa, ON, Canada.
  19. California Pellet Mill Master Model HD Series 1000, CPM Co., Crawfordsville, IN.
  20. American Society of Agricultural Engineers (ASAE). 1993. S269.4. Cubes, pellets, and crumbles-definitions and method for determining density, durability, and moisture. ASAE Yearbook of Standards. ASAE, St. Joseph, MI.
  21. Carthage Foundry and Machine Co., Carthage, MO.
  22. W. S. Tyler, Incorporated Combustion Engineering Inc., Menton, OH.
  23. Intestinal segments were wrapped around fasteners of a Texture Analyzer (Model TA-XT2 Texture Technologies Corp., Scarsdale, NY). Analyzer was operating with a crosshead speed of 100 mm/min.
  24. SAS Institute. 1985. SAS User’s Guide. Statistics. Version 5 Edition. SAS Institute, Inc., Cary, NC.
  25. Snedecor, G. W., and W. G. Cochran. 1989. Statistical Methods. 8th ed. Iowa State University Press, Ames.
  26. Rollins, D. 2002. The pelleting process. Arkansas Poult. Symp., Fayetteville, AR.
  27. Svihus, B., E. Juvik, H. Hetland, and A. Krogdahl. 2004. Causes for improvement in nutrient value of broiler chicken diets with whole wheat instead of ground wheat. Br. Poult. Sci. 45:55–60.[ISI][Medline]
  28. Hidalgo, M. A., A. J. Davis, N. M. Dale, and W. A. Dozier, III. 2004. Use of whole pearl millet in broiler diets. J. Appl. Poult. Res. 13:229–234.[Abstract/Free Full Text]
  29. Agri Stats, Inc. 2004. Live Production Analysis Manual. Agri Stats, Inc. http://www.agristats.com/




This Article
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Right arrow Articles by Branton, S. L.

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