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2010 Poultry Science Association, Inc.

2010 J. Appl. Poult. Res. 19:112120

doi:10.3382/japr.2009-00070

The effects of altering diet formulationand manufacturing technique on pellet quality

N. P. Buchanan, K. G. S. Lilly, C. K. Gehring, and J. S. Moritz1

Division of Animal and Nutritional Sciences, West Virginia University, Morgantown 26506

Primary Audience: Feed Mill Managers, Nutritionists, Researchers

SUMMARY

Least-cost diet formulations and pellet mill operating techniques vary widely. As a result,

pellet quality is often inconsistent. Past research has associated pellet quality changes with feed

formulation and manufacturing techniques. However, the interaction between the 2 factors has

rarely been explored. The objective of the current study was to evaluate the effects of altering

a least-cost diet (LC) formulation and altering manufacturing techniques on pellet process-

ing variables and quality. Generally, pellet quality improves with higher levels of protein and

moisture. Therefore, increased levels of CP and moisture were added to LC broiler starter and

grower formulations to compose a research-based (RB) formulation. The LC and RB formula-

tions were pelleted using 2 manufacturing techniques, a thin die with a fast production rate

(TF) or a thick die with a slow production rate (TS). During manufacture of the starter diets,

the RB formulation improved the pellet durability index (PDI) and modified PDI (MPDI) whiledecreasing pellet mill relative electrical energy usage (P 0.05) compared with the LC formu-

lation. The TS technique increased PDI and MPDI while decreasing production of fines (P

0.05) compared with the TF technique. During manufacture of the grower diets, the RB for-

mulation and TS technique resulted in decreased production of fines (P 0.05) compared with

the LC formulation and TF technique. A significant interaction observed for PDI and MPDI of

the grower diets indicated that the RB formulation improved pellet quality and would be even

more beneficial if a mill used a TF technique (P 0.05). We conclude that diet formulation

and manufacturing technique are, in fact, linked and must be considered when attempting to

optimize pellet quality.

Key words: diet formulation, manufacturing technique, pellet quality, broiler

DESCRIPTION OF PROBLEM

The pelleting process has been defined as

the agglomeration of small particles into larger

particles by means of a mechanical process in

combination with moisture, heat, and pressure

[1]. This combination results in thermomechani-

cal changes in feed constituents and an improve-

ment in feed form. The benefits associated with

pelleting include improved animal performance

and feed handling and decreased ingredient seg-

regation and feed spillage [2]. However, the feed

manufacturing process is costly both in capital

investment and in execution [3].

To minimize costs, the majority of production

animal diets are formulated on a least-cost basis.

1Corresponding author: [email protected]

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Least-cost diets allow nutritionists to minimize

feed ingredient costs by using a variety of ingre-

dients to meet or exceed the nutrient needs of the

animal. However, the use of some ingredients,

particularly by-product meals and alternative

grain sources, may inadvertently affect pellet

quality. For example, inclusion of inexpensive

by-product meals, such as dried distillers grains

with solubles [4] and oat hulls, has been shown

to decrease pellet quality [5]. In contrast, inclu-

sion of more expensive feed ingredients, such

as cellulose, soy protein isolate, and soybean

meal, has been shown to improve pellet quality

[5, 6]. These findings are particularly important

because nutritionists that formulate solely on a

least-cost basis may inadvertently decrease pel-let quality.

In addition to diet formulation, pellet qual-

ity is affected by manufacturing technique.

Currently, there are no industry standards for

manufacturing pellets. Each mill may operate

using different diet formulations, ingredient

particle sizes, steam pressures, conditioning

temperatures, and production rates [3]. For

example, in a survey conducted by Moritz [3],

commercial feed mills in the eastern UnitedStates used conditioning temperatures ranging

from 68 to 91C (155 to 195F), die length-to-

die hole diameter ratios (LDR) ranging from

6.5 to 13.1, and production rates ranging from

907 to 14,882 metric tons/wk (1,000 to 16,400

tons/wk). Variation in all these factors may af-

fect the amount of heat and moisture that feed

will accrue through the pelleting process. As a

result, thermomechanical changes in nutrients,

such as starch gelatinization and protein dena-turation, are widely variable. Inconsistency in

manufacturing technique, coupled with con-

stantly changing diet formulations, makes pre-

dicting and optimizing pellet quality difficult.

The objective of the current study was to pro-

vide a general recommendation for optimizing

the pelleting process based on diet formulation

and manufacturing technique.

MATERIALS AND METHODSA least-cost (LC) starter diet and an LC

grower diet were formulated using Cobb-Vant-

ress [7] nutrient recommendations for broilers

(Table 1). Based on previous results [5], 2 ad-

ditional diets were formulated, a research-based

(RB) starter diet and a RB grower diet (Table

1). The RB diets were formulated to have 3.87

percentage points more CP than the LC diets and

were supplemented with moisture (tap water) to

a calculated conditioned mash endpoint of 17%

[8]. The endpoint value was based on the con-

ditioned mash moisture recommendations of 16

to 18% established by Turner [9]. The LC and

RB starter diets and the LC and RB grower diets

were isocaloric and contained similar digestible

amino acid percentages [10]. It was necessary to

use digestible amino acids because these diets

were destined to be fed to broilers. If formula-

tion based on digestible amino acids were not

used, any improvements in growth could be at-tributed to changes in amino acid digestibility

rather than treatment differences.

All diets contained feedstuffs common to

commercial formulations, including corn, soy-

beans, dried distillers grains with solubles, wheat

middlings, and a blend of animal and vegetable

fat. For the LC and RB diets, a common inclu-

sion level of dried distillers grains with solubles,

wheat middlings, and animal-vegetable fat was

used to prevent any confounding effect that feedingredient might have on pellet quality.

The LC and RB diets were arranged in a fac-

torial design with 2 manufacturing techniques:

a thick die and a slow production rate (TS) or

a thin die and a fast production rate (TF). This

arrangement comprised 4 experimental treat-

ments: a RB diet manufactured using TS (RB-

TS); a RB diet manufactured using TF (RB-TF);

an LC diet manufactured using TS (LC-TS); and

an LC diet manufactured using TF (LC-TF).For the starter diets, a 1,089-kg (2,400-lb)

batch of each diet formulation was mixed using

a single-screw vertical mixer [11] and divided

into eight 136-kg (300-lb) aliquots. For each

diet formulation, 4 of the 8 aliquots were manu-

factured using TS and the other 4 aliquots were

manufactured using TF. Treatments were manu-

factured in a Latin square design over a 4-d pe-

riod; therefore, each treatment was replicated 4

times. Grower diets were mixed, allotted, and

manufactured in a similar manner, with the ex-

ception that 1,996 kg (4,400 lb) of LC and RB

was divided into 250-kg (550-lb) aliquots. The

starter diets were manufactured approximately

2.5 wk before the grower diets.

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Tap water was added before manufacture by

using a garden sprayer set to deliver a fine mist.All ingredients were conditioned using a short-

term conditioner [0.31 1.30 m (1.02 4.25 ft),

10 s retention time] set at a temperature of 82C

(180F) and a pressure of 262 kPa (38 psig).

Time needed to reach the optimal conditioning

temperature was standardized. The LC-TS and

RB-TS treatments were manufactured using a

40-horsepower California pellet mill [12] with a

4.76 44.96 mm (3/16 1.77 in.) die. The LDR

was 9.44. The LC-TF and RB-TF treatmentswere manufactured using the same 40-horse-

power California pellet mill [12] with a 4.76

38.10 mm (3/16 1.50 in.) die. The LDR was

8.00. After pelleting, each treatment was cooled

for 1.25 min in a horizontal belt cooler [13] us-

ing forced ambient air. The mean ambient tem-peratures in the mill during manufacture of the

starter and grower diets were 15C (58F) and

6.5C (44F), respectively.

After pelleting of each treatment, production

rate (metric tons/h) and relative electrical energy

usage (REE) of the conditioner and pellet mill

[kilowatt hours (kWh)/metric ton] were calcu-

lated. Mash, hot pellet, and cool pellet samples

were taken from each treatment and tested for

moisture content [14] on the day of manufac-ture. Moisture content of cool pellet samples

was measured again after a 3-d storage at ap-

proximately 21C (70F). Cool pellet samples

from each treatment were used to determine the

JAPR: Research Report114

Table 1. Diet formulations and nutrient parameters

Item

Broiler starter diet Broiler grower diet

Least cost Research based Least cost Research based

IngredientCorn 55.03 46.15 61.84 53.30

Soybean meal (48%) 26.75 34.92 19.55 27.38

Distillers grains with solubles 5.00 5.00 5.00 5.00

Wheat middlings 5.00 5.00 5.00 5.00

Meat and bone meal 2.53 4.63 3.00 5.04

Animal-vegetable fat 2.00 2.00 2.00 2.00

Dicalcium phosphate 1.23 0.69 1.02 0.50

Limestone 0.79 0.52 0.78 0.53

Lysine 0.41 0.06 0.55 0.23

Methionine 0.36 0.31 0.38 0.33

Salt 0.34 0.31 0.26 0.22

NB3000

1

0.25 0.25 0.25 0.25Threonine 0.18 0.03 0.23 0.09

Coban 602 0.08 0.08 0.08 0.08

BMD3 0.05 0.05 0.05 0.05

Calculated nutrient

ME, kcal/kg 3,028 3,028 3,172 3,172

CP, % 21.50 25.37 19.50 23.37

Supplemental moisture, % 2.02 1.64

Calculated digestible amino acid

Lysine 1.33 1.33 1.25 1.25

Methionine 0.69 0.69 0.68 0.68

Threonine 0.85 0.85 0.80 0.80

TSAA 1.03 1.03 1.01 1.01

1Supplied per kilogram of diet: manganese, 0.02%; zinc, 0.02%; iron, 0.01%; copper, 0.0025%; iodine, 0.0003%; selenium,0.00003%; folic acid, 0.69 mg; choline, 386 mg; riboflavin, 6.61 mg; biotin, 0.03 mg; vitamin B6, 1.38 mg; niacin, 27.56 mg;pantothenic acid, 6.61 mg; thiamine, 2.20 mg; menadione, 0.83 mg; vitamin B12, 0.01 mg; vitamin E, 16.53 IU; vitamin D3,2,133 ICU; vitamin A, 7,716 IU.2Active drug ingredient monensin sodium [60 g/lb (90 g/ton inclusion), Elanco Animal Health, Indianapolis, IN], as an aidin the prevention of coccidiosis caused byEimeria necatrix,Eimeria tenella,Eimeria acervulina,Eimeria brunette,Eimeriamivati, andEimeria maxima.3Bacitracin methylene disalicylate [50 g/lb (50 g/ton inclusion), Alpharma, Fort Lee, NJ], for increased rate of BW gain andimproved FE.

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bulk density (kg/m3), percentage of fines (%),

pellet durability index (PDI), and modified PDI

(MPDI) [15]. Starch gelatinization and protein

denaturation were determined on mash and cool

pellet samples [16].

To simulate the stressors that feed might in-

cur during transportation and conveyance, all

pelleted feed was divided into 91-kg (200-lb)

aliquots and remixed for 2 min in a single-screw

vertical mixer [11]. Through trial and error, the

combination of 91-kg (200-lb) aliquots of feed

and a 2-min remix time was found to produce

a pellet-to-fine ratio very similar to the MPDI

values. Samples of remixed pellets were used to

determine percentage of remixed fines (%) and

pellet length. For starter diets, all pelleted feedwas crumbled after remixing. For grower diets,

the feed remained in pelleted form after remix-

ing.

Data were analyzed using a Latin square de-

sign. Treatments were blocked by day of manu-

facture and run order. Two separate statistical

analyses were performed. A diet formulation

manufacturing technique factorial analysis

was performed to explore the main effects and

all possible interactions. Additionally, multiplecomparisons were performed. Significant differ-

ences were further explored using Fishers LSD

test. All statistics in experiments were calculat-

ed using the GLM procedure of the Statistical

Analysis System [17]. Alpha was designated as

0.05.

RESULTS AND DISCUSSION

Manufacturing Variables

Manufacturing data for the starter and grower

pelleting phases are represented in Tables 2 and

3, respectively. By design, manufacturing tech-

nique significantly affected production rate. The

use of TS resulted in slower production rates

compared with the use of TF for the starter and

grower phases (P= 0.0001 and 0.0001, respec-

tively). As a consequence of the slower produc-

tion rates, manufacturing technique also affected

energy usage. The use of TS resulted in higherconditioner REE (P= 0.02) and pellet mill REE

(P= 0.0001) during the starter phase (Table 2).

Moreover, a higher pellet mill REE (P= 0.001)

was observed during the grower phase (Table

3).

Diet formulation affected pellet mill REE (P

= 0.003), but only in the starter phase. The RB

contained more mash moisture than the LC (P

= 0.0004; Table 4); thus, energy usage was re-

duced. In fact, RB-TF resulted in the lowest pel-let mill REE (P< 0.05) compared with all other

treatments (Table 2). These results are in agree-

ment with those of Fairchild and Greer [18] and

Hott et al. [19], who observed reductions in pel-


Table 2. Starter diet manufacturing variables

Item

Production rate,

metric tons/h

Conditioner REE,1

kWh2/metric ton

Pellet mill REE,

kWh/metric ton

Bulk density,

kg/m3

Treatment3

RB-TS 0.74 0.02b 0.39 0.10 5.81 0.39a 606.58 5.60b

RB-TF 1.13 0.05a 0.31 0.05 4.76 0.41c 588.55 8.50c

LC-TS 0.76 0.02b 0.41 0.02 6.07 0.47a 621.16 3.48a

LC-TF 1.15 0.05a 0.29 0.11 5.28 0.36b 602.74 3.86b

P-value 0.0001 0.0981 0.0001 0.0001

SEM 0.01 0.03 0.08 1.33

Fishers LSD 0.05 0.29 4.61

Main effect and interaction,P-value

Diet formulation 0.2467 0.9288 0.0031 0.0001

Manufacturing technique 0.0001 0.0213 0.0001 0.0001

Diet formulation manufacturing technique 0.7590 0.5469 0.1689 0.8854

acMeans within a column without a common superscript differ (P 0.05).1Relative electrical energy usage.2Kilowatt hours.3RB-TS = research-based diet manufactured using a thick die run slowly; RB-TF = research-based diet manufactured usinga thin die run fast; LC-TS = least-cost diet manufactured using a thick die run slowly; LC-TF = least-cost diet manufacturedusing a thin die run fast.

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let mill energy usage with graded additions of

moisture. Similar findings were not observed

for the grower phase (P= 0.7; Table 3). In the

grower trial, moisture content of the mash and

hot pellets did not differ between treatments (P

> 0.05; Table 5) despite the addition of supple-

mental moisture, likely because less supplemen-

tal moisture was added to the grower diets [8].

Thus, any lubricating effect associated with sup-

plemental moisture would not be observed.

Bulk density was also affected by the in-

corporation of supplemental moisture. Moritz

et al. [20] observed a decrease in bulk density

as moisture addition increased. This study sup-

ports those findings. The use of RB in the starter

phase decreased bulk density compared with theuse of LC (P= 0.0001; Table 2). However, in the

grower phase, when no differences in moisture

content were observed, diet formulation had no

effect on bulk density (P= 0.3; Table 3).

Manufacturing technique affected bulk den-

sity for both the starter and grower phases. The

use of TF decreased bulk density compared with

the use of TS (P= 0.0001; 0.0001). Bulk densi-

ties of corn-soybean- and sorghum-based diets

decrease as pellet quality increases [21, 22].However, our findings in this study contradict

past research. It is likely that the use of TS in

this study resulted in greater compaction of pel-

leted feeds and thus a denser final product.

Pellet Quality

Starter Phase. Pellet quality data for the

starter phase are represented in Table 4. For

the starter phase pellets, diet formulation and

manufacturing technique significantly affectedPDI (P= 0.004; 0.0001) and MPDI (P= 0.0005;

0.0001). The use of RB resulted in greater pellet

quality compared with the use of LC, whereas

TS resulted in greater pellet quality compared

with TF. In fact, RB-TS improved PDI by 10.85

percentage points and improved MPDI by 15.90

percentage points compared with LC-TF (Table

4).

Production of fines was affected by manu-

facturing technique, but not by diet formulation.The use of TS reduced total fines by 53.06%

and remixed fines by 36.25% compared with the

use of TF (P= 0.0001; 0.0001). Several factors

contributed to increased pellet quality and de-

creased fines for the starter phase. For example,

the use of TS resulted in greater starch gelatini-

zation compared with the use of TF (P= 0.03).

Although it was expected that greater moisture

content (i.e., the RB diet) would result in more

starch gelatinization, it did not. It is plausiblethat the water-to-starch ratio necessary for thor-

ough gelatinization was never reached. Howev-

er, the thicker die and the slower production rate

associated with TS may have generated more


Table 3. Grower diet manufacturing variables

Item

Production rate,

metric tons/h

Conditioner REE,1

kWh2/metric ton

Pellet mill REE,

kWh/metric ton

Bulk density,

kg/m3

Treatment3

RB-TS 0.75 0.03b 0.25 0.04 6.16 0.85a 627.92 7.32a

RB-TF 1.13 0.04 a 0.21 0.06 4.52 0.23b 605.50 4.73b

LC-TS 0.75 0.01b 0.22 0.06 5.89 0.36a 626.13 3.10a

LC-TF 1.12 0.01a 0.22 0.01 4.98 0.48 b 601.69 8.25b

P-value 0.0001 0.2620 0.0059 0.0004

SEM 0.01 0.01 0.22 2.41

Fishers LSD 0.03 0.76 8.33

Main effect and interaction

Diet formulation 0.4777 0.3838 0.6741 0.2881

Manufacturing technique 0.0001 0.1456 0.0012 0.0001

Diet formulation manufacturing technique 0.4701 0.2699 0.1454 0.6918

a,b

Means within a column without a common superscript differ (P 0.05).1Relative electrical energy usage.2Kilowatt hours.3RB-TS = research-based diet manufactured using a thick die run slowly; RB-TF = research-based diet manufactured usinga thin die run fast; LC-TS = least-cost diet manufactured using a thick die run slowly; LC-TF = least-cost diet manufacturedusing a thin die run fast.

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Table

4.

Starterd

ietpelletquality

Item

PDI,1 %

MPDI,2

%

Total

fines,%

Remixed

fines,

%

Mash

moisture

content,%

Hotpellet

moisture

content,%

Coolpellet

moisture

content,%

Starch

gelatinization,%

Protein

d

enaturation,%

Treatment3

RB-TS

92.6

71.16a

90.0

91.56a

10.6

00.65b

18.8

93.85b

13.9

20.71a

17.7

10.58a

16.560.32a

28.3

94.67

7.887.17

RB-TF

84.7

20.78c

79.1

80.62c

24.3

30.93a

29.6

62.59a

13.6

80.64a

17.6

10.52a

16.290.28a

19.4

810.0

9

8.071.05

LC-TS

89.5

80.83b

85.2

11.24b

12.1

51.46b

19.4

54.07b

12.0

00.12b

16.3

40.47b

15.090.43b

25.2

85.87

7.894.20

LC-TF

81.8

21.68d

74.1

91.64d

24.1

81.82a

30.4

73.98a

12.1

50.15b

15.7

70.46b

15.240.46b

17.9

63.36

8.345.67

P-value

0.0001

0.000

1

0.0001

0.0010

0.0025

0.0144

0.0013

0.1122

0.9992

SEM

0.68

0.73

0.87

1.28

0.24

0.33

0.16

2.79

2.66

FishersLSD

2.34

2.53

3.01

4.44

0.85

1.14

0.55

9.65

9.20

Maineffectandinteraction

Dietformulation

0.0044

0.000

5

0.4532

0.6133

0.0004

0.0028

0.0002

0.4389

0.9608

Manufacturingtec

hnique

0.0001

0.000

1

0.0001

0.0001

0.8576

0.3533

0.7183

0.0270

0.9084

Dietformulation

manufacturingtechnique

0.8984

0.939

8

0.3647

0.9233

0.4623

0.5026

0.2325

0.7853

0.9622

adMeanswithinac

olumnwithoutacommonsuperscriptdiffer(P0.0

5).

1Pelletdurabilityindex.

2Modifiedpelletdurabilityindex.

3RB-TS=research-

baseddietmanufacturedusingathickdierunslowly;RB-TF=research-based

dietmanufacturedusingathindierun

fast;LC-TS=least-costdietmanufacturedusingathick

dierunslowly;LC-TF=least-costdietmanufacturedusin

gathindierunfast.

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Table

5.

Growerd

ietpelletquality

Item

PDI,1

%

MPDI,2

%

Pellet

length,mm

Total

fines,%

Remixed

fines,%

Mash

moisture

content,%

Hotpellet

mo

isture

content,%

Coolpellet

moisture

content,%

Starch

gelatinization

,

%

Protein

denaturation,

%

Treatment3

RB-TS

92.0

80.98a

89.47

1.52a

9.820.50a

9.820.49d

16.2

62.31d

12.7

00.39

16.63

0.37

15.9

60.72

10.6

23.84

5.972.66ab

RB-TF

84.6

20.67c

79.48

1.90c

8.080.36c

19.9

51.10b

26.5

32.74b

12.6

70.36

16.98

0.50

15.9

20.50

10.5

12.46

2.423.43b

LC-TS

87.8

90.51b

83.04

0.99b

9.200.25b

13.8

01.03c

20.7

51.57c

12.3

00.25

16.67

0.31

15.5

60.32

14.6

13.37

8.172.27a

LC-TF

78.6

60.72d

69.86

2.23d

7.640.45c

24.9

30.96a

33.6

40.33a

12.3

00.22

16.63

0.41

15.4

40.12

10.9

04.30

2.291.89b

P-value

0.0001

0.0

001

0.0001

0.0001

0.0001

0.4344

0

.6873

0.3127

0.4194

0.0271

SEM

0.16

0.3

2

0.13

0.53

0.78

0.21

0

.23

0.21

1.88

1.14

FishersLSD

0.54

1.1

1

0.47

1.83

2.69

3.93

Maineffectandinteraction

Dietformulation

0.0001

0.0

001

0.0076

0.0001

0.0003

0.1260

0

.5477

0.0855

0.2887

0.3983

Manufacturingtec

hnique

0.0001

0.0

001

0.0001

0.0001

0.0001

0.9397

0

.5367

0.6978

0.3489

0.0060

Dietformulation

manufacturingtechnique

0.0013

0.0

025

0.5381

0.3795

0.1424

0.9401

0

.4323

0.8614

0.3766

0.3436

adMeanswithinac

olumnwithoutacommonsuperscriptdiffer(P0.0

5).

1Pelletdurabilityindex.

2Modifiedpelletdurabilityindex.

3RB-TS=research-

baseddietmanufacturedusingathickdierunslowly;RB-TF=research-based

dietmanufacturedusingathindierun

fast;LC-TS=least-costdietmanufacturedusingathick

dierunslowly;LC-TF=least-costdietmanufacturedusin

gathindierunfast.

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heat and resulted in greater compaction of feed,

thus having a larger impact on starch gelatiniza-

tion. A larger LDR would require more frictional

force to extrude pellets through the die, leading

to more gelatinization and a higher pellet qual-

ity [19]. Protein denaturation was not affected

by diet formulation or manufacturing technique

(P> 0.05).

Grower Phase. Pellet quality data for the

grower trial are represented in Table 5. Diet for-

mulation manufacturing technique interactions

were observed for PDI (P= 0.001) and MPDI (P

= 0.003). When TS was used, the RB diet formu-

lation improved PDI by 4.19 percentage points

compared with the LC diet formulation. An even

greater effect was observed when TF was used;the RB diet formulation improved PDI by 5.96

percentage points compared with the LC diet

formulation. When using either manufacturing

technique, RB improved pellet quality. How-

ever, the positive effect of RB on PDI appears

to be more pronounced if a TF manufacturing

technique is used.

Similar results were observed for MPDI.

Compared with LC, RB improved MPDI by

6.43 percentage points when TS was used andimproved MPDI by 9.62 percentage points when

TF was used. Once again, the RB diet formula-

tion improved MPDI for each manufacturing

technique. However, the positive effect of RB

appears to be more pronounced if a mill chooses

to use a TF manufacturing technique.

Decreasing the LDR for a pellet die (i.e, us-

ing a thin die) would require less frictional force

during extrusion [18]. In this study, TF resulted

in less protein denaturation compared with TS(P= 0.0060). Considering that diet formulation

did not have an effect on protein denaturation

(P> 0.05), it is plausible that the smaller im-

provement in MPDI when RB-TS was com-

pared with LC-TS (6.43 percentage points) was

due to greater protein denaturation in both the

LC and the RB diets. Considering that protein

denaturation was not as pronounced in diets

manufactured using TF, it is plausible the higher

protein and moisture in RB resulted in a greater

improvement when RB-TF was compared to

LC-TF (9.62 percentage points). Starch gelati-

nization was not affected by diet formulation or

manufacturing technique (P> 0.05).

Diet formulation and manufacturing tech-

nique affected pellet length (P= 0.008; 0.0001),

total fines (P = 0.0001; 0.0001), and remixed

fines (P= 0.0003; 0.0001). Use of RB and TS

resulted in longer pellets and less fines. In fact,

RB-TS increased pellet length by 2.18 mm (P

= 0.001) and decreased total fines by 60.61%

(P= 0.0001) and remixed fines by 51.66% (P=

0.0001) compared with LC-TF (Table 5).

Diet formulation and manufacturing tech-

nique are important to pellet quality and, in

fact, may be intrinsically linked. In this study,

we demonstrate the importance of establishing

recommendations for producing high-quality

pellets. If producing high-quality pellets super-

sedes the need for producing high volumes offeed (i.e., TS), an LC diet formulation may pro-

duce a pellet of acceptable quality. However, if

producing high volumes of feed supersedes the

need for high pellet quality (i.e., TF), reverting

from an LC diet formulation to a RB formulation

could ameliorate low-quality pellet production.

CONCLUSIONS AND APPLICATIONS

1. The RB diet formulation improved PDI,

MPDI, and production of fines.

2. The TS improved PDI, MPDI, and pro-

duction of fines; however, production

rate decreased and energy usage in-

creased.

3. The combination of the RB grower diet

formulation and TS optimized PDI and

MPDI.

REFERENCES AND NOTES

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2. Behnke, K. C. 1994. Factors affecting pellet quality.Pages 4454 in Proc. Maryland Nutr. Conf. Feed Manuf.,College Park, MD. Maryland Feed Ind. Counc., Univ. Mary-land, College Park.

3. Moritz, J. S. 2007. Impact of the pelleting process ondietary nutrients and supplemental enzymes. Pages 1113 inProc. Arkansas Annu. Nutr. Conf., Rogers, AR.

4. Koch, K. B. 2007. Pelleting and distillers dried grains

with solubles. http://www.ddgs.umn.edu/ppt-proc-storage-quality/2007-Koch-%20Pelleting%20and%20DDGS.pdfAccessed May 2008.

5. Buchanan, N. P., and J. S. Moritz. 2009. Main effectsand interactions of varying formulation protein, fiber, and


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6. Briggs, J. L., D. E. Maier, B. A. Watkins, and K. C.Behnke. 1999. Effect of ingredients and processing param-eters on pellet quality. Poult. Sci. 78:14641471.

7. Cobb-Vantress, Siloam Springs, AR.

8. Endpoint conditioned mash moisture content wascalculated based on moisture content of the mash before pel-leting, ambient temperature of the mash at the time of pel-leting, and conditioning temperature. Turner [9] has statedthat for every 16.7C (30.0F) increase in conditioned mashtemperature, 1% moisture should be added. Samples ofmash were taken 12 h before pelleting and moisture contentwas measured. Tap water was added to the diet to maximizethe potential for thermomechanical interactions to occur: 1)(final conditioning temperature ambient temperature ofmash)/30 = % moisture added at conditioner moisture con-tent of mash + % moisture added at conditioner = total mois-ture; 2) 17 total moisture = % of supplemental tap water

added to mash.9. Turner, R. 1995. Bottomline in feed processing:

Achieving optimum pellet quality. Feed Manage. 46:3033.

10. Brill Feed Ration Balancer, Version 1.03.017, M.Feed Management Systems, Brooklyn Center, MN.

11. Vertical mixer, Avery Weigh-Tronix, Fairmont, MN.

12. Master Model Pellet Mill, California Pellet MillCompany (CPM), Crawfordsville, IN.

13. Vertical cooler, Pyramid Processing Equipment LLC,Stilwell, KS.

14. American Association of Cereal Chemists. 1995.AACC Method 44-15A: MoistureAir-Oven Method. InApproved Methods of the American Association of Ana-lytical Chemists. Vol. 2. Am. Assoc. Cereal Chem., St. Paul,MN.

15. American Society of Agricultural Engineers. 1997.ASAE S269.4: Cubes, pellets, and crumblesDefinitions

and methods for determining density, durability, and mois-ture. Standard 1997. Am. Soc. Agric. Eng., St. Joseph, MI.

16. Differential Scanning Calorimeter, Instrument Spe-cialists Inc., Twin Lakes, MN. Percentage of starch gelati-nization and percentage of protein denaturation were mea-sured by determining the prevalence of gelatinization and

denaturation in a mash sample before pellet processing.The gelatinization and denaturation of a corresponding pel-leted sample were then measured. The percentage of starchgelatinization and percentage of protein denaturation weredetermined by subtracting the enthalpy associated withthe pelleted sample from the enthalpy associated with themash sample and dividing by the enthalpy associated withthe mash sample: Mash enthalpy pellet enthalpy/mash en-thalpy = % gelatinization or denaturation.

17. SAS Institute. 2000. The SAS System for Windows2000. Release 8.1. SAS Inst. Inc., Cary, NC.

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20. Moritz, J. S., K. R. Cramer, K. J. Wilson, and R. S.Beyer. 2003. Feed manufacture and feeding of rations withgraded levels of added moisture formulated to different en-ergy densities. J. Appl. Poult. Res. 12:371381.

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