economics of black soldier fly

8/20/2019 Economics of Black Soldier Fly

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ECONOMICS OF BLACK SOLDIER FLY

(Herm etia illucens)

IN DAIRY WASTE

MANAGEMENT

THESIS

Presented to the College of Graduate Studies

Tarleton State University

In Partial Fulfillment of the Requirem ents

For the Degree of

Masters of Science

By

PRASHANT AMATYA

Stephenville, Texas

August, 2009


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UMI Number: 1466267

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ECONOM ICS OF BLACK SOLDIER FLY (H ermetia illucens) IN DAIRY W ASTE

MANAGEMENT

Prashant Amatya

THESIS APPROVED:

Chairman, Advisory Committee

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Comm ittee Member „ / "

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Comm ittee Member

Head, Department of Agribusiness, Agronomy,

Horticulture and Range Management

iorticulture and Kang e Mar

)ean, Co llege of Graduate

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ACKNOWLEGEMENTS

It is difficult to overstate m y g ratitude to Dr. Mark Yu , who shared with m e a lot

of his expertise and research insights. I am grateful for his guidance, encouragement, and

especially acknowledge the time and effort he has put into this project and the m anuscript

preparation. Special thanks are due to other members of my advisory committee, Dr.

Frank Ewell and Dr. Jeffery K. Tomberlin, for their constructive criticism and direction.

I would also like to take this opportunity to thank to Dr. Tomberlin for sharing his

research data on the black soldier fly and allowing the comp letion of this study.

I am thankful for the support from the Department especially, Dr. Roger Wittie,

M s.

Linda Sanders and Ms. Jessica Richmond. Thanks are also due to Dr. Randy Rosier

for his valuable inputs in manuscript preparation and Dr. Sankar Sundarrajan for

continuous encouragement during my graduate studies.

I am indebted to many friends and family, Dr. Sharon Batenhop, Rosella and Dr.

Ervin, and Lanish and Jerry, who has helped in many ways to make my stay at

Stephenville wonderful.

I am also thankful to my brother Dr. Pradyumna, sister Pratishtha, father-in-law

Mrigrendra B Pradhana ng and m other-in-law Sushma Pradhanang for their support.

I cannot finish without saying how grateful I am to my loving wife Shruti for her

support and for wonderful gift, "our daughter Sejal." Finally and most importantly, I wish

to thank my parents, Dr. Ananada Prasad Shrestha and Sagar Prabha Shrestha, for their

unconditional love, support and encouragement to bring out my best in all matters of

life.

in


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TABLE OF CONTENTS

LIST OF GRAP HICS vii

CHAPTER I 1

INTRODUCTION

1.1 Dairy W aste and Nu trient Excretion 4

1.2 Black Soldier Fly 5

1.3 Objectives 8

1.4 Scope of the Study 9

CHA PTER II 10

LITERATURE REVIEW

2.1 Dairy Production in Erath County, Texas 10

2.2 Dairy W astes and Nutrien t Excretion 11

2.3 Dairy Waste Man agem ent Systems 15

2.4 Black Soldier Fly Research 16

2.5 Benefit-Cost Analysis 20

2.6 Benefit-Cost Analysis in Black Soldier Fly Research 21

2.6.1 Dry-matter Conv ersion Rate of Black Soldier Fly 24

2.6.2 Reduction in Man ure Bulk 25

iv


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2.6.3 Economic Value of Harvested Pupae 25

2.7 Choices of Production Function 25

CHA PTER III 30

MATERIALS AND METHOD

3.1 Conceptual Fram e W ork 30

3.1.1 Benefit-Cost Ana lysis 30

3.1.2 Production Function 32

3.2 Data Considerations 33

3.3 DM CR and MBR Estimation 37

3.4 Benefit-Cost Analysis 37

3.4.1 Benefit Estimation 38

3.4.2 Cost Estimation 39

3.5 The Mod el Estimation 39

CHAPTE R IV 42

RESULTS AND DISCUSSION

4.1 Dry Matter Conversion Rate and Man ure Bulk Reduction Rate 42

4.2 Benefits-Cost Estimation 44

4.2.1 Value of Prepupae 44

4.2.2 Cost-saving 46

4.2.3 Labor Cost 47

4.3 Larval Production Mo del 51

4.4 Manure Bulk Reduction Models 57

v


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CHAPTER V 60

SUMMARY AND CONCLUSION

5.1 Summ ary 60

5.2 Conclusion and Implications 63

REFRENCES 65

APPENDIX 72

Abbreviations 73

vi


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LIST OF GRAPHICS

TABLES

I. Concen tration of Selected Elemen ts and Other Factors in the Dry Matter of

Black Soldier Fly Digested and Fresh Swine Manure 18

II . Percent of Am ino Acid Content in Black Soldier Fly Larvae Fed Beef and

Swine Manure 22

III.

Mineral Content and Proximate Analysis of Dried Black Soldier Fly

Prepupae Raised on Poultry and Swine Man ure (ppm) 22

IV. Av erage Weight of Black Soldier Fly Larvae at the Start and End of the

Trial 24

V. Constituents and Com position of the Gainesville Diet 34

VI.

Sum mary of Experim ent Data in Three Cohorts 35

VII. Sum mary of Overall Experim ent Data 36

VIII. Calculation of DMCR and MBR of Black Soldier Fly in Cow M anure

Digestion 43

IX. Estimated Value of Harvested Larvae (Prepupae) 45

X. Cost Savings for Reduced Man ure Bulk Handling based on 4,994 kg

Manure/Cow/Year 47

XI. Total Labor Cost of Larval Production ($/kg of Larvae on DM basis) 48

XII. Total Benefit of Incorporating Black Soldier Fly in Dairy Waste

Man agem ent System ($ per cow per year) 50

XIII. Correlation Coefficients Between the Variables, and Its Probabilities > |r|.... 52

XIV . Value Estimation of Increased Larval Yield 56

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FIGURES

1. Concentrate Anim al Feeding Operations (CAF Os) 2

2. No rth Bosque River W atershed in Erath County, Texas 3

3. Blac k Soldier Fly in Different Stages 7

4. Decision Rule for Benefit-Cost Criterion 32

5. Sensitivity of Revenue to the Change in Price of Its Substitutes (Existing

Scenario) 46

6. Respon se of Larval Yield with respect to Manu re Feeding 54

7. Sensitivity of Revenue to the Chang e in Price of

Its

Substitutes (Improved

Scenario) 57

8. Response of Man ure Feeding on M anure Bulk Reduction 58

vui


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Amatya, Prashant, Economics of Black Soldier Fly in Dairy waste Management, Master

of Science (Agricultural Econ omics), M arch, 2009 , 70 pp., 14 tables, 7 figures, 51

references, 37 titles.

The black soldier fly (BSF) has been recognized as an effective means to deal

with access manure accumulation at Concentrated Animal Feeding Operations (CAFOs).

Using BSF larvae to digest dairy manure can generate $100 to $279 income per cow

every year through (1) sales of harvested prepup ae, which can be used as feed ingredient

($90 - $230) and (2) cost-savings in reduced m anure bulk handling ($10 -$49). Thus, a

facility with low operating cost to maintain warm temperature throughout the year and a

market for harvested larvae could prove BSF an economically viable option for dairy

CAFOs to manage their wastes. Estimated models on larval yield as well as manure bulk

reduction suggest that outcomes can be improved by 17.45% in larval yield and 146.75%

in manure bulk reduction with a simple chan ge in manure-feeding rate.

IX


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CHAPTER I

INTRODUCTION

Dairy producers in the United States are under continuous pressure to reduce

production costs in order to become more economically competitive. The number of

concentrated animal feeding operations

1

(CAFOs) has increased over the recent years. A

CAFO can be defined as a animal lot or facility, together with any associated treatment

works, wh ere the following two conditions are met. First, animals have been, are, or will

be stabled or confined and fed or maintained for a total of 45 days or more in any 12-

month period. Second, crops, vegetation, forage growth, or post-harvest residues are not

sustained over any portion of the operation lot or facility. This definition is used as part

of waste management and environmental protection laws to deal with the concentrated

pollution from large quantities of animal w aste (Speir et al., 2003). Growing popularity of

CAFOs in agriculture is due to financial opportunities in operating larger businesses.

However, these CAFO operations represent a greater risk for water pollution (Van Horn

et al.,

2003;

Burkholder et al , 2007).

Erath County is the largest dairy producing county in Texas. In 2002 it was

estimated that the county had nearly 78,800 milking cows (USDA-ARS, 2003) with dairy

herds above 500 cows constituting 39% of the total dairies in the area. Despite the fact

1

Also known as confined animal feeding op erations, intensive livestock operations (ILOs) or factory

farming.

1


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that the total number of dairy producers in Erath County has declined steadily in recent

years, both total milk production and number of dairy cows have exhibited a growing

trend (USDA-ARS, 2004; Jafri and Buland, 2006). These dairies are estimated to be a

$228,000,000 industry and estimated to contribute 36% of all goods produced in the

County (Jarfri and Buland, 2 006).

Figure 1. Concentrate Animal Feeding Operations (CAFOs)

2

Erath County is on the upper North Bosque River watershed, an area of

approximately 320,000 hectare (ha) in north central Texas (Adams and McFarland,

2001). This water source provides drinking water for a human population of 150,000

(TNRCC, 2002). The North Bosque River is also one of the longest among the four

branches which runs into the Waco Lake in McLennan County, Texas. Nearly half of the

total number of dairy cows in Erath County is within the boundaries of this watershed

(Munster et al., 2004). These dairies are alleged to be one of the primary sources of water

pollution in North Bosque River watershed and downstream areas as well e.g., Lake

Waco (S tephenville, Em pire Tribune, March 2, 2004). The severity of the situation was

2

The Pictures are downloaded from google.com images.

http://google.com/http://google.com/http://google.com/http://google.com/


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highlighted by litigation filed by City of Waco in Texas against upstream dairies

(Stephenville, Empire Tribune, March 2, 2004).

Figure 2. North Bosque R iver Watershed in Erath County, Texas

CAFOs pose greater risks to water quality because they can increase both volume

of waste and concentration of contaminants, such as antibiotics and other veterinary

drugs. These waste and contaminants pose risks to both environment and public health.

There were also concerns regarding water contamination due to pharmaceuticals and

other compounds that were present in the dairy cattle feeds and resulting wastes

(Burkholder et al., 2007 ).

3

The map is downloaded from http://www.brazos.org/DVDFlyover/pdfs/Erath.pdf.

http://www.brazos.org/DVDFlyover/pdfs/Erath.pdfhttp://www.brazos.org/DVDFlyover/pdfs/Erath.pdfhttp://www.brazos.org/DVDFlyover/pdfs/Erath.pdf


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1.1 Dairy W aste and Nutrient Excretion

Each dairy cow excretes between 36.3 to 39 kg of raw waste each day per 454 kg

(1000 lbs) body weight (Morse et al., 1994). Van Horn et al. (1994) studied the

components of

a

dairy man ure manag emen t system and reported that on an average a cow

excretes 18 kg per year (yr) of phosphorus, which being less volatile, remains in the

manure and ultimately runs off or leaches to streams. Once in the waterways

eutrophication occu rs. The primary reason for high presence of phosphorus in dairy

waste is due to the feeds provided to the animals containing higher limit of phosphorus

content (Klausner et al., 1998; Erickson et al., 2000). Therefore, earlier studies proposed

the use of low phosphorus excretion dairy diet (Erickson et al., 2000) with the notion

"don't feed it if they don't need it." However, dairy producers were reluctant to use

minimum level of phosphorus in the feed (CAST, 2002) due to fears that it would

compromise milk production or reproduction efficiency of the cows (CAST, 2002).

Similarly, other phosphorus management practices suggested are land area requirement

(LAR) for nutrient utilization, vegetative buffer strip, and phosphorus based manure

application system. The LAR system defines the number of acres required to manage a

dairy of a certain heard size. The buffer strip along the affluent is recommended to check

the run-off of the nutrients from a holding tank (ND ESC, 200 5).

Thus dairy CAFO s resulted in huge accumu lation of manure wastes and nutrients:

nearly 6,500 metric ton (Mt) of dung, 37 Mt of nitrogen and 9.2Mt of phosphorus every

year per 500 dairy cows (ASAE, 1993; Morse et al., 1994; Van Horn et al., 1994). If

well-managed, these wastes would serve as valuable substitutes of expensive fertilizers


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(Gill 1 and M ee lu l, 1982). However, it is often no t feasible to transport the h uge

quantities of manure to crop production areas and hence needs to be stored and spread

near by crop lands (Sheppard and Newton, 2000). This economic constraint resulted in

excessive accumu lation of water-soluble phosph orus in the soil that runs off to streams or

leaches to ground water, thereby polluting th e ecosystem (Dou et al., 2000 ; Burkholder et

al., 2007).

Among several dairy waste-handling systems, the liquid tank (slurry) and the

lagoon system were am ong the mo st popular especially with larger dairies with more than

100 cows (Van Horn et al., 2003). Both of these systems use hydraulic equipment, such

as pumps, pipelines, irrigation equipments, and various other appropriate equipments to

manage manure in liquid form (slurry or dilute), thereby reducing labor costs (Van Horn

et al., 2003). Generally, nutrient value of the manure was taken into account to estimate

the net cost of handling the manure. However, the average total cost of dairy-waste

handling (without accounting for nutrient value of the dairy manure) was estimated on a

per cow per year basis to range from $47 for 1,000 cows to $87 for 100 cows in lagoon

system while $121 for 1,000 cows to $219 for 100 cows in liquid talk system (Bennett et

al.,

2007).

1.2 Black Soldier Fly

The black soldier fly

{Hermetia illucens)

is a large (13 to 20 mm) wasp like fly

which is considered a beneficial insect (Tomberlin et al., 2002). The fly produces three

generations per year in the southern United States and can be collected from late spring

through early fall (Sheppard, et al., 1994). An egg needs 4 days to hatch and 21 to 24


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days for larval developme nt into pupa, if reared in standard larval diet (Tom berlin et al.,

2002).

It takes an additional 20 days for the adult to emerge from the pupa; and it will

live for 9 to 15 days (Tom berlin et al., 2002). How ever, the development rate of larvae is

dependent on temperature and feed provided (Tomberlin et al., 2008). Normally, they

utilized a wide variety of decomposing plant and even animal carcasses as a medium of

development (Sheppard et al., 2002).

The black soldier fly is of interest to agriculture for many different reasons. The

larvae significantly reduce manure accumulation and associated nutrient content

(Sheppard, 1983; Sheppard et al., 1994; and Erickson et al., 2004). Black soldier fly

larvae can also be used as a substitute for soybean or fish meal to formulate diets of

cockerels

(Gallus domesticus)

(Hale, 1973), swine

(Sus domesticus)

(New ton et al.,

1977) and fish (catfish

Ictalurus punctatus

and tilapia

Oreochromis aureus)

(Bondari and

Sheppard, 1987). The larvae have also been reported to reduce the development of

common house fly

(Musca domesticd)

larvae, the smell of the decomposing manure

(Sheppard, 1983; Sheppard and Newton, 2000; Newton et al., 2005) and elimination (or

reduction) of several harmful pathogens such as

E. coli

(Liu et al., 2008), salmonella and

helminth eggs (Eawag, www.Eawag.ch).

4

Standard L arval Diet is formulated from constituents like Alfalfa meal, Wheat Barn, Corn Me al and

Brewers' dried grain etc (Table V).

http://www.eawag.ch/http://www.eawag.ch/http://www.eawag.ch/


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Several researchers have previously tested the soldier fly larvae's suitability and

confirmed it as a substitute to conventional sources of protein and fat (Hale, 1973;

Bondari and Sheppard, 1987; Sheppard and Newton, 2000). Other benefits include a 50%

reduction in manure residue with less available nitrogen and phosphorus (24% in total

nitrogen con centration or 6 2% of total nitrogen m ass and significant amount reduction in

P). It has also been reported that it suppressed house fly Musca domestica populations,

which are an annoying pe st in production facilities. Ho use fly females did not lay eggs on

the manure that had been colonized by black soldier fly (Sheppard and Newton, 2000).

Furthermore, treating manure with black soldier fly larvae substantially reduced its odor,

which could be of substantial considerations for public and environment near dairy

production sites. The research suggested that the economic value of the larvae produced

could be a strong incentive for the dairies to adopt the black soldier fly digested manure

handling system. Finally, the study also suggested that the value would be much higher if

it could be marketed as specialty feeds, or further processed for biodiesel, chitin, essential

fatty acids and/or other prod ucts.

1.3 Objectives

The general objective of the study was to assess economic implication of

incorporating black soldier fly larvae in dairy waste-managements. More specifically, it

includes the following specific objectives:

1.

To determine the dry matter conversion rate, reduction in manure bulk and

duration required for black soldier fly larvae to digest cow manu re.


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2.

To estimate cost and benefit of using black soldier fly in digesting the dairy

manure in CAFOs.

3.

To establish a production function of black soldier fly larvae with respect to

quantity of manure fed, numb er of larvae harvested, average development time

and other variables.

4.

To estimate a man ure reduction function with respect to rate of manure feeding,

the larval growth, num ber of larvae harvested, average development tim e and

other variables.

5.

To determine the optimal rate of man ure feeding to maximize larval yield as well

as manure bulk reduction.

1.4 Scope of the Study

An estimation of costs and benefits of incorporating black soldier fly larvae into a

dairy waste-management system would facilitate dairy producers to establish the

economically profitable level of investment needed to incorporate the facility into their

systems. The dry matter conversion rate, manure bulk reduction rate, and duration of

digestion are the three key considerations to estimate the benefit-cost criterion of

incorporating black soldier fly into the dairy system. Similarly, estimation of prepupae

production function with respect to its major determining factors will facilitate producer

to estimate optimum levels of production to maxim ize profit.


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CHAPTER II

LITERATURE REVIEW

Literature was reviewed regarding dairy production in Erath County, TX; dairy

waste and nutrient excretion; dairy waste management systems; black soldier fly

research; benefit-cost analysis; and benefit-cost analysis in black soldier fly research.

Also reviewed were choices of production functions, and their applicability and

limitations.

2.1 Dairy Production in Erath County, Texas

Erath Co unty is the largest dairy-producing county in Texas. Despite the fact that

the total number of dairy producers declined steadily from 138 in 2001 to 106 in recent

years,

total milk production and numb er of dairy cows have increased (Jafri and Buland,

2006),

which means CAFOs are getting bigger. Erath County is part of the upstream

portion of the North Bosque River watershed, which covers approximately 320,000 ha in

north-central Texas (Adams and McFarland, 2001) is a water source for approximately

150,000 individuals (TNRCC, 2002). Approximately 45% of the total number of dairy

cows in the Erath County is within the boundaries of the watershed (Munster et al.,

2004).

These dairies are allegedly one of the primary sources of water pollution

10


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million tons

6

of animal wastes annually in Erath County. If well-managed, these wastes

could serve as fertilizer for a variety of crops and could be a substantial substitute for

commercial fertilizers (Mader et al., 2002). However, it is not economically feasible to

transport this manure to crop production areas because of

its

bulkiness and distance to be

transported. Hence it is stored and eventu ally spread on nearby crop lands (Sheppard and

Newton, 2000). This restriction in application sites resulted in excessive accumulation of

water-soluble phosphorus in the soil that ultimately ran off into streams or leached to

groundw ater polluting the ecosystem (Dou et al., 2000; Burkholder et al., 2007).

Van Horn et al. (1994) determined an average cow exerted 18 kg per yr of

phosp horus. H owever, the quantity of phosphorus in the manu re excretion is variable and

depends on the dietary intake (Morse et al., 1994). Phosphorus is less volatile and

remains in the manure and the soil, which ultimately runsoff or leaches into streams

resulting in eutrophication impacts to stream flora and fauna (Van Horn et al.,

2003;

Massey et al., 2007). The primary reason for high phosphorus in dairy waste is due to

feeds used (Klausner et al., 1998; Erickson et al., 2000). Earlier studies proposed using

low phosphorus excretion dairy diets. However, the practice was not adopted due to

producers being reluctant to use minimum level of phosphorus in the feed out of fear

milk production or reproduction efficiency would be compromised (CAST, 2002).

Inadequate documentation of phosphorus digestibility had been a major concern and

limitation.

6

The ton h ere is represents 2200 lbs (English ton).


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The fecal excretion of a dairy cow mainly depends on the quantity of dry matter

intake. The quantity of dry matter intake is governed by the body weight as well as milk

productivity. The estimate for total waste in a day per 454 kg body weight of a cow

ranged from 36.3 to 39.0 kg. Similarly, total solid ranged from 4.5 to 5.4 kg, nitrogen

from 0.19 to 0.20 kg and phosphorus from 0.02 to 0.032 kg, respectively (Morse et al.

1994). Agricultural Engineering Year book (1993) estimated an average Holstein dairy

cow excreted a total 39 kg manure and 27.27 kg of feces per day per 454 kg of body

weight (A SA E, 1993). How ever, Mo rse et al. (1994) and Wilkerson et al. (1997) revealed

that these values are greater. Morse et al. (1994) studied production and characteristics of

manure from lactating dairy cows in Florida and estimated that an average Holstein cows

excreted 44.6 kg of raw waste and 6.08 kg of total solids in feces, and 0.16 kg of fixed

solids in feces daily per 454 k g of body w eight. Also , total solid feces represented 36.4%

of the daily diet dry matter intake and feces to urine ratio (w/w) ranged from 1.4:1 to

1.9:1. They further noted that dry matter intake for dairy cows have increased from 30 to

50 %

during past 20 years.

Wilkerson et al. (1997) tried to predict excretion of manure and nitrogen by

Holstein cows by estimating it based not only on body weight but also on their daily

average milk production. The study also included concentration of crude protein and

neutral detergent fiber in the diet, days in lactation, and days of pregnancy to develop

regression equation. They reported cows producing 29 kg per day of milk excreted 40.45

kg of total manure including 27 .27 kg of feces, wh ile cows producing 14 kg per day milk

excreted 25.86 kg of total man ure including 18.73 kg of feces per 454 kg body weight of


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a cow. The study found that ex cretion was largely determined by average milk production

of

cows.

The increased excretion could be attributed to increase feed intake for increased

milk productivity. These researchers determined that estimation of excretion based on

body weight and daily average milk production had practical implications. The

measurements for excretion were given for growing and replacement cattle as well as

ASAE

7

standard beef cattle. Furthermore, the study regressed aforementioned factors to

predict the excretion of man ure and nitrogen for a dairy cattle herd.

In a similar effort, researchers (Roseler et al., 1993; Ciszuk and Gebregziabher,

1994) reported a positive correlation between amount of urinary urea excreted by a cow

to concentration of urea in blood as well as the concentration of urea in the milk. Jonker

et al. (1998) attempted to develop and evaluate a mathematical model predicting

excretion, intake, and utilization of efficiency of nitrogen in lactating dairy cows based

on milk urea nitrogen. Other variables under consideration were milk production, milk

protein, and dietary crude protein. The developed model predicted nitrogen excretion and

efficiency with no significant mean or linear bias for most predictions. Model prediction

error was approximately 15% of mean predictions. The majority of unexplained error in

the model was due to variation among cows, including cattle breed. Jonker et al. (1998)

suggested caution in interpreting such model predictions. They concluded that milk urea

nitrogen was a simple and noninvasive measurement that could be used to monitor

nitrogen excretion from lactating dairy cows. The model could also be useful for

American Society for Agricultural Engineers.


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environmental application by quantifying the potential excretion of nitrogen on the farm

or in a watershed.

2.3 Dairy W aste M anagem ent Systems

The three most common dairy waste-handling systems popular among the large

dairies are the solid, the liquid tank (slurry) and lagoon system. However, other systems

include anaerobic lagoon, removal of suspended solids, composting, and combination of

these (Bennett et al., 2007). All of these system include five major activities: collection,

storage, processing and treatment, transportation and utilization (Van Horn et al., 2003).

Bennett et al. (2007) studied the economics of dairy waste-management systems and

determined the most economic way of handling waste depended on herd size and soil

type and/or geological considerations. The traditional system of solid or dry scrap

handling of dairy waste would be cost-effective for small-size dairies (less than 100

cows),

while the lagoon system would be more economical for larger dairies with more

than 100 cows. The liquid tank method would be preferred to lagoon treatment in

situations where unfavorable geological or edaphic features prevent the use of lagoons

and it was especially so with herds between 350-500 dairy cows. They estimated the net

cost of a lagoon system ranged from $0.24 per hundredweight (cwt) of milk produced by

1,000 cows to $0.43 per cwt for 100 cows. The net cost of liquid tank system ranged from

$0.39 per cwt of milk produced with 1,000 cows to $1.04 per cwt with 100 cows. The net

cost included the economic value of the waste, which accounted for the nutrient value

present in the manure when applied to crop field. Thus, the average total cost of dairy

waste handling, w ithout accounting for nutrient value of the dairy manure, was estimated


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on per cow per year basis to be from $47 for 1,000 cows to $87 for 100 cows in lagoon

system. It was $121 for 1,000 cows up to $219 for 100 cows using liquid tank systems.

This study also suggested that liquid tank systems preserve more nutrients in man ure than

lagoon systems. Lagoon systems for more than 300 milking cows were recommended to

use an on dairy traveling gun irrigator rather than hiring custom irrigation system at $60

per hour (Bennett et al., 2007). The study was conducted in Missouri with statewide

liquid tank and lagoon system. It was also concluded that lagoon or liquid tank systems

were the two most likely alternatives for upgrading manure handling systems for any

dairy with mo re than 100 cows.

2.4 Black Soldier Fly Research

The black soldier fly,

Hermetia illucens,

is a large (13 to 20 mm) wasp-like

beneficial insect, found in tropical and warm-temperate regions and is non-pest in nature

(Tomberlin et al., 2002). Larvae of this fly are voracious feeders of organic wastes. The

voracity of these larvae was presented in a video clip posted at The Swiss Federal

Institute of Aquatic Science and Technology website (www.Eawag.ch), in which

5,000

larvae have completely digested two adult rainbow trout in just 24 hours. Mature soldier

fly larvae (i.e. prepupae) are about 25 mm in length, 6 mm in diameter, and weigh about

0.2 g. These larvae have been identified as negatively phototactic with nocturnal

migratory activities (Olivier, www.esrla.com). On the webpage, "Engineering, Separation

and Recycling LLC", Dr. Olivier explained that the black soldier fly is the fastest,

cleanest, most efficient, and most economic way to recycle food waste. A simple

self-

harvesting bin has been designed and proposed for recycling the food waste with fly

http://www.eawag.ch/http://www.eawag.ch/http://www.esrla.com/http://www.esrla.com/http://www.esrla.com/http://www.eawag.ch/


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larvae and harvesting the prepu pae. This required n o mov able parts or external energy for

operation (Olivier, www.esrla.com ).

Sheppard and Newton (2000) studied the by-products of a manure management

system using the black soldier fly. Their research found that using black soldier fly could

be one o f the most inexpen sive ways to transform manure into a 42% protein and 35 % fat

feedstuff.

This system resulted in an 8% dry matter conversion rate that required only

minor modifications of the waste management system currently designed for CAFOs.

The percentage dry matter conversion rate has been defined as number of grams of

prepupae that could be harvested from every 100 g of manure, both taken in dry matter

basis.

The experiment was carried out using poultry and swine manure digestion. Other

benefits reported were 50% reduction in manure residue with less available nitrogen and

phosphorus (62% in total nitrogen mass and 53% in phosphorus reduction) in the residue

(Table I). House flies population control is another benefit associated with the black

soldier fly. House flies do not lay eggs on manure that has been colonized by black

soldier fly larvae. Furthermore, treating manure with black soldier fly larvae significantly

reduced the odors, which could be of substantial benefits for health and public and other

environmental considerations. These larvae were also reported to change the microflora

of manure thereby potentially reducing harmful and undesirable species like bacteria

(Erickson et al., 2004 ).

http://www.esrla.com/http://www.esrla.com/http://www.esrla.com/


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incentive for dairies to adopt the black soldier fly digested manure handling system. This

value would be much higher if marked as specialty feeds, or further processed for

biodiesel, chitin, essential fatty acids and/or other products. In furthering their research

Newton et al. (2005) proposed a simple facility that could be successfully incorporated on

hog farms. The full scale black soldier fly manure digestion system used a conveyer belt

to separate hog urine from feces. It was then sprayed to black soldier fly larvae-rearing

chamber by means of a compressed air-driven piston pump. The manure was digested by

the larvae and at the pre-pupal stage they climbed up the 40° sloped walls of the rearing

chamber to a self collection site. Despite the usefulness of these flies, lack of adaptation

has been recognized due to difficulties in adapting insect culture to modern animal

production facilities, difficulties in producing eggs or larvae consistently on a year-round

basis, and effective, low-cost me thods for cold weather operations (Newton et al., 2005).

While studying the effects of temperature on development of black soldier fly,

Tomberlin et al. (2008) noticed that temperature had a significant effect on growth rate of

black soldier fly larvae as well as the survival and longevity in adults. Larvae were reared

under three temperatures 27°, 30° and 36°C on grain-based diet. Parameters included

were duration required for larval as well as pupal development, pre-pupal and adult

weights, and adult longevity. The larvae show ed highest survival rate to adulthood at 27 °

and 30°C (74% to 97% respectively), while the upper limit for the development of these

larvae was identified to lie between 30° and 36°C. Increasing temperature was associated

with smaller adults with shorter life spans at adulthood. Further, larvae required

1 -9

days

longer to complete larval and pupal development at 27°C than 30°C. Though, larvae


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showed 73.4% probability of becoming pupae at 36°C, its survival rate to adulthood was

only

0 .1%.

Th e reduced survival to adulthood at high temp erature was attributed to larvae

being unab le to attain necessary critical weight.

2.5 Benefit-Cost Analysis

The study attempted to conduct a benefit-cost analysis of the black soldier fly as a

means to reduce animal wastes. Such models are not uncommon in agriculture. In an

attempt to estimate relative profitability of cotton production under two irrigation

systems, namely low energy precision application (LEPA) irrigation and subsurface drip

irrigation (SDI), Bordov sky and Segarra (2000) carried o ut economic profitability of two

irrigation systems. The study assumed that dry land was irrigated and associated costs

were estimated for the total budget. This analysis included expected revenues, variable

costs,

and fixed costs under each irrigation system. These components were then used to

derive expected levels of net revenue to management and risk above variable and fixed

costs.

Cost of all variable inputs used for production constituted the variable cost

estimation. Annual fixed cost was separated into three categories: machinery; land, and

irrigation system. The irrigation system cost was composed of irrigation well cost and

irrigation system cost. Values for these parameters were assigned from secondary sources

reported by Segarra et al. (1999) and Bordovsky (2000). Similarly, constant prices were

considered for cotton lint and cotton seeds and were used through out the calculation. The

study concluded that LEPA resulted in higher net returns to management and risk than

SDI when irrigation capacity increased above 0.1 in per day levels. However, SDI could

also be profitable in situations where LEPA installation cost exceeded than $333 per ac;


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Physical constraints prevent the use of LEPA; or SDI installation cost are lower than

$800 per ac.

2.6 Benefit-Cost Ana lysis in Black Soldier Fly Research

Incorporating black soldier fly larvae in manure digestion could bring economic

benefits. Their use could significantly reduce manure volume, which saves cost of

handling the manure. These larvae also reduced significantly the nutrient contents in

digested manure. The digested manure is more readily applicable to the crops than the

undigested m anure. Secon dly, the larvae can be harvested and used as feed ingredients to

substitute fish meal or soy meal. The nutrient content of larvae makes it a more ready

substitute of fish meal (Newton et al., 2005). Further, the nutrient contents of the larvae

could be altered through its rearing me dium (St-Hilaire et al., 2007).

Newton et al. (1977; 2005) evaluated dried soldier fly larvae meal as a

supplement for swine feed. The study reported that mineral content as well as amino

acids levels in larvae varied with respect to medium for growth selected. To com pare the

mineral content in dried black soldier fly prepup ae, the larvae were fed p oultry and swine

man ure; and to test the amino acid content larvae were fed beef and swine manure. (Table

II and Table III).


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Table II. Percent of Amino Acid Content in Black Soldier Fly Larvae Fed Beef and

Swine Manure.

Essential Am ino Acids Additional Am ino Acids

Beef

Swine

Beef

Swine

Methio nine 0.9 0.83 Tyrosine

2.5

2.38

Lysine

3.4 2.21 Aspartic Acid

4.6

3.04

Leu cine 3.5 2.61 Serine 0.1 1.47

Isoleucine

2.0

1.51 Glutam ic Acid 3.8 3.99

Histidine

Phenylalanine

Valine

1-Arginine

Threonine

1.9

2.2

3.4

2.2

0.6

0.96

1.49

2.23

1.77

1.41

Glycine

Alanine

Proline

Cystine

Ammonia

2.9

3.7

3.3

0.1

1.3

2.07

2.55

2.12

0.31

. .

Tryptophan 0.2

0.59

Source: New ton et al., 2005. Using the black soldier fly, Herm etia illucens, as a value-added tool for the

management of swine manure.

Table III. Mineral Content and Proximate Analysis of Dried Black Soldier Fly

Prepupae Raised on Poultry and Swine Manure (ppm).

Minerals Poultry Swine

Proximate

Analysis Poultry Swine

P

K

Ca

1.51

1

0.69'

5.00

1

0.88

1

1.16

1

5.36

1

Crude protein

Ether extract

Crude fiber

42.1

1

34.8

7

43.2'

28.0


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Mg

Mn

Fe

B

Zn

Sr

Na

Cu

Al

Ba

0.39

1

246

1370

0

108

53

1325

6

97

33

0.44

1

348

776

~

271

~

1260

26

—

__

Ash 14.6 16.6

The figures are in percentage.

Source: New ton et al., 2005. Using the black soldier fly, Hermetia illucens, as a value-added tool for the

management of swine manure.

St-Hilaire et al. (2007) studied fish offal recycling by the black soldier fly and

concluded that the protein and fat content of black soldier fly could be altered through

their diet. The study found that larvae fed on fish offal diet had 8% more lipid than those

fed solely on cow manure. Larvae put on a fish offal diet had lipids with greater

concentrate of omega-3-fatty-acid after 24 hour (hr) feeding. This additional nutrition

ma de them mo re suitable as a substitute for fish m eal in various animal diets. It was also

observed that larvae grew more robustly on fish offal mixed with cow manure than cow

manure alone (Table IV).


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Table IV. Average Weight of Black Soldier Fly Larvae at the Start and End of the

Trial.

Group

Average weight Average weight Increase

of larvae at the of l rv e at the in

start of the trial end of the study Weight

(g) (g) ( g ) _

100%

cow manure

10% fish offal/ 90% cow m anure

25% fish offal/ 75% cow manure

50%

fish offal/ 50 % cow m anure

0.09

(0.003)

0.10

(0.005)

0.09

(0.008)

0.10

(0.006)

0.10

(0.008)

0.14

(0.003)

0.16

(0.004)

0.15

(0.010)

0.01

0.04

0.07

0.05

Note: The num bers in parentheses represent the standard error of the samples.

Source: Fish offal recycling by the black soldier fly produces a foodstuff high in omega-3 fatty acids (St-

Hilaire et al., 2007).

2.6.1 Dry-m atter Conversion Rate of Black Soldier Fly: The dry matter conversion

rate (DMCR) has been defined as the proportion of soldier fly larvae that could be

produced while digesting one unit of manure (or organic waste) on dry matter basis. The

formula is derived from the definition of feed conversion ratio. Hence, DMCR indicates

the efficiency of these insects in converting man ure to larval biomass of higher econom ic

values. There are two important economic aspects in the conversion process: dry matter

conversion rate and duration required for conversion. Both of these factors were affected

by manure type used for feeding larvae, temperature during digestion, and moisture

content of the manure (Newton et al., 2005). The dry matter conversion rate for poultry

manure was estimated to be 8% and swine manure conversion ranged from 12 to 16%

(Newton et a l, 2005).


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26

on the basis of observation, experience, and ease of calculation (Heady and Dillon, 1961;

Melsted and Peck, 1977; Colwell, 1978). The relationship was based on nature of

diminishing rate return of fertilizer and many other inputs equations such as quadratic,

Cob-Douglas and other polynomial functions. The polynomial models were popular

because they were readily linearized facilitating computations (Heady and Dillon, 1961;

Colwell, 1978). The Mitscherlich function was an exponential model that was based on

the law of diminishing return and many times gave better prediction of the relationship;

however, such function was difficult to fit to least squares and instead required iterative

procedures (Barreto and Westerman, 1987).

The economic optimality of input use not only depends on physical relations as

defined by the functions but also on the price structures of inputs and output. The

optimum input rate for maximum economic yield can be estimated using profit

maximization (i.e., solving profit function by taking its first derivative and equating with

the zero) (Heady and Dillon, 1961; Colwell, 1978). However, while developing a

computer program called "YIELDFIT" to determine economic fertilization rates Barreto

and Westerman (1987) argued that the statement held true for a situation of unlimited

resource availability. For limited capital, the quantity of fertilizer that maximizes the rate

of investment required determination of profit maximization. The optimum fertilization

rate can be obtained from crop value function by the total cost function, differentiated

with respect to fertilizer and solved for rate of fertilization. The program used functional

equations like Mitscherlich, quadratic and square root to predict the yield and estimated

econom ic fertilization rate using least square techniqu es.


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Bullock and Bullock (1994) attempted to calculate optimal nitrogen fertilizer

rates.

The researchers noted that determination of optimal nitrogen application rate

required sound economic theory and clear statements of economic assumptions. They

also pointed out a need for collaborative work for research on economic optimal

fertilization estimation procedure. The study concluded that prediction of economically

optimal rates of fertilizer applications currently had inappropriate methods that could lead

to incorrect results because of ignored risks and uncertainty in agricultural production

that influences p rodu cer's decisions. Also ignored w as the higher degree moment of yield

function. Thus, regression model should be used with appropriate functions to estimate

the coefficients and optimal input recomm endations.

Determining economically optimum nitrogen fertilization rate for any crop is

important for two reasons. First, it gives the maximum profitability of the crop

production. Second, it reduces the negative impact on the environment due to excess use

of fertilizer. However, the calculation of optimality is highly sensitive to choice of the

functional form.

Weliwita and Govindasamy (1997) in the study on alternative functional forms

for estimating economically optimum nitrogen fertilizer rates pointed out that the

estimate obtained for economic optimal rate of nitrogen fertilization was largely

governed by the choice of functional forms. They tested four production functions

namely quadratic, square root, Cobb-Douglas and transcendental models to get the

comparative analysis on corn yield response of nitrogen fertilization. The research was

carried out on Rutgers Plant Science Research Station and Rutgers Snyder Research and


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Extension Farm, New Jersey from 1992 to 1995 using a typical cropping sequence where

corn following soybean. Soil types in the experiment were sandy loam and silt loam

respectively. The selection of appropriate functional form was crucial in fertilizer

response studies. It was suggested that the procedure suggested by Bullock and Bullock

(1994) was appropriate to calculate the economic optimum rate of nitrogen. Statistical

results showed that transcendental model was a better predictor of economic optimum

nitrogen fertilizer rates than the quadratic, square root, and Cobb-Douglas production

functions.

Clark et al. (1991) attempted to find economic optimum fertilization rates for sub-

irrigated meadow hay production. They included values of hay quality when investigating

the interactive effect of phosphorus and sulfur nutrients along with nitrogen fertilizer.

The study found all three fertilizers to influence hay yield production but could not find

significant interaction effect among the nutrients. Thus, they calculated the forage

response to economic optimal rate for each nutrient independently. The study was carried

out on the data obtained from the research plots for 4 years at University of Nebraska's

Gudmundsen Sandhills Laboratory. They estimated that the optimum dose of nitrogen as

70 lbs per acre for given av erage price of hay at $50 per ton and nitrogen at $0.30 per lbs.

However, taking CP into account the optimum dose recommended at 77 lbs per acre

provided ha y price or values $65 per ton. Similarly, with the prices of 0.25 per lbs P2O5

plus application cost, 40 lbs of P2O5 was profitable at hay value exceeding $51 per ton. If

S was to be applied alone at prices ($ 0.17 per lbs plus application cost), hay values

exceeding $34 per ton would bring more return than the cost.


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29

General theoretical know ledge about production functions are readily available in

Q

many text books . Literature shows that the empirical model like linear, multi-linear and

polynomial functions (including quadratic, square root, linear von Liebig, Mitscherlich-

Baule, nonlinear von Loiebig, Cob-Douglas, and transcendental) are commonly used to

construct input-output relationships in agriculture. Since there was no fundamental

theoretical model to represent the effect of inputs on crop yield, the selection of a

particular mathematical model is generally made on the basis of observation, experience,

and ease of calculation (Barreto and Westerman, 1987). Some factors were more

important for yield than others. Thus, a model should be simple and use minimum,

readily available information that has a potential to predict with a certain given precision

(Baier, 1977). Attempts have been made to identify and incorporate factors that are likely

to have statistical significance.

Heady and Dillion (1961) studies on the characteristics of the production functions constructed for

agricultural crop grown in USA for detail.


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CHAPTER III

METHODS AND PROCEDURES

This chapter is divided into five sections: (1) conceptual framework, (2) data

considerations, (3) dry matter conversion rate (DMCR) and manure bulk reduction rate

(MBR ) estimation, (4) benefit-cost analysis, and (5) model estimation.

3.1 Conceptual Framework

3.1.1 Benefit-Cost Analysis: A benefit-cost analysis is a systematic evaluation of the

economic advantages (benefits) and disadvantages (costs) of a project or investment. It

has two important components: the costs and the benefits. Based on the economic theory

of benefit-cost analysis, profit would be maximized where marginal benefit

(MB)

equals

marginal cost

(MC).

The mathematic equivalence of the graphical statement is to

maximize the profit function by taking fist order derivative and equate it to zero

(Equations (1) - (4)).

TT

= TB-TC (1)

^ = ^{TB-TC)

(2)

ax ax

— (TB-TC) = 0

(3)

dx

30


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32

TC,

TB

/

S\

/


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33

The goal of any commercial producer would be to maximize profit through the

optimal production. Thus, economical optimal level of input is obtained by maximizing

the profit function. However, in case of abundant resource that cost no money,

maximizing the production would be the economic goal following the same procedure

that is adopted to attain the maximum profit.

In order to maximize production function, the first order derivative of Equation

(5) would be taken with respect to input and equated with zero,

dY

MPP =

= 0 (6)

dx

dY

where, M PP = — represents the marginal phy sical productivity of the input. Solving

dX

Equation (6) for single variable factor

X

would give the optimal rate of the input use that

maximizes the production and the revenue.

3.2 Data Considerations

Exam ination of the suitability of black soldier fly in dairy waste-management was

carried out at Texas A&M AgriLife Research and Extension Center, Stephenville, Texas

in 2006. Black soldier fly larvae were first reared for 14 days on standard larval diet (also

called Gainesville diet), which is a mixture of several grains that poses a definite

proportion of fiber, nutrients and m inerals. Detail constituents are presented in Table V.


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Table V. Constituents and Composition of the Gainesville Diet.

Con stituents Gainesville Diet °/

1 Alfalfa Meal 30.0

2 W heat Barn 50.0

3 Corn Meal 20.0

4 Brew ers' Dried Grain

Compositions

1

2

3

4

5

Protein

Fat

Fiber

Ash

Calcium

15.3

3.8

12.6

6.3

4.9

Source: A comparison of selected life history traits of the black soldier fly (Diptera: Stratiomyidae) when

reared on three diets (Tomberlin et al., 2002).

One thousand larvae were then released into a container for manure digestion and

further growth. The experiment was carried out from mid-June to mid-October.

Observations were taken from 18 different containers. Each container represented a

replicate, which was defined as egg clutches from individual female flies maintained in a

colony at the TAE S. The colony was maintained using methods described by Sheppard

et al. (2002). These containers were divided into three cohorts (generations): containers

1-6 as a 1

st

cohort, containers 7-12 as 2

n d

cohort, and containers 13-18 as 3

r d

cohort.

th th

Cohorts 1 and 3 had started on June 20 and July 24 , respectively. However, containers

in 2

n

cohort had three starting dates, July 10

th

for containers 7 and 8, July

27

th

for

containers 9 and 10, and July 2 2

nd

for containers 11 and 12.

During the experiment, quantities of manure fed to larvae, duration of digestion,

total number and weight of the harvested prepupae (or larval yield), and residue left after


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digest ions were obtained from the experiment . The summary of data observed for the

three cohorts are presented in Table VI.

Table VI . Summary o f Exper iment Data in Three Cohorts .

V a r ia b le s M in im u m M a x im u m M e a n S t a n d a r d

Error

Co hort 1 (Con tainers 1-6)

Average Laryal Weight per

m 9 6 § Q ?

^

Container (g)

Number ofHarvested Larvae per

5 n QQ

^

QQ m M ? 4 J 6

Container

Averag e Developm ent Time (d) 19.60 28.50 23.15 1.37

M anu re Feedin g per Con tainer (g) 1500.00 1800.00 1625.00 60.21

M anu re Residu e Left (g) 435.10 734.00 636.12 42.58

Cohort 2 (Containers 7-12)

Average Larval Weight per ^ ^ ^ ^

Container (g)

Number of Harvested Larvae per

Container

826.00 871.00 843.00 9.27

Average Development Time (d) 29.01 67.04 48.64 6.53

Man ure Feeding per Container (g) 1440.00 2700.00 2256.00 226.57

M anur e Resid ue Left (g) 390.80 1206.60 899.54 163.09

Coho rt 3 (Conta iners 13-18)

Average Laryal Weight per ^ ^ ^

g 2 3 2 Q

Container (g)


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Number of Harvested Larva e per

m o Q

^ ^

Container

Average Development Time (d) 42.35 69.58 58.07 4.94

Manu re Feeding per Container (g) 2490.00 3060.00 2730.00 108.17

Ma nure Residu e Left (g) 882.30 1432.30 1201.57 83.16

Stat i st ical parameters for each variable were est imated by pool ing data obtained

from these 18 containers. Unless mentioned specifically, al l the data for the study used

these pooled parameters. A summary of these variables in al l containers are presented in

Table VII.

Table VII . Summary o f Overa l l Exper iment Data .

Var iab les Tota l M m M ax M ean Standard

Error

Larval Weight (g) 920.59 37.19 68.07 51.14 1.63

Num ber of Harvested 14,511.00 511.00 927.00 806.17 29.06

Larvae

Average Development

Time (d)

19.60 69.58 43.69 4.22

Manure Feeding (MF

dm

) (g) 40,620.00 1,440.00 3,060.00 2,256.67 139.06

Ma nure Residu e Left 15,523.80 390.80 1,432.30 913.16 80.31

(MRd

m

) (g)

Moisture Content of Raw

Manure (%)

Moisture Content of

Digested Manure (%)

73.54 73.54 73.54 0.00

44.90 55.60 47.98 0.01


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Data and information were also looked for daily manure excretion of a cow,

mineral content in their dung, dry matter content of a black soldier fly larvae and their

nutrient constituent, and prices of fish and soy meals. Other sources of information used

were Agricultural Marketing Service website (USDA, June 2008); Year Book (American

Society for Agricultural Engineers, 1993); and various other research papers and

literature.

3.3 DMCR and MBR Estimation

The dry matter conversion rate (DMCR) and manure bulk reduction rate (MBR)

for each co ntainer were calculated using Equations (7) and (8) respectively.

D M C R = = f ^ * ^ ( % )

( 7 )

^

10

°

MBR (%) = ^

J^~^

— * 100

(8)

L

MF

dm

where, X^Fis the collective weight of the harvested prepupae for each container,

DMC

represents the dry matter content of the larvae,

YMF dm

is the total quantity of the m anure

fed to the larvae (on DM basis) in each container, and

YMRdm

is the manure residue left

after larval digestion (on DM basis) in each container. The mean values and the standard

errors

(SE)

for both these parameter are estimated following statistical procedures.

3.4 Benefit-Cost Analysis

Incorporating black soldier fly larvae into dairy waste-management system could

bring two tangible benefits: benefits from the sale of harvested larvae and cost-saving in


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man ure handling due to reduction in the vo lume of manure as a result of larval digestion.

The total costs, which comprises fixed and variable costs, include the development of

facility to incorporate the larvae into system results in fixed costs, while labor

requirement, maintenance of the facility and equipments, and others would constitute

variable costs.

3.4.1 Benefit Estimation: The benefit estimation is divided into two com ponents: benefit

from the sales of harvested larvae (i.e., prepupae) and cost-saving in reduced manure bulk

handling. The procedure started with the estimation of dairy cattle excretion on both per

day and per annum basis (60.3 kg manure per cow per day). Information was cited from

the literature and Agricultural Engineering Year Book (1993).

Based on per annum excretion of a cow and estimated

DMCR

of the larvae,

volume of prepupae that could be produced in a year was calculated. Since the harvested

pupae can substitute the fish or soy meals to formulate poultry, swine or fish feeds, the

market value of fish and soy meals were taken into account to estimate the value of the

prepupae that could be harvested annually from cow manure.

The estimated

MBR

rate was used to calculate the reduction of manure bulk

produced by a cow in a year. The cost of handling m anure ranged from $47 for 1,000

cows to $87 for 100 cows in lagoon system, while $121 for 1,000 cows to $219 for 100

cows in liquid talk system of manu re manag ement (Bennett et al., 2007). The information

was used to estimate the cost-saving due to reduced bulk of manure handling. The

estimation is done by assuming that these flies would be incorporated into the existing

dairy system. Adding these two values (i.e., value of harvested larvae and cost saving in


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39

manure hauling) gave the total economic benefit of using black soldier fly in dairy

manure management.

3.4.2 Cost Estimation: The total cost includes fixed and variable costs. Estimation of

these costs could have facilitated in the estimation of the cost of incorporating black

soldier fly into the system. Tools such as extrapolation or taking a fraction of cost per

unit in the lab condition could have been used to represent the field condition. However,

the experiment was conducted in controlled conditions to meet its research objectives.

Thus, this study was unable to provide required information to estimate cost constituents

except labor. There was 10 hours of labor spent each week for the research with six

containers been handled at a time. The major portion of the labor was spent on feeding

and hand-picking the mature larvae from the containers. The equation for total labor cost

can be seen in Equ ation (9).

L

N

*C

T

*W

L

*D/

TLC = —

— O-

(9)

where, TLC is total labor cost, L

N

represents the number of labor hours required each

week, CT is the total num ber of con tainers, W i is wage rate, D is average larval

development time in days, and

CN

represents the num ber of containers handled at a time.

Then, average labor cost to produce one kg of larvae (on DM basis) was estimated by

dividing total cost by total larvae produced from 18 containers.

3.5 The Model Estimation

The quantity of larval production and the manure bulk reduction are the two main

economically measurable outcomes of incorporating black soldier fly into the dairy


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40

man ure managem ent system. The objective of these estimations is to maxim ize the larval

production as well as manure bulk reduction. Estimation of both larval production and

manure reduction models started with the estimation of correlation among the variables

under study that included larval weight, manure volume reduction (on dry matter basis),

quantity of manure fed, number of larvae (or prepupae) harvested, and average larval

development duration (Table VII). Then, the regression was done between the dependent

factors with respect to above mentions factors. The dependent factors were larval weight

and manure bulk reduction. Thus, two separate regressions models were estimated. The

iteration started with SAS generalized linear model (GLM) procedure using various

function formats to determine the best fit, beginning with simple linear regression. Each

time the fit of the model was evaluated on the basis of coefficient of multiple

determinations (R ), signs of included factors, and significance of the

t

statistics for the

regression coefficients estimated of each variable. The larval production model

estimation started with the single variable, i.e., manure feeding rate, and gradually

included the other variables, such as, number of larvae harvested and larval development

duration. To capture the effect of temperature of growing season, another variable was

inserted with values ranging from one to five for each starting date with a numerical

progression order.

The same procedure was repeated for the multiple regression model and non

linear regression models by inserting quadratic, contradictory, interactive, and cubical

terms into the model. The interactive term were tried among the pair of variables which

showed highest correlations. This was done by attempting several combinations


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43

compared to thei r performance on poul t ry manure digest ion and almost one-thi rd to one-

fourth to swine manure digest ion (Newton et al . , 2005).

The larvae reduced the manure bulk to 15,523.8 g after digest ing 40,620 g of raw

manure col lect ively. The manure residue, after larval digest ion, had an average moisture

content of 47.98% (Table VII) . However, i t ranged from 44.9 to 55.6% in di fferent

containers. The manure bulk reduct ion rate (MBR) of black soldier f ly in digest ing cow

manure was est imated to be 22.18% with standard error of 3.19% (Table VIII) . The

average manure bulk reduct ion rate for each cohort ranged from

16 .73%

to 28 .49%

(Table VIII) . The low MBR at dai r ies could be the resul ts of unfavorable temperature as

wel l as diff icul ty in digest ing cow m anu re co mpare d to that of poul t ry or swine ma nure.

Table VIII . Calculat ion of DM CR and MB R of Black Soldier Fly in Cow Man ure

Digestion.

V ar i ab le s M i n i m um M ax i m um M ean S tandard

Error

Cohort 1

Dry Matter Conversion Rate .

1 9

(DMCR)

Manure Bulk Reduction Rate (%) 17.70

Cohort 2

Dry Matter Conversion Rate _

Q

(DMCR)

Manure Bulk Reduction Rate (%) 6.05

6.29

39.59

5.05

43.49

5.17

28.49

3.64

20.05

0.32

3.68

0.33

8.32

C ohort 3


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Dry Matter Conversion Rate

(DMCR)

Manure Bulk Reduction Rate (%) 7.82 26.21 16.73 3.53

All 18 Containers

Dry Matter Conversion Rate

(DMCR) (%)

Manure Bulk Reduction Rate

(MBR) (%)

2.82 6.29 3.99 0.25

6.05 43.49 22.18 3.19

The average development time required for these larvae ranged from 19.6 to

69.58 days with an average of 43.69 days (Table VII). These soldier fly larvae also

required longer duration to digest cow manure comparing to 14-22 days reported for

poultry or swine manure (Newton et al., 2005). However, the average development time

of these larvae in digestion cow manure in summer months of mid-June to early July

(cohort 1) was observed to be 23.15 days.

4.2 Benefit-Cost Estimation

4.2.1 Value of Prepupae:

A previous study revealed that an average Holstein cow

excreted 60.3 kg of manure waste per cow per day (on raw weight basis) (Morse et al.,

1994), which equaled to 22,010 kg of manure per cow per year. Since manure contained

73.54% m oisture, the quantity of ma nure excreted per cow per year would be 5,825.91 kg

dry matter. At 3.99% of dry matter conversion rate (DMCR), the larval yield could be

extrapolated to 232.68 kg per cow per year. The value of prepupae generated estimated to

range from $89.58 to $2 30.36, depen ding on w hether considering it as a fish or soy meal


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equivalent. The price of fish meal and soy meal considered in the study were $900 and

$350 per ton, respectively (i.e., $0.99 per kg for fish m eal and $0.39 per kg for soy m eal)

(Table IX). Both of these prices were obtained from USDA-AMS website on June 20,

2008.

However; taking into account of fly being active for only 8 months a year, total

larval yield can be extrapolated to two-thirds of explained above i.e. 155 kg of larval

yield with econom ic value ranging from $59.72 to $153.57.

Table IX. Estimated Value of Harvested Larvae (Prepupae).

Parameters Unit Quantity

Total manure excretion/cow

Moisture content in manure

Dry matter content in manure

Total manure excretion/cow/day (DM basis)

Total manure excretion/cow/year (DM basis)

Dry matter conversion ratio

Larval Yield

Soy-meal Price

Fish-meal Price

Value of

larave

(as soymeal substitute)

Value of larave (as

fishmeal

substitute)

kg/day

%

%

kg

kg

%

kg/cow/yr

/ton

/ton

/cow/yr

/cow/yr

60.30

73.53

26.47

15.96

5825.91

3.99

232.68

350.00

900.00

89.58

230.36

Consequently, the value of harvested larvae can change with the changes in price

of soy meal or fish meal. A sensitivity analysis was performed by using different prices

of soy meal or fish meal and the results are presented in the Figure 5. It was observed that

soy meal prices fluctuated from $250 to $450 per ton, total revenue would range from


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$64 to $115.18. If fish meal prices varied from $800 to $1050 per ton, total revenue

would range from $204.76 to $268.75.

Revenue ( /ton)

350.00 -

300.00 -

250.00 -

200.00 -

150.00 -

100.00 -

50.00 -

0.00 -

0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00

Figure 5. Sensitivity of Revenu e to the Chan ge in Price of Its Substitutes

(Existing Scenario)

4.2.2 Cost-saving:

Based on the estimated results in Section

4.2.1,

a Holstein cow

produced 22,010 kg of manure waste per year. With the average manure bulk reduction

rate (MBR) of 22.18% (Table VIII), the volume of manure could be estimated to reduce

by 4,881.71 kg after larval digestion. The cost of manure handling for a dairy with 100 to

1,000 cow s in a lagoon system ranged from $87 to $47 per cow per year. While in liquid

tank system , it ranged from $219 to $121 p er cow per year (Bennett et al., 2007). Since a

cow excretes 22 ,010 kg of manu re waste per year, the cost of manure handling for a dairy

with 100 to 1,000 cows in lagoon system can be calculated to range from 0.21 cents to

0.40 cents per kg per year, while the cost 0.55 cents to 0.99 cents per kg per year in liquid

tank system, depending upon dairy size (Table X). Therefore, the total cost-savings of

•Fishmeal

Substitute

-Soymeal

Substitute

Price (S/ton)


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manure hauling estimated to range from $10.42 to $19.30 per cow per year in lagoon

system, while $26.84 to $48.57 in liquid tank system (Table X). If one accounts for the

fly being active for only 8 months, the total cost savings would be two-thirds o f what has

been explained a bove i.e. the total cost savings range from $6.83 to $13.02 in the case of

lagoon system wh ile $17.90 to $32.22 in the case of liquid tank system.

Table X. Cost-Savings for Reduced Manure Bulk Handling based on 4,994 kg of

Manure/Cow/Year.

ing Cost-Savings in Manure

Handling ($/cow/yr)

Tank

0.995

0.682

0.654

0.572

0.554

0.550

Lagoon

19.30

15.08

13.31

11.98

10.87

10.42

Liquid Talk

48.57

33.27

31.94

27.95

27.06

26.84

4.2.3 Labor Cost: The research required 10 hours of labor per week to handle 6

containers at a time. The labor was paid on the basis of $7 per hour. As mentioned in

Chapter III (Equation 9), the total labor cost incurred to handle 18 containers and to

produce 920.59 g of live larvae (or 405.06 g in DM basis) that had average development

time of 43.69 days was estimated to be $1,310.70. In other words, $3,236.14 of labor was

spent to produce on e kg of larvae on dry matter basis.

Dairy size

100

200

300

500

750

1000

Cost of Manure Hand

(e7kg/yr)

Lagoon Liquid

0.395

0.309

0.273

0.245

0.223

0.214


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1 0 * 1 8 * 7 * 4 3 . 6 9 /

TLC = ^ - = $1,310.70

A change in labor wage or average larval development time could result in the

variation in total labor cost of handling the larvae. The variations in total labor cost of

handling one kg o f larvae are presented in Tab le XI. It can be seen that labor cost ranged

from $6 to $10 and average larval developm ent tim e ranged from 3 to 7 weeks. The labor

cost would range from $540 for labor wage at $6 per hour and average larval

development time of 3 weeks to $ 2,100 for labor wage of $10 per hour and larval

development time of 7 weeks.

Table XI. Total Labor Cost of Larval Production ( /kg of Larvae on DM basis).

Labor

Price

6/hr

7/hr

8/hr

9/hr

10/hr

3

$540

$630

$720

$810

$900

Larval Development D uration (weeks)

4

$720

$840

$960

$1,080

$1,200

5

$900

$1,050

$1,200

$1,350

$1,500

6

$1,080

$1,260

$1,440

$1,620

$1,800

7

$1,260

$1,470

$1,680

$1,890

$2,100

However, the labor cost estimated here would not reflect field reality because of

two main reasons. First, the labor required for any research cannot directly translate to

commercial level production. Second, the matured larvae were hand-picked during the

research which would not feasible for mass production. Besides, facilities like

self-

harvesting or collecting, as proposed by Newton et al. (2005), would not require any


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49

labor at all for harvesting. Th e only labor that would be required in such facility would

be collection of self-harvested b ins at the end of the day. Thu s, use of such facility could

drastically reduce the labor cost in handling the larvae

The benefits that the black soldier fly can bring into a dairy system depend on the

market value for the harvested prepupae, manure handling system, and size of a dairy.

The range of benefits for three different dairy sizes (with 100, 500, and 1000 cow s), with

two popular manure management system are presented (Table XII). The minimum

benefit of $99.92 per cow per year would be realized for dairies with 1,000 cows using

lagoon system and harvested larvae fetch price equivalent to soy meal. The maximum

benefit could reach $27 8.70 per cow per year for dairies with 100 cows using liquid tank

system and harvested larvae fetch the price of fish meal. For a dairy with 500 cows (the

average size of dairy in Erath County) using a lagoon system can reap the benefit of

$101.47 - $242.11 per cow per year, while with liquid tank system the range vary from

$117.44 to $258.08 per cow per year, depending upon the price the larvae are able to

fetch (Table XII).


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Table XII. Total Benefit of Incorporating Black Soldier Fly in Dairy Waste

Managem ent System ( per cow per year).

Value

of

Larvae

( )

(1)

Cost-

100

(2)

•saving in man ure

handling

(Dairy Size)

500 1000

(3) (4)

Total Benefit

(Dairy Size)

100 500 1000

(5)=(D+(2) (6)=(l)+0) (7)=(l)+(4)

A. Lagoon System

Soy meal

Fish meal

89.58

230.30

19.30

19.30

11.98

11.98

10.42

10.42

108.79

249.43

101.47

242.11

99.92

240.55

B. Liquid Tank System

Soy meal

Fish meal

89.58

230.30

48.57

48.57

27.95

27.95

26.84

26.84

138.07

278.70

117.44

258.08

116.33

256.97

Incorporating black soldier fly into dairy waste-management system, however,

requires additional cost for facilities, equipment and labor in a dairy system. Newton et

al.

(2005) reported that w ith a simp le arrangement o f additional concrete trench with 45°

sloped-walls and a motor p um p to spread m anure w ould be sufficient to incorporate black

soldier fly into manure management system. These facilities utilize the migrating instinct

of the larvae to dry places during pupating for self-harvesting and keeping labor and

handling cost to minimal. The matured larvae would climb the 45° sloped trench walls,

which end in a gutter leading to self harvesting bin. Thus, the estimated figures above can

give a producer an idea of maximum investment one can make to incorporate a facility

into the system. Further, incorporating black soldier fly in waste-management generates

environmental and social benefits, such as fewer house flies, reduction in smell, lower

nutrient runoff to streams especially nitrogen & phosphorus, and final disposal with less


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infected harmful microorganism, such as

E. Coli,

thus making it more desirable for the

policy-ma kers to support through subsidies or other credit facilities.

In the scenario of pre-achieved success to maintain black soldier fly colonies

year-round in a greenhouse condition

10

(Sheppard et al., 2002), the biggest challenge to

translate above theoretical estimation into field reality, would be to develop a facility that

could provide constant warm temperature (above 27° C) all round the year especially in

winter mo nths. These flies have b een described as tropical insects (Sheppard et al., 1994).

And their effectiveness has been found to drop drastically with plunging temperatures

(Tom berlin et al., 200 8). The favorable range of temp erature for these insects falls

between 27° to 36° C (Tomberlin et al., 2008). Similarly, as the voracity and growth of

the larvae could be altered through the nutrient contents of the feeding materials

(Tomberlin et al., 2002; St-Hilaire et al., 2007), finding appropriate and cost-effective

manure mix could drastically improve the results and the benefits. Research has shown

that addition such as fish offal to cow manure by a small proportion could substantially

influence the larval growth (Table IV).

4.3 Larval Production Model

The correlation among the variables larval weight, number of prepupae harvested,

average development time, quantity of manure fed and manure bulk reduction and their

significance are presented in Table XIII, where W is the total weight of the larvae

harvested from each container,

Num.

is the num ber of prepupae h arvested from each

10

A new study has also indicates that the black soldier fly could be m ass produced indoors, which could

eliminate the need for a greenhouse.


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52

container, D is the average developm ent tim e (in days) of the prepupae, M F is quantity of

manure fed to the larvae in each container, and

M R

is the manure bulk reduction (on DM

basis) due to larval digestion observed per container.

Table XIII. Correlation Coefficients Between the Variables, and Its Probabilities >

|r|-

w

N u m

D

M F

M R

W

1.00000

0.83584

(


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In the likely scenario with abundant manure availability, maximization of larval

yield would be the econo mic o bjective. Thus, maximizing larval yield function (Equation

10) revealed room for improvem ent. Resu lts showed that 58.31 g of live prepupae can be

harvested from 2,057.24 g of manure keep ing the larval inoculation (1,000 per container)

and the survival rate at the same levels (Figure 6). At this rate of larvae production, the

dry matter conversion rate of these larvae (Equation 7) increases to 4.69%, which means

an increment of 17.54% over the exiting conversion factor of 3.99% realized in the

experiment.

The result obtained from the estimated model suggested there was over

abundance of manure to these larvae. Hence, the possibility that excess moisture hindered

larval growth. Excess moisture has already been reported to hinder the growth of these

larvae (Newton et al., 2005). The increase in larval harvest translates to 273.24 kg of

larvae per cow manure excretion per year. Compared to the results obtained through the

research, the increased larval production brings in addition income of $15.61 to $40.15

per cow per year (Table IX and XIV).


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Table XIV. V alue Estimation of Increased Larval Yield.

Parameters

Total manure excretion/cow

Moisture content in manure

Dry matter content in manure

Total manure excretion/cow (DM basis)

Total manure excretion/cow (DM basis)

Dry matter conversion ratio

Larval Yield

Soy-meal Price

Fish-meal Price

Value of larave (as soymeal substitute)

Value of larave (as fishmeal substitute)

Unit

kg/day

%

%

kg/day

kg/yr

%

kg/cow/yr

/ton

/ton

/cow/yr

/cow/yr

Quantity

60.30

73.53

26.47

15.96

5825.91

4.69

273.24

350.00

900.00

105.20

270.50

A sensitivity analysis of the increased benefit from the sale of harvested larvae

was presented in Figure 7, whe re the two possible scenarios of of black soldier fly larvae

substitution as a feed ingredient (i.e., soy or fish meals equivalents) have beeen

presented. Prices are given in the x-axis and corresponding revenue that would be

generated are presented in the y-axis. The revenue would range from $74.14 to $135.25

for soy meal price fluctuating from $250 to $450 per ton. Similarly, the revenue would

range from $240.45 to $315.59 for fish meal price ffuctuaing from $800 to $1050 per ton.


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57

Rvenue

( /ton)

400.00

350.00

H

300.00

250.00

200.00

150.00

100.00

50.00

0.00

-Fishmeal

Substitute

-Soymeal

Substitute

ric

e

( /ton)

0.00 200.00 400.00 600.00 800.00 1000.00 1200,00 1400.00

Figure 7. Sensitivity of Revenue to the Change in Price of Its Substitutes

(Improved Scenario)

4.4 Manure Bulk Reduction Model

Rate of manure feeding and the growth of the larvae (i.e., cumulative weight of

the larvae) are the two important cofactors in determining manure bulk reduction.

How ever, the rate of man ure feeding also influences the growth of the larvae. Hence, the

following m odel was cho sen to explain the relationship based on the observed data.

MBR = -101.37 +

0.02S*Num -

6l.22 Dum + 0.083*MF-

03*W

6

*M F

2

*W +

0.51 *D

(-2.05) (1.45) (-2.63) (2.48) (-3.27) (2.26)

R

2

=

0.8297

(11)

where, MBR is manure bulk reduction rate (in percentage), and W is the total weight of

harvested larvae, and other variables are the same as explained earlier in Equation (10).

The model predicted 82.97% of the variability in MBR with respect to the independent

factors considered in the Equation (11). The estimated coefficients for factors

Dum, MF,


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58

MF

2

*W were significant at 95% level, intercept and

D

were significant at 90

economics of black soldier fly

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