economics of black soldier fly
TRANSCRIPT
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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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C \ y••••
ISZ'-PV'M C CC
7
Comm ittee Member „ / "
o^^o-
Comm ittee Member
Head, Department of Agribusiness, Agronomy,
Horticulture and Range Management
iorticulture and Kang e Mar
)ean, Co llege of Graduate
J
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7
Date
H~ 70
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Date
704^^71
Date
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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
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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
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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
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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
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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
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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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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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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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TC,
TB
/
S\
/
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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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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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47
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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51
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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55
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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MF
2
*W were significant at 95% level, intercept and
D
were significant at 90