01994Applied Poultry Science. Inc

           OF POULTRY
                          TIANDE CAI and OSCAR C. PANCORB02
       Department of Food Science and Technology, University of Georgia, Athens, G A 30602
                                     Phone: (706) 542-1001
                                      FAX: (706) 542-7472
                                    WILLIAM C. MERKA
             Department of Poultry Science, University of Georgia,Athens, G A 30602
                                       JEAN E. SANDER
             Department of Avian Medicine, University of Georgia, Athens, G A 30602
                                   HAROLD M.BARNHAR?
       Department of Food Science and Technology, University o Georgia, Athens, G A 30602

    Primary Audience: Poultry Producers, Flock Supervisors, Rendering
                      Managers, Processing Managers

        Laboratory and field experiments were conducted to evaluate lactic acid fer
      th industrial carbohydrate by-products as fermentation subs
             r processing offal, blood, and dissolved air flotationwastewater
             carcasses. Additions of 15% brewer's solubles, 15% dry mol
    molasses, 6% cane sugar,6%whey product, or higher proportion
                                    ge (pHS4.2) at 30°C or 37°C o
                                    15% or less putrefied. Reduced te
                           a commercial silage culture of lactic acid
      rmentation. Offal mixed with DAF sludge at 12% and 24% was
    alone. Fermentation with 15% brewer's solubles was the
           d for preserving both poultry processing by-products and waste
           for subsequent nutrient recovery.

                                    cts, carcasses, fermentation, lactic a

                                                                   1994J. Appl. Poul

1 A portion of this paper was presented at the 1992 Food Industry Environmental Conference,
  Georgia Tech Research Institute, Atlanta, GA.
2 Present address: Division of Environmental Analysis, Senator William X. Wall Experiment
  Station, Massachusetts Department of Environmental Protection, 37 Shattuck Street,
  Lawrence, MA 01843.
3 To whom correspondence should be addressed
18                                                    FERMENTATION OF POULTRY WASTE

                    with 10-20% fermentable combined carbohy-
          OF PROBLEM
  DESCRIPTION       drates produced an acidic silage.
     Broiler processing plants produce large               In our previous studies on direct acidifica-
quantities of offal, feathers, blood, and dis-        tion of poultry offal and carcasses [12], putre-
solved air flotation (DAF) sludge. Most offal         faction was prevented when silage pH was
is shipped to rendering plants for processing         maintained below 4.5 and volatile nitrogen
into animal feed supplements. However, rapid          (NH3-N) content was less than 0.3%. The
putrefaction of offal requires immediate ren-         present study sought to evaluate lactic acid
dering of fresh offalto prevent odor problems.        fermentation using inexpensive carbohydrate-
The hauling fee per ton of offal increases when       rich industrial by-products as fermentation
less-than-truckload quantities of offal are           substrates and to establish a technically and
transported. The utilization of offal becomes         economically feasible lactic fermentation pro-
more difficult when high summer tempera-              cess that would stabilize poultry offal, blood,
tures accelerate offal deterioration, which re-       DAF sludge, and poultry carcasses. Specific
sults in a poorer quality of poultry meal.            objectiveswere: 1) to determine industrial car-
Holding offal on weekends is most troul?!e-           bohydrate by-product fermentability and the
some to manage since a typical rendering plant        minimum levels required to stabilize poultry
stops operations on weekends to maintain              carcass and offal silage, 2) to evaluate the
plant equipment. Thus, developing a techni-           effect of temperature on fermentation, 3) to
cally feasible and economical method to stabi-        test the feasibility of fermenting various poul-
lize poultry offal would benefit both poultry         try processing by-products and waste (offal,
processing and rendering plants.                      blood-offal mixture, and DAF sludge-offal
     The disposal of poultry carcasses also           mixtures) and poultry production wastes
presents significant environmental, biological,       (broiler carcasses, dead male chicks, and
and financial problems for the poultry indus-         hatchery waste), 4) to determine whether sup-
try. Currently, carcasses are disposed of by          plementation with a commercial silage culture
burial, incineration, rendering, composting, or       was necessary, and 5 ) to demonstrate the eco-
landfilling [1,2]. Each of these processes, how-      nomic feasibility of the optimal fermentation
ever, has its unique flaws. Burial of dead birds      process.
in a pit can lead to ground water contamina-
tion. Incineration is expensive and can poten-          MATERIALSMETHODS
tially pollute the air. Rendering dead birds into
by-product meal is constrained by transporta-         CARBOHYDRATE SOURCES A N D
tion cost and restrictions on the movement o      f   SILAGE CULTURE
diseased birds from one location (e.g., a                  Industrial carbohydrate-rich by-products
county) to another [l].   Landfilling is subject to   tested for fermentability were liquid molasses,
land availability and limitations on diseased         dry molasses, corn meal, non-delactosed dry
carcass movement.                                     wheys, and brewer’s solubles. Cane sugar was
      Lactic acid fermentation offers potential       used as a carbohydrate control since it was a
hope for economically disposing of dead birds         good fermentation substrate [4]. A commer-
without contaminating the environment and             cial microbial silage culture used in this study
may also provide an income from the recovery          contained Lactobacillus plantarum, Lactoba-
of nutrients since the fermented product (si-         cillus acidophiliis, Streptococcus faecium,
lage) is suitable for rendering [l]. In fact, fer-    Bacillus subtilk, and Aspergillus otyzae .
mentation of dead birds, poultry offal, and
edible food wastes with lactic acid bacteria is       FERMENTATIONPROCESS
very effective in inactivating pathogenic vi-             Laboratoty Experiments: Dead broilers
ruses and bacteria [3,4, 51. The ensiled prod-        (dead-on-arrival birds), offal, and DAF sludge
ucts from poultry viscera [ 6 ] ,poultry offal [7],   were obtained from a local broiler processing
swine slaughter-house offal [8],and waste fish        plant. Dead male chicks and hatchery waste
(9,101have been demonstrated to be useful for         came from a local commercial hatchery farm.
incorporation into swine and poultry diets.           Broiler carcasses (axe-chopped before grind-
More recently, Murphy and Silbert [ l l ] re-         ing), offal, chicks, and hatchery waste consist-
ported that fermentation of broiler carcasses         ing of egg shells, non-fertile eggs, dead
                                                      embryos, and deadkull chicks were separately
                                       Research Report
CAI et al.                                                                                        19

ground using an Enterprise meat grinder with        sive of the added water. The mixture was trans-
a 12 mm sizing dice. The ground poultry waste       ferred by an auger to a truck tank, held and
was then mixed with a carbohydrate and incu-        accumulated each day. When the tank was full,
bated in a partially sealed plastic container at    the silage was shipped to a plant in north Geor-
a specified temperature. Samples taken at           gia for rendering, where samples were taken
various times during fermentation revealed          for quality analysis.
pH measurement and ammonia nitrogen
analysis.                                           DATA RECORDING AND ANALYSIS
     Silage culture inoculum (by weight of 0%,           Ammonia nitrogen (volatile nitrogen) in
0.01% dry powder, or 2% activated liquid            samples was analyzed according to Section
culture) was added to carbohydrate-supple-          417D of APHA Standard Methods [16].
mented ground poultry waste in a 2.3 liter          Acidity (pH) wasmeasured with a CorningpH
(0.5 gal) plastic container containing 1.5 kg of    meter equipped with a flat surface combina-
the final mixture. The activated liquid culture     tion probe electrode. Statistical methods of
was prepared by inoculating 0.3% dry silage         regression, general linear model, paired t test,
culture into 5% whey product solution in            and Duncan's multiple comparison proce-
water. This mixture was incubated at 37°C for       dures [ 171 analyzed the experimental data.
six to nine hr until lactic acid bacteria reached   Significance was defined as probability of 0.05
108-109 CFU/ml. To ensure adequate mixing           or less. All treatments and samples were run
and to raise the final moisture of silage to        in duplicate, unless otherwise specified.
60-70% for lactic acid bacterial fermentation
[l, 151, carbohydrate materials were diluted          RESULTS DISCUSSION
before use with reagent-grade ( m e I) water
[16] in the following ratios (w/w): dry             SUBSTRATE FERMENTABILITY AND
mo1asses:water = 1:2; corn meakwater = 1:2;         CONCENTRATION
dried whey:water = 1:2; cane sugar:water =               Poultry carcasses and offal are deficient in
1:2; liquid mo1asses:water = 1:l; brewer's          carbohydrates necessary to support the
solub1es:water = 1:0-0.5. After mixing with         growth of lactic acid bacteria. Therefore, inex-
the carbohydrate and silage culture, the            pensive carbohydrate supplements were
ground carcass or offal was incubated at 21",       tested to evaluate pH reduction as a measure
30", or 37°C for up to twenty-eight days, unless    of fermentability at 37°C with the addition of
otherwise specified.                                2% activated liquid silage culture. All pH
     Field Experiments: Poultry processing          values of carbohydrates (except corn meal)
offal was obtained from a rendering plant in        decreased from about 6.0 to 14.2 during the
north Georgia. The offal was ground and             first two days of fermentation (Figure 1).
mixed with 6% whey product or 15% brewer's          Carcasses treated with cane sugar (100%
solubles, and with or without 0.01% dry silage      sucrose), dry wheys (83% lactose for whey
culture. The final mixture (about 40 kg) in a       product and 72% lactose for sweet dry whey),
57 liter (15 gal) covered plastic container was     liquid molasses (50% invert sugar), and dry
manually homogenized with a metal potato            molasses (38% invert sugar) had significantly
masher and stored at ambient temperatures           greater pH reductions (P c .05). This finding
for twenty-two days. Ammonia nitrogen and           indicates that sucrose, lactose, glucose, and
pH were monitored during fermentation.              fructose were more fermentable by indigenous
     Fermentation of poultry carcasses in field     microflora and the silage culture than the
trials was carried out on a poultry farm in north   starch in corn meal. The addition of 6% liquid
Georgia. Dead layer carcasses were received         molasses (LM), 10% dry molasses (DM), 10%
from the farm and ground with a 20" G.P.R.          or 15% corn meal (CM), or 10% brewer's
poultry grinder (Animal Health Sales, Inc.,         solubles (BS) did not produce adequate acids
Selbyville, DE). About 1.5 kg of a 34% whey         to stabilize the carcasses for eight days. Car-
solution in water inoculated with 0.057% dry        casses treated with corn meal yielded pH pat-
silage culture was added to every five birds        terns different from those with other
(about 8 kg) during grinding. Therefore, the        substrates during fermentation (Figure 1)
ground mixture contained approximately 6%           because the starch in corn meal was not
dry whey and 0.01% dry silage culture exclu-        directly fermentable. It had to be broken down
                                                    by the silage culture, particularly Aspergillus
20                                                     FERMENTATION O F POULTRY WASTE



                                                                                                 10%   es

                                                                                                 15% es
       4-                                                                             -*         20% BS


                             Days                                              Days
FIGURE 1. Effectsof supplemental carbohydrate type and concentration on the p H of broiler carcasses during
fermentationat 37°C: LM = liquid molasses, DM =dry molasses, CM = corn meal, WP = whey product, DW = dry
sweet whey, CS= cane sugar, and BS= brewer's solubles.

oyzae and Bacillus subtilis, before sufficient         of tested substrate concentration (R2 > 0.91,
acids could be produced. As a result, pH in-           P < .OOl) for each of the carbohydrate supple-
creased after the depletion of available sugars        ments. A projected minimum of 6% CS, 8%
and decreased again after the starch began to          WP, 12% LM, 13% DM, 15% BS, or 24% CM
break down. Carcasses fermented with 15%               should have produced a pH of 4.2 and 4.4 or
corn meal had approximately the same pH as             less in carcasses ensiled for two and eight days,
with 20% corn meal on day 8, but the former            respectively. The minimum fermentable car-
became putrid on day 6, having high pH and             bohydrate levels required to produce end-
NH3-N concentrations (Figures 1and 2). The             point pH (14.2) are close to those reported
pH (54.2) of carcasses fermented with 2 10%            previously [9], but lower than those reported
LM, 215% DM, 215% BS, 26% WP, 510%                     by Murphy and Silbert [ll].The discrepancy
dry sweet whey (DW), or 2 6 % CS was signif-           may be attributed to the different ground car-
icantly lower than the pH of other silage dur-         cass sizes. The larger the ground tissue size,
ing storage for eight days (Figure 1).                 the more acid is nccded to penetrate it; there-
Regression analysis showed that the pH was             fore, more fermentable carbohydrate is re-
highly correlated linearly with the square root        quired as supplement.
                                          Research Report
CAI etal.                                                                                                   21

                                                    contained 0.32% 2 0.11% NH3-N (Table 1).
                                                    These findings were similar to those of the
                                                    laboratory silage produced from one-day-old
                                                    carcasses fermented with 6% whey product
                                                    for eight days (Table 2).

                                                    FERMENTATION TEMPERATURE
                                                        Temperature is an important factor influ-
                                                    encing fermentation. Carcasses and offal fer-

         LM     DY     CY    WP      DW     CS
                                                    mented at 30°C and 37°C yielded acidic silage
                                                    in the presence of sufficient carbohydrate
                Ca rbohyd rats Source               (Figure 3). No differences (P > .60) in pH re-
FIGURE 2. Ammonia nitrogen in broiler carcasses     duction occurred between 30°C and 37°C. A
fermented for eight days at 37°C with liquid        considerably higher pH of poultry offal at 21°C
molasses (LM), dry molasses (DM), corn meal (CM),
whey product (WP), dry sweet whey (DW), or cane     than 30°C and 37°C was observed when the
sugar (CS).                                         offal was fermented for eight days with 6% WP,
                                                    10% WP, 10% LM, or 15% BS because of slow
     Ammonia is an index of lactic acid fer-
mentation because high values indicate high
protein degradation. A successful lactic acid
fermentation would result in low pH and low
ammonia content. At least 10% LM, 13%DM,              MONTH         BATCH#          pH           NH3-N(%)
20% CM, 6% W, DW, or 6% CS was
                      8%                            July               1            4.9              0.21
needed in the carcasses to achieve an NH3-N                            2            5.4              0.48
content of less than 0.3% (Figure 2). Ammo-
nia nitrogen increased with pH and they were         September         3            4.8              0.36
positively correlated linearly (R = 0.91,            October           4            4.9              0.26
P < .Ol). Thus, pH to agreat extent can be used      November          5            4.6              0.28
to evaluate silage quality and stability.            Mean 2 Standard              4.920.3          0.3220.11
     Field studies on the fermentation of            Deviation
ground offal from three broiler processing
plants at ambient temperatures of 6°C to 22°C
showed that the addition of 6% whey product         TABLE 2. p H of one-day-oldcarcassesfermentedfor
and 0.01% silage culture stabilized the offal for   eiaht d a w with carbohvdrate sumlement
twenty-two days with an endpoint pH of 4.81
2 0.05 and an endpoint NH3-N concentration
of 0.19% 2 0.01%. No statistically significant
differences in pH and NH3-N content oc-
curred among the offal from the different                  670 WP
plants during fermentation for twenty-two                                                 4.73a       0.40a
days. Ammonia nitrogen concentration in                                                   4.69a       0.3Sa
offal was not significantly different before and           10% LM            37           4.79a        -
after fermentation. The ground offal control
                                                                             30           4.61a        -
(untreated offal) in this study putrefied during
storage and had an NH3-N content of 0.7% at                                  21           4.61a        -
eight days. These results indicate that fermen-            15% BS            37           4.21b       0.33a
tation at low temperatures inhibited ammonia                                 30           4.2.1b      0.32a
production.                                                                  21           4.5?        0.30a
     Fermentation of poultry carcasses at am-
bient temperatures on a 650,000 layer farm in
north Georgia has been in operation since
June of 1991. Carcasses fermented for five
months from July to November showed that
the carcass silage had a pH of 4.9 2 0.3 and
22                                                            FERMENTATION OF POULTRY WASTE

                                                              bation and the high buffering capacity of egg
                                                              yolk and egg shell (calcium) accounted for the
                                                              unsuccessful fermentation of this waste. Thus,
                                                              proper fermentation of poultry waste requires
                                                              the material to be fresh and have a low buffer-
                                                              ing capacity. Studies of broiler carcass fresh-
                                                              ness also revealed that it was more difficult to
                                                              stabilize one-day-old carcasses than fresh car-
                                                              casses. A substrate concentration of 10% liq-
     -                                                        uid molasses or 6% whey product added to
         37 30 21 37 30 21 37 30 21 37 30 21 37 30 21
                                                              one-day-old carcasses might not produce suf-
                                                              ficient acids to stabilize the carcasses for more
                                                              than eight days, as the carcass pH was unstable
                                                              and increased to 4.8 during storage for eight
                                                              days (Table 2). Therefore, old carcasses may
a    5                                                        need a higher concentration of fermentable
                                                              carbohydrate to have a satisfactory lactic acid
     4                                                        fermentation for preservation. Spoiled poultry
                                                              materials, however, cannot be stabilized by
     3                                                        fermentation.
         37 3 o z i   373021     ~ 7 ~ 0 2 1 3021
                                         37         3730            Offal silage had a higher acidity than car-
                                                              cass (broiler or chick) silage (Figure 4A). A
                      T e m p e r a t u r e (OC)              similar phenomenon was observed (Figure 3)
FIGURE 3. Effect of temperature on pH of broiler              based on the same substrate treatment
offal (A) and carcasses (8)fermented for eight days           (e.g., 6% WP and 10% LM), since offal
with whey product (WP), liquid molasses (LM), or
brewer's solubles (BS).                                       (viscera, heads, and feet) contains more car-

fermentation at the lower temperature
(Figure 3A). The opposite occurred when the                        "'A                           A I4akh.r). W a s h
substrate concentration was low ( i e . ,6% LM),                                                 A Doad Yale Chicks

presumably because the depletion of ferment-                       5.0                           0 BmilwOffal

able carbohydrate stopped the production of
acid at the higher temperatures (Figure 3A).
Similar results appeared in fermented car-
casses with 10% BS and 15% BS (Figure 3B).                         4.0
A fermentation temperature of 21°C pro-
duced a lower pH with 10% BS, but yielded a                        3.5   '
                                                                         0       2       4       6           8
higher pH with 15% BS than at 30°C and 37°C
at eight days. Thus, an interaction between
substrate concentration and temperature
occurred. Whenever there was adequate car-
bohydrate available for fermentation of poul-                 I
try offal and carcasses, a higher pH would be
observed at 21°C than at 30°C or 37°C.

                                                                         0   2       4   6   8   IO     12       14    16
     Fermented broiler offal, carcasses, and
male chicks had a pH of 4.3 or less when stored                                 Days of F e r m e n t a t i o n
for eight days at 37°C (Figure 4A). However,                   FIGURE 4. pH of poultry waste materialsfermented
the pH of fermented hatchery waste was sig-                    at 37%: (A) with 15% brewer's solubles; (8)mixtures
                                                               of DAF sludge, brewer's soluble, and offal;
nificantly (P c .OS) higher, resulting in putre-               10SLGIOBS80FL = 10% OAF sludge, 10% brewer's
faction of the material after four days. The                   solubles, and 80% offal; 15BS85FL = 15% brewer's
poor quality of the raw material before incu-                  solubles and 85% offal; etc. (wet weight basis).
                                      Research Report
CAI et al.                                                                                      23

bohydrate than the whole carcass on a weight      of fermentation probably stemmed from mold
basis. Thus, carcasses should require more        growth resulting from repeated opening of the
supplemental carbohydrate than offal for suc-     container for pH measurements.These results
cessful comparable fermentation.                  indicate that the level of indigenous lactic acid
    DAF sludge added to offal did not have a      bacteria in poultry offal and carcasses was
significant effect on pH at sludge concentra-     adequate to ferment carbohydrates, also lead-
tions of O%, 10% and 20% when fermented for       ing to the rapid production of acid to prevent
fourteen days (Figure 4B). The difference in      putrefaction. A field study of the fermentation
sludge-offal pH resulted from the influence of    of broiler processing offal for eight days at
brewer's solubles (BS) concentration rather       ambient temperatures of k16"C at the render-
than from the effect of sludge concentration.     ing plant also showed no significant differ-
Offal or sludge-offal ensiled with 15% BS had     ences in acidity and ammonia content between
a more stable pH than that with 10% BS. All       offal silages with and without silage culture
15% BS-based offal and sludge-offal mixtures      inoculation. Both offal silages had a pH of 5.0
had a pH close to 4.0 after storage from one to   and NH3-N concentrations of 0.30%-0.34%.
fourteen days (Figure 4B).                        We can conclude that adequate lactic acid
                                                  bacteria are naturally present in poultry offal
SUPPLEMENTAL SILAGE CULTURE                       and carcasses and that supplementation of
     Fermentation with a commercial silage        commercial lactic acid bacteria is unnecessary
culture inoculum (2% liquid culture or 0.01%      for effective fermentation of these materials.
dry powder) was not significantly different
from that without inoculation (Figure 5). Some           ECONOMIC FEASIBILITY
differences in pH observed at the later stage                 Fermentationwith 15% brewer's solubles
                                                         (BS, which contained 50-52% solids) was the
     6.0 I                                 1
                                                         most inexpensive of the effective carbohydrate
                                                         sources and concentrations tested (Table 3).
                                                         The cost of this substrate was $8.3/1,000 kg
                                                         silage (based on 1992 cost estimate). In addi-
                                                         tion, fermentation of broiler offal, fresh car-
                                                         casses, and one-day-old carcasses confirmed
                                                         that 15% BS silage produced lower pH than
                                                         the 6%                          or 10% liquid
     3.5 L                          A molasseswhey product (WP)2). Although the
                                                                     (LM) silage (Table
       I                                               i
                                                         cost of 10% LM was approximately the same
     5.5t      Offa'                                     as for 15% BS (Table 3), offal and carcasses
                                                         ensiled with the latter were more stable during
                                                         storage for twenty-eight days. The endpoint
                                                         pH of 15% BS based silage was 4.3, whereas
                                                         the pH of 10% LM silage was 5.2. Moreover,
                                                         the addition of 15% BS to ground broiler car-
     3.5 I                                     .       1                          ,                      .
                                                         casses, offal, or DAF sludge-offal mixture
          I----------                                    (1:3.3 by wet weight) stabilized silage pH
                                                         ( ~ 4 . 5 for sixty days.
                                                              A typical poultry farm with 650,000 birds
                                                         spends thousands of dollars annually on trans-
                                                         portation costs and fees for landfilling dead
                                                         birds. When lactic acid fermentation stabilizes
                                                         the carcasses, the annual cost including over-
                                                         head and materials will cost approximately
                                                         $4,400 for fermentation with 6% whey product
                     Days of Fermentation                or $3,090 for fermentation with 15% brewer's
 FIGURE 5. Effect of silage culture supplementon the     solubles (Table 4). If the fermented carcasses
 p H of broiler carcasses, offal, and DAF sludge-offal   are saleable, the farm can realize a financial
 mixture (1:3.3 by wet weight) fermented with 15%
 brewer's solubles at 30°C.                              return on the fermentation investment, be-
24                                                    FERMENTATION OF POULTRY WASTE

TABLE 3. Cost estimates of carbohydrate supplements

  Based on sale in bu

                                            Whey product                    Brewers solubles

Grinder, auger                                 $1750/yr                        $175O/yr
Facilities, supplies                           $ 400&                          $400/yr
Whey product (6%)                              $2250/yr                            -
Brewers solubles (15%)                            -                             $ 94Otvr
Annual cost                                      y
                                                0/                 I            $309O/yr

Carcass silage sales ($0.02/lb)                S5600/yr                        $5rn/yr
Possible net return               I            $1200/vr                         SZlO/vr

cause renderers may pay $0.02-0.03/lb [l].            dollars/provide economicbenefit for the poul-
Therefore, unlike other disposal methods, fer-        try farm but also reduce environmental con-
mentation of carcasses could not only save            tamination significantly.

                                   AND APPLICATIONS
 1. Effective stabilization of chicken processing offal, blood-offal and DAF sludge-offal mix-
    tures, and chicken carcasses can be achieved by lactic acid fermentation supplementedwith
    cane sugar, dried whey, molasses, and brewer’s solubles. The minimum concentration of
    substrate used to stabilize chicken offal or carcasses for eight days was 6% for cane sugar,
    6% for dried whey, 10% for liquid molasses, and 15% for brewer’s solubles. Higher levels
    may be needed for longer stabilization of coarsely-ground older carcasses or offal.
 2. Corn meal was a poor fermentation substrate. Carcasses ensiled with 10-15% corn meal
    putrefied after storage for four to six days at 37°C.
                                               Research Report
CAI et al.                                                                                                         25

 3. Fermentation of offal and carcasses was slower at 21°C than at 30°C and 37°C. Adding
    adequate fermentable carbohydrate produced a more stable silage at 30-37°C.
 4. Stabilization of poultry carcasses required more supplemental carbohydrate than stabili-
    zation of poultry offal.
 5. Indigenous lactic acid bacteria in chicken offal and carcasses fermented carbohydrates
    equally well with or without the supplementation of a commercial microbial silage culture.
    Thus, the addition of silage culture can be eliminated to reduce the cost of fermentation of
    these poultry wastes.
 6. The addition of 15% brewer’s solubles to ground chicken offal, DAF sludge-offal mixtures,
    and chicken carcasses produced stable, acidic silage (pH < 4.5) for sixty days. This process
    seems to be the most economical and technically sound stabilization method to use on a
    large scale to preserve these materials for subsequent nutrient recovery.
 7. Carcass silage production on a poultry farm proved that lactic acid fermentation to stabilize
    carcasses was technically and economically feasible if a renderer could provide a truck tank.
    Lower fermentation cost and higher silage quality would be expected if 15% brewer’s
    solubles was used as the supplement on the farm. Fermentation of carcasses may provide
    additional income for farms since the product was suitable for rendering. Furthermore,
    ensiled carcasses were reused and would not contaminate the environment like other
    carcass disposal methods.

                                           AND NOTES
   1.Dobbins, C.N., J.r., 1990. Dead birddisposal through        10. Tibbells, C.W., R.W. Seerley, H.C. McCampbell,
the use of Iactobaclllus fermentation (ensilage). Pre-       and S .Vezey, 1981. An evaluation of an ensiled waste
sented at the Southeastern Poultry and Egg h o c . Conf.,    fish product in swine diets. J. Animal Sci. 52:93-100.
Atlanta, GA.
                                                                 11.Murphy, D.W. and S.A. Silbert, 1992. Presewation
   2. Murphy, D.W. andT.S. Handwerker, 1988. Prelim-         of and nutrient recovery from poultry carcasses subject to
inary investigations of composting as a method of dead       lactic acid bacteria fermentation. J. Appl. Poultry Res.
bird disposal. Pages 65-72 in: Proc. 1st National Poultry    156-74.
Waste Management Symp., Ohio State Univ., Columbus,
OH.                                                             12. Cai, T., 1993. Stabilization of Poultry Processing
                                                             Wastes and Poultry Carcasses through Direct Chemical
    3. Dobbins, C.N., Jr., 1988.m              fermen ta-    Acidification and Lactic Acid Fermentation. Doctoral
tion: A method of disposal/utilization of carcasses con-     Dissertation, University of Georgia, Athens, GA.
taminated by pathogenic organisms or toxic chemicals.
Pages 76-80 in: Proc. 1st National Poultry Waste Manage-        13. McCullough, M E , 1978. Silage: Some general
ment Symp., Ohio State Univ., Columbus, OH.                  considerations. Pages 3-25 in: Fermentation of Silage: A
                                                             Review. M.E. McCullough, ed. NFIA, West Des Moines,
    4. Pancorbo, O.C., W.C. Merka, S.M. Russell, D.L         IA.
Fletcher, and R.W. Baslien, 1990. Destruction of bacte-
rial pathogens and indicators in broiler processing waste        14. APHA, 1985. Standard Methods for the Ekamina-
(offal) during lactic acid fermentation. Pa es 104-112 in:   tion of Water and Wastewater. 16th ed. American Public
Food Ind. Environ. Conf., Georgia Tech kesearch Insti-       Health Assoc., Washington, DC.
tute, Atlanta, GA.                                              15. SAS Instilute, 1988. SASiSTAT User’s Guide:
   5. Sholls, EB. Jr., R . E Wooley, and J.A. Dickens,       Release 6.03 Edition. SAS Institute Inc., Cary, NC.
1984. Anti-microbiceffects of
                            -             fermentation
on edible waste material contaminated with infected car-     ACKNOWLEDGEMENTS
casses. Am. J. Vet. Res. 452467-2470.                            Financial sup ort for this study by Georgia Proteins,
   6. Tlbbells, C.W. and RW. Seerley,. 1988. Poultry         Inc., Cummin &A (Grant No. 25-21-RC294-113to the
viscera ensiledwith
                                        . for owing          University of h , , a Research Foundation) is gratefully
and finishing s w i n e f 8 8 S 9 1 3 .                      acknowledged.
  7. Tibbells, G.W., R.W. Seerley, a n d H.C.                    Liquid molasses (Blackstrap), dry molasses (Sweetlix
McCampbell, 1987.Poultry offal ensiled with Lactobaril-      3 ) non-delactosed dry wheys (Whey Product and Sweet
lusi.ld@h for growing and finishing swine diets. J.
                                                             Dry Whey), and brewer’s solubles (Brewex) were ob-
Animal Sci. 64:182-190.                                      tained from Savannah Food and Industries (Savannah,
                                                             GA), PM ag Product (San Francisco, CA), Land O’Lakes
   8. Szakacs, C., J. Cyory, and L Slankovin, 1985.          (Minnea olis, MN), and Anheuser-Busch (Williams-
Presexvation of autoclaved slaujhter-house by-product.       burg, VA?, respectively.
Pages 1 6 2 1 in: Agric. Waste tilization and Manage-
ment, Proc. 5th International S p p . on Agric. Wastes,         The microbial silage culture used (SII-All in freeze-
American Society of Agric. Engineers, St. Joseph, MI.        dried powder form) was provided by Alltech, Inc.,
                                                             Nicholasville, KY.
   9. Hassan, T.E. and J.L. Heath, 1986. Biological fer-
mentation of fish waste for potential use in animal and
poultry feeds. Agric. Wastes. 191-15.

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