Evaluation of Processing Food Refuse and By-products for Growing Finishing Swine

Final Report for SW98-041

Project Type: Research and Education
Funds awarded in 1998: $121,850.00
Projected End Date: 12/31/2002
Matching Non-Federal Funds: $30,000.00
Region: Western
State: Guam
Principal Investigator:
Farouq Abawi
University of Guam
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Project Information


The concept envisioned in this study was to convert institutional food waste into swine feed using the dry extrusion technology. Due to the high moisture content of food refuse, moisture was
reduced by adding dry feed ingredients and nutrient deficiencies were adjusted by adding
appropriate supplements before extrusion process. The moisture content of the food refuse, as
currently disposed off, is as high as 90%. This means that, at most we can only process about
25% food refuse with 75% imported dry ingredients in order to have the acceptable stable moisture of no more than 11% in the final product. Considering all the added cost of transportation, labor, electricity, machine parts and maintenance, the present approach is not
economically feasible.

Project Objectives:

Objective 1: Estimate volume and feeding value by source of food refuse.

Objective 2: Process representative samples and determine feed value after processing.

Objective 3: Develop and evaluate feed formulations for growing and finishing swine using food refuse and by-products.

Objective 4: Establish cost and benefits of processed food refuse.


Guam is faced with two major problems that are unique to small Island Nations. Waste disposal is a serious environmental problem due to limited land fill. The other problem is that Guam is almost entirely dependent on imported animal feed. With the present imported feed prices and high shipping cost, there is little or no incentive for expansion in the animal industry. However, there is one major resource on Guam
which has often been overlooked which has the potential of alleviating both problems is the vast untapped food refuse. Recyclable waste such as food refuse , slaughter house by-products, and fishery by-products can be properly processed both as means of good environmental management and as a viable source of animal feed. Presently, much of the refuse from Guam's flourishing 1.2 million visitors per year tourism industry, fairly large military bases, school lunch programs and fast food establishments are dumped at a
close to capacity landfill. Alternatives to expensive rendering and fish meal plants have not been researched
to trigger smaller scale private investment.
Data obtained elsewhere, although quite useful, do not necessarily apply to the tropical humid conditions and the unique feed situations on Guam. Animal feed is at least twice as expensive on Guam compared to Mainland U.S.
Two aspect of garbage feeding which has discouraged further research and interest elsewhere are: variability in composition and hence animal performance; and tendency to result in more soft fat deposition. Based on observations of the market structure and consumer preference on Guam and neighboring Islands, it appears that lack of uniformity of market hogs and degree of fatness are well tolerated. Moreover, optimum feeding levels for best animal performance do not necessarily correspond to
the optimum level for the most economic production. In Guam, which is totally dependent on expensive imported cereal grains, a reasonable decrease in animal performance and variability can be weighed against lower cost of production.
A major drawback for food refuse and by-product processors has been the high capital cost of a rendering plant which would, in all probability, have a capacity far in excess of its needs. In addition, transport of an essentially worthless material to a rendering or incineration plant is both difficult and costly. Disposal at limited landfill is unacceptable from an environmental and health stand point.
For an island such as Guam, what is needed is a relatively inexpensive processor capable of processing tropical feeds, food refuse and by-products with low labor input.
Application of dry extrusion technology which has been widely used for processing soybean meal, poultry waste and other by-products to food refuse and by-products on Guam is a subject of interest in this research


Research results and discussion:

Objective 1:
Survey forms were prepared and hand carried to the management of major hotels,
restaurants, major food warehouses, fast food outlets, all private and public schools (Department of Education school lunch programs) and the military establishment on Guam. The survey was carefully designed to obtain an accurate volume of food refuse. Unfortunately, with the exceptionof a few major hotels, most people on Guam do not separate recyclable material and generally all waste material are dumped into the already overcapacity land fill. Hence, due to non food and potentially harmful material, the feeding value is severely compromised. With follow up visits and visual estimation, we arrived at an estimate of 29 tons of food refuse generated daily on Guam.
The above figure does not include food waste generated by the individual households and
excludes wasted oil and fat.
Objective 2:
Due to the variability in the composition of food waste from the hotel industry, additional test
trials were conducted to arrive at an optimum configuration of the dry-extruder for maximum
efficiency. The extrusion process was replicated 10 times over a 4 month period using an Insta-
pro, model 600JR extruder (Insta-Pro International, Des Moines, IA). The following
configuration was chosen: One single screw, four 9.53 cm steam locks, three double screws.
Food refuse was manually inspected . Paper, metal, plastic, aluminum foil were removed prior to grinding using a heavy duty commercial meat grinder. The material was mixed with millrun at a
ratio of 38 ground food waste to 62 millrun using a 300 lb vertical mixer prior to extruding. Pre-
extrusion moisture averaged 30.5. Post extrusion moisture averaged was 14% after cooling in
room temperature.
The shelf life of extruded samples were examine under room temperature as well as in air-
conditioned feed storage facility over a period of 6 months. Extruded feed samples with post
extrusion moisture of more than 12% became moldy. The higher the moisture, the most rapid was
the mold development. Mold development was more rapid under room temperature where
relative humidity averaged 75% which is quite typical of tropical environments such as Guam.
Further trials were conducted to arrive at a post extrusion moisture of no more than 12%.
Based on average moisture content of food refuse from one large hotel, it was determined that the
maximum amount of wet food refuse on weight basis should not exceed 25% of the pre-extrusion
wet/dry ingredient mixture resulting in average pre-extrusion mixture moisture of 20% and post
extrusion moisture of 10-12 % which was found to be stable for at least a month under room
Objective 3:
Throughout the trial, several pre extruded and post extruded samples were analyzed
for moisture, dry matter (DM), crude protein (CP) , crude fiber (CF), crude fat (EE) and total
ash. The pre extruded samples were quite variable from week to week even those that were
collected from the same establishment.
The composition of the post extruded feeds prepared feeding trials were adjusted by the choice of dry ingredient mix such as soybean meal and fish meal to increase the protein content Cassava meal, corn and millrun were primarily used as the major dry ingredient. All diets were
supplemented with vitamin and mineral premix.
The animal feed trails were prematurely terminated twice due to an outbreak of non-feed related diarrhea in the first attempt and the death of the cooperating farmer during the second attempt.
However, we were able to conduct an acceptability trial instead.
After an initial adjustment of 2-3 days animals were eating the extruded feed similar to the control group that was given pig starter diet. However, feed consumption was improved by wetting the dry extruded feed or the control with either milk or water.

Research conclusions:

Economic Analysis

Objective 4:
There are good reasons to justify recycling food refuse on Guam. The major reasons are: 1)
animal feed is very expensive as all feeds are imported to the Island at a considerable cost. 2)
There is sufficient food waste volume where all major hotels, restaurants and other food
warehouses are clustered close together which makes it convenient for collection. 3) The only
land fill on Guam has already been filled over its capacity and is becoming an environmental
nightmare for the local government. Our research was aimed at providing an alternative cheaper
feed supply while reducing the burden on the landfill. Unfortunately, we came across two major
obstacles that make food refuse recycling at the present time economically not feasible.
1. The concept of recycling as a whole has not really been put into practice on Guam. In order for the food refuse to be economically processed, it must be separated from other type of waste to
minimize contamination and reduced labor cost involved in removing metals, foils, plastics, paper etc.
2. The moisture content of the food refuse, as currently disposed is extremely high. Sometimes as
high as 90%. The procedure proposed in this study rely on moisture reduction by adding dry feed
ingredients before extrusion process. This means that we can process only about 25% at most
with 75% imported dry ingredients in order to have the acceptable stable moisture of no more
than 11% in the final product. Considering all the added cost of transportation, labor, electricity, machine parts and maintenance, the present approach is not economically feasible.

Participation Summary

Research Outcomes

No research outcomes

Education and Outreach

Participation Summary:

Education and outreach methods and analyses:

There has been a keen interest in our research by our neighboring Islands of Tinian, Rota and
Saipan. Upon a request from the Commonwealth of Northern Marianas (CNMI) Land Grant
Institution, training was provided for one technician in the use of extruding and milling equipment as well as food waste recycling for a period of 4 months.

A workshop/ seminar was conducted for the general public followed by a demonstration of food
waste recycling . A total of 45 persons that included swine farmers, teachers, environmentalist as well as a number of interested officials from CNMI government attended the workshop . The event received extensive coverage in the local media.

An Environmental Conference was organized by Guam Hotel & Restaurant Association and
Guam Environmental Protection Agency. More than 200 individuals attended the conference. My
presentation entitle: “Evaluation of Processing Food Refuse and By-Products for Animal Feed”
was well received.

Abawi, F.G., 2001. Evaluation of processing food
refuse and by-products for animal feed.
Proceedings, Environmental Conference, Guam
Hotel & Restaurant Association, Guam.

Abawi, F.G. , 2001. Educator turns garbage into
animal feed. Pacific Daily News, Mar. 29,2001.
P. 1, 32.formatting elements (bullets, list numbers, etc.) and use one of the styles available below.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.