Agriculture Reference
In-Depth Information
P
RACTICAL
P
RODUCTION
OF
E
ARTHWORM
F
EED
P
ROTEIN
FOR
A
NIMALS
The efficient production of earthworm protein depends mainly on detailed knowledge and man-
agement of the population dynamics of the appropriate earthworm species, maintenance of optimal
environmental conditions, and the availability of efficient production and processing methods and
particularly on the development and use of systems of harvesting earthworms from organic wastes
that involve relatively little labor input.
Earthworms that process organic wastes grow best at relatively high moisture levels (80 to 90%
moisture content); this raises subsequent harvesting problems because it is not easy to separate
earthworms mechanically from finely divided organic matter at high moisture contents, and some
drying of the vermicompost before harvesting is usually necessary. There are various methods of
separating earthworms from fully worked organic wastes, but they tend to be labor intensive, and
an improved separation method was developed at Rothamsted and the National Institute for Agri-
cultural Engineering, Silsoe, U.K. (Price and Phillips 1990). The efficiency of this machinery in
terms of percentage recovery of earthworms is very high. The machine described will separate the
worms from about 1 ton of waste per hour and can be automated and scaled up in size to increase
its output and efficiency. After earthworms are collected from the separating machine, they may
have small particles of waste attached to their bodies and are likely to contain organic waste in
their guts. The earthworms must be washed thoroughly and left standing in water for several hours
to evacuate the residual waste particles from their guts completely. A range of different methods
of processing the earthworms into materials suitable for animal feed has been developed (Edwards
and Niederer 1988). Two of these methods produced a moist paste product, and the other four
produced dry meals; all the products were acceptable formulations for particular types of animal
feeds. The ultimate choice of a method of processing depends on (1) the species of animal to be
fed, (2) the type of animal feed required, (3) minimal loss of dry matter allowed, (4) minimal loss
of nutrient value allowed, and (5) the costs of production. The following were the methods
developed:
1.Incorporation of earthworms with molasses
2.Ensiling earthworms with formic acid
3.Air-drying earthworms at room temperatures
4.Freeze-drying earthworms
5.Oven-drying earthworms at 95AC
6.Acetone immersion of earthworms followed by oven-drying at 95AC
The type of processing method used affected the amounts of total and essential amino acids in
the feeds very little; however, the lysine content was decreased slightly by ensiling with molasses
using formic acid and by freeze-drying compared with the other methods. The dry weight matter
yields differed slightly among methods. Clearly, a stable protein feed can be produced by any of
the methods listed, and the choice of method must depend mainly on the use to which the protein
is to be put, the animal that is to be fed, and the cost of the processing method in relation to the
feed value of the protein.
T
HE
V
ALUE
OF
W
ORM
P
ROTEIN
AS
F
EED
FOR
F
ISH
, P
OULTRY
,
AND
P
IGS
The main outlets suggested for utilization of earthworms as animal feed protein have been in fish
farming and poultry and breeder pig feeds. All have been tested experimentally (Sabine 1978; Tacon
et al. 1983; Edwards 1982, 1985; Edwards and Niederer 1988).
