|
|
LivingAquatic Resources Research
Center(LARReC)
NaongThang Villged, Vientiane City, Laos
PDR
Meetouna@yahoo.com
Livestock excreta are a major source of environmental pollution
in intensive, specialized animal agriculture (Steinfeld et
al., 2006). According to Kirschenmann (2007)
"Agro-ecologists increasingly are convinced that the most viable
alternative technology will spring from the biological synergies
inherent in multispecies systems and that additionalresearch might
make such systems the next new technology". Integration of crops
and livestock, with recycling of the manure, is considered to be
the basis of new management systems, "with the potential to
increase the quantity and quality of production and the economic
return to the farmers while at the same time placing less degrading
pressure on soil and water resources."(Franzluebbers, 2007). One
way of improving animal production without negative effects on the
environment and increasing the efficiency of resource utilization
is by integrating all the processes in the system, in the context
of the sustainable use of those resources (Sophin and Preston,
2001).
To solve the problem of pollution, and to make better use of
animal excreta, there are several techniques that can be applied.
Anaerobic biodigestion is one of the most efficient technologies
for converting animal manure into useful products: gas for cooking
and effluent for fertilizer (Preston and Rodriguez 1998). For
small-scale farms the plastic biodigester, because of its low cost
and simple construction and management, may be the preferred
technology (Bui Xuan An et al., 1997). The effluent is a
valuable product from biodigesters and has been shown to be
superior to the original manure for fertilization of crops (Le Ha
Chau 1998) and fish ponds (Pich Sophin and Preston 2001). The
effluents from biodigesters, when suitably diluted, are very
effective media for growing duckweed (Le Ha Chau
1998).
The cultivation of earthworms can be another component of manure
recycling. They have a comparative advantage over other forms of
recycling when the manure is from goats or rabbits (Preston and
Rodriguez 1998).
Manure is the principal food of many insects in nature, house
fly (Muscadomestica Linnaeus). The larvae convert
residual manure proteins and other nutrients into their biomass,
which is rich in high quality animal protein. Also, while occupying
the manure they aerate and dry it, reducing odors.
Aquatic plants are being promoted as important components in
management of livestock wastes, especially in large scale intensive
units (Steinfeld et al., 2006). According to Leng
(1995).farmers throughout Asia have harvested naturally produced
aquatic plants for a number of purposes including animal feed,
green manure and for their family feed resources. "The best known
of these is "duckweed", which has become prominent, because of its
ability to concentrate minerals in heavily polluted water such as
that arising from sewage treatment facilities"(Leng 1995). It has
also high potential as a feed resource for fish (Leng et
al., 1994), ducks (Bui Xuan Men et al., 1997) and pigs
(Du Thnh Hang 1998). Duckweed grows on water with relatively high
levels of N, P and K and concentrates the minerals and synthesises
protein.
Live stock play two roles in waste recycling. On the one hand
they maybe the cause of pollution if their manure is discharged
directly to the environment. However, certain species may be able
to benefit directly from products that arise in an efficient system
of waste recycling. Aquatic animals are most suited for the
utilization of products of recycling since their normal habitat is
either wholly or partially in natural or artificial water bodies.
The common lowland frog (Rana rugulosa) appears to
be specially adapted for cultivation in integrated farming systems,
since its natural feed source includes insects and earth worms. In
the Northern region of Laos, there is a high demand for consumption
in family households and local markets. The frog is fast growing.
From hatching to market size, it takes 3 to 4 months which is
similar to other commercial species such as catfish and tilapia.
Frogs can be raised in all locations in Laos, as they require small
area and lower quantity of water than other aquaculture species
(Bounsong, 2001).
The aims of the present study were to investigate components in
a waste recycling system which could be used for the cultivation of
frogs, to reduce the present dependency on imported concentrate
feeds, and to make the system more attractive for small-scale
farmers in Laos.
Two experiments have been carried out.
The first experiment was a study of the effect of different sources of household waste, irrigated with biodigester effluent, on the production of fly larvae.
The second experiment compared the use of fly larvae and earth worms, with or without duck weed, as the basal diet for growing frogs raised in ponds.