Pekar, F. and J. Olah
Fisheries Research Institute
P.O. Box 47, H-5541 Szarvas, Hungary
ABSTRACT
Management parameters and culture techniques for integrated fish-pig, fish-chicken and fish-sheep
farming experiments conducted in Hungary are presented, together with data on physicochemical
environment and natural fish food resources.
Autotrophic algal and heterotrophic bacterial production pathways were quantified by simultaneous
measurement of primary, planktonic and benthic bacterial carbon production rates. Bioenergetic
efficiencies of fish production were calculated on the basis of primary and bacterial production, and
compared in these three organic carbon-fed systems. Energy requirements of different aquaculture
and animal husbandry production systems are also presented.
INTRODUCTION
The utilization of organic manure as the principal nutrient input to the pond is a traditional management practice in freshwater fish farming in China and other parts of Asia. The main reason for developing these efficient fish-livestock integrated systems was the requirement for producing high quality animal protein at low cost from inputs which have no nutritional values for man and livestock.
Intensive manuring of ponds is an effective method to increase practically all nutrient and fish food compartments in fish pond ecosystems. Organic manuring is usually linked to polyculture, because a variety of fishes with different food preferences can exploit different fish food resources in the ponds. The manure can be used in direct or indirect integration of fish and livestock.
The use of organic manure in fish farming is based on the assumption that the manure is utilized through two pathways. The manure organic matter provides dissolved and particulate substrates for bacteria and the bacterial laden particles provide food to the filter-feeding and detritus-consuming animals, while the mineralized fraction of the manure stimulates phytoplankton productivity similar to the action of inorganic fertilizers. The manure organic matter coated with bacteria is considered a link in the food web and should be treated as a food (Hepher and Pruginin, 1981).
In intensively manured fish ponds, both autotrophic and heterotrophic production contribute to fish growth (Schroeder, 1978, 1987), however, the role of heterotrophic bacterial production in the food web and its effects on fish yield are poorly understood and have not been quantified (Moriarty, 1987). Quantification of autotrophic algal and heterotrophic bacterial productivity would increase our present knowledge of pond dynamics.
To understand the basic biological production processes related to the alternative food chains created by manuring fish ponds, experiments with indirect integration of fish-pig, fish-chicken and fishsheep were performed in Hungary between 1980-1987. Primary, planktonic and benthic bacterial production rates were quantified and bioenergetic efficiencies of fish production were estimated and compared in these three organically loaded ecosystems.
MANAGEMENT PARAMETERS
Fourteen earthen fish ponds each with a surface area of 1700 m2 were used for fish-pig indirect integration experiments. The manure was applied in liquid form by spraying through rotary sprinklers over the pond surface.
Ten and seven earthen fish ponds with a surface area of 200 m2 were used for fish-chicken and fishsheep indirect integration experiments respectively. The manures were applied in wet, solid form spread over the pond surface by hand.
Dry matter content of pig, chicken and sheep manure used were 1, 26 and 24.5% respectively. Daily manuring was applied in each pond during the morning hours (Table 1).
CULTURE TECHNIQUES
In the pig manuring experiment the ponds were stocked in May with silver carp, common carp and grass carp at a stocking density of 12600 fish ha-1. For the chicken manuring experiments the ponds were stocked in April or May with silver carp, common carp and tench at a stocking density of 17500 fish ha-1. Silver carp and common carp were stocked in May at a stocking density of 13500 fish ha-1 to the ponds in the sheep manuring experiment.
No fish feed or inorganic fertilizers were used either in fish-pig or fish-chicken and fish-sheep integration. Different manure loading rates were applied ranging from 4.7 – 21.4 m3ha-1 day-1, 50–400 and 250 kg ha-1 day-1 for raw pig, chicken and sheep manure, respectively.
The fish were harvested in September. The net fish production ranged between 9.0 – 21.0, 7.9 – 22.1 and 13.0 – 15.6 kg ha-1 day-1 in pig, chicken and sheep manured ponds, respectively (Table 2).
PHYSICO-CHEMICAL ENVIRONMENT AND NATURAL FOOD RESOURCES
Fish health and production are associated with the pond environment. The temperature, pH, dissolved oxygen and free ammonia may have a direct adverse effect on fish condition and growth, determining the upper limit of the nutrient load into the fish ponds.
The physico-chemical environmental parameters varied widely in the investigated ponds, but the ranges indicate that the organic manure, while promoting fish growth, exerted a moderate and tolerable environmental stress for the fishes (Table 3).
The water quality was stable in each pond with occasional exception of ponds receiving very high organic carbon load. The highest free ammonia concentrations appeared occasionally as stressful for the fish.
A rich standing crop of natural fish food organisms occurred in all ponds. The rich supply of food organisms was maintained by the high algal and bacterial production and by the organic matter content of the manures (Table 4).
CARBON PATHWAYS
To quantify the basic biological production processes, primary production, planktonic and benthic bacterial production were measured simultaneously in fish-cum-pig, chicken and sheep ecosystems (Table 4).
Gross primary production was estimated by the direct measurement of diurnal changes of oxygen concentrations in the whole water column using our own calculating model with seven measuring points (Olah et al., 1978) in the pig manured ponds. In the chicken and sheep manured ponds the diurnal oxygen concentrations were monitored with three measuring points and the McConnell (1962) equation was used to calculate primary production.
Planktonic and benthic bacterial production were usually measured by the 3H-thymidine (Fuhrman and Azam, 1980; Bell et al., 1983; Moriatry, 1986) and the dark 14C-bicarbonate incorporation method (Romanenko, 1964; Overbeck, 1979), and occasionally by the 35S-sulphate uptake method (Monheimer, 1972; Jordan and Likens, 1980).
The primary production fluctuated widely in all organic carbon-fed systems. High annual average values were detected in the chicken and pig manured ponds, and relatively lower value in the sheep manured system.
Table 1. Management parameters in manured ponds.
Parameters | Pig manured | Chicken manured | Sheep manured |
Pond size, m2 | 1700 | 200 | 200 |
Pond bed | Earthen | Earthen | Earthen |
Water movement | Stationary | Stationary | Stationary |
Water supply | River | River | River |
Water depth, m | 1.0 | 1.0 | 1.0 |
Aeration | Nil | Nil | Nil |
Draining and drying | Yes, in winter | Yes, in winter | Yes, in winter |
Liming | Nil | Nil | Nil |
Manure application | By rotary | By hand | By hand |
Time of manure application | Morning, daily | Morning, daily | Morning, daily |
Type of manure applied | Fermented, liquid | Fermented, solid | Fermented, solid |
Dry matter content of manure, % | 1 | 26 | 24.5 |
Table 2. Culture techniques in manured ponds.
Parameters | Pig manured | Chicken manured | Sheep manured |
Stocking density, fish ha-1 | 12600 | 17500 | 13500 |
Stocking structure | |||
weight, g; density, fish ha-1 | |||
Silver carp1 | 15;6000 | 50;7500 | 38;7500 |
Silver carp2 | 200;800 | - | - |
Common carp1 | 70;3000 | 36;5000 | 22;6000 |
Common carp2 | 180;800 | - | - |
Grass carp1 | 30;2000 | - | - |
Tench1 | - | 5;5000 | - |
Stocking time | May | April;May | May |
Feeding | Nil | Nil | Nil |
Inorganic fertilization | Nil | Nil | Nil |
Dose of raw manure | 4.7–21.4 m3ha-1day-1 | 50–400 kg ha-1 day-1 | 250 kg ha-1 day-1 |
Dose of manure as dry | 47–214 | 13–104 | 61 |
matter, kg ha-1 day-1 | |||
Growing period, days | 120 | 105–160 | 130 |
Harvesting time | Sept | Sept | Sept |
*Net fish production, kg ha-1 day-1 | 9.0–21.0 | 7.89–22.1 | 13.0–15.6 |
Table 3. Annual ranges of physico-chemical parameters in manured ponds.
Parameters | Pig manured | Chicken manured | Sheep manured |
Temperature, °C | 8.0–26.0 | 14.5–27.6 | 18.6–26.7 |
pH | 7.9–9.0 | 7.2–9.0 | 7.3–9.0 |
Dissolved oxygen, mg d m-3 | 3.0–21.0 | 0.9–24.4 | 4.2–20.6 |
Unionized ammonia, μg NH3 -N dm-3 | 0.04–105 | 0.04–35.8 | 0–146 |
Table 4. Annual ranges of fish food compartments in manured ponds.
Compartment | Pig manured | Chicken manured | Sheep manured |
Chlorophyll-a, μg dm-3 | 150 –250 | 5 –172 | 1.1–109 |
Bacterioplankton, 106 cm-3 | 3.3 –56.0 | 1.8–16.8 | 2.2–17.1 |
Zooplankton, i dm-3 | 1000–10000 | 25 –3700 | 50 –600 |
Zoobenthos, i m-2 | 8000–33000 | 100–5500 | 100–2900 |
The highest planktonic bacterial production rates were measured in the pig manured ponds, while the highest values of benthic production were observed in the sheep manured system. The explanation for these pronounced differences may be the form and mode of manure application. The pig manure was introduced in a diluted liquid form remaining mainly in the water column in suspension. The chicken and sheep manure were introduced in solid form. Although well dispersed on the water surface, much of the manure particles settle slowly or rapidly to the bottom creating a very rich nutrient condition for the sediment bacteria.
High total (planktonic + benthic) bacterial production was obtained in pig and sheep manured ponds due to the high planktonic and benthic bacterial production, respectively.
Comparing the gross primary production and total bacterial production rates it is obvious that in the pig manured ponds the available organic carbon pool is almost duplicated every day, even in the sheep manured ponds the total bacterial organic carbon production exceeds the primarily produced carbon pool. In spite of the fact that the annual average total bacterial production and the sum of the primary and total bacterial production were the lowest in the chicken manured ponds, the fish production was the highest (Table 5 and 6). This contradiction, however, may be explained by the direct consumption of the chicken manure particles by the fish, which was usually observable during the time of manuring, presumably due to remnant chicken food in the manure.
FISH PRODUCTION AND BIOENERGETIC EFFICIENCIES
The fish production efficiency that is the percentage of the daily produced organic carbon transferred to the daily fish production is a very significant indication of the production processes. Since it was assumed that in organic manured pond ecosystems a large part of fish production originated from the heterotrophic bacterial-detrital food chains, and it was evident from the magnitudes of bacterial production rates measured (Table 5) that the available organic pool is usually duplicated every day via bacterial production, beyond primary production the bacterial production, was also taken into account for calculating fish production efficiencies.
Therefore, bioenergetic efficiencies were calculated on the basis of primary production, the sum of primary and planktonic bacterial production and the sum of primary and total bacterial rates, respectively (Table 6). In the chicken and sheep manured ponds the average fish production efficiencies were similar, while in the pig manured ponds it was lower. An explanation is the different stocking density and structure used and the age of fish stocked, since the efficiency is highly regulated by the fish feeding on the available fish food resources.
ENERGY COST
A comparison of industrial energy requirement for aquaculture systems and livestock farming is shown in Table 7. Calculating the production cost in terms of industrial energy for different management methods it is obvious that in all pond fish farming systems, energy input is less compared to the livestock farming systems including egg production which is the most energy effective technology among all of the animal husbandry technologies.
Among the different aquaculture technologies, ponds without supplementary feed and fertilization and ponds with minimum feed and fertilization were the best systems requiring the lowest amount of energy.
Table 5. Organic carbon load, autotrophic and heterotrophic bacterial carbon pathways in manured ponds, gCm-2 day-1 (range, mean ± S.D., n).
Parameters | Pig manured | Chicken manured | Sheep manured |
Organic carbon load | 2.3 – 4.8 | 0.7 – 5.2 | 3.1 |
Gross primary production | 0.55 – 11.6 | 0.40 – 14.2 | 0.89 – 7.36 |
4.68 ± 1.93 | 5.22 ± 2.93 | 2.87 ± 1.46 | |
n = 95 | n = 296 | n = 48 | |
Planktonic bacterial production | 0.85 – 8.35 | 0.08 – 1.29 | 0.11 – 2.16 |
2.91 ± 1.97 | 0.40 ± 0.25 | 0.58 ± 0.41 | |
n = 28 | n = 83 | n = 77 | |
Benthic bacterial production | 0.17 – 1.05 | 0.78 – 2.53 | 0.04 – 7.99 |
0.58 ± 0.34 | 1.46 ± 0.68 | 3.64 ± 2.34 | |
n = 6 | n = 6 | n = 19 | |
Total bacterial production | 1.28 – 7.07 | 1.10 – 2.72 | 0.34 – 8.67 |
3.82 ± 2.26 | 1.82 ± 0.64 | 4.44 ± 2.50 | |
n = 6 | n = 6 | n = 19 |
Table 6. Fish production and bioenergetic efficiencies in manured ponds (range, mean ± S.D., n).
Pig manured | Chicken manured | Sheep manured | |
Net fish production, | 0.09 – 0.30 | 0.04 – 0.55 | 0.04 – 0.26 |
gCm-2 day-1 | 0.16 ± 0.05 | 0.18 ± 0.10 | 0.16 ± 0.06 |
n = 14 | n = 58 | n = 28 | |
Fish production × 100 % | 1.70 – 7.50 | 1.54 – 18.8 | 1.78 – 13.0 |
Primary production | 3.64 ± 1.77 | 6.42 ± 3.87 | 5.71 ± 2.67 |
n = 8 | n = 78 | n = 48 | |
Fish production × 100 % | 1.05 – 2.67 | 1.37 – 14.8 | 1.78 – 10.0 |
Primary + planktonic bact. prod. | 1.84 ± 0.55 | 5.92 ± 3.30 | 4.37 ± 1.69 |
n = 6 | n = 52 | n = 47 | |
Fish production × 100 % | 0.94 – 1.03 | 2.04 – 4.92 | 0.43 – 8.99 |
Primary + total bact. prod. | 0.99 ± 0.04 | 3.00 ± 1.18 | 2.69 ± 2.11 |
n = 6 | n = 5 | n = 19 |
Table 7. Comparison of energy cost for foods from aquaculture and animal husbandry (Olah and Sinha, 1986).
kj input/kj output | kj input/gram protein | |
Aquaculture | ||
Fish pond without feed and fertilization in India | 0.9 | 22 |
Rural pond in India with minimum feed and fertilization | 2.1 | 64 |
Fish pond with fertilization in India | 4.2 | 109 |
Fish pond with feed in India | 5.6 | 145 |
Fish pond with feed and fertilization in India | 7.9 | 205 |
Fish pond with manure in Hungary | 5.1 | 132 |
Fish pond with fertilization in Hungary | 10.6 | 275 |
Fish pond with feed and fertilization in Hungary | 16.1 | 418 |
Aerated fish pond in Hungary with pellet | 18.0 | 468 |
Cage culture in Hungary | 23.0 | 622 |
Recycling system in Hungary | 69.0 | 1791 |
Animal husbandry | ||
Eggs | 21.3 | 552 |
Broilers | 24.1 | 624 |
Pork | 30.1 | 779 |
Milk | 42.5 | 1101 |
Beef | 111 | 2869 |
Feed beef | 129 | 3349 |
Lamb | 132 | 3424 |
In Hungary, ponds with polyculture of fishes and with organic manuring showed a better input/output ratio compared to inorganically fertilized ponds or when fertilizer was applied and also feed (usually cereals) were supplied to the fish. Partial or complete replacement of inorganic fertilization by organic manuring would reduce the industrial energy cost. Global attention needs to be paid and high priority assigned for proper pond nutrient recycling and organic waste recycling through fish farming in order to make these systems still more energy effective for protein production.
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