INTEGRATION OF DUCK-CUM-FISH FARMING SYSTEM

N.K.Yadava and V.Bhatnagar
Department of Zoology,
Haryana Agricultural University,
Hisar, India.

ABSTRACT

This paper gives a report on Static Bioassay experiments conducted to determine the toxicity and ‘safe’ levels of duck wastes for zooplankton (Daphnis longiremis and Simocepalus serrulatus) and fry of Cyprinus carpio. The ‘safe’ concentration of duck wastes was calculated as 0.005 percent. Further studies were conducted in the Screen House (Semi-field out whether the ‘safe’ concentration of duck wastes calculated on the basis of laboratory conditions, was applicable, as well as in fish ponds under field conditions. It was found that the levels of GPS, DO, pH, chloride contents, phosphates, nitrates and sulphates gradually increased with the application of every new split dose of wastes in the waters. While, on the other hand, BOD, conductivity and hardness levels decreased. The estimated potency of wastes, based on the above factors were as follows: duck wastes alone D^*: C^** (4:1) > D:C (3:1) > D:C (2:1) > D:C (1:1) > cowdung wastes alone.
It was observed that 100 ducks per hectare of water body would be needed to excrete duck droppings (6000 Kg/ha/yr), to meet the ‘safe’ level dose of the duck wastes for one year. Experiments conducted at fish ponds indicated 100 percent recovery of test fish from duck waste treated water and the estimated net and gross fish production were high.

INTRODUCTION

Usefulness of livestock wastes such as cowdung, poultry and pig excreta, goat and sheep pellets, in fish culture to enhance the production of fish food organisms, as well as, in cutting down the expenditure on costly feeds and fertilizers have been well documented (Kapur, 1981, 1984; Kapur & Lal, 1986; Yadava, 1987).

Cowdung is at present, the most widely used manure in fish culture while other animal excreta like poultry, pig, sheep and goat pellets have been tried effectively. No systematic and scientific based studies have been done till now on duck excreta and its utilization for fish-culture. At present our knowledge regarding the suitability and in different combinations with other livestock wastes, rate of mineralization under varying physico-chemical characteristic of the medium, their toxic and ‘safe’ levels for autotrophs, zooplankton and fish and the specific food requirements of the carp fry and adult fish under integrated system, is very meagre. Therefore, the present invstigations have been taken up keeping above lacunae in view.

MATERIAL AND METHODS

Test organism viz. fish fry (C. carpio) and zooplankton (Daphnia longiremis) were collected from the fish farm ponds, Department of Zoology, H.A.U. Hisar, and transferred to the fisheries laboratory. Fish fry were acclimated to the laboratory conditions in an aquarium, and fed on zooplankton.

The test organisms were subjected to the Static Bioassay procedure following APHA (1976) using 500 ml conical flasks for zooplankton and 10 1 glass aquaria for fish fry.

In order to work out the LC₅₀ of duckery wastes, concentrations of duck waste ranging from 0.001 to 0.1 percent were initially tested. Suitable test concentrations from the above broad-range of concentrations were investigated, with respect to the mortality of treated carp fry after 24 to 96h (sample size = 20).

To find out the suitability of the estimated ‘safe’ concentration of duck waste in the aquatic medium, levels of gross primary productivity (GPP) and dissolved oxygen (DO) were conducted in a screen house under semi-field and field conditions.

Some experiments were conducted at the animal sheds of the College of Animal Sciences, HAU, Hisar, in the duck cage house of the Department of Livestock Production and Management. Eight duck birds of different age groups ranging between 1 year to 1.5 years and having different body weights ranging between 2.0 and 2.5 kg were taken. The process of feeding the birds, recollection of left-over food and the collection of excreta from each bird's pen was repeated after every 24 hrs.

Field experiments were conducted at the fish farn of the Department of Zoology HAU, Hisar, for 96 days, to study GPP and DO levels in waters treated with duck and duck-cowdung wastes combinations as well as secondary productivities (Zooplankton no / litre). The methods of estimation were those from APHA (1976).

The tested fish fry (C. carpio) with an average length of 5.9 cm, were stocked in all the experimental ponds at a density of 8000 fry/ha. Gross doses of duck, duck and cowdung combinations at ‘Safe’ concentrations were estimated as per ha per yr. These doses were further split into six equal doses and applied at intervals of 15 days in the experimental ponds.

Survival and growth of test fish (C. carpio) were studied in relation to some physico-chemical characteristics, primary productivity and secondary productivity (Zooplankton) of the waste-treated waters. Correlations were also drawn between growth (based on length and weight) of fish and various factors given above, of the treated waters.

RESULTS

Data from the present studies on the survival of fish (C. carpio) and related physico-chemical characteristics of duck waste-treated waters are presented in Fig. 1 (a-c), which depicts only mean levels of physico-chemical characteristics during the observation time (0–96 h) vis-a-vis fish survival after 24 and 48 h. The later data was utilized for calculating the ‘Safe’ concentration of the wastes.

No mortality was observed between 0.005 and 0.015 % concentrations of duck wastes up to 96h, possibly due to the existence of favourable hydrological conditions like dissolved oxygen, pH, BOD, hardness, conductivity etc. for the survival of fish (Table 1).

It has been clearly indicated during the present studies that with the increase in concentration of duck wastes from 0.005 to 0.07 %, DO gradually decreased, while on the contrary, BOD, conductivity and chloride contents gradually increased, whereas pH and hardness fluctuated between 7.6 and 8.3, 58.4 and 61.9 mg/1 respectively.

During the above observations, temperature ranged between 24.2°C and 24.8°C, 24 and 48h LC₅₀ values for the duck waste were found to be 0.06 and 0.04% respectively, based on the regression equations, and the ‘safe’ concentration was calculated as 0.005 % [Fig. 1 (a)]. The heterogeneity between the observed and calculated survival values was non-significant. Based on the above experiments conducted in the laboratory, the observed data were further tested under semi-field and field conditions.

Estimation of excreta produced by ducks per day under cage conditions

Eight duck birds with ages ranging from 1.2 years to 1.6 years and weights from 2.0 to 2.5 kg. were used (Table 1). The bird of 1 yr and 2 months excreted a minimum of 110.0 g and maximum of 225.0 g excreta in the seven-day experiment, giving an average of 160.5 g per day. Likewise eight birds of 1.5 yrs excreted a minimum of 170.0 g a maximum of 260.0 g excreta, hence an average excreta per bird per day of 205.2 g. In general, average excreta per bird per day was 170.7 g.

Therefore, 90–100 ducks excretes 6000 kg excreta/ha/yr are given in Fig 2 (a-j).

Out of duck waste treated pond waters, 100 % recovery of experimental fish was obtained and the estimated net and gross fish production so obtained were 3688.0 and 6557.7 kg/ha/yr respectively (Table 2). In duck and cowdung waste treated pond waters, in the ratio of 1:1 respectively, a recovery of 95.6 % was recorded and the estimated net and gross fish production came out to be 2775.4 and 4607.1 kg/ha/yr respectively. In duck and cowdung wastes treated pond waters in the ratio of 2:1 respectively, a recovery of 91.3 % was noted. The estimated net and gross fish production so obtained were 2874.3 and 5124.5 kg/ha/yr respectively. In another experimented of duck and cowdung wastes treated pond water in the ratio of 3:1 respectively, a recovery of 95.6 % test fish was made. The estimated net and gross fish production came to be 3011.2 and 5175.1 kg/ha/yr respectively. In duck and cowdung waste treated pond waters in the ratio of 4:1 respectively, a recovery of 100 % was recorded and the estimated net and gross fish production attained were 3444.6 and 5860.1 kg/ha/yr respectively. In cowdung waste treated pond waters, a recovery of 95.6 % test fish was recorded. The estimated net and gross fish production came to be 2524.5 and 4369.0 kg/ha/yr respectively, as depicted in (Table 2). In control waters, a recovery of 100 % was obtained at the end of the 96 day experiments. The average length and weight are also shown in (Table 2). The estimated net and gross fish production came out to be 380.2 kg/ha/yr and 1803.5 kg/ha/yr respectively.

Table 1. Estimation of excreta secreted by ducks/day (24 h) under cage conditions.

Av. excreta/duck/day = 170.7 gms

The analysis of possible pathogenecity symptoms to fish (C. carpio) due to duck and cowdung waste treated pond water was conducted and it revealed negative results for experimental fish as well as in the culture medium.

DISCUSSION

The studies conducted during the present investigation, clearly demonstrate that with the increase in concentration of duck wastes, dissolved oxygen decreased and BOD increased, which are the most critical factors reponsible for the mortality of test fish at concentrations higher than that of the ‘Safe’ level (0.005 %). The toxicity experiments conducted by Gopalkrishnan et al. (1973), Gill (1974) and Yadava (1987;1988) who found complete depletion of dissolved oxygen due to discharge of untreated city sewerage wastes as well as livestock wastes in water systems, results in higher percent of fish mortality. Present studies, showed that the efffect of wastes on the autotrophic and heterotrophic production was as follows; duck > poultry piggery > goat and sheep > cowdung.

It was observed and calculated that 100 duck birds per hectare of water body are required to produce about 6000 kg of duck droppings/ha/yr to meet the requirement of ‘Safe’ concentration of the duck wastes for one year (Table 1). Similar type of studies were also made by Woynarovich (1979) and Yadava (1987), Jhingran and Sharma (1980).

The level of primary as well as secondary productivity was highest in duck waste compared with other wastes treated waters such as duck-cowdung combinations and cowdung alone. Similar studies were also made by many workers (Wilber, 1971; Jhingran, 1982; Kapur, 1981; 84a; Kapur and Lal, 1986) have stressed on the importance of application of organic wastes in fish ponds for a steady level of primary production and ultimately, influencing the fish food organisms, including fish production.

Table 2. Influence of Safe' concentrations of duck wastes and other livestock wastes on the net and gross production of C. carpio under field conditions.

* Initial stocking range 46 fry/pond (estimated density 8000 fry/ha)
** Length at the end of the experiment (96 days)

It was further observed that levels of GPP, DO, pH, chloride contents, phosphates, nitrates and sulphates gradually increased with the application of every new split doses of wastes in the treated waters. While on the other hand, BOD, conductivity and hardness levels decreased. The estimated potency of wastes based on the above factors, were as follows: Duck wastes alone > D:C (4:1) > D:C (3:1) > D:C (2:1) > D:C (1:1) > cowdung wastes alone. A similar pattern was also found as far as primary, secondary and fish productions were concerned. The above findings were also confirmed by Kaliyamurthy (1978), Schroeder (1980) and Yadava, (1987).

REFERENCES

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