Effects of stocking levels of ducks on production of Indian Major Carps in village ponds under duck-fish integrated system in West Bengal state of India

B K Chand, A Goswami, P K Biswas , P Biswas* and B C Patra**

Directorate of Research, Extension and Farms, West Bengal University of Animal and Fishery Sciences,
68, K.B. Sarani, Kolkata, India, 700 037
bimalkinkar@yahoo.co.in
* Faculty of Fishery Science, West Bengal University of Animal and Fishery Sciences, Mohanpur, Nadia, India 741 252
^#Department of Zoology, Vidyasagar University, Midnapore, West Bengal, India 721101

Abstract

Three stocking levels of ducks along with control (D₀ : no duck, D₂₀₀: 200 ducks ha^-1, D₃₀₀: 300 ducks ha^-1, D₄₀₀ : 400 ducks ha^-1) were tried out in duplicate to evaluate the efficacy of duck manure on fish production. The study involved 8 ponds each of 0.38±0.04 ha, located at Barua village of Midnapore district in West Bengal state. The ponds were stocked with fingerlings of Indian Major Carps (Catla catla, Labeo rohita and Cirrhinus mrigala at the ratio of 4:3:3) at stocking density of 7500 ha^-1. Ducks were housed on the dyke of the fishpond (Khaki-Campbell male and native strain female at the ratio of 1: 6). No supplementary feed was used for fish, whereas ducks were fed ad libitum with mixed ration containing commercial duck feed concentrate (20%), paddy (50%) and rice bran (30%). During 10 months of culture period (Oct.-July); water parameters, plankton biomass, growth parameters of fish species and duck were recorded at monthly intervals.

The mean dry matter loading rates of duck manure were 4.1, 6.5 and 7.8 kg ha^-1day^-1 for D200, D300 and D400, respectively. The corresponding loading rates were 0.18, 0.3 and 0.35 kg ha^-1day^-1for nitrogen; and 0.08, 0.1 and 0.14 kg ha^-1day^-1 for phosphorus. The weight gain of fish was significantly higher  in all treatments under integrated system than in the control. The mean fish production rates of 2576, 3384, 3643 and 3578 kg ha^-1 crop^-1 were obtained in D200, D300 and D400, respectively. The average egg production rates of crossbred ducks were 172, 156 and 164 bird^-1 yr^-1 in D200, D300 and D400, respectively.

The results suggest that the integration of duck-fish is more profitable than fish alone.

Key words: Duck-fish integration, growth, India, productivity

Introduction

Duck-fish integration is very common in countries like China, Hungary, Germany, Poland, Russia and to some extent in India (Ayyappan et al 1998). The fish pond being a semi-closed biological system, with several aquatic animals and plants, provides an excellent disease-free environment for ducks. In turn, ducks consumes tadpoles, juvenile frogs, dragonflies and other insects, making a safer environment for fish. Duck excreta are used as fertilizer in a fishpond, which stimulates the growth of fish food organisms in the pond. Ducks feed on snails and gastropods available in the pond which otherwise serve as vectors for certain diseases and the ducks thus serve in reducing their incidence (Thakur and Thakur 1991). Ducks further help in aerating the pond water along with pond bottom raking effects, which is beneficial for fish. As small-scale farmers comprise the bulk of the population in India, their socio-economic conditions encourage them for duck-fish integration to raise farm productivity (Edwards et al 1988). In the present study three stocking density levels of ducks along with a control were used to evaluate the effects of different loading rates of duck manure on fish production.

Materials and Methods

Three stocking levels of ducks were:  a control (D₀ : no ducks) and 200, 300 and 400 ducks ha^-1 (D200, D300 and D400), respectively. The study involved 8 ponds each of 0.38±0.04 ha, where the experiment was conducted for 10 months from October '02 - July '03. The ponds were located at Barua village in Midnapore West district of West Bengal state of India and belonged to the farmers. Duck houses were constructed on the dykes of the ponds to provide stocking density of 5 ducks m^-2 of house. Ponds were filled with rainwater. Advanced fingerlings of Indian Major Carps (Catla catla, Labeo rohita and Cirrhinus mrigala at the ratio of 4:3:3) were stocked at the rate of 7500 ha^-1. Ducklings of 5-6 weeks old were housed on the dyke of the fishpond (Khaki-Campbell male and native strain female at the ratio of 1: 6). Ducks were vaccinated against duck plague and duck cholera diseases at the age of 8 and 9 weeks respectively.

Before stocking, each pond was fertilized with 500 kg lime, 3000 kg composted cattle dung, 30 kg urea and 30 kg single super phosphate per ha. basis. Water quality parameters of the ponds were checked monthly for dissolved oxygen, total alkalinity, ammonia nitrate, total phosphorous, pH, total and volatile suspended solids, phytoplankton and zooplankton (APHA 1980). Duck houses were cleaned with pond water twice a week. Manure loading rates were determined by randomly collecting representative samples from 6 ducks from each treatment. Selected ducks were housed in a cage, feed and water were supplied, and faeces were collected for 24 hours. Approximately 4% of duck feed was contaminated with faeces. However, no attempt was made to separate feed and faeces before analysis, assuming that a similar amount of feed mixture may have spilled to the ponds.

No supplementary feed was used for fish, whereas ducks were fed ad libitum with mixed ration containing commercial duck feed concentrate (20%), paddy (50%) and rice bran (30%). Duck feed was analyzed for moisture, crude protein, crude lipid, crude fiber and ash content (AOAC 1975). The gross energy content was calculated based on the standard physiological fuel values as described by Teng et al (1978). The proximate composition of ingredients and the feed mixture is shown in Table 1. In addition, duck feed and manure were analyzed for phosphorus (Yoshida et al 1971) and organic carbon (Dewis and Freitas 1970). Growth and survival rates of fish were determined every month from sample catchs obtained from cast netting. Partial harvestings were carried out monthly from 8^th month onwards with total harvesting at the 10^th month.

Results and discussion

The proximate composition of duck feed mixture used in the study is shown in Table 1.

The mean loading rates of duck manure were estimated to be 4.1, 6.5 and 7.8 kg ha^-1day^-1 for duck stocking densities of 200, 300 and 400 ducks per ha/pond respectively (Table 2).

Corresponding loading rates were 1.67, 2.68 and 3.27 kg ha^-1 day^-1 for carbon, 0.18, 0.3 and 0.35 for Nitrogen; and 0.08, 0.1 and 0.14 for phosphorous. The proximate composition showed N:P ratio of approximately 2.5.

Mean along with minimum and maximum values of water quality parameters during the experimental period are presented in Table 3.

Water temperature fluctuated widely between 19.0 to 37.8 ⁰C, which was due to change of climate from winter to summer. Since the ponds were rain fed, after monsoon period, water depth declined to 50-60 cm. The pH of water varied from 7.6 to 8.9 with moderate fluctuation. Marked reduction in pH was observed during January and February, which was increased after application of lime. Dissolved oxygen was relatively high in D400 followed by D300, D200 and D0. This indicates that oxygen content increased with increase of stocking density of ducks. It may be concluded that the movement of ducks in the pond helped in aerating the water. Irrespective of treatment, oxygen content was comparatively low during the later stage of the culture period, which might be due to increase in fish biomass and reduction of water level due to the summer period. Phytoplankton and zooplankton biomass were high in treatments with high stocking density of ducks, which might be due to high rate of manuring.

The growth parameters of fish species under different treatments are shown in Table 4.

Irrespective of treatments, the yield of catla was highest followed by rohu and mrigal. Catla is the fastest growing species among Indian major Carps. At the end of 10 month culture period, the average final weights (g) of each fish species in the treatments D0, D300, D300 and D400, respectively   were: catla  602, 763, 827and 708g ; rohu 516, 688, 715, 721 ; mrigal 475, 516, 623 and 636 (Figures 1 a,b,c).

The results of the analysis of variance showed significant effect of duck density on final weight of all three fish species. The final weight of fish increased with increasing stocking density of ducks. However, further analysis of data with Students' t-test indicated that there was no significant difference between D300 and D400.  The mean fish production rates of 2576, 3384, 3643 and 3578 kg ha^-1 crop^-1 were obtained in D0, D200, D300 AND D400, respectively (Table 5).

Upgradating of the local breed of the duck by crossing native females with Khaki Campbell males yielded encouraging results. The average egg production of crossbred ducks in F₁ generation increased from 138 to 164 bird^-1yr^-1.
 

Conclusions

• From data on benefit : cost ratio, it may be concluded that integration of duck with fish was more profitable to farmers than general fish farming.

•  The duck stocking rate of 300 / ha. was found to have best benefit : cost ratio though stocking rate of 400 duck / ha. yielded best profit.

Acknowledgements

This study was a part of World Bank assisted National Agricultural Technology Project, ICAR, New Delhi, which was carried out through Institution village Linkage Programme.

References

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