Growing azolla as livestock feed

By Our Agriculture Correspondent

A SIMPLE and low-cost technology to grow azolla, the aquatic fern, has been developed by the Technology Resource Centre of the Natural Resources Development Project (NARDEP), an organ of Vivekananda Kendra in Kanyakumari, Tamil Nadu.

This method will be particularly useful for dairy farmers, according to Dr. Kamalasanan Pillai, Biotechnology Consultant at NARDEP.

It has been well established that azolla is an ideal feed substitute, and NARDEP has ventured into developing a low-cost mass multiplication technology for azolla in farmers' holdings to meet the livestock needs.

In this method, an artificial pond made of silpauline sheets of 2,6 m by 1.6 m is used to grow azolla. Initially a pit of 2 m long, 1 m wide and 20 cm deep is dug under a tree shade.

The pit is first covered by used plastic sacs in order to prevent the growth of the roots of trees nearby, which may puncture the silpauline sheets, according to Dr. Pillai.

The silpauline sheet is laid over the pit avoiding any folds. About 10 to 15 kg of sieved fertile soil is uniformly spread over the sheet. One kg of cowdung mixed in 10 litres of water is poured over it.

Powdered rock phosphate should be added along with the cow dung slurry at a rate of 10 to 20 g per pit. Water should be poured into the pond to a depth of 10 cm. Then 0.5 to 1 kg of pure culture of azolla is inoculated in the pond.In about 10 to 15 days, azolla will fill up the pond, and daily 0.5 to 1 kg fresh azolla can be harvested there after. About 10 g of super phosphate or rock phosphate and 500 g of cow dung should be added once every five days to keep azolla in rapid multiplication phase and to maintain a production of one kg per pond every day.

Micronutrient mixture containing magnesium, iron, copper, sulphur and others should be added to the azolla pond at weekly intervals to enhance the mineral content of azolla.

In this method the cost of azolla production worked out to less than 50 paise per kg. Care should be taken to retain the temperature below 25 degrees Celsius. Shade nets can be used to cut the light intensity.

The azolla biomass should be removed daily to avoid over crowding. The pH of the pond should be maintained between 5.5 and 7.0.

Azolla should be protected from pests and diseases by adopting suitable and need-based plant protection measures. Suitable nutrients should be supplies whenever deficiency symptoms are manifested.

Fresh inoculation of azolla should be done at least once in four months after draining and cleaning the pond. Fresh ponds should be prepared and inoculated with pure azolla culture when contamination of lemna and other competing algae and pests and diseases are noticed, according to Dr. Pillai.

After harvesting, the fresh azolla should be washed thoroughly to get rid of cow dung smell. Washing in a net will be useful as it will allow small plantlets to get out, and they can be poured back in to the pond.

The cleaned azolla can be mixed with equal quantity of commercial feed, and the mixture can be directly fed to dairy cattle and pig. For poultry, azolla can be fed as such. For fish also it can be fed directly by broadcasting it in the fishponds and tanks.Azolla has 50 to 60 per cent protein (on dry weight basis), and is rich in almost all essential amino acids, vitamin A, vitamin B-complex, beta-carotene and minerals such as calcium, phosphorus, potassium, iron, copper and magnesium.

The unique combination of proteins, minerals, vitamins and essential amino acids make it a promising and most economic feed substitute for livestock, according to Dr. Pillai.

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Section  : Science & Tech
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