Despite being largest producer of milk, in India there acute shortage of feed and fodder for dairy animals. Shortage of dry fodder, green fodder and concentrate has been estimated to be 12 to 14 per cent, 25 to 30 per cent and 30 to 35 per cent, respectively. The shortage of fodder is therefore, compensated with the use of readymade commercial feed resulting in increased cost of milk production. The search for alternatives to green fodder and concentrates led to a wonderful plant Azolla, which holds the promise of providing a sustainable feed for livestock. Azolla is a free floating, rapidly growing aquatic fern on water surface and it is useful feed supplement for livestock, poultry and fish. It floats as small, flat, compact green mass. Under ideal conditions it grows exponentially, doubling its biomass in every three days. There are at least eight species of Azolla worldwide; Azolla caroliniana, Azolla circinata, Azolla japonica, Azolla mexicana, Azolla microphylla, Azolla nilotica, Azolla pinnata and Azolla rubra. The common species of Azolla in India is Azolla piñnata. It produces more than 4 to 5 times of protein of excellent quality in comparison to lucerne and hybrid napier. Besides this, the bio- mass production is almost 4 to 10 times when compared with hybrid napier and lucerne, respectively. These two parameters are very important to enhance economic livestock production to establish that Azolla is reckoned as “The Super Plant”.
Azolla is a free floating water fern. It is a common bio-fertilizer in rice crop. The blue-green algae (Anabaena azollae) grow in symbiotic association with this fern and are responsible for nitrogen fixation. Among different species of genus Azolla, A. pinnata is popular. The higher crude protein content (above 20 %) and presence of essential amino acids (high lysine content) vitamins like A& B and minerals like calcium, phosphorous, 12 potassium and magnesium made Azolla useful feed supplement for livestock, poultry and fish.
Requirements for Growth
Azolla is naturally found in ponds, ditches and wetlands of warm temperate and tropical regions throughout the world. It requires light for photosynthesis and grows well in partial shade. Generally, Azolla needs 25 to 50 per cent of full sunlight for its normal growth. Water is the basic requirement for the growth and multiplication of Azolla and is extremely sensitive to lack of water. Maintenance of adequate water level (at least 4 inches in the pond) is essential. The species vary in their requirement of ideal temperature. In general, the 0 0 0 optimum is 20 C to 30 C. Temperatures above 37 C will seriously affect the multiplication of Azolla. The optimum relative humidity is 85 to 90 per cent. The optimum pH is 5 to 7. Too acidic or alkaline pH has an adverse effect on this fern. Azolla absorbs the nutrients from water. Though all elements are essential, phosphorus is the most common limiting element for its growth. About 20 ppm of phosphorus in the water is optimum. Micronutrient application improves the multiplication and growth.
Cultivation of Azolla
For cultivation of Azolla, a shallow freshwater pond is ideal. The detailed procedure for the production of Azolla is explained below :-
Maintenance of the Pond:
Application of about one kg of cow dung and about 100 grams of super phosphate once in two weeks will ensure better growth of Azolla. Any litter or aquatic weeds seen in the pond should be removed regularly. The pond needs to be emptied once in six months and cultivation has to be restarted with fresh Azolla culture and soil.
Production of Azolla :
Sieved fertile soil mixed with cow dung and water need to be spread uniformly in the pond. About one kilogram of fresh Azolla culture is needed for a pond of 6 X 4 feet size. It has to be applied uniformly in the pond. Biogas slurry can also be used instead of dung. The depth of water should be four to six inches. During the monsoon season, if rain water can be harvested from the rooftops and used for cultivation of Azolla, it will ensure excellent and faster growth of Azolla. A few farmers used this practice in the project area (Chitradurga district of Karnataka) and got encouraging results. If the total salt content of the water used for growing Azolla is high, it will adversely affect the growth.
Selection of Location for the Pond:
It is better to select an area near to the house to ensure regular upkeep and monitoring of the pond. A suitable water source should be nearby for regular water supply. The site under partial shade is ideal or else, shade has to be created to reduce the evaporation of water and also, for better growth of Azolla. The floor area of the pond should be free of pointed stones, roots and thorns that can puncture the sheet and cause leakage of water.
Pond Size and Construction:
The size of pond depends on factors like number of animals, quantity of supplemental feed required and availability of resources. For small holders, an area of 6 X 4 feet for Azolla cultivation can produce about one kg of supplemental feed per day. Selected area should be cleaned and levelled. The side walls of the pond can be of either bricks or raised embankment with the excavated soil. After spreading the durable plastic sheet (s in the pond, all the sides have to be secured properly by placing bricks over the side walls. After the inoculation of culture, the pond needs to be covered with a net to provide partial shade and also, to prevent the fall of leaves and other debris into the pond. Thin wooden poles or bamboo sticks are to be placed over the pond walls to support the shade net. Bricks or stones can be used as weights on the edges for securing the plastic sheet and also, the net over the pond area.
Harvesting and Feeding of Azolla :
Depending on the initial quantity of culture added, environmental conditions and nutrition, Azolla’s growth in the pond will be complete in about two to three weeks time. It can be harvested daily after the full growth. Plastic sieves can be used to harvest the biomass from the pond’s surface. About 800 to 900 grams of fresh Azolla (mean yield per day in a season) can be produced from an area of 6 X 4 feet. Azolla can be fed to the livestock either in fresh or dried form. It can be given directly or mixed with concentrates to cattle, poultry, sheep, goat, pigs and rabbits. In the studies with over 100 dairy farmers done at various villages of Chitradurga district of Karnataka under NAIP livelihood project, feeding of Azolla @ 800 grams (fresh weight) on an average per day, improved the monthly milk yield by at least 10 liters per cow. It takes a few days for the animals to get used to the taste of Azolla. So, it is better to feed it along with the concentrates in the initial stages. Azolla has to be washed thoroughly with fresh water to remove the smell of dung.
The expenditure on preparing a 6 X 4 feet pond is minimal at Rs.500 (sheet plus labour cost). A farmer can realize a net profit of over Rs. 4000 per annum from the additional milk yield and reduced usage of concentrates’ feeding for livestock.
As the dry matter content is only about 7 per cent, it is difficult to rely solely on Azolla as the feed resource. Environmental constraints like very high (summer in dry areas) or low (winters in North India) temperatures, low humidity, limited water availability and poor quality of water makes it difficult to adopt Azolla’s production.
- A shady place, preferably under a tree, with sufficient sunlight should be chosen for the Azolla production unit. A place of direct sunlight should be avoided.
- All corners of the pit should be of the same level so that the water level can be maintained uniformly.
- Azolla biomass @ 300 gms – 350 gms/sq.meter should be removed daily to avoid over crowding and for keeping the fern at rapid multiplication phase.
- Suitable nutrients should be supplied, as and when, nutrient deficiency is noticed.
- Plant protection measures against pests and diseases should be taken as and when required,
- About 5 kg bed soil should be replaced with fresh soil, once in 30 days, to avoid nitrogen build up and prevent micro-nutrient deficiency.
- 25 to 30% water also needs to be replaced with fresh water, once in 10 days, to prevent nitrogen build up in the bed.
- Replacement of water and soil should be followed by fresh inoculation of Azolla, at least once in six months.
- A fresh bed has to be prepared and inoculated with pure culture of Azolla, when contaminated by pest and diseases.
Azolla has enormous potential as a livestock feed due to:
- Its high content in proteins, essential amino acids, vitamins (vitamin A, vitamin B12, Beta Carotene), growth promoter intermediaries and minerals.
- Its ability to proliferate without inorganic nitrogen fertilization.
- Its high rate of growth in water without the need to displace existing crops or natural ecological systems.
It has been used for many years throughout Asia and parts of Africa to feed pigs, ducks, chickens, cattle, fish, sheep and goats and rabbits.
Suitability of Azolla as a Livestock Feed
Green plants have long been recognized as the cheapest and most abundant potential source of proteins because of their ability to synthesize amino acids from a wide range of virtually unlimited and readily available primary materials.
Azolla is very rich in proteins, essential amino acids, vitamins (vitamin A, vitamin B12, Beta Carotene), growth promoter intermediaries and minerals including calcium, phosphorous, potassium, ferrous, copper, magnesium. On a dry weight basis, Azollahas 25-35% protein content, 10-15% mineral content, and 7-10% comprising a combination of amino acids, bio-active substances and biopolymers . Azolla’s carbohydrate and oil content is very low.
Azolla is also rich in iron (1000–8600 ppm dry weight), copper (3–210 ppm dry weight) manganese (120–2700 ppm dry weight), vitamin A (300–600 ppm dry weight.), vitamin A (300–600 ppm dry weigh), chlorophyll and carotenoids. It contains 4.8–6.7% dry weight crude fat, with 6.1–7.7% and 12.8– 26.4% total fat for the polyunsaturated acids omega 3 and omega 6 (Paoletti et al., 1987).
Azolla meal contains 25.78% crude protein, 15.71% crude fiber, 3.47% ether extract, 15.76% ash and 30.08% nitrogen free extract on the air-dry basis (Basak et al., 2002). In addition, aquatic plant species including Azolla do not to accumulate secondary plant compounds and therefore has a greater potential than tree leaves to source protein for monogastric animals.
Azolla is the most promising aquatic plant for livestock feed due to its ease of cultivation, productivity and nutritive value. Azolla’s use as a feed for fish, swine and poultry was also tested and recommended that one hectare of Azolla can produce 540-720 kg of protein per month.
Azolla’s composition therefore makes it one of the most economic and efficient feed substitutes for livestock, particularly as can be easily digested by livestock due to its high protein and low lignin content.
Poultry and in particular ducks and chickens can be raised on a diet including fresh Azolla. It has long been recognized as a feed for wildfowl in the USA and for domesticated ducks in China and it has been used as a feed to domestic fowl in Vietnam .
The poultry industry has traditionally been one of the most profitable businesses in India’s agriculture, providing nutritious meats and eggs for human consumption within the shortest possible time.
However, the industry is now threatened by higher prices and the non-availability of feed ingredients, reflecting feed costs comprising 65-70% of the total cost of poultry production.
In India, Subudhi & Singh (1978) concluded that fresh Azolla could replace about 20% of commercial feed in the diet of young chickens. They estimated that to replace this much commercial feed would require about 9 kg of fresh Azolla each day for 100 chickens and that this amount could be produced in a shallow pond 60 m² in area.
The nutrient digestibility of crude protein, crude fat, and crude fiber were not affected by the level of Azolla in the ration, and that broilers can readily digest the crude fiber in Azolla, but not that in rice bran, so that digestibility is not a limiting factor when Azolla is used.
The nutrient constitution of Azolla is almost identical to that of commercial poultry feed, except that Azolla protein content is high and calcium content is slightly low.
Their feeding trials showed that 20–25% of commercial feed could be replaced by supplementing it with fresh Azolla, with the addition of Azolla feed also having a variety of benefits:
- Birds with 75% of the regular feed and 12.5% in the form of Azolla had an almost equal weight to birds with 100% regular feed.
- Furthermore, birds receiving normal feed with 5% extra in the form of Azolla grew faster than the birds with 100% feed alone and had a 10–12% increase in the total body weight.
- Live weight, production number and protein efficiency are significantly improved.
- Feed conversion ratio and energy efficiency are significantly improved.
- The total broiler is cost significantly lower with the Azolla meal.
- Dressing and giblet percentages is significantly increased on diet with 5% Azolla meal.
- Azolla meal has no deleterious effect on the palatability of the broiler diets.
- The addition of Azolla meal has no deleterious effect on palatability of the diets.
Co-culture of Azolla-rice-duck
The Japanese farmer Dr Takao Furuno has developed rice-duck-Azolla-loach cultivation as an integrated biosystem which eliminates the need for fertilizers, herbicides and pesticides by incorporating duck-raising into organic rice cultivation. The approach is now being replicated with substantial success all over south-east Asia as an effective way to boost farmers’ incomes, reduce environmental impact and improve food security.
Azolla as a Feed for Mallards
Azolla’s potential as a feed for Mallard (egg production) and Muscovy (meat production) ducks has also been investigated in Vietnam. Becerra et al. (1995)conducted feeding trials to determine the effect of feeding Azolla microphylla as partial replacement of the protein in boiled soya bean in diets based on sugar cane juice for meat ducks.
Fresh Azolla was offered ad libitum three, four or five times per day, at a rate of 1 kg fresh weight per pen at each feeding and the times increased with the age of the birds to minimize losses. The rations were fed from the age of one month to 70 days old.
Cattle and Milk Production
Fodder is an important requirement for cattle. Even if the animals are fed with commercial feeds from the market, fresh green grass or dry straw is essential as fodder availability greatly reduces the expenditure on commercial feeds. The success of a dairy plant depends largely on increasing milk production without escalation in feeding cost. Growing fodder grass is a good option. Another is Azolla cultivation.
Although the demand for milk and meat has increased in countries such as India, there has also been a substantial decline in fodder production owing to the decreasing forest and grassland areas. The fodder availability from various crops has also decreased largely due to the introduction of high yielding dwarf varieties. Shortages of fodder are therefore being compensated with commercial feed, resulting in increased cost of meat and milk production. Moreover, as commercial feed is mixed with urea and other artificial milk boosters, it has a deleterious effect on the quality of milk produced and the longevity of the livestock, which in turn leads to degenerative diseases like cancer and coronary ailments in human beings.
Cultivating Azolla as a Livestock Feed
Several cost-effective methods can be used for the cultivation of Azolla as a livestock feed. The one described here was developed by India’s Natural Resources Development Project (NARDEP).
NARDEP’s Cultivation Method
Nardep therefore developed a method for cultivating Azolla that is easy and economical for livestock farmers. One of its attractions is that the dung produced by livestock is used to help fertilize the Azolla plants which, in turn, provide nutrition for the livestock.
- A water body is made, preferably under the shade of a tree, with the help of a silpaulin sheet. Silpaulin is a polythene tarpaulin which is resistant to the ultra violet radiation in sunlight. A pit of 2 x 2 x 0.2 m is dug as a first step.
- All corners of the pit should be at the same level so that a uniform water level can be maintained. The pit is covered with plastic gunnies to prevent the roots of the nearby trees piercing the silpaulin sheet, which is spread over the plastic gunnies.
- About 10 – 15 kg of sieved fertile soil is uniformly spread over the silpaulin sheet. Slurry made of 2 kg cow dung and 30 g of Super Phosphate mixed in 10 litres of water, is poured onto the sheet. More water is poured on to raise the water level to about 10 cm.
- About 0.5 – 1 kg of fresh and pure culture of Azolla is placed in the water. This will grow rapidly and fill the pit within 10 – 15 days. From then on, 500 – 600 g of Azolla can be harvested daily. A mixture of 20 g of Super Phosphate and about 1 kg of cow dung should be added once every 5 days in order to maintain rapid multiplication of the Azolla and to maintain the daily yield of 500 g.
- A micronutrient mix containing magnesium, iron, copper, sulphur can also be added at weekly intervals to enhance the mineral content of Azolla.
Key Points of NARDEP’s Method of Azolla production
- It is important to keep Azolla at the rapid multiplication growth phase with the minimum doubling time. Therefore biomass (around 200 g per square meter) should be removed every day or on alternate days to avoid overcrowding.
- Periodic application of cow-dung slurry, super phosphate and other macro and micronutrients except nitrogen, will keep the fern multiplying rapidly.
- The temperature should be kept below 25°C. If the temperature goes up the light intensity should be reduced by providing shade. If possible, it is best to place the production unit where it is shady.
- The pH should be tested periodically and should be maintained between 5.5 and 7.
- About 5 kg of bed soil should be replaced with fresh soil, once in 30 days, to avoid nitrogen build up and prevent micro-nutrient deficiency.
- 25 to 30 percent of the water also needs to be replaced with fresh water, once every 10 days, to prevent nitrogen build up in the bed.
- The bed should be cleaned, the water and soil replaced and new Azolla inoculated once every six months.
- A fresh bed has to be prepared and inoculated with pure culture of Azolla, when contaminated by pest and diseases.
- The Azolla should be washed in fresh water before use to remove the smell of cow dung.
Harvesting and Preparing Azolla as Livestock Feed
- Harvest the floating Azolla plants using a plastic tray having holes of 1 cm2 mesh size to drain the water.
- Wash the Azolla to get rid of the cow dung smell. Washing also helps in separating the small plants which drain out of the tray. The plants along with water in the bucket can be poured back into the original bed.
- For use as a livestock feed, the fresh Azolla should be mixed with commercial feed in 1:1 ratio to feed livestock. After a fortnight of feeding on Azolla mixed with concentrate, livestock may be fed with Azolla without added concentrate.
- For poultry, Azolla can be fed to egg layers as well as broilers.
- In case of severe pest attack the best option is to empty the entire bed and lay out a fresh bed in a different location.
Azolla can be used as an ideal feed substitute for cattle, fish, pig and poultry, apart from its utility as a biofertilizer for wetland paddy. Azolla technology will be taken up in a big way by the dairy farmers, especially, by those who experience land scarce conditions for fodder production.
Dr Rajesh Kumar Singh, Jamshedpur, Jharkhand, India
Mo:9431309542, Email: [email protected]