AZOLLA AS LIVESTOCK FEED
Introduction
Azolla is the most promising aquatic plant for livestock feed due to its ease of cultivation, productivity and nutritive value. It was also examined and suggested that one hectare of Azolla can yield 540–720 kg of protein per month use as a feed for fish, swine, and poultry. Because of its composition, azolla is one of the most affordable and effective feed substitutes for livestock, since its high protein and low lignin content allow for easy digestion by the animals.
Azolla is very rich in protein (25-35%), Calcium (67 mg/100g) and Iron (7.3 mg/100g). The comparative analysis of the nutrient content of azolla vis-à-vis other fodder source is depicted in the following table.
Table: Comparison of Biomass and Protein Content of Azolla with other Fodder
| S.No | Item | Annual production of biomass (MT/ha) Dry | Dry matter content (MT/ha) | Protein content (%) |
| 1 | Hybrid Napier | 250 | 50 | 4 |
| 2 | Kolakattao grass | 40 | 8 | 0.8 |
| 3 | Lucerne | 80 | 16 | 3.2 |
| 4 | Cowpea | 35 | 7 | 1.4 |
| 5 | Subabool | 80 | 16 | 3.2 |
| 6 | Sorghum | 40 | 3.2 | 0.6 |
| 7 | Azolla | 1000 | 80 | 24 |
Source : Dr P Kamalasanan et al. 2004 “Azolla -A sustainable feed substitute for livestock”, Spice India
Cultivation Process
Azolla fodder plot setup is simple and doesn’t require special knowledge; farmers may do it themselves with ease. If set up in backyard, the area should be levelled and lined with bricks. The side of the plots should be raised to enable the water to stand. Alternatively, the fodder plot can be in a pit with depth of 0.2 m. A polythene sheet is spread over the bed in such a way that 10 cm of standing water can be maintained. Width of the bed is maintained at 1.5 m to enable the cultural operation from both sides. Length can be changed according on the unit’s needs for feed. For a pair of cows, 2- 2.5-meter-long beds each with an area of around 8 sq m can meet 50% of the green fodder requirements.
Once the bed of size 2.5 m x 1.5 m is ready, about 15 kg of fine sieved soil is spread over the bed, which will provide nutrient to the azolla plant. About 5 kg of pre-decomposed (2 days) cow dung is mixed with the water, which provides carbon source for the azolla. About 40 g of mineral mixture is added to the azolla bed. The solution is fortified with micronutrient of desired quantity. This not only takes care of the micronutrient requirement of azolla but also the cattle when it is fed with the azolla. Sufficient water is added to make the water level of the bed to 10 cm. Production of azolla scientifically and on a continuous basis requires cement concrete tanks of size 2 m long, 1 m wide and 0.5 m deep. Due care should be taken so that water can stand in the tank. Ten or more tanks can be constructed in one place covering an area of 25 sq. m.
Soil is distributed evenly across the bottom of the tank. The depth of soil layer should be about 10 cm. Cow dung is to be added at the rate of 1 to 1.5 kg per sq m of the tank area (2 to 3 kg of cow dung per tank). Single Super Phosphate (SSP) is to be added at the rate of 5 g per sq m of the tank area every week. (10 g SSP per tank). Fill the tank with water till the water collects to a height of 10 to 15 cm above the soil. Allow the soil particle to settle down. Allow the tank to stand overnight. On the following day, spread around 200 g of fresh Azolla inoculum over the surface of the water. It takes about 2 weeks for Azolla to form a mat over the water surface.
Maintaining the water level in azolla tank is important, particularly in the summer season. One possible solution to reduce excessive ambient light is to cover the tank with a shade net. Additionally, this keeps dew from forming on the Azolla plants during the winter. After agitating the water in the azolla bed, approximately 1.5 kg of mother culture of azolla seed material brought from azolla mother nursery is spread uniformly over the bed. The azolla seed’s source needs to be carefully considered. Azolla will cover the whole bed at first, and in seven days it will form a thick mat. It should provide 10 kg of azolla in seven days at most. 50% of the necessary amount of green fodder. During the initial seven days azolla is not harvested. Water level is maintained by applying water everyday. After the seventh day, 1.5 kg of azolla can be harvested every day. Azolla should be harvested in plastic trays with sieve. Harvested azolla should be washed in fresh water before it is fed to the cattle. Washing is necessary to remove the smell of cow dung. Azolla harvested can be mixed with the commercial feed in 1:1 ratio. Cow dung and mineral mixture removed by azolla mass has to be supplemented at least once in seven days after harvest. A mixture made of cow dung, mineral mixture, soil and water should be added once in seven days. After every 60 days, soil is removed from the bed and another 15 kg of fresh fertile soil is added into the bed to avoid nitrogen build up and also provide nutrient to the azolla. Fresh inoculation of azolla after removing soil and water should be made at least once in six months repeating the whole process afresh.
Precaution
- Azolla should be harvested regularly to avoid overcrowding.
- Temperature is an important factor for good growth. It should be around 35 degrees Celsius. The fodder plot is to be covered with a plastic sheet in cold regions so as to reduce the impact of cold weather.
- Places with direct and adequate sunlight should be preferred. A shady place yields less.
- pH of the medium should be between 5.5 to 7. 6. Suitable nutrients such as cow dung slurry, micronutrients should be supplemented as and when required.
