The demand for milk and meat has been increasing and animal husbandry, as a profitable occupation, is expanding. However, there is a substantial decline in fodder production, owing to the decreasing area under forest and grasslands. The fodder availability from various crops has also decreased largely due to the introduction of high yielding dwarf varieties.
The shortage of fodder is, therefore, being compensated with commercial feed, resulting in increased cost of production of meat and milk. 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.
Search for an alternative took us to a wonderful plant, “Azolla”, which holds the promise as a sustainable feed substitute for livestock.
Importance of Azolla
Azolla is very rich in proteins, essential amino acids, vitamins (vitamin A, vitamin B12, Beta Carotene), growth promoter intermediaries and minerals like calcium, phosphorous, potassium, ferrous, copper, magnesium etc. Azolla, on a dry weight basis, is constituted of 25-35% protein content, 10-15% mineral content and 7-10%, a combination of amino acids, bio-active substances and bio-polymers. Carbohydrate and oil content in Azolla is very low. Thus the bio-composition of Azolla, makes it one of the most economic and efficient feed substitutes for livestock. Moreover, Azolla can be easily digested by livestock owing to its high protein and low lignin content.
Trials were carried out by Natural Resources Development Project (NARDEP), Vivekananda Kendra, with Azolla as a feed substitute in Tamil Nadu and Kerala. Trials on dairy animals showed an overall increase of milk yield by 15–20% when 1.5–2 Kg of Azolla was combined with regular feed. 15–20% of commercial feed, especially oil cake, can be replaced with the same quantity of Azolla on dry weight basis, without affecting milk production. It was also found that Azolla feeding improves the quality of milk and the health and longevity of livestock.
Feeding Azolla to poultry birds improves the weight of broiler chicken and increases the egg production of layers. Azolla can also be fed to sheep, goat, pig and rabbit as feed substitute. In China, cultivation of Azolla along with paddy and fish is said to have increased the rice production by 20% and fish production by 30%. Trials conducted on Azolla as fish feed substitute are also encouraging.
NARDEP method of Azolla production
Natural Resources Development Project (NARDEP) has been working on Azolla for the last 3 – 4 years, finding its potential as a feed substitute and exploring cost effective methods for the mass multiplication of Azolla in farmers’ homesteads.
In NARDEP method, an artificial water body is made, preferably under the shade of a tree, with the help of a silpauline sheet. A pit of the size of 2M X 2M X 0.2M is dug as a first step. This pit is covered with plastic gunnies to prevent the roots of the nearby trees piercing the silpauline sheet, which is spread over the plastic gunnies. About 10 – 15 kgs of sieved fertile soil is uniformly spread over the silpauline sheet. Slurry made of 2-kg cow dung and 30 gms of Super Phosphate in 10 litres water, is poured onto the sheet. More water is poured to make the water level reach about 10 cm. About 500 gms to 1kg of fresh and pure culture of Azolla is inoculated in the pit. Azolla will rapidly grow and fill the pit within 10-15 days and about 500 gms – 600 gms of Azolla can be harvested daily thereafter. A mixture of 20 gms of Super Phosphate and about 1 kg of cow dung should be added once in 5 days. This is done to keep the Azolla in rapid multiplication phase and to maintain the daily yield of 500 gm./pit. Micronutrient mix containing magnesium, iron, copper, sulphur etc., can also be added at weekly intervals to enhance the mineral content of Azolla. In this method the cost of production of Azolla is less than 65 ps./kg (See Table III)
Azolla plant can be easily manipulated (special manipulation technique has been developed to enhance a particular mineral or amino acid content in Azolla) to synthesize more quantities of desired secondary metabolities. These include, amino acids, vitamins, anthocyanines and even mineral compounds derived through proper manipulation with nutrients and environmental factors. Adding the respective salts in the medium can increase the much needed iron, copper and calcium content of Azolla biomass.
Though there is no large-scale incidence of pests and diseases in Silpauline based production system, the pest and disease problems have been noticed during intensive cultivation. The pest attack can be controlled by the application of Furodan @ 10 gram / sq.meter. Similarly, treating Azolla with Bavestine 2% solution can control most of the fungal diseases. In case of severe pest attack, the entire bed should be cleaned and a fresh bed may be laid out in a different location. Biomass collected from field applied with pesticide should not be used as a feed for livestock. It is better to have a fresh inoculation after every pesticide / fungicide application.
Using Azolla as livestock feed
Azolla should be harvested with a plastic tray having holes of 1 sq.cm mesh size to drain the water. The tray along with Azolla should be kept in a bucket, half filled with water. Azolla should be washed to get rid of the cow dung smell. Washing also helps in separating the small plantlets which drain out of the tray. The plantlets along with water in the bucket can be poured back in to the original bed. Fresh Azolla thus collected should be mixed with commercial feed in 1:1 ratio to feed livestock. For poultry, Azolla as such can be fed both for layers and broilers. However, it is advisable to mix Azolla in regular feed in 1:1 ratio at the beginning, for one week. After a fortnight of feeding on Azolla mixed with regular feed, livestock may be directly fed with Azolla with out the addition of regular feed material.
Nutrient content and its impact on growth
The nutrient constitution of Azolla is found to be almost similar to that of commercial poultry feed, except that the protein content is high and calcium content is slightly low. Feeding trials carried out on poultry with different combinations of commercial feed and Azolla, showed that 20–25% of commercial feed could be replaced by supplementing it with fresh Azolla in diet. Birds with 75% of the regular feed and 12.5% in the form of Azolla, weighed almost equal to the birds with 100% regular feed (Table II). The birds receiving normal feed with 5% extra, in the form of Azolla grew faster than the birds with 100% feed alone. 10–12% increase in the total body weight was also observed. The trials on broiler chicken showed a substantial increase in their body weight. The number of eggs laid per bird and quality of eggs (the yellow yolk portion of egg being more prominent and yellowish) was also better than those of the control birds.
There was a substantial improvement in the quantity, as well as, quality of milk produced, when dairy cattle were fed with Azolla combined with commercial feed along with an improvement in the health of the cattle. The increase in the milk yield was to the tune of 10–15%, which went up to 20%, during summer months from February to May. It is found that the increase in the quantity of the milk produced on the base of nutrient was higher than the quantity of Azolla fed. Hence, it is assumed that more than the carbohydrate, protein content and other components, like carotinoids, bio-polymers, probiotics etc., may be contributing to the over all increase in the production of milk.
Conclusion
Azolla can be used as an ideal feed substitute for cattle, fish, pig and poultry, apart from its utility as a bio-fertilizer for wetland paddy. It is popular and cultivated widely in other countries like China, Vietnam, and Philippines etc., and is yet to be taken up in India, in a big way. The production technology has to be standardized to the diverse and different agro-climatic zones of the country, to enable its wider spread.
Dairy farmers of South Kerala and Kanyakumari district have taken up the low cost production technology developed by NARDEP as part of the project funded by Department of Bio-technology (Government of India). It is hoped that in the coming days, 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.
Acknowledgement :
We acknowledge with thanks the financial assistance received from department of Bio-technology (Government of India) for carrying out the research on the propagation of BGA and Azolla in NARDEP, Vivekananda Kendra, Kanyakumari.
