Black soldier fly larvae can be a cheap, nutritious alternative to cereal-based poultry feed; here’s how

Ease of handling, safety as well as nutritious value make them a highly recommended alternative for poultry farmers


Illustration: Yogendra Anand

Illustration: Yogendra Anand / CSE

India is among the top five chicken and egg producers in the world. One of the factors that determine sustainability of the sector and economic viability of the business for small poultry farmers, is the quality, quantity and cost of feed.

According to estimates, feeds account for up to 70 per cent of the entire cost of poultry production. Besides, the conventional feed supplied to the poultry, majorly cereals and soya, competes with the food demands of a growing human population. Hence, in addition to rising cost, the feed resource availability is a major determinant of the sustainability of the poultry sector.

These concerns have in recent years drawn the attention of researchers towards exploring low-cost alternatives to conventional poultry feed. One such alternative is brewers dried grains, a byproduct of the brewing industry.

Though rich in protein and amino acid, its limitations include high moisture and fibre content. Rice bran is another economically viable alternative to wheat in certain parts of the country. It has a comparable apparent metabolisable energy as wheat. However, studies show that the laying performance of the chicks declined on incorporation of rice bran to the feed.

Some recent research therefore focus on the utilisation of insects as substitute for conventional poultry feed. The larvae of black soldier fly (Hermetia illucens), for instance, have a high nutritional value and are easy to raise.

The larvae feed on a variety of organic matter, from rejected food waste to manure. Insects also have high waste-to-biomass conversion efficiency. This means, unlike hot-blooded mammals and birds, which use a lot of energy to keep themselves warm, insects are efficient converters of food into body mass.

The black soldier fly larvae can thus be a low-cost, low footprint, eco-friendly as well as natural feed companion to poultry farmers.

Of its very short life span of 45 days, the maximum feed intake takes place during the larval stage, which lasts for two weeks. In other words, this is the time required for useful conversion of waste. These benefits prompted the development of a simple and inexpensive larval trapping mechanism, capable of yielding fresh black soldier fly larvae in the farm itself.

The novel trapping mechanism uses organic food waste and some eggs of black soldier fly to churn out larvae to be used as feedThe trap consists of two major components, the primary collection vessel (PCV) and a larval segregation bucket (LSB), which together cater to the entire process of egg-laying, hatching and segregation of larvae.

The gas release cum egg-laying assembly is placed at the top of the primary collection vessel and acts as the stimulator to facilitate movement of the fly.

The egg-laying assembly is designed to make the system capable enough to effectively hold and hatch the eggs.

A bottom composite drainage layer of 7-8 cm, comprising coconut coir and sand, is used to captivate larval movement towards the drain valve and primary screening of the leachate.

The leachate is recirculated back into the system to withhold the moisture content between 50 and 60 per cent and also to ensure automated larval movement towards the segregation bucket.

A full-grown larva older than a week consumes nearly 200 ml of diet every day. Therefore, the frequency of refilling the substrate (or waste products) in the reactor of the trapping mechanism is a direct variable of the larval count.

With 9 gm of average larval weight and germination rate of 15,000 gm per day, the active count of larvae is up to 400 sq cm of substrate area.

At this consumption and germination rate, the substrate requires refilling every 18 days. Anyhow, during the experiment 15 days refilling frequency was practised to avoid the risk of starvation.

Larval footprints have been recorded from the fifth day onwards and soon 2 kg of larvae were harvested per day over the next 20 days.

Gain analysis

A comparative analysis of the nutritional excellence of black soldier fly larvae with respect to conventional diet shows encouraging results.

A black soldier fly larvae is capable of converting the organic waste into wide range of useful vitamins and minerals. They are thus are rich in calcium, phosphorus, magnesium, sodium, potassium, iron, zinc, copper, manganese and so on, which makes them a promising candidate for livestock feed.

The higher amino acid content also makes the grub a good source of protein. The nutritional composition of the larvae, however, varies with the food they consume.

In the present investigation, the larvae were fed a mixed consortium of waste including vegetable market waste (30 per cent), fruit waste (30 per cent), cooked food waste (30 per cent), and poultry litter (10 per cent). Post germination, the diet for the larva increases parallel to its body weight until the 7th day from hatching.

Since, feed-conversion efficiency is a reliable indicator to understand how efficiently the diet is converted into chicken mass, to assess the nutritional value of the feed, an experiment was carried on two pairs one-week-old healthy chicks (Gallus gallus domesticus).

The initial weight of each chick varied between 34 to 39 gm. The experimental group was supplied with a larval diet of 10 gm per chick for the first two days and successively increased to 200 gm over a period of one month.

The control group was supplied wheat bran based hybrid diet of a similar amount. The mean body growth observed during the primary, intermediate, and final phases for the experimental group are assessed as 39 per cent, 87.6 per cent and 55.91 per cent respectively against the subsequent phases.

The values were 22, 51, and 87 per cent respectively for the control group. The cumulative weights of the chicks were ascertained as 145 gm and 142 gm for the experimental group and 128 gm and 121 gm for the control group at the end of the experimental tenure.

Hence, black soldier fly larvae can be a high-quality feed replacement to conventional soya and corn-based feeds. Protein and fat value, which are considered the two most significant parameters, were 20 per cent and 25 per cent, respectively on following the above-mentioned diet.

A comparison shows that black soldier fly larvae comes loaded with macro- and micronutrients

Ease of handling is one of the most user-friendly characteristics that is to be maintained while deciding live feeds. In that standpoint, the non-slimy and dry body nature of black soldier fly larvae fosters the social acceptance of the same.

Apart from this, the most benefitted groups include small families who grew chicken for non-commercial purpose. The odourless nature of the housing mechanism makes it the best choice for those growing chicken in house barns or backyards.

Safety of food is another point of concern for customers. And in this aspect black soldier fly larvae can be considered to be the safest as they do not spread diseases or cause any harm to fauna and flora.

Black soldier fly larvae can be considered as a great insect feed that comes loaded with qualitative fat and superior proteins as compared with other costly non-renewable conventional feeds.

To summarise in the near future, black soldier fly larvae feed can turn out as a low-cost, low footprint, eco-friendly as well as natural feed companion to the poultry farmers.

In addition to this, the black soldier fly larvae not only have the advantage of flora friendly insect feed but also can be beneficial as nutritional source for plants/crops in the form of black soldier fly larvae frass or poops. Once the novel trapping mechanism is installed, the system becomes self-sustainable as long as you keep feeding them with the organic wastes.

(Atun Roy Choudhury is head-technical at Cube Bio Energy Pvt Ltd, waste management company in Telangana; Neethu B is scientist with Kerala State Council for Science, Technology and Environment; Neha Singh and Namita Banka are with Banka BioLoo, waste management services company; and P Sankar Ganesh is professor at Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, Hyderabad Campus)

This was first published in the 16-31 January, 2023 print edition of Down To Earth


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