Did you know that insects, including house flies, will give you the best fish feed?

Dr Tanga Mbi, of the International Centre of Insect Physiology and Ecology (Icipe) trains farmers on the use of local insects as an alternative source of protein in animal feed-making at Wambugu Agricultural Training Centre in Nyeri. Rearing these insects and feeding them as a whole or grinding them and adding the meal to other feed blends could be a better way of improving the your animals' nutrition. PHOTO | FILE | NATION MEDIA GROUP

What you need to know:

  • Animal protein sources such as bone meal and blood meal have also been explored. However, their nutritional content cannot be directly compared to that of fish.
  • Insects can breed faster, have a higher feed conversion ratio and produce less greenhouse gases compared to the animals from which alternative protein sources have been sourced.
  • Black soldier fly larvae also contains different minerals such as iron, phosphorus, zinc, sodium and potassium. The larvae migrate from the organic waste, hence they are self-harvesting.
  • Rearing these insects and feeding them as a whole or grinding them and adding the meal to other feed blends could be a better way of improving the birds’ nutrition.

Many processors of fish feeds are still relying on fish meals as a source of protein.

Unfortunately, this has led to high competition for fish among fish feed processors, human consumers and factories that utilise fish and fish products.

Even though attempts have been made to substitute fish meal with vegetable protein sources such as soy meal, the major hindrance to this has been the anti-nutritional factors and high demand for soy by human consumers and soybean oil processing companies.

Animal protein sources such as bone meal and blood meal have also been explored. However, their nutritional content cannot be directly compared to that of fish.

These products may also transmit some zoonotic diseases such as mad cow disease (bovine spongiform encephalopathy) if not properly selected and processed. Therefore, all these are unsustainable.

The good thing is that some insects have higher protein content than that found in fish meal. Some of them, especially the aquatic insects, which also feed on phytoplankton have the fatty acid profile similar to that of fish.

This is evident in insects that feed on mammalian wastes such as black soldier flies, housefly pupae and dung beetles.

Rearing of black soldier fly larvae and houseflies not helps convert organic wastes into body mass but also reduces pathogenic micro-oganisms such as Escherichi coli and Salmonella enterica serovar enteridis in dairy and chicken manure respectively.

Similarly, the protein content of terrestrial insects such as crickets is higher than that of fish meals. Insects can breed faster, have a higher feed conversion ratio and produce less greenhouse gases compared to the animals from which alternative protein sources have been sourced.

Black soldier fly, the common house fly, the yellow mealworm, the lesser mealworm, silkworm, crickets and grasshopper can be used as alternative sources of proteins in making fish feeds and those of other animal.

Black soldier fly larvae

They convert organic wastes into body mass having 42 per cent crude protein and 35 per cent crude fats. They can be reared on cheap and available organic waste material such as poultry and cattle manure and kitchen wastes at a temperature of 29-31 degrees Celsius with relative humidity of 30-90 per cent.

The larvae are also able to inhibit growth of pathogenic microorganism such as E. coli and Salmonella in the manure.

The larvae are able to make the manure more fluid inhibiting oviposition by the housefly. This in turn reduces housefly population on manure, lowering cases of dysentery.

Their fatty acid profile can be modified to mimic that of fish meal by addition of fish offal in their diet. This modifies the polyunsaturated fatty acids to resemble that of fish meals.

And the amino acid profile of these insects range from 0.1-9.0g/16g nitrogen, high levels of lysine and methionine, which are limiting amino acids in cereals and legumes used in animal feed processing.

Black soldier fly larvae also contains different minerals such as iron, phosphorus, zinc, sodium and potassium. The larvae migrate from the organic waste, hence they are self-harvesting.

House fly pupae

These have been used to degrade manure particularly rotting vegetables, human excreta, animal manure, distiller grains and fish offal. In the process, they molt into pupae that have a protein content of about 50-61 per cent and fat content of 9-26 per cent.

They have been used as poultry feeds, leading to high growth rate attributed to the high levels of calcium and phosphorus, which promote development of the skeletal structure of birds.

It also improves growth and quality of carcass in broilers. They are reared on poultry and pig manure, cattle blood, rumen content and rotten fruits or animal offal at a temperature of 25-30 degrees Celsius with a relative humidity of 60-75 per cent.

Their lysine and methionine content range from 5-8 per cent g/16g and 1.3-3.7g/16g nitrogen respectively. Its fatty acid profile includes high levels of essential fatty acids linoleic and linolenic which promote growth and development.

The inclusion level of housefly larvae in livestock feeds should not go beyond 10 per cent of the total feeds. Higher inclusion may lead to amino acid imbalance and dark colour in the feeds, reducing feed palatability.

Grasshoppers, locusts and crickets

Chicken reared on free-range system subsist on the insects together with green vegetation. These birds take long to mature due to uncontrolled feeding and low level of the “hunt” especially in the dry season.

However, the nutritional content of the chicken are high and more preferred by many consumers. This is because the chickens are free from antibiotics and artificial feed ingredients (especially amino acids) added to the commercial feeds.

Therefore, rearing these insects and feeding them as a whole or grinding them and adding the meal to other feed blends could be a better way of improving the birds’ nutrition.

Nutritionally, locusts have 50-60 per cent crude protein, 4.2-14.1 per cent crude fat. Their amino acid profile ranges from 1.1-15.4g/16g nitrogen.

The most common types are house crickets and field crickets. The protein content of house cricket (Acheta domesticus) is same as that of fish meal (55-67 per cent) with a fat content of between 9.8-22.4 per cent.

Crickets and grasshoppers can also be reared easily in special crates and cages, respectively. They can be reared on a wide range of organic matter like green vegetation, bran and soybean floor.

Ideal condition for rearing crickets is 28-30oc to produce 2,000 crickets /M2.

Godfrey Were Juma is from the Department of Dairy, Food Science and Technology, Egerton University