It is common for free-range chickens to consume earthworms. Earthworms are very efficient at converting plant and animal wastes into biomass that can be used as a feed ingredient in animal production: a ton of animal wastes will produce about 100 kg of worms (Edwards, 1985). Earthworms are a good quality protein for use in animal feeds, but the practical use of earthworm meal is influenced by economics. Technology is available for large-scale production of earthworms, but separating the earthworms from the organic wastes in which they are growing is labor intensive, thus hindering the use of earthworm meal in developed countries. The potential is greater for producing earthworm meal in developing countries where labor costs are lower.
The nutritional profile of earthworms is comparable to other protein sources currently used in poultry feeds, especially fish meal (Edwards, 1985). On a dry matter basis, earthworms contain 60-70% protein, 6-11% fat, 5-21% carbohydrates, and 2-3% minerals and a range of vitamins, including niacin. Earthworms are higher in the essential amino acids, such as lysine and methionine, than either meat or fish meal. Earthworm meal is high in essential long-chain fatty acids.
Table 1. Nutrient content of earthworms (Lumbricus terrestris) (Finke, 2002)
|Metabolizable Energy, Kcal/kg||708|
|Crude protein, %||10.5|
Feeding Earthworms to Poultry
There is very little information on the use of earthworm meal in poultry diets. A study in Indonesia showed that 10% earthworm meal could replace a large portion of the fish meal in the diet with no adverse affect on body weight gain or feed efficiency. Feed intake was reduced at the 15% inclusion level (Prayogi, 2011).
Care must be taken when growing earthworms for use in animal feeds. Heavy metals and other pollutants are taken up by the worms and can be passed on to the birds consuming the earthworms (Sharma et al., 2005). It is important, therefore, to know what material was used in the vermicomposting process.