Dr. Jacquie Jacob Ph.D., University of Kentucky
NOTE: Before using any feed ingredient make sure that the ingredient is listed your Organic System Plan and approved by your certifier.
Eggs from chickens on range have been found to be higher in total fat content than those in a cage production environment (Anderson, 2011). A drop in the total fat content of eggs may be observed when the hens are 74 weeks old, generally corresponding to the winter months when fat intake from insects is at its lowest. It has been observed that the consumption of insects results in the increased fat content of eggs from hens on pasture. The nutrient content of poultry meat or eggs may differ due to the type of insects attracted to the pasture crops.
Bambara and Watson (2011) reported that several insect species could be present on forages and pastures in North Carolina. This includes alfalfa weevil (Hypera postica), potato leafhopper (Empoasca fabae), true armyworm (Pseudaletia unipuncta), fall armyworm (Spodoptera frugipenda), cutworms (Agrotis and Feltia), green june beetle (Cotinis nitida), meadow spittlebug (Philaenus spumarius), and clover root curculia (Sitona hispidulus), as well as aphids, grasshoppers, and crickets.
A variety of insects have been used as a food source for both animals and humans. As a result, reports on their nutrient content are published in a variety of different journals ranging from anthropology to zoology. Finke (2008) completed an extensive review of the published literature related to the nutrient content of insects commonly used as food for humans or animals, including poultry. In this review, it was found that the moisture content of raw, whole insects varied from 55% to 85%. The insects with the lowest moisture content generally had a high fat content. On a dry matter basis, protein is a major component of raw, whole insects with values ranging from 21% to 80%. Feeding trials with different insects have suggested that the quality of insect protein is similar to that of fishmeal or soybean meal. The other major component of most raw, whole insects is fat—ranging from 2.2% to 60%. Based on the limited data available Finke (2008) concluded that, in general, female insects contain more fat than male insects.
Insects have a protein-rich exoskeleton rather than a calcified skeleton, so the mineral content of most insects is relatively low (Finke, 2008). All insects, however, are reported to contain a high level of phosphorous and a low level of calcium. The result is a calcium to phosphorus ratio of less than one. While the phosphorus availability in plant sources is low, the phosphorus found in insects is almost 100% available. Most insects are a good source of trace minerals including iron, zinc, copper, manganese and selenium. Finke (2008) concluded, however, that the mineral composition is mainly a reflection of the material that the insects were feeding on. Studies with wild insects have shown seasonal variation in mineral content, corresponding with differences in material available to the insects.
While some researchers have reported that soft-bodied insects contain less fiber than those with a hard exoskeleton, a critical evaluation of the literature by Finke (2008) suggests this may not be so clear-cut. The content of the gastrointestinal tract may be the reason for the high fiber values reported for some insect species.
For poultry raised on pasture, the type of insects available to them depends on the type and quantity that are attracted to the forage. Insects can also be grown commercially, and different insect meals are available for use in poultry diets.
Adult field crickets (Gryllus testaceus Walker) were reported to contain 58.3% crude protein, 10.3% fat, 8.7% chitin, 2.96% ash, and 2960 kcal/kg, on a dry matter basis. The levels of methionine, cystine and lysine were 1.93%, 1.01% and 4.79%, respectively (Wang et al., 2005). When included in diets formulated to equal nutrient levels, up to 15% field cricket was included in broiler diets with no adverse effects on performance (Wang et al., 2005).
Recent research in China (Sun et al., 2012) indicated that meat from chickens raised on pastures with a heavy grasshopper population had more antioxidant potential and a longer storage life.
This is an eOrganic article and was reviewed for compliance with National Organic Program regulations by members of the eOrganic community. Always check with your organic certification agency before adopting new practices or using new materials. For more information, refer to eOrganic's articles on organic certification.