Insect larvae production on dairy cow manure: a potential windfall for dairy farmers and sustainable aquaculture

View the project final report

Commodities

• Animals: bovine, fish, Insects for use as feed ingredients
• Animal Products: dairy, Fish, as well as Insect Meal

Practices

• Animal Production: aquaculture, feed additives, feed formulation, manure management, probiotics
• Crop Production: nutrient cycling, nutrient management, winter storage
• Education and Training: display, on-farm/ranch research
• Energy: byproduct utilization
• Farm Business Management: new enterprise development, value added
• Production Systems: agroecosystems, integrated crop and livestock systems, organic agriculture
• Soil Management: composting
• Sustainable Communities: employment opportunities, local and regional food systems, new business opportunities

We have recently developed a system to produce insect meal (IM) from housefly (Musca domestica) larvae raised on dairy cow manure. The study proposed here will follow up on this result by demonstrating the utility and value of this system to Northeast farmers: we will raise Rainbow trout (Oncorhychus Mykiss) on diets including IM. Rainbow trout are an important commercial species for hatcheries and aquaculture in the region, and there is significant room for growth of aquaculture production. To achieve this growth however, there is a need for sustainable and cost-effective alternatives to Fishmeal and Fish oil, which are currently limiting ingredients for fish feed. IM is one of the most promising such alternatives – it is high in protein and fat and has a favorable amino acid profile – and is thus poised to become a valuable feed commodity in the near future. We will also examine a recent finding about housefly IM that, if reproducible, would increase its value significantly: its ability to stimulate the fish immune system and increase resistance to disease. This project will take a sustainable and safe method of manure management, apply it in a local context, and investigate how it could open new revenue streams to dairy farmers while also diversifying agricultural production. Under this paradigm, the growth of a sustainable aquaculture industry in the Northeast would provide employment, local healthy food, and additional revenue streams for traditional farmers and farm communities.

1) Raise housefly larvae on organic dairy manure. Our group’s previous publication on production of housefly larvae (M. domestica) used manure from the Cornell teaching barn. To demonstrate this technique using manure from an actual dairy farm, we will partner with Jerry Dell Farm, a local organic dairy producer.

2) Produce diets for rainbow trout using insect meal (IM). Diets with both high and low inclusion of IM will be formulated to meet the nutritional requirements of juvenile rainbow trout (O. mykiss). Modern fish feeds typically contain some fishmeal (FM), with most protein coming from plant ingredients to save on cost. In this preliminary stage, we aim to demonstrate that IM is a superior replacement for fishmeal than the modern alternatives (soy protein concentrate and corn gluten meal). This design gives our experiment the best balance of relevance (using IM in the context of a realistic modern diet) and control (direct comparison of FM replacements). If these results are encouraging, future studies will investigate the feasibility of using IM to cut down FM content even further.

3) Conduct trout feeding trial using IM diets. Juvenile rainbow trout will be fed diets with both high and low inclusion of IM to evaluate nutritional value of these feeds. A secondary hypothesis we are interested in evaluating is that IM diets are less pro-inflammatory than diets with high levels of plant ingredients, owing to lower levels of pro-inflammatory omega-6 fatty acids and trout’s evolutionary adaptation to eating insects. In addition to growth parameters, specific assays of immune health and inflammatory stress will be conducted.

Immune challenge with Bacterial Coldwater Disease (BCWD). At the end of the feeding trial, juvenile trout will be exposed to a bacterial infection. The objective is to broadly screen for possible immune-stimulatory effects of insect meal, as these have been reported in recent work [10]. BCWD is a common infection in salmonids in both the hatchery and aquaculture context. Mortality can be as high as 85% in fry and fingerlings [12] and fish that survive the infection often present with scoliosis and lordosis as a result of muscle fiber destruction. There is no commercial vaccine for this disease, therefore development of an IM diet that enhances resistance to BCWD would provide additional value for both hatcheries and commercial fish farms. Absence of immune effects would, however, still be an additional and important verification of the viability of IM ingredients.