A Low-Input Manure Management System in Animal Housing for Housefly Control, Waste Reduction and Feed
Manure in caged layer houses poses problems. Two of these are dense housefly populations and manure disposal. Currently, caged layer manure is periodically spread on pastures, or a relatively expensive system is needed to scrape the manure and pump it to a lagoon. The large numbers of flies produced are a nuisance which can bring litigation from neighbors and result in facility closures. Fly control with insecticides is expensive and short-lived. Houseflies rapidly develop resistance to any insecticide widely used. Current pest management systems call for drying the manure. This approach was first developed in California and is not practical in the humid southeast.
The proposed study is necessary prior to on-farm testing of a low-input system that will reduce the bulk of manure by half, essentially eliminate housefly breeding and produce a high quality feedstuff. This system could save a 60,000 hen operation $6,000 for fly control and $5,000 or more in manure hauling each year. The native black soldier fly has shown the potential to accomplish these benefits in experimental and practical situations. We plan to test the engineering principles involved in this system to avoid major problems in a subsequent on-farm test. This system may have application in housing designed for other farm animals.
A 40′ long California style caged layer house was designed to utilize the beneficial aspects of black solider fly larvae in a manure management system. In a typically dense, naturally occurring population these larvae totally eliminate house fly breeding and reduce the manure accumulation by half. Also, the soldier fly larvae can be used as an animal feedstuff containing 42% protein and 35% fat.
Our experimental house was designed to control the larvae (whose mass movements can cause problems), and to cause the mature larvae to self harvest for use as animal feed. This was accomplished with a 12″ deep concrete basin under each bank of cages. The basin wall towards the walkway was vertical and the wall towards the outside of the house was a 40 degree slope. A 6″ PVC pipe was fastened at the top of this slope. Migrating mature larvae, seeking a pupation site were captured as they entered a slit in the pipe. Once in this pipe they travelled until they exited the end and fell in a receptacle. This initial design worked so well it has not been modified. The walkway was kept free of manure and larvae and the self-collection system worked very well. A modification of the commonly used small tractor push out system worked very well to remove manure residue.
Collections of prepupae (mature larvae) were about 0.3 pounds per hen per month during the summer, or a total of 600 pounds from June to December. This would amount to 26,000 pounds for a modest sized caged layer house (20,000 hens) with a feed value of $1,900 or more.
House fly control was excellent. No house fly breeding could be detected during the summer. A very few adults were present and these were probably migrants. The few soldier fly adults noticed at any given time were ovipositing females, and these were never a nuisance.
The house fly control achieved with this system was better than could currently be achieved with Larvadex, which would have cost ca. $2,000 per annum for 20,000 hens.
Reduction in manure residue was estimated to reduce manure hauling costs $3,250, for this hypothetical 20,000 hen facility. Value of feedstuff, plus savings on fly control and manure hauling would be worth over $7,000 to this 20,000 hen operation, or 35 cents per bird. House fly control and reduction of environmental pollution are less easily valued, but are valuable contributions of this system.
Potential economic benefits to the caged layer industry are 36.8 cents per hen, which would be over $4 million annually to Georgia’s table egg producers, and proportionally more on a national scale. Environmental benefits near production areas would be much lower house fly numbers, and less abuse to nearby lands and watersheds through overapplication of manure. In some high egg production counties there is inadequate land area for spreading hen manure at the proper rates.
Similar economic and environmental benefits should be readily achievable in swine production systems. A study of this is underway.
(1) Determine manure pit design compatible with:
a. periodic manure removal with existing equipment;
b. self harvest of mature soldier fly larvae for feedstuff;
c. preventing larval access to walkways; and
d. shallow flooding for early season housefly control.
(2) Develop an effective low-energy storage systemf or the larval feedstuff.
(3) Determine the palatability of this larval feedstuff to swine.