Pig manure, a waste or treasure
Pig farming stands as an indispensable pillar within the expansive world of meat production. Yet, beneath this thriving industry lies a pressing issue – the substantial waste generated in the form of pig manure. This issue isn’t limited to a single locale; it is a global concern, especially in regions where intensive pig farming reigns supreme.
According to a comprehensive investigation conducted by the esteemed Food and Agriculture Organization (FAO), the staggering statistics come to light: annually, pig production generates a colossal 1.4 billion tons of manure across the globe, accounting for a staggering 35% of the entire livestock-generated manure. This isn’t just a byproduct; it’s an environmental challenge of monumental proportions.
- Soil Contamination: Excessive manure can lead to nutrient overload in the soil, making it unproductive. Copper and Zinc are essential minerals in pig growth, continuous manure application to cropland and direct dumping may cause these metals to accumulate in soils, resulting in unessential and even toxic plant development.
- Water Pollution: Runoff from surplus manure can contaminate local water sources and put a threat on aquatic life and human health.
- Air Pollution: Ammonia (NH3) formation from manure can react with atmosphere inorganic acid to form ammonium salts, the main components of fine inhalable particles, PM2.5
- Climate change : Nitrous oxide (N20) from manure decay has a global warming potential 298 times higher than carbon dioxide. Methane (CH4) from manure storage contributes to climate change as well.
The time has come to revolutionise pig farming, not only as a vital sector of the meat industry but as an agent of positive change for our environment and public health.
More than 50% of the nutrients present in feed end up as manure. In natural ecosystems,this organic waste along with other decaying organic matter, is typically broken down by a diverse range of organisms. One such organism is the Black Soldier Fly (BSF) larvae, which possesses the ability to digest pig manure effectively. These larvae boast a high protein and fat content, making them a promising candidate for animal feed. Scientific studies conducted on animals have demonstrated that the protein quality of BSF larvae is comparable to that of fish meal, a critical component in animal feed formulations.
The Potential of BSF
The current state of marine resources reveals a concerning trend – the overexploitation of fish populations has led to a steady decline in the availability of fish meal. This diminishing supply is anticipated to result in further price hikes for this essential ingredient in animal diets.
Harnessing the potential of BSF larvae, reared on pig manure and subsequently integrated into animal feed, offers a promising solution to mitigate the environmental impact associated with pig farming. Additionally, this approach could alleviate the dependence on imported feeds, thereby reducing the strain on unsustainable protein sources like fishmeal and soybean meal.
BSF Performance on Pig manure
When examining the rearing performance on pig manure, it’s noteworthy that 10,000 4-day-old BSF larvae were fed with 7 kg of pig manure, resulting in a consumption rate of 0.7 g per larva. These larvae can reach a maximum weight of 150 mg per individual, with a crucial threshold of 95 mg required to proceed to pupal development. Impressively, 73% of the larvae survived to the prepupal stage when fed pig manure.
BSF Affinity for Pig Manure
BSF larvae have a natural affinity for pig manure. A preference experiment comparing BSF larvae’s choice between pig manure and other commercially used rearing diets (such as ProtiWanze, DB-Blend), clearly demonstrated their strong inclination towards pig manure. This finding provides the 1st evidence that BSF larvae express a distinct diet preference.
BSF vs Housefly
It is worth contrasting the behaviour of BSF with that of the housefly, another dipteran species known to feed on pig manure. Despite sharing a similar diet, houseflies are still considered pests. Housefly larvae primarily feed on bacteria, some of which can be harmful and persist into their subsequent life-stages. Consequently, adult house flies actively move around in search of food and breeding sites, increasing the risk of pathogen transmission among different substrates. In contrast, BSF larvae tend to be less active, do not approach or pose a threat to humans, and do not engage in feeding behaviour, thus reducing the likelihood of pathogen transfer.
Frass: BSF manure
Manure-fed BSF larvae leave a special byproduct, here referred to as frass. Frass comprises a combination of larval faeces, exoskeleton sheds, and manure leftover. Notably,frass contains chitin, a compound with potential anti-fungal properties. Exposing plants to chitin can stimulate the production of antifungal substances, such as chitinase, as a defence mechanism against fungal infections.
In summary, BSF larvae’s remarkable ability to digest pig manure, their preference for this substrate, and their environmentally friendly characteristics make them a promising solution for reducing the environmental impact of pig farming, alleviating the reliance on unsustainable feed sources, and potentially contributing to plant disease management through their unique byproduct, frass.