Manure, By-products and Integrated Livestock Farming
Manure and its value
- Cattle dung contains roughly 0.5–0.6% N and urine about 1% N; FYM is dung, urine and bedding composted together.
- Nitrogen escapes as ammonia from exposed heaps, so cover the heap, add straw or ash, and compost before field use.
- Vermicompost and biogas slurry are better balanced than fresh dung; slurry can be applied directly to the field.
- Approximate gas yield: 1 kg fresh cattle dung gives about 0.04 m³ biogas containing roughly 60% methane.
By-products
Hide and skin to leather; bones to bone meal (calcium and phosphorus); blood to blood meal; horn and hoof to horn meal; fat to tallow; feathers to feather meal; gut to surgical sutures; offal to meat meal. Fallen animals must never enter the food chain.
Integrated systems
Crop–livestock, dairy + biogas + fish, poultry or duck over the pond (droppings fertilise the water and cut feed cost), rice–fish–duck, silvopasture, and azolla - a water fern with about 25% crude protein - as a cheap supplement for cattle and poultry.
Worked example
Five cows yielding 10 kg dung each give 50 kg dung a day. Gas = 50 × 0.04 = 2 m³ a day, enough for a family's cooking, and the spent slurry supplies much of the nitrogen for a small plot. Show the multiplication and interpret the result.
Traps
Fresh dung is not compost; biogas is not LPG (it is methane plus carbon dioxide); azolla is a fern, not a grain or cake; hides from fallen animals are a disease risk and are never sold as normal by-product.