Life-cycle assessment of animal feed ingredients: Poultry fat, poultry by-product meal and hydrolyzed feather meal

This study presents an environmental life cycle assessment of poultry fat (PF), poultry by-product meal (PBM) and steam hydrolyzed feather meal (HF). These ingredients are obtained by rendering poultry by-products and can be used as valuable feedstuffs for the fish feed industry, displacing traditional fishmeal and fish oil, promoting a circular economy system by reducing waste, adding value to by-products of the poultry production and reintroducing them in the economy as high-value products. A life cycle inventory and model were implemented for the PF, PBM and HF production chains based on data collected from two poultry by-product rendering units: the first producing both PF and PBM, and the second producing only HF. Four environmental impact categories were assessed using the CML life-cycle impact assessment method: global warming (GW), abiotic depletion (AD), acidification (AC) and eutrophication (EUT). The impacts calculated with economic allocation for 1 t of PF, 1 t of PBM and 1 t of HF from poultry by-products are 666, 726 and 597 kg CO₂ eq (GW); 3.8, 4.2 and 3.2 kg Sb eq (AD); 4.2, 4.6 and 4.7 kg SO₂ eq (AC); and 1.8, 2.0 and 2.1 kg PO₄ ³⁻ eq (EUT), respectively. The rendering process of by-products is mainly responsible for GW and AD (mainly due to process heat), while the poultry production is the main contributor for AC and EUT. In more detail, a sensitivity analysis of alternative multifunctionality procedures for dealing with poultry by-products was performed, showing that the selected allocation method has a huge influence on the life cycle impacts, with higher impacts when mass allocation is employed instead of economic allocation. Additionally, a sensitivity analysis was conducted on the type of energy used in the rendering process, and distances in poultry by-product transportation to the rendering plants. The results show that the fuel source for process heat or the electricity generation system has a significant influence on the impacts, while the transportation distance has much less.