Evaluation of housefly (Musca domestica) larvae meal and frass as alternative protein sources in late-phase laying hens: Effects on ileal digestibility and energy utilization.

The present study evaluated the effects of housefly (Musca domestica) larvae meal (HFLM) and housefly larvae plus frass (HFLF), with or without a commercial synbiotic-enzyme supplement, on apparent ileal nutrient digestibility and apparent ileal digestible energy (AIDE) in Lohmann LSL-Lite laying hens. Two 10-week feeding trials were conducted, each involving 192 hens at 56 weeks of age, using a 4 × 2 factorial design with four inclusion levels (0, 5, 10, and 15%) of HFLM or HFLF and two synbiotic-enzyme supplementation levels (0 and 0.05%). In Experiment 1, HFLM inclusion did not affect nutrient digestibility or AIDE (P > 0.05), and no HFLM × synbiotic-enzyme interactions were observed. Synbiotic-enzyme supplementation reduced ash digestibility by 24.1% (42.20 vs. 55.63%; P = 0.0312), whereas it increased nitrogen-free extract digestibility (NFE) by 37.1% (72.81 vs. 53.09%; P = 0.0099) and AIDE by 23.2% (2836.2 vs. 2301.5 kcal/kg; P = 0.0240). In Experiment 2, significant HFLF × synbiotic-enzyme interactions were detected for crude protein (CP), ether extract (EE), ash, NFE, and AIDE (P ≤ 0.0401). The 10% HFLF diet supplemented with 0.05% synbiotic-enzyme produced the highest CP (87.49%), EE (79.15%), ash (70.72%), and NFE (87.49%) digestibility values and AIDE (3402.29 kcal/kg), representing increases of 42.3%, 99.8%, 69.6%, 116.8%, and 96.1%, respectively, relative to the corresponding lowest observed values. The lowest CP, NFE, and AIDE values were observed with 5% HFLF without supplementation, whereas the lowest EE and ash digestibility occurred with 15% HFLF with and without supplementation, respectively. HFLF inclusion also affected crude fiber (P = 0.0100) and calcium (P = 0.0166) digestibility, which increased by 36.4% and 52.4%, respectively, at 10% HFLF compared with the control. Overall, under the conditions of the present study, HFLM inclusion up to 15% did not adversely affect apparent ileal nutrient digestibility or energy utilization. The responses to HFLF varied with synbiotic-enzyme supplementation, with 10% HFLF plus 0.05% supplementation showing favorable nutrient digestibility and energy utilization responses.