Effects of housefly larvae meal and multi-enzyme-probiotic supplementation on performance, egg quality, and blood biochemistry in laying hens

• Housefly larvae meal (HFLM) at 10% improved feed efficiency without affecting egg production. • 15% HFLM + Rayabold enhanced eggshell quality and yolk height. • HFLM reduced glucose, cholesterol, triglycerides, AST, and ALP levels. • Elevated ALT at 15% HFLM + Rayabold suggests possible hepatic stress. • 10% HFLM is an effective and safe alternative protein source for layers. This study investigated the effects of dietary housefly larvae meal (HFLM) and Rayabold (multi-enzyme-probiotic supplement) on the performance, egg quality, and blood biochemistry of 192 Lohmann LSL-Lite laying hens at 56 weeks of age. A 10-week feeding trial was conducted using a 4 × 2 factorial design, with four HFLM inclusion levels (0, 5, 10, and 15%) and two Rayabold levels (0 and 0.05%). The inclusion of HFLM, with or without Rayabold, significantly reduced feed intake compared to the control; however, Rayabold partially offset this reduction at the 5% and 10% HFLM levels. Although feed intake was reduced, egg production remained unaffected, while egg weight increased notably in hens receiving 15% HFLM combined with Rayabold. Both 10% and 15% inclusion levels of HFLM improved feed conversion ratio, protein efficiency, and energy efficiency, with Rayabold further enhanced protein and energy utilization at the 15% inclusion level. Eggshell weight, thickness, and yolk height improved significantly in the 15% HFLM + Rayabold group. Metabolic responses included reduced blood glucose at 5% and 10% HFLM, and lower cholesterol at 10%. Furthermore, triglyceride levels declined with both HFLM and Rayabold supplementation. Aspartate aminotransferase activity decreased in the 10% and 15% HFLM groups, while alanine aminotransferase was highest in the 15% + Rayabold group, suggesting possible hepatic stress. Overall, 10% inclusion of HFLM, with or without Rayabold, offers a nutritionally effective and metabolically safe strategy to enhance laying hen productivity and physiological health, supporting its potential as a sustainable alternative protein source.