Phytogenic feed additives as an approach to prevent fatty liver hemorrhagic syndrome in laying hens

Fatty liver hemorrhagic syndrome (FLHS) is a major concern in laying hen production, causing significant economic losses and animal welfare issues. This study aimed to comparatively evaluate the preventive effects of three functional feed additives—a multi-mix (MM), citrus pectin (CP), and phytogenic additives (PA)—in hens fed either a standard diet (SD) or a high-energy, low-protein challenge diet (CD) formulated to induce FLHS. A total of 384 Lohmann LSL-Lite hens (65 to 77 weeks of age) were randomly assigned in a 4 × 2 factorial design. Feeding the CD significantly reduced feed intake (FI), egg production (EP), egg weight (EW), and egg mass (EM) compared to the SD (P < 0.05). Significant diet × additive interactions were observed for all performance traits across all periods (P = 0.0001). MM supplementation notably restored FI and significantly improved EP and EM in CD-fed hens, while also yielding the highest EW among CD treatments (P < 0.05). CP improved feed conversion ratio (FCR) in the CD group (P = 0.0191), but reduced EW (P = 0.0237). Additives had minimal effect in hens fed the SD. For hematological parameters, significant diet × additive interactions were detected. MM significantly decreased aspartate aminotransferase (AST) activity (P = 0.0001), uric acid (UA) (P = 0.0049), and triglycerides (TG) (P = 0.0001), whereas it increased total protein (TP) (P = 0.0001) and high-density lipoprotein-cholesterol (HDL-c) (P = 0.0075) in CD-fed hens. Low-density lipoprotein-cholesterol (LDL-c) was significantly reduced in SD + CP and SD + MM groups (P = 0.0001). Hepatic lesion scores were markedly higher in CD-fed hens (P = 0.001); however, MM supplementation significantly reduced liver damage in this group. In conclusion, MM showed the most consistent protective effect against FLHS, improving performance, blood parameters, and liver health under dietary challenge.