Effects of Fish Bone Meal Supplementation on Growth Performance, Blood Immunity, Intestinal Morphology, and Gut Microbiota in Laying Hens

The poultry industry relies heavily on soybean meal to feed egg-laying chickens, but its high cost and price instability necessitate the exploration of more affordable and reliable alternatives. Fish bone meal, a nutritious byproduct from fish processing, offers high-quality protein and essential minerals, making it a promising addition to poultry diets. In this study, 240 Hy-Line Brown laying hens (31 weeks old, average weight 1.90 ± 0.1 kg, egg laying 11 weeks) were randomly assigned to two dietary treatments for 12 weeks: one group received a regular diet, while the other was fed a diet containing 3% fish bone meal. Each treatment included 12 replicates with 10 hens per replicate, and all birds were maintained under identical environmental conditions using a completely randomized experimental design. The results showed that hens fed the fish bone meal diet produced more eggs (<i>p</i> < 0.05) and had heavier yolks (<i>p</i> < 0.05) compared to the control group. Furthermore, intestinal health indicators, including villus height and crypt depth, were significantly improved (<i>p</i> < 0.05), along with enhanced immune markers (<i>p</i> < 0.05) in the fish bone meal group. However, no significant differences were observed in other egg quality parameters or feed conversion efficiency between the two groups (<i>p</i> > 0.05). These findings demonstrate that fish bone meal can improve egg production, yolk quality, intestinal health, and immune function in laying hens.